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HomeMy WebLinkAboutPR16-000503_HEX REPORT_KCTransmittal_05-11-2018_Final.pdfCritical Area Regulation
RMC 4-11-140 Definitions:
NATIVE GROWTH PROTECTION EASEMENT: A restrictive area where all native, predevelopment
vegetation shall not be disturbed or removed except for removal pursuant to an approved enhancement
program. The purpose of an easement is to protect steep slopes, slopes and/or riparian corridors.
King County Comment: Requirement of NGPE on the landscaped wet area (FNA: Wetland
“A”); does not fall within the Renton’s defined purpose of an NGPE. This area was
landscaped after being used for staging during several different previous projects at the
treatment plant and is outside of a riparian corridor and was not restored as project
mitigation.
RMC 4-3-050 G
3. Native Growth Protection Areas:
a. Required: A native growth protection area shall be instituted to protect a critical area from any
proposed development for a non-exempt activity as follows:
i. Protected slopes and their associated buffers.
ii. Very high landslide hazard areas and their associated buffers.
iii. Class F, Np, and Ns, as defined in subsection G7 of this Section, streams or lakes and
their associated buffers.
iv. Category I, II, III, or IV wetlands, as defined in subsection G9c of this Section, and their
associated buffers.
King County Comment: Category IV wetland Critical Areas shall institute Native Growth
Protection. The code does not specify that the protection shall be an NGPE. Furthermore,
the wetland would have to meet criteria as a regulated critical area and it does not.
Critical Area Regulation
Applicability
RMC 4-3-050.B.1
1. Lands to Which These Regulations Apply and Non-regulated Lands: The following critical areas are
regulated by this Section. Multiple development standards may apply to a site feature based upon
overlapping critical area(s) and/or critical area classifications:
a. Flood hazard areas.
b. Steep slopes (must have a minimum vertical rise of fifteen feet (15')), landslide hazards,
erosion hazards, seismic hazards, and/or coal mine hazards or on sites within fifty feet (50') of
steep slopes, landslide hazards, erosion hazards, seismic hazards, and/or coal mine hazards
classified under RMC 4-3-050G5a which are located on abutting or adjacent sites.
c. Habitat Conservation Areas.
d. Streams and Lakes. All applicable requirements of this Section apply to Class F, Np, and
Ns water bodies, as defined in subsection G7 of this Section or on sites within one hundred
feet (100') of Class F, Np, and Ns water bodies, except Type S water bodies, inventoried as
“Shorelines of the State,” are not subject to this Section, and are regulated in RMC 4-3-090,
Shoreline Master Program Regulations, and RMC 4-9-190, Shoreline Permits.
e. Wellhead Protection Areas.
f. Wetlands, Categories I, II, III, and IV or on sites within two hundred feet (200') of Category I,
II, III, and IV wetlands.
Critical Area Regulation
Wetlands created or restored as a part of a mitigation project are regulated wetlands.
Regulated wetlands do not include those artificial wetlands intentionally created from nonwetland
sites, including, but not limited to, irrigation and drainage ditches, grass-lined swales, canals, detention
facilities, wastewater treatment facilities, farm ponds, and landscape amenities, or those wetlands
created after July 1, 1990, that were unintentionally created as a result of the construction of a road,
street, or highway.
King County Comment: The landscaped wet area does meets criteria of a Category IV
wetland, it does not meet criteria as a regulated wetland. Regulated wetlands do not
include artificial wetlands created from landscape amenities.
Critical Area Regulation - Photos
Location of Landscaping and past construction at South Plant
1998 2000 2002
2005 2007 2009
2012 2013 2015 ~1998
Critical Area Regulation - Photos
1995 – Waterworks garden staging area
Critical Area Regulation - Photos
2004 - Cogeneration Project Staging Area
Essential Public Facility
WAC 365-196-550
Essential public facilities.
(3) Preclusion of essential public facilities.
(a) Cities and counties may not use their comprehensive plan or development
regulations to preclude the siting of essential public facilities. Comprehensive plan
provisions or development regulations preclude the siting of an essential public facility if
their combined effects would make the siting of an essential public facility impossible or
impracticable.
(i) Siting of an essential public facility is "impracticable" if it is incapable of being
performed or accomplished by the means employed or at command.
(ii) Impracticability may also include restrictive zoning; comprehensive plan policies
directing opposition to a regional decision; or the imposition of unreasonable conditions
or requirements.
(iii) Limitations on essential public facilities such as capacity limits; internal staffing
requirements; resident eligibility restrictions; internal security plan requirements; and
provisions to demonstrate need may be considered preclusive in some circumstances.
King County Comment: South Plant is an essential public facility. WAC 365-196-550,
prevents Cities from using development regulations from precluding the siting of essential
public utilities. In this case, the HEX Report decision requiring placement of a Native
Growth Protection Easement (defined as: A restrictive area where all native,
predevelopment vegetation shall not be disturbed or removed except for removal pursuant
to an approved enhancement program.) over this location on the South Plant site would
preclude the siting of expansion buildings and facilities necessary to provide a public
service. With such a restrictive condition on the land use, it would be impossible and
impractical to use this space for the future expansion needs of the site.
Essential Public Facility
Proposed future expansion configuration 1 – South Plant
~Location of NGPE
requirement.
Prevents future
digester 8.
Essential Public Facility
Proposed ultimate layout for full expansion configuration 1 – South Plant 1991 facility plan
~Location of NGPE
requirement. Prevents
future digester 8.
|
South Plant Biogas and Heat Systems Improvement i ESA / 150513
Wetland Assessment May 2018
TABLE OF CONTENTS
South Plant Biogas and Heat Systems Improvements Project
Page
1.0 PROJECT AUTHORIZATION AND SCOPE OF WORK ................................................... 1
2.0 EXECUTIVE SUMMARY ..................................................................................................... 1
3.0 PROJECT OVERVIEW ....................................................................................................... 1
3.1 Project Description ..................................................................................................... 1
3.2 Site Conditions ........................................................................................................... 2
4.0 METHODS ........................................................................................................................... 3
4.1 Review of Existing Information ................................................................................... 3
4.2 On-site Investigation ................................................................................................... 3
4.2.1 Determining the Presence of Wetlands and Delineating Wetland
Boundaries ................................................................................................... 3
4.2.3 Assessing Wetland Functions ........................................................................ 4
5.0 REVIEW OF EXISTING INFORMATION ............................................................................ 4
5.1 Soils Mapping ............................................................................................................. 4
5.2 Wetland Inventories .................................................................................................... 4
6.0 RESULTS ............................................................................................................................ 5
6.1 Wetland Delineation ................................................................................................... 5
6.1.1 Wetland B ....................................................................................................... 5
6.1.1 Landscaped Amenity “wet area” (previously identified as “Wetland
A”) ................................................................................................................. 6
7.0 REGULATORY REQUIREMENTS ..................................................................................... 7
7.1 Federal Regulatory Requirements ............................................................................. 8
7.2 State Regulatory Requirements ................................................................................. 8
7.3 Local Regulatory Requirements ................................................................................. 8
8.0 PROJECT IMPACTS ......................................................................................................... 10
8.1 Project Impacts Reviewed Under RMC 4-3-050 – Critical Areas Regulations ........ 10
8.2 Project Impacts Reviewed Under RMC 4-3-090 - Shoreline Master Program
Regulations ........................................................................................................... 11
9.0 CONCLUSIONs ................................................................................................................. 11
10.0 LIMITATIONS .................................................................................................................. 11
11.0 REFERENCES ................................................................................................................ 12
South Plant Biogas and Heat Systems Improvement ii ESA / 150513
Wetland Assessment May 2018
Appendices
A. Wetland Definition ........................................................................................................ A-1
B. Wetland Determination Data Sheets ............................................................................ B-1
C. Washington State Wetland Rating System and Rating Forms .................................... C-1
Figures and Photos
Figure 1. ................................................................................................................. Project Limits
Figure 2. ................................................................................................................... Vicinity Map
Figure 3. ......................................................................................................... Wetland Locations
Photos
Table of Contents
Page
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Wetland Assessment May 2018
Acronyms and Abbreviations
COR City of Renton
Ecology Washington State Department of Ecology
ESA Environmental Science Associates
GPS Global Positioning System
HERB Heat and Energy Recovery Building
HSSG high pressure scrubber sludge gas
iMap Interactive Mapping
NRCS Natural Resources Conservation Service
NWI National Wetlands Inventory
PHS Priority Habitats and Species
PSE Puget Sound Energy
South Plant South Treatment Plant
USFWS U.S. Fish and Wildlife Service
WDFW Washington Department of Fish and Wildlife
WRIA Water Resource Inventory Area
WTD King County Wastewater Treatment Division
South Plant Biogas and Heat Systems Improvement 1 ESA / 150513
Wetland Assessment May 2018
1.0 PROJECT AUTHORIZATION AND SCOPE OF
WORK
Environmental Science Associates (ESA) was retained by Brown and Caldwell, on behalf of King County
Wastewater Treatment Division (WTD), to conduct a critical areas review for the South Treatment Plant
Biogas and Heat Systems Improvements Project. At the request of WTD, ESA conducted wetland
determinations on the project site and delineated wetland boundaries north of the project site, and
prepared this technical report. This report is organized to meet the requirements of City of Renton
Critical Areas Ordinance (Renton Municipal Code [RMC] 4-3-050). ESA’s scope of work was limited to the
identification and delineation of wetlands within the project area and within 200 feet of the project area
as required by (RMC 4-3-050(B)(1)(f)). Other types of critical areas regulated by the City, such as
streams, critical aquifer recharge areas, geologically hazardous areas, and frequently flooded areas, are
not addressed in this report.
2.0 EXECUTIVE SUMMARY
Review of the existing information did not indicate the presence of any wetlands within the project area.
One wetland (Wetland B) was identified and delineated off-site to the north in the Waterworks Gardens
during the September 2017 site visit (Figure 3). This wetland meets the regulatory definition of wetland
under RMC 4-30-050.B.1. During the field investigation on November 2016, ESA also identified a small
landscaped area with shallow surface water and wetland tolerant plants at the southwest end of a
shallow swale south of the proposed building location. This feature was initially identified as “Wetland
A” in the January 2018 Wetland Assessment Report. After further investigation, including review of
historic aerial photos and discussions with King County Wastewater Treatment Division staff regarding
past South Treatment Plant activities, this area was determined not to meet the regulatory definition of
wetland under RMC .4-30-050.B.1. This report has been updated to describe this finding.
3.0 PROJECT OVERVIEW
3.1 Project Description
King County proposes to replace South Plant’s Biogas Upgrading System (BUS) and heating system to
improve the beneficial use of digester gas at South Plant while also reliably supplying heat to meet
process and space heating demands. The King County South Plant Biogas and Heating Systems Project
includes construction of a Heat and Energy Recovery Building (HERB), a new thermal oxidizer, heating
system improvements within the existing Digester Equipment Building, and utility connections.
The approximately 11,862 square foot (SF) HERB would be located in an area allocated for future plant
expansion to meet capacity needs and regulatory requirements, where spoils from previous South Plant
construction and expansion projects at the site were placed, forming a mound. The site slopes gradually
South Plant Biogas and Heat Systems Improvement 2 ESA / 150513
Wetland Assessment May 2018
to the east towards the existing Solids MCC building and is maintained lawn grass over the mounded
spoils. Previously placed spoils would be removed and the existing slope would be re-graded as part of
building construction. Spoils excavated for the HERB (approximately 11,000 CY) would be moved to a
separate spoils placement location on the South Plant site, located south of the HERB and the existing
digesters within an open lawn area. Spoils would be compacted and seeded and planted to match
existing grades and vegetation type.
The project would include installation of new thermal oxidizer equipment located outside on a new
concrete pad (approximately 2,437 SF) immediately south of the existing waste gas burners. The thermal
oxidizer will combust waste gas from the BUS. See Figure 1, Project Limits.
3.2 Site Conditions
The project is located at King County WTD’s South Plant, in an industrial area of the City of Renton at
1200 Monster Road SW. The project would occupy King County Parcel Numbers 2423049097 and
2423049006, which are located in the NE Quarter, Section 24, Township 23 North, Range 9 East. The
subject parcels have been previously developed for South Plant construction and related expansion
projects. The project site consists of maintained lawn grass on sloped terrain, created by fill from
previous expansion projects.
The entire site is located within Water Resource Inventory Area (WRIA) 9, the Green - Duwamish
Watershed and the Lower Green River Subwatershed (King County, 2017a). The Green and Black rivers
join the Duwamish River to the northwest of the South Plant. The Green River comes from the
southwest of the South Plant while the Black River starts at a large wetland complex to the north and
continues to the west and joins the Green River (Figure 2). Springbrook Creek flows along the east
perimeter of the plant site before joining the Black River to the north.
The proposed site for the HERB is currently a gently sloping area of maintained lawn grass that was filled
and graded as part of previous South Plant construction and expansion projects. A shallow swale is
located to the east and to the south of the proposed building location.
The site where the new thermal oxidizer would be constructed is currently a gravel area with adjacent
grass/lawn areas immediately south of the existing waste gas burners.
Immediately north of the South Plant is Waterworks Gardens, a King County WTD-owned 8-acre public
park. The gardens feature public use trails and constructed detention ponds and wetlands established to
treat stormwater runoff from South Plant. These stormwater facilities feed into a natural wetland
system that eventually outfalls through a culvert to Springbrook Creek.
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Wetland Assessment May 2018
4.0 METHODS
4.1 Review of Existing Information
ESA reviewed existing literature, maps, and other materials to identify wetlands in the study area. These
sources can only indicate the likelihood of the presence of wetlands; actual determinations must be
based on data obtained from field investigations. Key sources of information included the following:
Natural Resources Conservation Service (NRCS) soils mapping (2017).
National Wetlands Inventory (NWI) mapping (USFWS, 2017).
Washington Department of Fish and Wildlife (WDFW) Priority Habitats and Species (PHS) data
(2017).
King County Interactive Mapping (iMap) Tool (King County, 2017b).
City of Renton Critical Areas Map Series (City of Renton, 2017).
Washington Natural Heritage Program (WNHP) rare plant species and vegetation communities
mapping (WNHP, 2017).
4.2 On-site Investigation
4.2.1 Determining the Presence of Wetlands and Delineating Wetland
Boundaries
The characteristics of an area that result in its classification as “wetland” have been formally defined by
federal and state agencies, as described in Appendix A. Methods defined in Regional Supplements to the
U.S. Army Corps of Engineers 1987 Wetlands Delineation Manual were used to determine the presence
and extent of wetlands in the study area (Environmental Laboratory, 1987; Corps, 2010). The
Washington State Department of Ecology (Ecology) repealed Washington Administrative Code (WAC)
173-22-080 (the state wetland delineation manual) and replaced it with a revision of WAC 173-22-035
that states that delineations should be done according to the currently approved federal manual and
supplements (effective March 14, 2011).
The methodology outlined in the manual is based on three essential characteristics of wetlands: (1)
hydrophytic vegetation; (2) hydric soils; and (3) wetland hydrology. Field indicators of these three
characteristics must all be present in order to determine that an area is a wetland (unless problem areas
or atypical situations are encountered).
The “routine on-site determination method” was used to define the wetland boundaries at the project
site. The routine method is used for areas equal to or less than 5 acres in size, or for larger areas with
relatively homogeneous vegetative, soil, and hydrologic properties.
South Plant Biogas and Heat Systems Improvement 4 ESA / 150513
Wetland Assessment May 2018
Formal data plots were established, where information regarding each of the three wetland parameters
(vegetation, soils, and hydrology) was recorded. This information was used to distinguish wetlands from
non-wetlands. Wetland B, located off-site to the north, was investigated at a reconnaissance level, and
formal data plots were not established. The southern boundary of Wetland B was delineated with
sequentially numbered colored flagging imprinted with the words WETLAND DELINEATION. The
southern boundary of Wetland B is shown on Figure 33. Data plot locations were also marked with
colored flagging. Flagged points were recorded using a Global Positioning System (GPS) Trimble unit.
Wetland determination data forms are included in Appendix B.
4.2.3 Assessing Wetland Functions
Wetlands and buffers play important roles that provide valuable benefits to the environment and
society. Because detailed scientific knowledge of wetland functions is limited, evaluations of the
functions of individual wetlands are somewhat qualitative and dependent upon professional judgment.
For this project, wetland functions were assessed using Ecology’s Wetland Rating System for Western
Washington (Hruby, 2014). Although this system is designed to rate wetlands, it is based on whether a
particular wetland performs a particular function and the relative level to which the function is
performed. An assessment of wetland functions is inherent in the rating system. This system was
developed by Ecology to differentiate wetlands based on their sensitivity to disturbance, their
significance, their rarity, our ability to replace them, and the beneficial functions they provide to society.
Appendix C provides additional information about the rating system, wetland categories, and completed
rating forms for Wetland B.
5.0 REVIEW OF EXISTING INFORMATION
5.1 Soils Mapping
The NRCS maps soils within the site as Puyallup fine sandy loam. Puyallup fine sandy loam is not
considered a hydric soil type, although it has minor hydric inclusions. It is described as a well-drained
soil, typically found on terraces and floodplains. This soil forms in alluvium in areas with average annual
precipitation of 35 to 60 inches and mean annual temperature about 50 degrees Fahrenheit. Slopes are
typically 0 to 2 percent. Minor components in the soil include Briscott (hydric), Newberg (hydric),
Woodinville (hydric), Nooksack (nonhydric), and Oridia (hydric) (NRCS, 2017).
5.2 Wetland Inventories
Wetland maps prepared by the NWI do not indicate the presence of any on-site or off-site wetlands
within 200 feet of the project area. NWI mapping does show a riparian area associated with Springbrook
Creek, which is several hundred feet east of the project area (USFWS, 2017). The WDFW PHS database
does not identify any wetlands in the study area (WDFW, 2017).
South Plant Biogas and Heat Systems Improvement 5 ESA / 150513
Wetland Assessment May 2018
City of Renton (COR) Critical Areas Mapping (City of Renton, 2017) does not identify any wetlands on the
project site. COR mapping identifies a regulated shoreline associated with Springbrook Creek, east of the
study area. In addition, an off-site wetland is mapped north of the project area within Waterworks
Gardens.
No rare plant species or high-quality vegetation communities are mapped in the study area or vicinity
(WNHP, 2017).
6.0 RESULTS
To identify and delineate wetlands on the project site, ESA biologists conducted two field investigations.
The site was first visited by Claire Hoffman and Michael Muscari on November 22, 2016, and again by
Tobin Story and Michael Muscari on September 7, 2017. The following sections describe the results of
the two field visits.
6.1 Wetland Delineation
Review of the existing information did not indicate the presence of any wetlands within the project area.
On-site investigations also concluded that no wetlands occur within the project area. One wetland
(Wetland B) was identified and delineation off-site to the north in the Waterworks Gardens during the
September 2017 site visit (Figure 3). During the field investigation on November 2016, ESA also
identified a small area with shallow surface water and wetland tolerant plants at the southwest end of a
shallow swale south of the proposed building location.
Review of the existing information did not indicate the presence of any wetlands within the project area.
One wetland (Wetland B) was identified and delineated off-site to the north in the Waterworks Gardens
during the September 2017 site visit (Figure 3). This wetland was found to meet the regulatory definition
of wetland under RMC 4-30-050.B.1. During the field investigation on November 2016, ESA also
identified a small landscaped area with shallow surface water and wetland tolerant plants at the
southwest end of a shallow swale south of the proposed building location. This feature was previously
identified as “Wetland A” in the January 2018 Wetland Assessment Report. After further investigation,
including review of historic aerial photos and discussions with King County Wastewater Treatment
Division staff regarding past South Treatment Plant activities, this landscaped area was determined not
to meet the regulatory definition of wetland under RMC 4-30-050.B.1. Conditions in Wetland B and in
the landscaped wet area are described in detail below.
6.1.1 Wetland B
Overview. Wetland B consists of a series of depressions separated by a gravel pedestrian path, located
north of the South Plant fence. The wetland has a gentle slope to the east, toward Springbrook Creek.
Due to its offsite location, Wetland B was investigated at a reconnaissance level. Only the southern
boundary was delineated by ESA, and total wetland size was not estimated. Formal data plots were not
established for Wetland B. Confirmation of wetland presence and delineation of the wetland boundary
was based on the presence of obligate wetland vegetation, clearly visible hydrology indicators, and
South Plant Biogas and Heat Systems Improvement 6 ESA / 150513
Wetland Assessment May 2018
landscape topography. The wetland contains both palustrine emergent and palustrine forested
vegetation communities. The wetland appears to be an enhanced or modified wetland feature
associated with the constructed Waterworks Gardens, and only the south edge (nearest the property
boundary and proposed project) was delineated; the wetland continues further north. Flag locations
were surveyed using a handheld Trimble GPS unit. Photo 3 shows one of the seasonally ponded areas of
Wetland B that was dry during the September 2017 site visit.
Hydrology. The gravel path appears to be permeable and allows water exchange between depressions.
A portion of the wetland is a wide swale. Hydrology for the wetland appears to enter from stormwater
ponds to the west and north, and appears to exit through a 24-inch standpipe in the far eastern corner
of the wetland (Photo 4). Water exiting the wetland through the standpipe drains to Springbrook Creek.
Flow is unidirectional, as the standpipe elevation is approximately 15 feet higher than that of
Springbrook Creek. Water was not observed at the standpipe during the site visit, but clear signs of
prolonged inundation were observed in the vicinity. The wetland meets hydrology indicators B1, water
marks, and B8, sparsely vegetation concave surface.
Soils. Formal data plots were not established for Wetland B.
Vegetation. Two Cowardin vegetation classes were observed in Wetland B. Forested areas observed on
site consist of a forested overstory dominated by black cottonwood and red alder (Alnus rubra) with a
shrub understory of dogwood (Cornus alba), salmonberry (Rubus spectabilis), and Himalayan blackberry
(Rubus armeniacus). Vegetation in the palustrine emergent pockets consists primarily of cattail (Typha
latifolia), although other native emergent species may be present in small amounts.
Wetland Functions. Wetland B was rated as a depressional wetland. The wetland received an overall
score of 20 points, which corresponds to a Category II rating. The wetland received a moderate score for
water quality improvement functions (7 points); the wetland receives pollution inputs from several
sources and has significant vegetative cover necessary to filter pollutants. The water quality functions
provided by Wetland B have a high value to society, as Springbrook Creek, the Black River, and the
Green River are all on the Washington State 303d list for water quality. Wetland B received a high score
for hydrologic functions (8 points) due to a highly constricted outlet and significant depth of flooding
during wet periods. The hydrologic functions provided by Wetland B have a high value due to providing
flood attenuation for frequently flooded downstream reaches.
Wetland B received a moderate score (5 points) for habitat functions. The wetland has a diverse number
of habitats and hydroperiods, but lacks the landscape potential to support habitat since most of the
surrounding landscape is highly developed. The wetland buffer is generally disturbed.
6.1.1 Landscaped Amenity “wet area” (previously identified as
“Wetland A”)
The landscaped area that extends along the east and south sides of the HERB project site was
investigated with four data plots; locations for DP1, DP2, DP3, and DP4 are shown on Figure 3. At one of
the data plots (DP3) conditions met all three wetland parameters. Data sheets are included in Appendix
B. The wet area was estimated to be less than 2,000 square feet in size. Shallow surface water on highly
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Wetland Assessment May 2018
compacted soil was observed in November 2016 (Photo 6). Photo 7 shows the southwest end of the
constructed swale that appears to bring surface flows to this wet area.
Based on the young age of the trees and shrubs, and the constructed nature of the landscaped area, it
appears as though this area is only recently developing wetland characteristics due to past development
activities. The landscape in the project area has been reworked many times over at least the last 30
years and conditions are considerably different than the natural state. King County Wastewater
Treatment Division staff have indicated that this area was constructed as a landscape amenity following
a major project to upgrade South Treatment Plant’s secondary treatment. Review of aerial imagery
(Google Earth) shows that in 1990 this entire area was an open field (Photo 8). In the mid-1990s, this
area was used for heavy equipment staging during the plant’s secondary treatment upgrade (Photo 9).
An aerial image from 2002 shows relatively new landscaping including grading, construction of a
pathway, and planting of trees (Photo 10). Relatively current conditions are show in a 2017 aerial image
(Photo 11). This series of aerial photos shows that the landscape was altered in the past, including
stockpiling of spoils from other projects in the center of the field, use as staging area for construction,
and landscaping including construction of a walking path and planting of trees and shrubs. The shallow
swale flows south and then west along the edge of the field and terminates near the area we observed
shallow surface ponding in November.
RMC 4-30-050.B.1 exempts some artificially created wetlands from regulation.
Regulated wetlands do not include those artificial wetlands intentionally created from
nonwetland sites, including, but not limited to, irrigation and drainage ditches, grass-lined
swales, canals, detention facilities, wastewater treatment facilities, farm ponds, and landscape
amenities, or those wetlands created after July 1, 1990, that were unintentionally created as a
result of the construction of a road, street, or highway.
It is our conclusion that the area near DP3 containing wetland conditions is not a regulated wetland by
City of Renton Municipal Code 4-30-050.B.1.
The area around DP3 was created as a landscape amenity for the wastewater treatment facility in a
location that is poorly drained due to previous soil compaction. Plants tolerant to poorly drained
conditions were installed during landscaping. The landscape amenity appears to have been created in an
area that was not previously wetland, based on our site observations and the aerial imagery discussed
above. Water from this area does not flow out into the roadway to the west. Water ponds on the
compacted soil and remains in the area until evaporated or transpired by plants, causing wetland
conditions to develop in this artificially created feature. This wet area is isolated from any downslope
wetlands and streams.
7.0 REGULATORY REQUIREMENTS
This section provides an overview of regulations that may apply to the South Plant Biogas Project.
Before approving a project that will impact wetlands, agencies require project applicants to document
South Plant Biogas and Heat Systems Improvement 8 ESA / 150513
Wetland Assessment May 2018
that impacts have been avoided and minimized in accordance with the following preferred sequence for
mitigation (e.g., WAC 197-11-768):
a) Avoiding the impact altogether by not taking a certain action or parts of actions;
b) Minimizing impacts by limiting the degree or magnitude of the action;
c) Rectifying the impact by repairing, rehabilitating, or restoring the affected environment;
d) Reducing or eliminating the impact over time by preservation and maintenance operations
during the life of the action; or
e) Compensating for the impact by replacing, enhancing, or providing substitute resources or
environments.
Applicants for permits to alter wetlands or their buffers must demonstrate that the above sequence has
been followed to the greatest extent possible. Wetland impacts that cannot be avoided through the first
two steps of the above sequence will require compensatory mitigation.
7.1 Federal Regulatory Requirements
The U.S. Army Corps of Engineers regulates discharges of dredged or fill materials into waters of the
United States, including wetlands and streams, under Section 404 of the Clean Water Act. The South
Plant Biogas Project does not propose fill or other impacts to wetlands or waters of the U.S. As such, a
Section 404 permit is not anticipated.
7.2 State Regulatory Requirements
State permitting for activities in wetlands is administered by Ecology. The state certification process
under Section 401 of the federal Clean Water Act is usually triggered through a Section 404 permit
application. The South Plant Biogas Project does not propose fill or other impacts to wetlands or waters
of the U.S., and a Section 404 permit is not anticipated. As such, a Section 401 permit is not anticipated.
7.3 Local Regulatory Requirements
The City of Renton regulates critical areas and associated buffers through RMC 4-3-050, which requires
that wetlands be rated using the Washington State Wetland Rating System for Western Washington
2014 update (RMC 4-3-050(G)(9)(c)). Using the 2014 Wetland Rating System, Wetland is classified as a
Category II wetland with moderate habitat function (5 points). Wetland B requires a standard buffer
width of 150 feet (RMC 4-30-050(G)(2)).
In addition, RMC 4-3-050(G)(9)(d)(iv) requires applicants to document that increased wetland buffers
are not warranted. Increased buffer widths may be required if:
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a) The wetland is used by species listed by the federal or the state government as threatened,
endangered, and sensitive species and state-listed priority species, essential habitat for those
species or has unusual nesting or resting sites such as heron rookeries or raptor nesting trees or
evidence thereof; or
b) The buffer or adjacent uplands have a slope greater than 15 percent or is susceptible to erosion
and standard erosion control measures will not effectively prevent adverse wetland impacts.
c) The area is very fragile, or when a larger buffer is necessary to protect wetland functions and
values.
To the extent of our knowledge, Wetland B is not utilized by federal or state-listed species, nor does it
provide essential habitat for those species. Although the far eastern portion of the wetland is relatively
close to Springbrook Creek, it is physically disconnected from the creek, separated by approximately 15
feet vertically and 150 feet horizontally. The elevation difference precludes water from Springbrook
Creek entering the wetland, and thus there is no apparent connection for listed salmonids to access
habitat in Wetland B. A portion of the Wetland B buffer is located on slopes greater than 15 percent;
however, these slopes are heavily vegetated, and no clearing, grading, or other impact is proposed on
these slopes. Neither the wetland nor its buffer are especially fragile, and functions and values provided
by this wetland are adequately protected by the standard width buffer.
South Plant Biogas and Heat Systems Improvement 10 ESA / 150513
Wetland Assessment May 2018
8.0 PROJECT IMPACTS
8.1 Project Impacts Reviewed Under RMC 4-3-050 – Critical
Areas Regulations
As found in RMC 4-3-050(B)(1)(g), the City of Renton may not regulate certain upland sites separated
from critical areas, based on the following conditions: sites are separated from critical areas by pre-
existing, intervening, and lawfully created structures, roads, or other substantial existing improvements,
which must:
a) Separate the upland property from the critical area due to their height or width; and
b) Substantially prevent or impair delivery of most functions from the subject upland property to
the critical area.
In the case of this project, the north plant road separates Wetland B from all project areas. The north
plant road is approximately 20 feet wide, constructed of impervious material, with raised curbs
approximately 6 inches in height (Photo 5). In addition, an approximately 8-foot wide paved path is
located adjacent to road. The substantive width of the existing, impervious road, combined with the
width of an existing paved trail and presence of vertical curb will serve as an effective barrier. These
completely restrict and redirect the flow of ground and surface water, and otherwise impair delivery of
functions from upland sites located within the project area to Wetland B. Stormwater from the plant
road is collected and directed to the Waterworks Gardens located north of the plant. Current buffer
functions performed by the buffer area north of the existing plant road will not be altered by proposed
project actions.
South Plant Biogas and Heat Systems Improvement 11 ESA / 150513
Wetland Assessment May 2018
8.2 Project Impacts Reviewed Under RMC 4-3-090 -
Shoreline Master Program Regulations
Wetland B is physically disconnected from Springbrook Creek and is not within the 100-year floodplain
of Springbrook Creek, and, therefore, would not be considered an associated shoreline of Springbrook
Creek. However, if the City of Renton determines that the wetland is regulated as a shoreline, RMC 4-3-
090(D)(2)(d)(iv)(a) states that “Buffers shall not include areas that are functionally and effectively
disconnected from the wetland by a permanent road or other substantially developed surface of
sufficient width and with use characteristics such that buffer functions are not provided and that cannot
be feasibly removed, relocated, or restored to provide buffer functions.” As described above, the buffer
of Wetland B is separated by the intervening plant road and trail. The delivery of buffer functions from
the subject upland site to Wetland B is prevented by these intervening improvements. As a result,
shoreline jurisdiction would end at the north edge of the plant road and would not extend onto the
project site.
9.0 CONCLUSIONS
No wetlands were identified within the project area and one wetland was identified and delineated
within 200 feet of the project area. Wetland B is north of the project site and its regulated buffer does
not overlap the project site. Wetland B is a Category II wetland that requires a buffer of 150 feet for
high-impact land uses. The proposed project has been designed to avoid impacts to wetland areas and
associated buffers. No impacts are proposed to wetlands or wetland buffers as a result of this project.
No fill will be placed in wetlands or other waters of the U.S.
10.0 LIMITATIONS
Within the limitations of schedule, budget, scope-of-work, and seasonal constraints, we warrant that
this study was conducted in accordance with generally accepted environmental science practices,
including the technical guidelines and criteria in effect at the time this study was performed, as outlined
in the Methods section. The results and conclusions of this report represent the authors’ best
professional judgment, based on information provided by the project proponent in addition to that
obtained during the course of this study. No other warranty, expressed or implied, is made.
South Plant Biogas and Heat Systems Improvement 12 ESA / 150513
Wetland Assessment May 2018
11.0 REFERENCES
City of Renton. 2017. Online Mapping Portal. Available:
http://rp.rentonwa.gov/Html5Public/Index.html?viewer=CORMaps.
Corps (U.S. Army Corps of Engineers). 2005. Regulatory Guidance Letter No. 05-05: Ordinary High Water
Mark Identification. December 7, 2005.
Corps (U.S. Army Corps of Engineers). 2010. Regional Supplement to the Corps of Engineers Wetland
Delineation Manual: Western Mountains, Valleys, and Coast Region. Version 2. Wetlands
Regulatory Assistance Program. May 2010. ERDC/EL TR-10-3. Available:
https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1046494.pdf.
Corps (U.S. Army Corps of Engineers). 2014. 2014 NWPL Home v3.2 - Home Page, National Wetland
Plant List. Available: http://rsgisias.crrel.usace.army.mil/NWPL/.Environmental Laboratory. 1987.
Corps of Engineers Wetlands Delineation Manual. Technical Report Y-87-1. U.S. Army Engineer
Waterways Experiment Station, Vicksburg, Mississippi.
Hruby, T. 2014. Washington State Wetland Rating System for Western Washington – Revised. October
2014. Ecology publication number 14-06-029. Olympia, WA.
King County. 2017a. Map of WRIA 9. Green/Duwamish and Central Puget Sound Watershed. Available:
http://www.govlink.org/watersheds/9/. Accessed November 2017.
King County. 2017b. King County iMap, Interactive Mapping Tool. Available at:
http://www.kingcounty.gov/services/gis/Maps/imap.aspx. Accessed November 2017.Munsell Color.
2000. Munsell Soil Color Charts. GretagMacbeth, New Windsor, New York.
NRCS (Natural Resources Conservation Service). 1995. Hydric Soils List for Washington. Revised
December 15, 1995.NRCS (Natural Resources Conservation Service). 2010. Field Indicators of
Hydric Soils in the United States - A Guide for Identifying and Delineating Hydric Soils. Version 7.0,
2010. ftp://ftp-fc.sc.egov.usda.gov/NSSC/Hydric_Soils/FieldIndicators_v7.pdf.
NCRS (Natural Resources Conservation Service). 2017. Online soils mapping. Available:
http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.
USFWS (U.S. Fish and Wildlife Service). 2017. National Wetlands Inventory – online wetlands mapping.
Available: http://www.fws.gov/wetlands/Data/Mapper.html.
Vepraskas, M.J. 1999. Redoximorphic Features for Identifying Aquic Conditions. Technical Bulletin 301.
North Carolina Agricultural Research Service, North Carolina State University, Raleigh, North
Carolina.
WDFW (Washington Department of Fish and Wildlife). 2017. Priority habitats and species online
mapping. Available: http://wdfw.wa.gov/mapping/phs/.
WNHP (Washington Natural Heritage Program). 2017. Rare plant species and vegetation communities
GIS mapping.
South Plant Biogas and Heat Systems Improvement 13 ESA / 150513
Wetland Assessment May 2018
FIGURES AND PHOTOGRAPHS
EXISTING SPOILS TO BE
REMOVED
FIGURE 1 - PROJECT LIMITS
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King County SouthTreatment Plant
Project Site
B la c k R iv e r
DuwamishRiver
GreenRiverWaterworks Gardens
Spr
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ookCr
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k
61stAveSSW 27th St
MartinLutherKing Jun i o r W a y S
S 143rd St
Baker Blvd
Tukwila Parkway
RentonAveS
Andover Park WS 133rd St
Andover Park ESWSunset Blvd
MonsterRdSWS 132nd St
Southcenter Blvd
SW 7th St
Strander Blvd
S Langston Rd
SW 16th St
LindAveSWI
n
t
e
r
u
r
b
a
n
Av
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SSW Grady
Way
OakesdaleAveSW6
8
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S
W Valley RdPath: U:\GIS\GIS\Projects\15xxxx\D150513_SouthPlantBioGas\03_MXDs_Projects\Fig01_Vicinity.mxd, anakae 1/11/2017SOURCE: City of Renton 2015; OSM 2015; ESA 2017
0 2,000
Feet
South Plant Biogas and Heat Systems Improvements Figure 2
Vicinity Map
N
Project Site
Wetland B
Heating and Energy Recovery Building
Thermal Oxidizer $$$$150-ft. Wetland Buffer
buffer ends at r
o
a
d
e
d
g
e
$$Plant Road
12812
5
1
2
6 130129126128
127
DP-2
DP-1
DP-4
DP-3
Path: U:\GIS\GIS\Projects\15xxxx\D150513_SouthPlantBioGas\03_MXDs_Projects\Fig3_Wetlands_PDF.mxd, cstruthers 4/25/2018SOURCE: NAIP 2015 South Treatment Plant Biogas and Heat Systems Improvements Project
Figure 3Wetland Delineation
N 0 200
Feet
Wetland Survey Points
Wetland
Grading Contours
Project Area
150-ft. Wetland Buffer
Study Area
Photo 1. Proposed Thermal Oxidizer Site (November 2016).
Photo 2. Proposed HERB construction site to the right.
Northeast end of constructed swale in foreground (November 2016).
Photo 3. One of the seasonally ponded areas of Wetland B, off-site to the north
(September 2017).
Photo 4. Outlet to Wetland B (September 2017).
Photo 5. Looking west along Plant Road just north of the proposed HERB site. Wetland B
is off-site to the right of photo (November 2016).
Photo 6. Shallow ponding on compacted soil near DP3 (November 2016).
Photo 7. Looking east at southwest end of constructed swale near DP4 (November 2016).
Photo 8. Aerial image from 1990 showing proposed project area was open field.
Photo 9. Aerial image from mid-1990 during South Treatment Plant’s upgrade to
secondary treatment.
Photo 10. Aerial image from 2002 showing new landscaping.
Photo 11. Aerial image from 2017 showing approximate existing site conditions.
South Plant Biogas and Heat Systems Improvement A-1 ESA / 150513
Wetland Assessment May 2018
APPENDIX A: WETLAND DEFINITION AND METHODOLOGY
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Wetland Assessment May 2018
Wetland Definition
Wetlands are formally defined by the U.S. Army Corps of Engineers (Corps) (Federal Register 1982), the
Environmental Protection Agency (EPA) (Federal Register 1988), the Washington Shoreline Management
Act (SMA) of 1971 and the Washington State Growth Management Act (GMA) as follows:
… those areas that are inundated or saturated by surface or groundwater at a
frequency and duration sufficient to support, and that under normal
circumstances do support, a prevalence of vegetation typically adapted for life
in saturated soil conditions. Wetlands generally include swamps, marshes,
bogs, and similar areas (Federal Register, 1982, 1986).
In addition, the SMA and the GMA definitions add:
Wetlands do not include those artificial wetlands intentionally created from
non-wetland site, including, but not limited to, irrigation and drainage ditches,
grass-lined swales, canals, detention facilities, wastewater treatment facilities,
farm ponds, and landscape amenities, or those wetlands created after July 1,
1990 that were unintentionally created as a result of the construction of a
road, street, or highway. Wetlands may include those artificially created
wetlands intentionally created from non-wetland areas to mitigate the
conversion of wetlands.
Methods defined in the Western Mountains, Valleys, and Coast Regional Supplement (Corps, 2010) to
the U.S. Army Corps of Engineers 1987 Wetlands Delineation Manual (Manual) were used to determine
the presence and extent of wetlands on the subject property and within 200 feet. These methods are
consistent with state requirements in WAC 173-22-035.
The methodology outlined in the manuals is based upon three essential characteristics of wetlands: (1)
hydrophytic vegetation; (2) hydric soils; and (3) wetland hydrology. Field indicators of these three
characteristics must all be present in order to determine that an area is a wetland (unless problem areas
or atypical situations are encountered). These characteristics are discussed below.
Vegetation
Plants must be specially adapted for life under saturated or anaerobic conditions to grow in wetlands.
The Corps of Engineers has determined the estimated probability of each plant species’ occurrence in
wetlands and has accordingly assigned a “wetland indicator status” (WIS) to each species (Corps, 2016).
Plants are categorized as obligate (OBL), facultative wetland (FACW), facultative (FAC), facultative
upland (FACU), upland (UPL), not listed (NL), or no indicator status (NI). Definitions for each indicator
status are listed below. Species with an indicator status of OBL, FACW, or FAC are considered adapted
for life in saturated or anaerobic soil conditions. Such species are referred to as “hydrophytic”
vegetation.
Key to Wetland Indicator Status codes:
OBL Obligate: species that almost always occur wetlands under natural conditions (est. probability
>99%).
South Plant Biogas & Heat Systems Improvement A-4 ESA / 150513
Wetland Assessment May 2018
FACW Facultative wetland: species that usually occur in wetlands (est. probability 67 to 99%), but are
occasionally found in non-wetlands.
FAC Facultative: Species that are equally likely to occur in wetlands or non-wetlands (est. probability
34 to 66%).
FACU Facultative upland: species that usually occur in non-wetlands (est. probability 67 to 99%), but
are occasionally found in wetlands.
UPL Upland: species that almost always occur in non-wetlands under normal conditions (est.
probability >99%).
NL Not listed: species that are not listed by USFWS (1988, 1993) and are presumed to be upland
species.
NI No indicator: species for which insufficient information is available to determine status, or which
were not evaluated by USFWS.
Areas of relatively homogeneous vegetative composition can be characterized by “dominant” species.
The indicator status of the dominant species within each vegetative stratum is used to determine if the
plant community may be characterized as hydrophytic. The vegetation of an area is considered to be
hydrophytic if more than 50% of the dominant species have an indicator status of OBL, FACW, or FAC.
The Regional Supplements provide additional tests for evaluating the presence of hydrophytic
vegetation communities including the prevalence index, morphological adaptations, and wetland non-
vascular plants. The Supplements also address difficult situations where hydrophytic vegetation
indicators are not present but hydric soils and wetland hydrology are observed.
Soils
Hydric soils are indicative of wetlands. Hydric soils are defined as soils that are saturated, flooded, or
ponded long enough during the growing season to develop anaerobic conditions in the upper part of the
soil profile (Federal Register, 1994). The Natural Resources Conservation Service (NRCS), in cooperation
with the National Technical Committee for Hydric Soils, has compiled lists of hydric soils (NRCS, 1995).
These lists identify soil series mapped by the NRCS that meet hydric soil criteria. It is common, however,
for a map unit of non-wetland (non-hydric) soil to have inclusions of hydric soil, and vice versa.
Therefore, field examination of soil conditions is important to determine if hydric soil conditions exist.
The NRCS has developed a guide for identifying field indicators of hydric soils (NRCS, 2010). This list of
hydric soil indicators is considered to be dynamic; revisions are anticipated to occur on a regular basis as
a result of ongoing studies of hydric soils. In general, anaerobic conditions create certain characteristics
in hydric soils, collectively known as “redoximorphic features,” that can be observed in the field
(Vepraskas, 1999). Redoximorphic features include high organic content, accumulation of sulfidic
material (rotten egg odor), greenish- or bluish-gray color (gley formation), spots or blotches of different
color interspersed with the dominant or matrix color (mottling), and dark soil colors (low soil chroma)
(NRCS, 2010; Vepraskas, 1999). Soil colors are described both by common color name (for example,
“dark brown”) and by a numerical description of their hue, value, and chroma (for example, 10YR 2/2) as
South Plant Biogas & Heat Systems Improvement A-5 ESA / 150513
Wetland Assessment May 2018
identified on a Munsell soil color chart (Munsell Color, 2000). Soil color is determined from a moist soil
sample.
The Regional Supplements provide methods for difficult situations where hydric soil indicators are not
observed, but indicators of hydrophytic vegetation and wetland hydrology are present.
Hydrology
Water must be present in order for wetlands to exist; however, it need not be present throughout the
entire year. Wetland hydrology is considered to be present when there is permanent or periodic
inundation or soil saturation at or near the soil surface for more than 14 consecutive days during the
growing season at a minimum frequency of 5 years in 10 (Corps, 2010).
Indicators of wetland hydrology include observation of ponding or soil saturation, water marks, drift
lines, drainage patterns, sediment deposits, oxidized rhizospheres, water-stained leaves, and local soil
survey data. Where positive indicators of wetland hydrology are observed, it is assumed that wetland
hydrology occurs for a sufficient period of the growing season to meet the wetland criteria, as described
by Corps (2010). The Regional Supplements provide methods for evaluating situations in wetlands that
periodically lack indicators of wetland hydrology but where hydric soils and hydrophytic vegetation are
present.
South Plant Biogas Heat Systems Improvement B-1 ESA / 150513
Wetland Assessment May 2018
APPENDIX B: WETLAND DETERMINATION DATA SHEETS
South Plant Biogas Heat Systems Improvement C-1 ESA / 150513
Wetland Assessment May 2018
APPENDIX C: WASHINGTON STATE WETLAND RATING
SYSTEM AND RATING FORMS
South Plant Biogas Heat Systems Improvement C-1 ESA / 150513
Wetland Assessment May 2018
Washington State Wetland Rating System
The observed wetlands were rated using the Washington State Department of Ecology’s Wetland Rating
System for Western Washington (Hruby, 2014). This system was developed by Ecology to differentiate
wetlands based on their sensitivity to disturbance, their significance, their rarity, our ability to replace
them, and the beneficial functions they provide to society. Wetlands are categorized using the Ecology
rating system according to the following criteria:
Category I wetlands represent a unique or rare wetland type; or are more sensitive to disturbance; or
are relatively undisturbed and contain ecological attributes that are impossible to replace within a
human lifetime.
Category II wetlands are difficult, though not impossible, to replace, and provide high levels of some
functions.
Category III wetlands have a moderate level of function. They have been disturbed in some ways, and
are often less diverse or more isolated from other natural resources in the landscape than Category II
wetlands.
Category IV wetlands have the lowest levels of functions and are often heavily disturbed.
Wetland name or number Wetland B
Name of wetland (or ID #):Date of site visit:9/7/2017
Rated by Trained by Ecology? Yes No Date of training Mar-15
HGM Class used for rating Wetland has multiple HGM classes? Yes No
NOTE: Form is not complete with out the figures requested (figures can be combined ).
Source of base aerial photo/map
OVERALL WETLAND CATEGORY II (based on functions or special characteristics )
1. Category of wetland based on FUNCTIONS
Category I - Total score = 23 - 27 Score for each
X Category II - Total score = 20 - 22 function based
Category III - Total score = 16 - 19 on three
Category IV - Total score = 9 - 15 ratings
(order of ratings
is not
important )
M M 9 = H, H, H
H L 8 = H, H, M
H M Total 7 = H, H, L
7 = H, M, M
6 = H, M, L
6 = M, M, M
5 = H, L, L
5 = M, M, L
4 = M, L, L
3 = L, L, L
2. Category based on SPECIAL CHARACTERISTICS of wetland
None of the above
Coastal Lagoon
Interdunal
Value
Score Based on
Ratings 7 8 5 20
H
CHARACTERISTIC Category
Estuarine
Wetland of High Conservation Value
Bog
Mature Forest
Old Growth Forest
Depressional & Flats
RATING SUMMARY – Western Washington
List appropriate rating (H, M, L)
HydrologicImproving
Water Quality
MSite Potential
Landscape Potential
Habitat
M
FUNCTION
Biogas Wetland B
T. Story
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 1 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
Maps and Figures required to answer questions correctly for
Western Washington
Depressional Wetlands
Map of: Figure #
Cowardin plant classes
Hydroperiods
Location of outlet (can be added to map of hydroperiods )
Boundary of area within 150 ft of the wetland (can be added to another figure )
Map of the contributing basin
1 km Polygon: Area that extends 1 km from entire wetland edge - including
polygons for accessible habitat and undisturbed habitat
Screen capture of map of 303(d) listed waters in basin (from Ecology website)
Screen capture of list of TMDLs for WRIA in which unit is found (from web)
Riverine Wetlands
Map of: Figure #
Cowardin plant classes
Hydroperiods
Ponded depressions
Boundary of area within 150 ft of the wetland (can be added to another figure )
Plant cover of trees, shrubs, and herbaceous plants
Width of unit vs. width of stream (can be added to another figure )
Map of the contributing basin
1 km Polygon: Area that extends 1 km from entire wetland edge - including
polygons for accessible habitat and undisturbed habitat
Screen capture of map of 303(d) listed waters in basin (from Ecology website)
Screen capture of list of TMDLs for WRIA in which unit is found (from web)
Lake Fringe Wetlands
Map of: Figure #
Cowardin plant classes
Plant cover of trees, shrubs, and herbaceous plants
Boundary of area within 150 ft of the wetland (can be added to another figure )
1 km Polygon: Area that extends 1 km from entire wetland edge - including
polygons for accessible habitat and undisturbed habitat
Screen capture of map of 303(d) listed waters in basin (from Ecology website)
Screen capture of list of TMDLs for WRIA in which unit is found (from web)
Slope Wetlands
Map of: Figure #
Cowardin plant classes
Hydroperiods
Plant cover of dense trees, shrubs, and herbaceous plants
Plant cover of dense, rigid trees, shrubs, and herbaceous plants
(can be added to another figure )
Boundary of area within 150 ft of the wetland (can be added to another figure )
1 km Polygon: Area that extends 1 km from entire wetland edge - including
polygons for accessible habitat and undisturbed habitat
Screen capture of map of 303(d) listed waters in basin (from Ecology website)
Screen capture of list of TMDLs for WRIA in which unit is found (from web)
To answer questions:
D 1.3, H 1.1, H 1.4
D 1.4, H 1.2
D 1.1, D 4.1
D 2.2, D 5.2
D 4.3, D 5.3
H 2.1, H 2.2, H 2.3
D 3.1, D 3.2
D 3.3
To answer questions:
H 1.1, H 1.4
H 1.2
R 1.1
R 2.4
R 1.2, R 4.2
R 4.1
R 2.2, R 2.3, R 5.2
H 2.1, H 2.2, H 2.3
L 1.2
L 2.2
L 3.1, L 3.2
L 3.3
H 2.1, H 2.2, H 2.3
R 3.1
R 3.2, R 3.3
To answer questions:
L 1.1, L 4.1, H 1.1, H 1.4
S 3.1, S 3.2
S 3.3
S 4.1
S 2.1, S 5.1
To answer questions:
H 1.1, H 1.4
H 1.2
S 1.3
H 2.1, H 2.2, H 2.3
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 2 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
For questions 1 -7, the criteria described must apply to the entire unit being rated.
1. Are the water levels in the entire unit usually controlled by tides except during floods?
NO - go to 2 YES - the wetland class is Tidal Fringe - go to 1.1
1.1 Is the salinity of the water during periods of annual low flow below 0.5 ppt (parts per thousand)?
NO - Saltwater Tidal Fringe (Estuarine)YES - Freshwater Tidal Fringe
NO - go to 3 YES - The wetland class is Flats
If your wetland can be classified as a Flats wetland, use the form for Depressional wetlands.
3. Does the entire wetland unit meet all of the following criteria?
NO - go to 4 YES - The wetland class is Lake Fringe (Lacustrine Fringe)
4. Does the entire wetland unit meet all of the following criteria?
The wetland is on a slope (slope can be very gradual ),
The water leaves the wetland without being impounded.
NO - go to 5 YES - The wetland class is Slope
5. Does the entire wetland unit meet all of the following criteria?
The overbank flooding occurs at least once every 2 years.
NO - go to 6 YES - The wetland class is Riverine
NOTE: The Riverine unit can contain depressions that are filled with water when the river is not flooding.
If hydrologic criteria listed in each question do not apply to the entire unit being rated, you probably have a unit
with multiple HGM classes. In this case, identify which hydrologic criteria in questions 1 - 7 apply, and go to
Question 8.
At least 30% of the open water area is deeper than 6.6 ft (2 m).
HGM Classification of Wetland in Western Washington
If your wetland can be classified as a Freshwater Tidal Fringe use the forms for Riverine wetlands.
If it is Saltwater Tidal Fringe it is an Estuarine wetland and is not scored. This method cannot be
used to score functions for estuarine wetlands.
The vegetated part of the wetland is on the shores of a body of permanent open water (without any
plants on the surface at any time of the year) at least 20 ac (8 ha) in size;
The water flows through the wetland in one direction (unidirectional) and usually comes from seeps.
It may flow subsurface, as sheetflow, or in a swale without distinct banks.
NOTE: Surface water does not pond in these type of wetlands except occasionally in very small and shallow
depressions or behind hummocks (depressions are usually <3 ft diameter and less than 1 ft deep).
The unit is in a valley, or stream channel, where it gets inundated by overbank flooding
from that stream or river,
2. The entire wetland unit is flat and precipitation is the only source (>90%) of water to it.
Groundwater and surface water runoff are NOT sources of water to the unit.
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 3 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
NO - go to 7 YES - The wetland class is Depressional
NO - go to 8 YES - The wetland class is Depressional
NOTES and FIELD OBSERVATIONS:
7. Is the entire wetland unit located in a very flat area with no obvious depression and no overbank flooding?
The unit does not pond surface water more than a few inches. The unit seems to be maintained by high
groundwater in the area. The wetland may be ditched, but has no obvious natural outlet.
8. Your wetland unit seems to be difficult to classify and probably contains several different HGM classes. For
example, seeps at the base of a slope may grade into a riverine floodplain, or a small stream within a
Depressional wetland has a zone of flooding along its sides. GO BACK AND IDENTIFY WHICH OF THE
HYDROLOGIC REGIMES DESCRIBED IN QUESTIONS 1-7 APPLY TO DIFFERENT AREAS IN THE UNIT
(make a rough sketch to help you decide). Use the following table to identify the appropriate class to use for
the rating system if you have several HGM classes present within the wetland unit being scored.
6. Is the entire wetland unit in a topographic depression in which water ponds, or is saturated to the surface, at
some time during the year? This means that any outlet, if present, is higher than the interior of the wetland.
Riverine
Treat as
ESTUARINE
Slope + Lake Fringe
Depressional + Riverine along stream
within boundary of depression
Depressional + Lake Fringe
Riverine + Lake Fringe
NOTE: Use this table only if the class that is recommended in the second column represents 10% or more of
the total area of the wetland unit being rated. If the area of the HGM class listed in column 2 is less than 10%
of the unit; classify the wetland using the class that represents more than 90% of the total area.
HGM classes within the wetland unit
being rated
Slope + Riverine
Slope + Depressional
Depressional
Depressional
If you are still unable to determine which of the above criteria apply to your wetland, or if you have more than
2 HGM classes within a wetland boundary, classify the wetland as Depressional for the rating.
Salt Water Tidal Fringe and any other
class of freshwater wetland
HGM class to
use in rating
Riverine
Depressional
Lake Fringe
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 4 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
D 1.1. Characteristics of surface water outflows from the wetland:
points = 3
points = 2
points = 1
points = 1
Yes = 4 No = 0
Wetland has persistent, ungrazed, plants > 95% of area points = 5
Wetland has persistent, ungrazed, plants > ½ of area points = 3
Wetland has persistent, ungrazed plants > 1/10 of area points = 1
Wetland has persistent, ungrazed plants < 1/10 of area points = 0
D 1.4. Characteristics of seasonal ponding or inundation:
This is the area that is ponded for at least 2 months. See description in manual.
Area seasonally ponded is > ½ total area of wetland points = 4
Area seasonally ponded is > ¼ total area of wetland points = 2
Area seasonally ponded is < ¼ total area of wetland points = 0
Total for D 1 Add the points in the boxes above 9
Rating of Site Potential If score is: 12 - 16 = H 6 - 11 = M 0 - 5 = L Record the rating on the first page
D 2.1. Does the wetland unit receive stormwater discharges?Yes = 1 No = 0 1
Yes = 1 No = 0
D 2.3. Are there septic systems within 250 ft of the wetland?Yes = 1 No = 0 0
Source Yes = 1 No = 0
Total for D 2 Add the points in the boxes above 2
Rating of Landscape Potential If score is: 3 or 4 = H 1 or 2 = M 0 = L Record the rating on the first page
Yes = 1 No = 0
Yes = 1 No = 0
Yes = 2 No = 0
Total for D 3 Add the points in the boxes above 4
Rating of Value If score is: 2 - 4 = H 1 = M 0 = L Record the rating on the first page
D 3.3. Has the site been identified in a watershed or local plan as important
for maintaining water quality (answer YES if there is a TMDL for the basin in
which the unit is found )?
D 1.2. The soil 2 in below the surface (or duff layer) is true clay or true organic
(use NRCS definitions ).
D 1.3. Characteristics and distribution of persistent plants (Emergent, Scrub-shrub, and/or
Forested Cowardin classes):
D 2.4. Are there other sources of pollutants coming into the wetland that are
not listed in questions D 2.1 - D 2.3?
D 3.1. Does the wetland discharge directly (i.e., within 1 mi) to a stream, river,
lake, or marine water that is on the 303(d) list?
D 2.2. Is > 10% of the area within 150 ft of the wetland in land uses that
generate pollutants?
D 3.2. Is the wetland in a basin or sub-basin where an aquatic resource is on the 303(d) list?
D 3.0. Is the water quality improvement provided by the site valuable to society?
1
1
2
0
3
DEPRESSIONAL AND FLATS WETLANDS
1
0
Water Quality Functions - Indicators that the site functions to improve water quality
D 1.0. Does the site have the potential to improve water quality?
2
Wetland has an unconstricted, or slightly constricted, surface outlet
that is permanently flowing
Wetland has an intermittently flowing stream or ditch, OR highly
constricted permanently flowing outlet.
Wetland is a depression or flat depression (QUESTION 7 on key)
with no surface water leaving it (no outlet).
Wetland is a flat depression (QUESTION 7 on key), whose outlet is
a permanently flowing ditch.
4
D 2.0. Does the landscape have the potential to support the water quality function of the site?
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 5 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
D 4.1. Characteristics of surface water outflows from the wetland:
points = 4
points = 2
points = 1
points = 0
Marks of ponding are 3 ft or more above the surface or bottom of outlet points = 7
Marks of ponding between 2 ft to < 3 ft from surface or bottom of outlet points = 5
Marks are at least 0.5 ft to < 2 ft from surface or bottom of outlet points = 3
The wetland is a “headwater” wetland points = 3
Wetland is flat but has small depressions on the surface that trap water points = 1
Marks of ponding less than 0.5 ft (6 in)points = 0
The area of the basin is less than 10 times the area of the unit points = 5
The area of the basin is 10 to 100 times the area of the unit points = 3
The area of the basin is more than 100 times the area of the unit points = 0
Entire wetland is in the Flats class points = 5
Total for D 4 Add the points in the boxes above 10
Rating of Site Potential If score is: 12 - 16 = H 6 - 11 = M 0 - 5 = L Record the rating on the first page
D 5.1. Does the wetland unit receive stormwater discharges?Yes = 1 No = 0 1
D 5.2. Is > 10% of the area within 150 ft of the wetland in land uses that generate excess runoff?
Yes = 1 No = 0
Yes = 1 No = 0
Total for D 5 Add the points in the boxes above 3
Rating of Landscape Potential If score is: 3 = H 1 or 2 = M 0 = L Record the rating on the first page
points = 2
points = 1
Flooding from groundwater is an issue in the sub-basin.points = 1
points = 0
There are no problems with flooding downstream of the wetland.points = 0
Yes = 2 No = 0
Total for D 6 Add the points in the boxes above 2
Rating of Value If score is: 2 - 4 = H 1 = M 0 = L Record the rating on the first page
1
1
D 5.3. Is more than 25% of the contributing basin of the wetland covered with intensive human
land uses (residential at >1 residence/ac, urban, commercial, agriculture, etc.)?
The existing or potential outflow from the wetland is so constrained
by human or natural conditions that the water stored by the wetland
cannot reach areas that flood. Explain why
2
0
5
D 4.2. Depth of storage during wet periods: Estimate the height of ponding above the bottom of
the outlet. For wetlands with no outlet, measure from the surface of permanent water or if dry, the
deepest part.
D 4.3. Contribution of the wetland to storage in the watershed: Estimate the ratio of the area of
upstream basin contributing surface water to the wetland to the area of the wetland unit itself.
D 6.1. The unit is in a landscape that has flooding problems. Choose the description that best
matches conditions around the wetland unit being rated. Do not add points. Choose the highest
score if more than one condition is met.
D 6.2. Has the site been identified as important for flood storage or flood
conveyance in a regional flood control plan?
Hydrologic Functions - Indicators that the site functions to reduce flooding and stream degradation
D 4.0. Does the site have the potential to reduce flooding and erosion?
2
Wetland is a depression or flat depression with no surface water
leaving it (no outlet)
Wetland has an unconstricted, or slightly constricted, surface outlet
that is permanently flowing
Wetland has an intermittently flowing stream or ditch, OR highly
constricted permanently flowing outlet
Wetland is a flat depression (QUESTION 7 on key), whose outlet is
a permanently flowing ditch
3
D 5.0. Does the landscape have the potential to support hydrologic function of the site?
D 6.0. Are the hydrologic functions provided by the site valuable to society?
The wetland captures surface water that would otherwise flow down-gradient into areas
where flooding has damaged human or natural resources (e.g., houses or salmon redds):
Flooding occurs in a sub-basin that is immediately down-
gradient of unit.
Surface flooding problems are in a sub-basin farther down-
gradient.
DEPRESSIONAL AND FLATS WETLANDS
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 6 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
HABITAT FUNCTIONS - Indicators that site functions to provide important habitat
H 1.0. Does the site have the potential to provide habitat?
Aquatic bed 4 structures or more: points = 4
Emergent 3 structures: points = 2
Scrub-shrub (areas where shrubs have > 30% cover)2 structures: points - 1
Forested (areas where trees have > 30% cover)1 structure: points = 0
If the unit has a Forested class, check if :
H 1.2. Hydroperiods
Permanently flooded or inundated 4 or more types present: points = 3
Seasonally flooded or inundated 3 types present: points = 2
Occasionally flooded or inundated 2 types present: points = 1
Saturated only 1 types present: points = 0
Permanently flowing stream or river in, or adjacent to, the wetland
Seasonally flowing stream in, or adjacent to, the wetland
Lake Fringe wetland 2 points
Freshwater tidal wetland 2 points
H 1.3. Richness of plant species
If you counted:> 19 species points = 2
5 - 19 species points = 1
< 5 species points = 0
H 1.4. Interspersion of habitats
None = 0 points Low = 1 point Moderate = 2 points
All three diagrams
in this row are
HIGH = 3 points
2
Check the types of water regimes (hydroperiods) present within the wetland. The water regime
has to cover more than 10% of the wetland or ¼ ac to count (see text for descriptions of
hydroperiods ).
2
Count the number of plant species in the wetland that cover at least 10 ft2.Different patches of the same species can be combined to meet the size threshold and you do
not have to name the species. Do not include Eurasian milfoil, reed canarygrass, purple
loosestrife, Canadian thistle 1
Decide from the diagrams below whether interspersion among Cowardin plants classes
(described in H 1.1), or the classes and unvegetated areas (can include open water or mudflats)
is high, moderate, low, or none. If you have four or more plant classes or three classes and open
water, the rating is always high.
These questions apply to wetlands of all HGM classes.
The Forested class has 3 out of 5 strata (canopy, sub-canopy, shrubs, herbaceous,
moss/ground-cover) that each cover 20% within the Forested polygon
2
H 1.1. Structure of plant community: Indicators are Cowardin classes and strata within the
Forested class. Check the Cowardin plant classes in the wetland. Up to 10 patches may be
combined for each class to meet the threshold of ¼ ac or more than 10% of the unit if it is smaller
than 2.5 ac. Add the number of structures checked.
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 7 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
H 1.5. Special habitat features:
Large, downed, woody debris within the wetland (> 4 in diameter and 6 ft long)
Standing snags (dbh > 4 in) within the wetland
Total for H 1 Add the points in the boxes above 10
Rating of Site Potential If Score is: 15 - 18 = H 7 - 14 = M 0 - 6 = L Record the rating on the first page
H 2.0. Does the landscape have the potential to support the habitat function of the site?
H 2.1 Accessible habitat (include only habitat that directly abuts wetland unit ).
Calculate:
3 % undisturbed habitat + (5 % moderate & low intensity land uses / 2 ) = 5.5%
If total accessible habitat is:
> 1/3 (33.3%) of 1 km Polygon points = 3
20 - 33% of 1 km Polygon points = 2
10 - 19% of 1 km Polygon points = 1
< 10 % of 1 km Polygon points = 0
H 2.2. Undisturbed habitat in 1 km Polygon around the wetland.
Calculate:
21 % undisturbed habitat + (5 % moderate & low intensity land uses / 2 ) = 23.5%
Undisturbed habitat > 50% of Polygon points = 3
Undisturbed habitat 10 - 50% and in 1-3 patches points = 2
Undisturbed habitat 10 - 50% and > 3 patches points = 1
Undisturbed habitat < 10% of 1 km Polygon points = 0
H 2.3 Land use intensity in 1 km Polygon: If
> 50% of 1 km Polygon is high intensity land use points = (-2)
≤ 50% of 1km Polygon is high intensity points = 0
Total for H 2 Add the points in the boxes above -1
Rating of Landscape Potential If Score is: 4 - 6 = H 1 - 3 = M < 1 = L Record the rating on the first page
Site meets ANY of the following criteria:points = 2
It has 3 or more priority habitats within 100 m (see next page)
It is mapped as a location for an individual WDFW priority species
Site has 1 or 2 priority habitats (listed on next page) with in 100m points = 1
Site does not meet any of the criteria above points = 0
Rating of Value If Score is: 2 = H 1 = M 0 = L Record the rating on the first page
Check the habitat features that are present in the wetland. The number of checks is the number
of points.
It has been categorized as an important habitat site in a local or
regional comprehensive plan, in a Shoreline Master Plan, or in a
watershed plan
Undercut banks are present for at least 6.6 ft (2 m) and/or overhanging plants extends
at least 3.3 ft (1 m) over a stream (or ditch) in, or contiguous with the wetland, for at
least 33 ft (10 m)
Stable steep banks of fine material that might be used by beaver or muskrat for denning
(> 30 degree slope) OR signs of recent beaver activity are present (cut shrubs or trees
that have not yet weathered where wood is exposed )
At least ¼ ac of thin-stemmed persistent plants or woody branches are present in areas
that are permanently or seasonally inundated (structures for egg-laying by amphibians )
3
It is a Wetland of High Conservation Value as determined by the
Department of Natural Resources
1
Invasive plants cover less than 25% of the wetland area in every stratum of plants (see
H 1.1 for list of strata )
0
1
-2
H 3.0. Is the habitat provided by the site valuable to society?
H 3.1. Does the site provide habitat for species valued in laws, regulations, or policies? Choose
only the highest score that applies to the wetland being rated .
It provides habitat for Threatened or Endangered species (any plant
or animal on the state or federal lists)
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 8 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
Aspen Stands: Pure or mixed stands of aspen greater than 1 ac (0.4 ha).
Herbaceous Balds: Variable size patches of grass and forbs on shallow soils over bedrock.
Cliffs: Greater than 25 ft (7.6 m) high and occurring below 5000 ft elevation.
Priority habitats listed by WDFW (see complete descriptions of WDFW priority habitats, and the counties in
which they can be found, in: Washington Department of Fish and Wildlife. 2008. Priority Habitat and Species
List. Olympia, Washington. 177 pp.
Oregon White Oak: Woodland stands of pure oak or oak/conifer associations where canopy
coverage of the oak component is important (full descriptions in WDFW PHS report p. 158 – see
web link above ).
Riparian: The area adjacent to aquatic systems with flowing water that contains elements of both
aquatic and terrestrial ecosystems which mutually influence each other.
Westside Prairies: Herbaceous, non-forested plant communities that can either take the form of a
dry prairie or a wet prairie (full descriptions in WDFW PHS report p. 161 – see web link above ).
Instream: The combination of physical, biological, and chemical processes and conditions that
interact to provide functional life history requirements for instream fish and wildlife resources.
Nearshore: Relatively undisturbed nearshore habitats. These include Coastal Nearshore, Open
Coast Nearshore, and Puget Sound Nearshore. (full descriptions of habitats and the definition of
relatively undisturbed are in WDFW report – see web link on previous page ).
Snags and Logs: Trees are considered snags if they are dead or dying and exhibit sufficient decay
characteristics to enable cavity excavation/use by wildlife. Priority snags have a diameter at breast
height of > 20 in (51 cm) in western Washington and are > 6.5 ft (2 m) in height. Priority logs are > 12
in (30 cm) in diameter at the largest end, and > 20 ft (6 m) long.
Talus: Homogenous areas of rock rubble ranging in average size 0.5 - 6.5 ft (0.15 - 2.0 m),
composed of basalt, andesite, and/or sedimentary rock, including riprap slides and mine tailings. May
be associated with cliffs.
Caves: A naturally occurring cavity, recess, void, or system of interconnected passages under the
earth in soils, rock, ice, or other geological formations and is large enough to contain a human.
Note: All vegetated wetlands are by definition a priority habitat but are not included in this list because they are
addressed elsewhere.
WDFW Priority Habitats
Count how many of the following priority habitats are within 330 ft (100 m) of the wetland unit: NOTE : This
question is independent of the land use between the wetland unit and the priority habitat.
Biodiversity Areas and Corridors: Areas of habitat that are relatively important to various species
of native fish and wildlife (full descriptions in WDFW PHS report ).
Old-growth/Mature forests: Old-growth west of Cascade crest – Stands of at least 2 tree species,
forming a multi-layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha)
> 32 in (81 cm) dbh or > 200 years of age. Mature forests – Stands with average diameters
exceeding 21 in (53 cm) dbh; crown cover may be less than 100%; decay, decadence, numbers of
snags, and quantity of large downed material is generally less than that found in old-growth; 80-200
years old west of the Cascade crest.
http://wdfw.wa.gov/publications/00165/wdfw00165.pdf or access the list from here:
http://wdfw.wa.gov/conservation/phs/list/
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 9 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
Wetland Type Category
Check off any criteria that apply to the wetland. List the category when the appropriate criteria are met.
SC 1.0. Estuarine Wetlands
Does the wetland meet the following criteria for Estuarine wetlands?
The dominant water regime is tidal,
Vegetated, and
With a salinity greater than 0.5 ppt
Yes - Go to SC 1.1 No = Not an estuarine wetland
SC 1.1.
Yes = Category I No - Go to SC 1.2
SC 1.2.Is the wetland unit at least 1 ac in size and meets at least two of the following three conditions?
Yes = Category I No = Category II
SC 2.0. Wetlands of High Conservation Value (WHCV)
SC 2.1.
Yes - Go to SC 2.2 No - Go to SC 2.3
SC 2.2.Is the wetland listed on the WDNR database as a Wetland of High Conservation Value?
Yes = Category I No = Not WHCV
SC 2.3.Is the wetland in a Section/Township/Range that contains a Natural Heritage wetland?
http://www1.dnr.wa.gov/nhp/refdesk/datasearch/wnhpwetlands.pdf
Yes - Contact WNHP/WDNR and to SC 2.4 No = Not WHCV
SC 2.4.
Yes = Category I No = Not WHCV
SC 3.0. Bogs
SC 3.1.
Yes - Go to SC 3.3 No - Go to SC 3.2
SC 3.2.
Yes - Go to SC 3.3 No = Is not a bog
SC 3.3.
Yes = Is a Category I bog No - Go to SC 3.4
SC 3.4.
Yes = Is a Category I bog No = Is not a bog
NOTE: If you are uncertain about the extent of mosses in the understory, you may
substitute that criterion by measuring the pH of the water that seeps into a hole dug at
least 16 in deep. If the pH is less than 5.0 and the plant species in Table 4 are present,
the wetland is a bog.
Is an area with peats or mucks forested (> 30% cover) with Sitka spruce, subalpine fir,
western red cedar, western hemlock, lodgepole pine, quaking aspen, Engelmann
spruce, or western white pine, AND any of the species (or combination of species) listed
in Table 4 provide more than 30% of the cover under the canopy?
CATEGORIZATION BASED ON SPECIAL CHARACTERISTICS
Is the wetland within a National Wildlife Refuge, National Park, National Estuary
Reserve, Natural Area Preserve, State Park or Educational, Environmental, or Scientific
Reserve designated under WAC 332-30-151?
The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing,
and has less than 10% cover of non-native plant species. (If non-native species are
Spartina , see page 25)
At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-
grazed or un-mowed grassland.
The wetland has at least two of the following features: tidal channels, depressions with
open water, or contiguous freshwater wetlands.
Has WDNR identified the wetland within the S/T/R as a Wetland of High Conservation
Value and listed it on their website?
Has the WA Department of Natural Resources updated their website to include the list
of Wetlands of High Conservation Value?
Does the wetland (or any part of the unit) meet both the criteria for soils and vegetation
in bogs? Use the key below. If you answer YES you will still need to rate the
wetland based on its functions .
Does an area within the wetland unit have organic soil horizons, either peats or mucks,
that compose 16 in or more of the first 32 in of the soil profile?
Does an area within the wetland unit have organic soils, either peats or mucks, that are
less than 16 in deep over bedrock, or an impermeable hardpan such as clay or volcanic
ash, or that are floating on top of a lake or pond?
Does an area with peats or mucks have more than 70% cover of mosses at ground
level, AND at least a 30% cover of plant species listed in Table 4?
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 10 WSDOT Adapted Form - March 2, 2015
Wetland name or number Wetland B
SC 4.0. Forested Wetlands
Yes = Category I No = Not a forested wetland for this section
SC 5.0. Wetlands in Coastal Lagoons
Does the wetland meet all of the following criteria of a wetland in a coastal lagoon?
Yes - Go to SC 5.1 No = Not a wetland in a coastal lagoon
SC 5.1. Does the wetland meet all of the following three conditions?
The wetland is larger than 1/10 ac (4350 ft2)
Yes = Category I No = Category II
SC 6.0. Interdunal Wetlands
In practical terms that means the following geographic areas:
Long Beach Peninsula: Lands west of SR 103
Grayland-Westport: Lands west of SR 105
Ocean Shores-Copalis: Lands west of SR 115 and SR 109
Yes - Go to SC 6.1 No = Not an interdunal wetland for rating
SC 6.1.
Yes = Category I No - Go to SC 6.2
SC 6.2.Is the wetland 1 ac or larger, or is it in a mosaic of wetlands that is 1 ac or larger?
Yes = Category II No - Go to SC 6.3
SC 6.3.
Yes = Category III No = Category IV
Category of wetland based on Special Characteristics
If you answered No for all types, enter “Not Applicable” on Summary Form
The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing),
and has less than 20% cover of aggressive, opportunistic plant species (see list of
species on p. 100).
At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-
grazed or un-mowed grassland.
Is the wetland west of the 1889 line (also called the Western Boundary of Upland
Ownership or WBUO)? If you answer yes you will still need to rate the wetland
based on its habitat functions.
Is the wetland 1 ac or larger and scores an 8 or 9 for the habitat functions on the form
(rates H,H,H or H,H,M for the three aspects of function)?
Is the unit between 0.1 and 1 ac, or is it in a mosaic of wetlands that is between 0.1 and
1 ac?
The wetland lies in a depression adjacent to marine waters that is wholly or partially
separated from marine waters by sandbanks, gravel banks, shingle, or, less frequently,
rocks
The lagoon in which the wetland is located contains ponded water that is saline or
brackish (> 0.5 ppt) during most of the year in at least a portion of the lagoon (needs to
be measured near the bottom )
Does the wetland have at least 1 contiguous acre of forest that meets one of these
criteria for the WA Department of Fish and Wildlife’s forests as priority habitats? If you
answer YES you will still need to rate the wetland based on its functions.
Old-growth forests (west of Cascade crest): Stands of at least two tree species,
forming a multi-layered canopy with occasional small openings; with at least 8 trees/ac
(20 trees/ha) that are at least 200 years of age OR have a diameter at breast height
(dbh) of 32 in (81 cm) or more.
Mature forests (west of the Cascade Crest): Stands where the largest trees are 80-
200 years old OR the species that make up the canopy have an average diameter (dbh)
exceeding 21 in (53 cm).
Wetland Rating System for Western WA: 2014 Update
Rating Form - Effective January 1, 2015 11 WSDOT Adapted Form - March 2, 2015
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DUCTILE IRON UNLESS OTHERWISE NOrrD ON PLAN
EXISTING (C4) RECLAIMED WATER MAIN
DUCTILE IRON UNLESS OTHERWISE NOTED ON PLAN
NEW RECLAIMED WATER MAIN 2" (UNLESS OTHERWISE NOTED ON PLANS)
SCH. 80 PVC. TO BE INCLUDED IN THIS CONTRACT
NEW (C3) EFFLUENT WATER MAIN 2" (UNLESS OTHERWISE NOTED)
SCH. 80 PVC. TO BE INCLUDED IN THIS CONTRACT
NEW (C4) IRRIGATION SLEEVE
TO BE INCLUDED IN THIS CONTRACT
NEW (C3) EFFLUENT IRRIGATION AREAS
INSTALL POP-UP HEADS SIMILAR TO THE LAYOUT FOR IN DETAIL 2 SHEET 13.
NEW RECLAIMED WATER IRRIGATION AREAS
INSTALL 1" QUICK COUPLERS AS SHOWN ON PLANS.
EXISTING (C4) RECLAIMED WATER IRRIGATION AREAS
MAINTAIN EXISTING IRR. SYSTEM AND INSTALL 1" QUICK COUPLERS
AS SHOWN ON PLANS.
EXISTING (C3) EFFLUENT IRRIGATION AREAS CONTRACTOR
SHALL ENSURE THESE AREA REMAIN IN FUNCTIONING
ORDER. REWIRE VALVES WHERE INDICATED.
"UTILITY GRADE" IRRIGATION
1" QUICK COUPLER BASED SYSTEM
SPACE COUPLERS AS SHOWN ON PLANS.
AREA OF EXISTING AND NEW IR~l~N
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PLAN SHEETS L300-L323 TO ENSURE THAT ALL
NEW PLANTING RECEIVES IRRIGATION. WHERE
EXISTING IRRIGATION CROSSES OUTSIDE OF THIS
BOUNDARY CONTRACTOR IS TO ENSURE THAT
IRRIGATION SERVICE IS MAINTAINED TO THE EXISTING
PLANTING OUTSIDE THE BOUNDARY DURING
CONSTRUCTION AND IN WORKING CONDITION AFTER
WORK HAS BEEN COMPLETED.
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(2) EXISTING RAINBIRD
IRRIGATION CONTROLLERS
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SOL"TH TREATMENT PLANT
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INTERNAL AND PERIMETER LANDSCAPING
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I EAST WALKWAY EDGE NECKLACE CURVE DATA
CURVE PC PT
NORTHING EASTING NORTHING EASTING RADIUS
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C41 1811.61 1640.68 1887.85 1635.49 15.00'
C43 1887.85 1635.49 1914.47 1635.94 31.50'
C45 1921.56 1639.39 1935.65 1638.89 15.00'
C47 1643.97 1634.07 1958.00 1630.44 27.00'
C49 1958.00 1630.44 1961.64 1635.93 4.00'
C51 1961.64 1635.93 1953.21 1643.37 12.50·
C53 1945.87 1645.29 1933.77 1654.37 20.00·
I 4 C55 1933.77 1654.37 1929.36 1656.80 5.00'
C57 1918.20 1656.53 1899.65 1652.29 50.00'
WEST WALKWAY EDGE NECKLACE CURVE DATA
CURVE PC PT
I NORTHING EASTING NORTHING EASTING RADIUS
C44 1857.38 1626.07 1887.60 1624.81
C46 1887.60 1624.81 1910.93 1625.65
C48 1920.61 1630.96 1932.29 1629.47
C50 1936.05 1625.91 1962.41 1615.83
C52 1962.41 1615.83 1972.83 1633.20
I
C54 1972.83 1633.20 1952.37 1649.81
C56 1947.51 1651.10 1941.35 1655.85
C58 1941.35 1655.85 1929.01 1662.96
C60 1926.14 1662.93 1921.30 1668.54
EAST WALKWAY EDGE NECKLACE LINE
I LINE PC PT # NORTHING EASTING NORTHING EASTING
L3 1914.47 1635.94 1921.56 1639.39
L5 1935.65 1638.89 1943.97 1634.07
L7 1953.21 1643.37 1945.87 1645.29
I L9 1929.36 1656.80 1918.20 1656.53
WEST WALKWAY EDGE
I
LINE PC # NORTHING EASTING
L4 1910.93 1625.65
L6 1932.29 1629.47
LB 1952.37 1649.81
L10 1929.01 1662.96
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2
Regional Wastewater Services Plan (RWSP)
2013 Comprehensive Review
June 2014
King Street Center, KSC-NR-0512
201 South Jackson Street
Seattle, WA 98104
http://dnr.metrokc.gov/wtd/
For comments or questions, contact:
Pam Elardo, P.E., Division Director
King County Wastewater Treatment Division
201 South Jackson Street
KSC-NR-0512
Seattle, WA 98104-3856
206-477-4530
Pam.Elardo@kingcounty.gov
This information is available in
alternative formats on request at
206-477-5371 (voice) or 711 (TTY)
Contents
Executive Summary .................................................................................................................................. ES-1
Chapter 1 Introduction .............................................................................................................................. 1-1
King County’s Wastewater Treatment System ...................................................................................... 1-2
Regional Wastewater Services Plan ....................................................................................................... 1-4
Chapter 2 RWSP Achievements in 2007−2013 .......................................................................................... 2-1
RWSP Policies Implementation .............................................................................................................. 2-1
RWSP Capital Projects ............................................................................................................................ 2-2
Brightwater Treatment System .......................................................................................................... 2-3
Carnation Treatment Plant ................................................................................................................ 2-4
Conveyance System Improvement Projects ...................................................................................... 2-5
Reducing Infiltration and Inflow ........................................................................................................ 2-8
Protecting Our Waters Program ........................................................................................................ 2-9
Implementing the Sediment Management Plan .................................................................................. 2-14
Cleaning Up the Lower Duwamish Waterway Superfund Site ............................................................ 2-14
Creating Resources from Wastewater ................................................................................................. 2-15
Biosolids Recycling Program ............................................................................................................ 2-15
Energy Recovery and Efficiency Program ........................................................................................ 2-17
Reclaimed Water Program ............................................................................................................... 2-18
Protecting our Assets ........................................................................................................................... 2-20
Chapter 3 Financial Stewardship ............................................................................................................... 3-1
Establishing Annual Sewer Rate and Capacity Charge ........................................................................... 3-1
Residential Customer Equivalents ..................................................................................................... 3-2
Sewer Rate and Capacity Charge Projections .................................................................................... 3-4
Continuous Improvement Programs ..................................................................................................... 3-7
Productivity Initiative Pilot Program .................................................................................................. 3-7
Bright Ideas Program ......................................................................................................................... 3-8
Policy Guidance on Construction Fund and Emergency Reserves ......................................................... 3-8
Chapter 4 Forecasting Future Wastewater Treatment Plant Capacity Needs ........................................... 4-1
Summary ................................................................................................................................................ 4-1
Methodology .......................................................................................................................................... 4-2
Planning Assumptions ............................................................................................................................ 4-2
RWSP 2013 Comprehensive Review i
Contents
Population and Employment Forecasts ................................................................................................. 4-4
Average Wet Weather Flow Forecasts .................................................................................................. 4-7
Estimating Flow Factors for the Baseline Year ................................................................................... 4-7
Forecasting Future Flows ................................................................................................................... 4-8
Wasteload Forecasts ............................................................................................................................ 4-10
Estimating Loading Factors for the Baseline Year ............................................................................ 4-10
Forecasting Future Loadings ............................................................................................................ 4-10
Comparison of Future Flows, Loadings, and Capacities....................................................................... 4-12
Implications for Future Planning .......................................................................................................... 4-16
Chapter 5 Preparing for the Future ........................................................................................................... 5-1
Climate Change ...................................................................................................................................... 5-1
Regulatory Environment ........................................................................................................................ 5-2
Nutrient Removal ............................................................................................................................... 5-2
Source Control ................................................................................................................................... 5-3
Chemicals of Concern......................................................................................................................... 5-3
Other Topics ....................................................................................................................................... 5-3
Technology Trends ................................................................................................................................. 5-3
Decentralized Wastewater Systems .................................................................................................. 5-4
Nutrient Recovery .............................................................................................................................. 5-4
Energy Recovery ................................................................................................................................. 5-5
Indirect and Direct Potable Reuse ..................................................................................................... 5-5
Building Equity and Opportunity ........................................................................................................... 5-6
Chapter 6 Conclusions and Next Steps ...................................................................................................... 6-1
Conclusions ............................................................................................................................................ 6-1
Next Steps .............................................................................................................................................. 6-2
Appendix A. RWSP Policies Implementation in 2007−2013…………………………………………………………………A-1
Appendix B. Odor Prevention and Control Program……………………………………………………………………………B-1
Appendix C. Water Quality and Sediment Monitoring in 2013……………………………………………………………C-1
ii RWSP 2013 Comprehensive Review
Contents
Tables
Table 3-1. Residential Customer Equivalents (1994–2013) ....................................................................... 3-3
Table 3-2. WTD Capacity Charge (2003−2014) .......................................................................................... 3-7
Table 4-1. Previous and Updated Planning Assumptions .......................................................................... 4-3
Table 4-2. Per-capita and Employee Flow Factors for 2010 ...................................................................... 4-8
Figures
Figure 1-1. King County Wastewater Service Area and Facilities .............................................................. 1-3
Figure 1-2. Regional Wastewater Services Plan Projects and Service Areas (1999-2030) ........................ 1-5
Figure 2-1. Brightwater Treatment Plant ................................................................................................... 2-3
Figure 2-2. Brightwater Education and Community Center ...................................................................... 2-4
Figure 2-3. Carnation Treatment Plant ...................................................................................................... 2-5
Figure 2-4. Juanita Bay Pump Station ........................................................................................................ 2-6
Figure 2-5. Hidden Lake Pump Station ....................................................................................................... 2-6
Figure 2-6. Bellevue Pump Station ............................................................................................................. 2-6
Figure 2-7. Sources of Infiltration and Inflow ............................................................................................ 2-8
Figure 2-8. Location of the Puget Sound Beach CSO Control Projects .................................................... 2-11
Figure 2-9. King County’s Long-Term CSO Control Plan Projects ............................................................. 2-12
Figure 2-10. WTD’s 2012 Carbon Impact ................................................................................................. 2-17
Figure 3-1. Relationship Between the Monthly Sewer Rate and Capacity Charge .................................... 3-2
Figure 3-2. 2007 and 2013 Residential Customer Equivalent Forecasts (1993 to 2030) ........................... 3-4
Figure 3-3. Sewer Rate Projections with Inflation (2002–2014) ................................................................ 3-5
Figure 3-4. Sewer Rate Projections with Inflation (2002–2030) ................................................................ 3-5
Figure 3-5. Annual Capital Spending for the Wastewater Treatment Division (2000 to 2030) ................. 3-6
Figure 4-1. Previous and Current Population and Employment Projections for the WTD Service Area ... 4-4
Figure 4-2. King County’s Wastewater Treatment Service Areas .............................................................. 4-5
Figure 4-3. Previous (2004) and Current (2013) Population and Employment Forecasts For West Point
Service Area ............................................................................................................................ 4-6
Figure 4-4. Previous (2004) and Current (2013) Population and Employment Forecasts For South Plant
Service Area ............................................................................................................................ 4-6
Figure 4-5. Previous (2004) and Current (2013) Population and Employment Forecasts For Brightwater
Service Area ............................................................................................................................ 4-7
Figure 4-6. Regional Water Purveyor Predicted Water Usage Reductions from Water Conservation ..... 4-9
Figure 4-7. Historical and Forecasted Average Wet Weather Flow at West Point, South, and Brightwater
Treatment Plants, 1990−2060 .............................................................................................. 4-10
gure 4-8. Historical and Forecasted Average BOD load at Treatment Plants, 1990−2060 ...................... 4-11
Figure 4-9. Historical and Forecasted Average TSS load at Treatment Plants, 1990−2060 ..................... 4-12
Figure 4-10. Comparison of Actual and Forecast Solids Loadings with Systemwide Treatment Capacities,
1980−2060 ............................................................................................................................ 4-13
Figure 4-11. Actual and Forecast AWWF and Solids Loadings Compared to West Point Treatment Plant
Capacities, 1990−2060 ......................................................................................................... 4-14
RWSP 2013 Comprehensive Review iii
Contents
Figure 4-12. Actual and Forecast AWWF and Solids Loadings Compared to South Treatment Plant
Capacities, 1990−2060 ............................................................................................................................. 4-15
Figure 4-13. Actual and Forecast AWWF and Solids Loadings Compared to Brightwater Treatment Plant
Capacities, 2010−2060 ............................................................................................................................. 4-16
Figure 4-14. Historical and Projected Systemwide Average Wet Weather Flow .................................... 4-17
iv RWSP 2013 Comprehensive Review
Executive Summary
The Regional Wastewater Services Plan (RWSP) outlines important projects, programs, and policies for
King County to implement through 2030 to continue to protect public health and water quality and
ensure sufficient wastewater capacity to meet future growth. In adopting the RWSP in 1999, the
Metropolitan King County Council recognized the importance of reviewing implementation of the RWSP
and adopted specific RWSP reporting policies that call for regular reviews and reports.
The Wastewater Treatment Division (WTD) of the Department of Natural Resources and Parks (DNRP)
has completed the RWSP 2013 Comprehensive Review as required by Ordinance 17232. The RWSP
reporting policies were established through adoption of Ordinance 15384 and amended in 2012 through
Ordinance 17480. A work plan for this review was approved by Motion 13758 in 2012. The review covers
RWSP policy implementation from 2007 through 2013. This is the third comprehensive review report
since adoption of the RWSP.
Implementation of the RWSP protects the region’s water quality, environment, and economy by
providing dependable, high-quality wastewater treatment. One of the RWSP’s primary objectives under
the treatment plant policies was construction of a new Brightwater Treatment Plant in south Snohomish
County. The Brightwater Plant, which uses membrane bioreactor (MBR) technology, started full
operations in 2012. The Brightwater Plant produces high-quality effluent and Class A reclaimed water
that is used for irrigation in the Sammamish Valley. In 2008, the Carnation Treatment Plant was
completed. The Carnation Plant also uses MBR technology and is designed to treat all wastewater to
Class A reclaimed water standards for discharge to an enhanced wetland in the Chinook Bend Natural
Area in the Snoqualmie River basin.
The RWSP 2013 comprehensive review included evaluating and updating future regional wastewater
treatment capacity needs. The review confirmed the benefits of having a three-plant regional system
(West, South and Brightwater treatment plants). Updated forecasts indicate that a full expansion at
South Plant is unlikely to be needed in 2029 as previously projected, but may be needed in the 2030s. As
the regional population has increased, treatment plant solids loadings have grown in proportion with
population while average wet-weather flows decreased by 15 percent because of reduced water usage.
These trends are likely to continue in the next few decades. WTD will conduct a study in 2015 to
determine the most cost-effective methods to manage solids loading increases over time.
Actual population growth and water use rates could be more or less than projected. Of the factors that
affect treatment plant capacity, climate change is expected to have a significant impact on future peak
flows at treatment plants. WTD will continue to track factors and trends that affect treatment plant
capacity needs, including climate change impacts over time, monitor flow data, and work with local
agencies as they implement their land use and sewer plans.
In accordance with RWSP conveyance and infiltration/inflow (I/I) policies, WTD completed five
conveyance system improvement (CSI) projects and one I/I reduction project between 2007 and 2013.
These projects were designed to meet projected peak flow demands and the RWSP 20-year peak flow
design standard. An update of the CSI plan, which will include a projection of future peak flows for the
RWSP 2013 Comprehensive Review ES-1
Executive Summary
treatment plants and future CSI projects, is scheduled for completion in 2015. Treatment plant capacity
requirements may be adjusted when these projections are available.
The RWSP policies provide guidance to maximize the beneficial reuse of byproducts from wastewater
treatment. WTD makes use of biosolids and digester gas from the solids treatment process and
reclaimed water from the liquids treatment process. In 2007−2013, 100 percent of biosolids were used
as a fertilizer and soil amendment in agriculture and forestry or as an ingredient in compost, the Waste-
to-Energy cogeneration system at West Point Plant was completed and is now operational, and
reclaimed water was produced and distributed from the Carnation and Brightwater plants. WTD
continues to produce and use reclaimed water for treatment processes and irrigation at the West and
South plants and provides additional reclaimed water to the City of Tukwila from South Plant.
WTD made significant progress from 2007 through 2013 to control combined sewer overflows (CSOs) to
the Washington State standard of no more than one overflow per year on average at each CSO site.
Construction began on four projects to control CSOs along Puget Sound beaches. Projects are under way
or planned to control all remaining uncontrolled CSOs by 2030, under a consent decree with U.S.
Department of Justice, U.S. Environmental Protection Agency, and Washington State Department of
Ecology that was signed in 2013. CSO projects currently in design include the Georgetown Wet Weather
Treatment Station, the Rainier Valley Wet Weather Storage project, and several green stormwater
infrastructure projects that have the potential to reduce stormwater flows into the combined sewer
system and reduce CSO project costs. King County is coordinating with the City of Seattle to identify cost
savings and efficiencies and possible joint project opportunities to minimize impacts to communities and
maximize water quality improvements.
Maintaining the region’s wastewater assets is a high priority for WTD. The objectives of the Asset
Management Program are to manage the lifecycle of a facility or asset; deliver a level of service that
meets regulatory requirements and ratepayer expectations; and fulfill WTD’s mission to protect public
health and enhance the environment by treating and reclaiming water, recycling solids, and generating
energy. WTD’s Strategic Asset Management Plan (SAMP) will be updated in 2015 and will include action
plans to improve asset management practices using data collected and analyzed under the program.
WTD is committed to continuous improvement and strives to be a state-of the-art, energy-efficient,
lean, continually improving agency. WTD completed a 10-year pilot Productivity Initiative Program in
2011 that generated nearly $84 million in savings for ratepayers. In 2011, WTD initiated a Bright Ideas
Program that asks employees to identify efficiencies and cost saving measures in the division’s
operations, which has generated over 550 ideas and is expected to save about $400,000 in 2014.
RWSP comprehensive review reporting policies call for the review of the effectiveness of policy
implementation. Based on results of this review, policy amendments are not recommended at this time.
However, this report will serve as a foundation for upcoming policy discussions with the Metropolitan
Water Pollution Abatement Advisory Committee, Regional Water Quality Committee, and County
Council regarding future recommended policy revisions and changes to guide the future of the regional
wastewater system.
ES-2 RWSP 2013 Comprehensive Review
Chapter 1
Introduction
The Regional Wastewater Services Plan (RWSP) 2013 Comprehensive Review is presented in response to
the RWSP reporting policies outlined in Ordinance 15384 and King County Code 28.86.165.1 Each
chapter in this report describes a specific set of RWSP policies and how the policies were implemented
in 2007–2013.
The major topics of each chapter are as follows:
• Chapter 2 summarizes RWSP implementation achievements made from 2007−2013. The chapter
includes information on regional treatment and conveyance capital projects, infiltration and
inflow (I/I), combined sewer overflow (CSO) control projects, and achievements made in
implementing the County’s Sediment Management Plan, cleaning up the Lower Duwamish
Waterway Superfund site, creating resources from wastewater, protecting the region’s
wastewater assets, and implementing RWSP policies.
• Chapter 3 describes how annual sewer rates and capacity charges are established, provides
sewer rate and capacity charge projections through 2030, and compares them to projections in
previous RWSP comprehensive review reports. The chapter also describes programs
implemented in 2007−2013 to increase efficiency and policy guidance on construction fund and
emergency reserves.
• Chapter 4 summarizes future population and economic growth projections and the expected
impact on the regional wastewater treatment system. It provides detail on the methodology and
assumptions for developing projections and discusses the findings as they relate to future
treatment plant capacity needs.
• Chapter 5 summarizes WTD activities under way to address emerging issues and priorities such
as climate change, chemicals of emerging concern, increased use and demand for the
byproducts of wastewater treatment, sustainable building, technology trends, regulations that
are more stringent, and equity and social justice.
• Chapter 6 summarizes conclusions from the RWSP review and identifies next steps in continuing
to implement the RWSP to protect the region’s water quality.
The remainder of this chapter describes King County’s wastewater treatment system and the RWSP.
1 RWSP annual reports and comprehensive reviews are available on the Web at http://dnr.metrokc.gov/wtd/rwsp/library.htm.
RWSP 2013 Comprehensive Review 1-1
Chapter 1. Introduction
King County’s Wastewater Treatment System
King County protects water quality and public health in the central Puget Sound region by providing
high-quality and effective treatment to wastewater collected from 17 cities, 16 local sewer utilities, and
1 Indian Tribe. The County's Wastewater Treatment Division (WTD) serves about 1.5 million people,
including most urban areas of King County and parts of south Snohomish County and northeast Pierce
County.
The wastewater system (Figure 1-1) includes three large regional treatment plants (the West Point Plant
in the City of Seattle, the Brightwater Plant in south Snohomish County, and the South Plant in the City
of Renton), one small treatment plant on Vashon Island, one community septic system (Beulah Park and
Cove on Vashon Island), one reclaimed water treatment plant in the City of Carnation, four CSO
treatment facilities (Alki, Carkeek, Mercer/Elliott West, and Henderson/Norfolk—all in the City of
Seattle), over 360 miles of pipes, 19 regulator stations, 43 pump stations, and 38 CSO outfalls.
Visit WTD’s website for more information on projects and programs:
http://www.kingcounty.gov/environment/wtd.aspx.
1-2 RWSP 2013 Comprehensive Review
Chapter1. Introduction
Figure 1-1. King County Wastewater Service Area and Facilities
RWSP 2013 Comprehensive Review 1-3
Chapter 1. Introduction
RWSP Comprehensive Review Reporting Policies
The policies below were established through adoption of
Ordinance 15384, and amended in 2012 through
Ordinance 17480. They guide the preparation of the
RWSP comprehensive reviews.
B.1. Comprehensive regional wastewater services plan
review. The executive shall submit a written report to
council and RWQC that provides a comprehensive
review of the RWSP. The report will review the
following:
a. assumptions on the rate and location of growth, the
rate of septic conversions and the effectiveness of water
conservation efforts;
b. phasing and size of facilities;
c. effectiveness of RWSP policies implementation,
for infiltration and inflow reduction, water reuse,
biosolids, CSO abatement, water quality protection,
environmental mitigation and public involvement; and
d. policy guidance for the construction fund and the
emergency capital reserves.
2. The next comprehensive regional wastewater
services plan review is due in June 2014. Subsequent
reports will be prepared every three to five years as
established by the council and RWQC following their
review of the current report. The specific due date will
be based upon the availability of necessary information,
the completion of key milestones, and the time needed
to collect and analyze data. The executive may
recommend policy changes based on the findings of the
report and other information from changing regulations,
new technologies or emerging or relevant factors.
Regional Wastewater Services Plan
In the 1990s, wastewater flow estimates based on projected population growth estimates in King
County’s wastewater service area indicated that the regional wastewater treatment system would run
out of capacity by 2010. To ensure the continuation of high-quality and effective wastewater treatment
services in the future, the County carried out an intensive planning effort, involving numerous elected
officials, representatives from local sewer agencies, organizations, and individuals from around the
region. The RWSP resulted from this effort and was adopted by the Metropolitan King County Council in
November 1999, by Ordinance 13680.
The RWSP outlines a number of important
projects, programs, and policies for King County
to implement through 2030 (Figure 1-2). It called
for building a new Brightwater Treatment Plant
to accommodate growth in the northern portion
of the wastewater service area. The plan also
called for improvements to the County’s regional
conveyance system to meet the 20-year peak
flow design standard and accommodate
increased flows; improvements to reduce
existing and future levels of I/I (clean
groundwater and stormwater) into local
collection systems; and improvements to control
CSOs so that an average of no more than one
untreated discharge occurs per year at each CSO
site by 2030.2
The RWSP also identified the need to expand
South Plant by 2029 to handle projected
increased wastewater flows in the southern and
eastern portions of the the wastewater service
area.
2 The Washington State Department of Ecology and the United States Environmental Protection Agency entered into a consent
decree with King County in July 2013 to ensure control of King County CSOs to one event per year at each CSO location by 2030.
1-4 RWSP 2013 Comprehensive Review
Chapter 1. Introduction
Figure 1-2. Regional Wastewater Services Plan Projects and Service Areas (1999-2030)
RWSP 2013 Comprehensive Review 1-5
Chapter 1. Introduction
1-6 RWSP 2013 Comprehensive Review
Chapter 1. Introduction
Ordinance 13680 was codified in the King County Code (KCC) as Chapter 28.86. Amendments to
Ordinance 13680 and KCC Chapter 28.86 made during 2007−2013 are summarized below:
• Ordinance 17587 was adopted by the King County Council in May 2013 to amend CSO control
policies to ensure they are consistent with the 2012 amended long-term CSO control plan that
the Council approved through Ordinance 17413 and the consent decree that was signed in 2013.
• Ordinance 17492 was adopted by the King County Council in December 2012 to revise a
financial policy addressing debt financing and borrowing.
• Ordinance 17480 was approved by the King County Council in December 2012 to amend RWSP
reporting policies regarding construction fund and emergency reserves in RWSP comprehensive
review reports; provide guidance for completion of the RWSP comprehensive review in June
2014; and delete the requirement for Brightwater monthly reports.
• Ordinance 16033 was approved by the King County Council in March 2008 to amend RWSP
conveyance policies to provide guidance regarding field verifications and decennial flow
monitoring; add a policy to update the CSI Program every five years; provide guidance on
information to include in CSI Program updates; and added a policy to include evaluation of other
demand management alternatives to meet identified conveyance needs
Appendix A discusses how each RWSP policy was implemented in 2007−2013. This report does not
recommend policy amendments at this time, but does serve as a foundation for upcoming discussions
with MWPAAC, RWQC and the Council on any proposed policy changes for the years ahead.
Visit the RWSP website for more information on this regional plan and to view the entire contents of the
RWSP 2013 Comprehensive Review:
http://www.kingcounty.gov/environment/wtd/Construction/planning/rwsp.aspx.
RWSP 2013 Comprehensive Review 1-7
Chapter 1. Introduction
1-8 RWSP 2013 Comprehensive Review
Chapter 2
RWSP Achievements in 2007−2013
This chapter summarizes RWSP implementation achievements made from 2007 through 2013. The
chapter includes information on RWSP capital projects designed to provide needed regional treatment
and conveyance capacity to meet population and employment growth, reduce infiltration and inflow
(I/I), and meet the County’s commitment to control its combined sewer overflows (CSOs) by 2030. The
chapter also summarizes achievements made in implementing the County’s Sediment Management
Plan, cleaning up the Lower Duwamish Waterway Superfund site, creating resources from wastewater,
protecting the region’s wastewater assets, and implementing RWSP policies.
RWSP Policies Implementation
The RWSP policies are part of the King County Code Chapter 28.86. Appendix A includes each policy and
summary information on how the policy was implemented in 2007−2013. The policies provide guidance
on the following areas:
• Ensuring there is sufficient regional treatment and conveyance capacity to meet population and
employment growth projections
• Reducing I/I into the regional conveyance system
• Achieving control of all the County’s CSOs by 2030
• Creating resources from the wastewater treatment process
• Protecting and monitoring water quality of the region’s water bodies
• Providing wastewater services in a cost-effective and environmentally responsible manner
• Planning comprehensively
• Being a good neighbor through controlling nuisance odors, engaging the public, and providing
mitigation measures for environmental impacts from the construction and operation of
wastewater facilities
• Financing, including setting sewer rates and capacity charges for the regional wastewater
system
• Reporting on the progress of RWSP implementation
RWSP comprehensive review reporting policies call for the inclusion of information on the effectiveness
of policy implementation and note that the County Executive may recommend policy changes based on
the findings of the report and other information from changing regulations, new technologies, or
emerging or relevant factors. Appendix A discusses how each policy was implemented in 2007−2013,
and as a next step in the RWSP comprehensive review process, WTD will be working with MWPAAC’s
RWSP 2013 Comprehensive Review 2-1
Chapter 2. RWSP Achievements in 2007−2013
Engineering and Planning Subcommittee and the County Council’s Regional Water Quality Committee
(RWQC) to discuss policy implementation and effectiveness and any recommendations for policy
amendments. This report does not recommend policy amendments at this time, but does serve as a
foundation for the upcoming discussions with MWPAAC and RWQC.
Several policy amendments were made during 2007−2013. They are summarized below and noted in
Appendix A.
• Amendments to RWSP CSO control policies. In May 2013, the County Council approved
Ordinance 17587, amending CSO control policies. The amendments ensure the policies are
consistent with the 2012 amended long-term CSO control plan that the County Council
approved through Ordinance 17413 and the Consent Decree that was signed in 2013.
• Amendments to RWSP financial policies. In December 2012, the County Council approved
Ordinance 17492, revising a financial policy addressing debt financing and borrowing.
• Amendments to RWSP reporting policies. In December 2012, the County Council approved
Ordinance 17480, amending RWSP reporting policies. The amendments included the following:
o Adding information on policy guidance for construction fund and emergency reserves in
RWSP comprehensive review reports
o Providing guidance for the next RWSP comprehensive review to be completed in June
2014
o Deleting requirement for Brightwater monthly reports
• Amendments to RWSP conveyance policies. In March 2008, the County Council approved
Ordinance 16033, amending RWSP conveyance policies. The amendments included the
following:
o Added policy guidance to confirm assumptions and needs (field verifications,
decennial flow monitoring)
o Added a policy to update the CSI Program every five years and provided guidance on
information to include in CSI Program updates
o Added a policy to include evaluation of other demand management alternatives to
meet identified conveyance needs
RWSP Capital Projects
RWSP policies call for the County to ensure there is sufficient treatment plant and conveyance system
capacity to meet population and employment growth through 2030. The policies provide guidance for
facility sizing to accommodate population growth.
2-2 RWSP 2013 Comprehensive Review
Chapter 2. RWSP Achievements in 2007−2013
RWSP policies also call for the County to carry out projects to reduce the impact of I/I on the regional
system’s capacity and to control CSOs to the Washington State standard of one untreated overflow from
each CSO location per year based on a 20-year moving average.
This section provides information on the treatment plant, conveyance, I/I, and CSO control projects that
were under way or completed in 2007−2013.
Brightwater Treatment System
A major achievement was the completion and startup of the Brightwater Treatment System. The new
facilities include a state-of-the-art treatment plant (Figure 2-1), 13 miles of conveyance, including the
pipes and pumps taking wastewater to and from the plant, and a marine outfall. The Brightwater system
began full operations in fall 2012, and its completion marks the region’s largest clean-water project of
the last half century. Brightwater’s membrane bioreactor (MBR) technology produces effluent that is 70
percent cleaner than that produced by conventional wastewater technologies.
Figure 2-1. Brightwater Treatment Plant
The RWSP also provides guidance for the County’s wastewater facilities to be a good neighbor and to
meet or exceed its regulatory requirements. A commitment during the design of Brightwater was to
ensure there are no detectable odors at the treatment plant’s property boundary and beyond. To date,
no odor complaints have been attributed to the Brightwater Plant.
More information on the Brightwater Treatment System is available at
http://www.kingcounty.gov/environment/wtd/Construction/North/Brightwater.aspx.
RWSP 2013 Comprehensive Review 2-3
Chapter 2. RWSP Achievements in 2007−2013
Brightwater Education and Community Center
The Brightwater Education and Community Center (Figure 2-2) opened in September 2011. The center
features:
• 70 acres of public open space with three miles of walking trails and 40 acres of natural habitat
• A community center with meeting rooms available for public rental
• A clean water learning space featuring both indoor and outdoor settings
Figure 2-2. Brightwater Education and Community Center
During the Brightwater siting process, the public asked King County to include the center as part of
treatment plant design to provide an asset to the host community. In the first year of operation, the
center served approximately 4,000 4th-8th graders in school programs, 300 participants in family
programs, and 150 teachers in professional development workshops.
More information on the Brightwater Education and Community Center is available at
http://www.kingcounty.gov/environment/brightwater-center.aspx.
Carnation Treatment Plant
In 2002, the King County Council amended the Comprehensive Water Pollution Abatement Plan and
added the City of Carnation to the County’s wastewater service area. The City of Carnation decided to
replace on-site septic systems with a new wastewater treatment facility and collection system to better
protect public health and the environment, achieve the City’s comprehensive plan goals, and maintain
and enhance community livability. The City designed and built the local wastewater collection system
and contracted with King County to design, build, operate, and maintain a new treatment plant and
associated discharge facilities.
The Carnation Treatment Plant (Figure 2-3) was completed in 2008. The plant uses MBR technology and
is designed to treat wastewater to Class A reclaimed water standards. In March 2009, the plant started
discharging its Class A reclaimed water to enhance a wetland in the Chinook Bend Natural Area. The
plant has a dual discharge system. In addition to the wetland, an outfall discharges to the Snoqualmie
2-4 RWSP 2013 Comprehensive Review
Chapter 2. RWSP Achievements in 2007−2013
River only when required by a regulatory agency (such as when necessary to augment flows in the
Snoqualmie River), in case of plant upset or failure of ultraviolet disinfection system, or during periods of
scheduled maintenance.
More information on the Carnation Treatment Plant is available at
http://www.kingcounty.gov/environment/wtd/About/System/Carnation.aspx.
Figure 2-3. Carnation Treatment Plant
Conveyance System Improvement Projects
In accordance with RWSP policies, the Conveyance System Improvement (CSI) Program works to provide
sufficient capacity in areas of the separated conveyance system to meet projected demands and the
RWSP 20-year peak flow design standard. The 20-year peak flow design standard was adopted by the
King County Council to serve as an objective measure for designing and building conveyance facilities
intended to meet National Pollutant Discharge Elimination System (NPDES) permit requirements. A 20-
year peak flow consists of both storm flow (I/I) and base flow (wastewater from homes and businesses).
In setting this standard, the King County Executive and King County Council recognized that it is one of
the most stringent standards in the nation and would require time to upgrade the conveyance system to
meet this standard.
RWSP CSI Projects Completed in 2007-2013
The RWSP CSI projects that were completed during 2007 through 2013 are as follows:
• Juanita Bay Pump Station Replacement project (Figure 2-4). Construction of this project was
completed in 2008. It replaced the aging 14.2-mgd (million gallons per day) Juanita Bay Pump
Station with a 30.6-mgd pump station.
• Hidden Lake Pump Station and Sewer Improvement project (Figure 2-5). Construction of this
project was completed in 2009.The project included building a new Hidden Lake Pump Station in
the City of Shoreline, replacing approximately 12,000 feet of the Boeing Creek Trunk, and
RWSP 2013 Comprehensive Review 2-5
Chapter 2. RWSP Achievements in 2007−2013
building a 500,000-gallon underground storage facility in Boeing Creek Park. The new pump
station has a pumping capacity of 6.8 mgd, an increase of 2.5 mgd over the replaced pump
station’s capacity.
• Bellevue Pump Station Upgrade and Force Main Installation project (Figure 2-6). Construction
of this project was completed in 2010. The project included construction of a new force main
and replacement of an 8-mgd pump station. The refurbished pump station’s capacity is able
to convey more than 13 mgd of wastewater from west and central Bellevue to the South
Treatment Plant.
• Bellevue Influent Trunk Improvement project. Construction of this project was completed in
2012. The project included constructing a pipeline that parallels the Bellevue Influent Trunk to
serve the rapidly growing downtown Bellevue area.
• Kent-Auburn Conveyance System Improvements project (Phase A). Construction on this project
was completed in early 2014. The project included construction of two new pipelines, the Kent
East Hill Diversion in Kent and the Stuck River Trunk in Auburn.
Figure 2-4. Juanita Bay Pump Station Figure 2-5. Hidden Lake Pump Station
Figure 2-6. Bellevue Pump Station
2-6 RWSP 2013 Comprehensive Review
Chapter 2. RWSP Achievements in 2007−2013
RWSP CSI Projects in Development in 2007-2013
CSI projects that are currently being developed are as follows:
• Sunset and Heathfield Pump Stations and Force Main Upgrade project. This project began
predesign in 2013. The project will update the undersized Sunset and Heathfield pump stations
and associated sewer force main in Bellevue. Originally constructed in 1965 (with upgrades in
1987), the pump stations have a system capacity of 18 mgd. The upgraded system will convey a
peak flow of 30 mgd and will improve odor control. Construction is expected to begin in 2016.
More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/East/SunsetHeathfield.aspx.
• North Creek Interceptor project. This project will replace a main wastewater conveyance
pipeline that serves parts of Bothell and unincorporated Snohomish County. The project
includes construction of approximately 10,000 feet of new sewer line and connecting it to
previously constructed pipe. This new pipeline ranges from 30 to 48 inches in diameter.
Construction will take place in both the City of Bothell and unincorporated Snohomish County.
Construction is expected to begin in 2014. More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/North/NCI.aspx.
• North Lake Sammamish Flow Diversion project. Alternatives analysis is under way for this
project. The project will divert wastewater flows from the North Lake Sammamish Basin to the
Brightwater Treatment Plant to free up capacity in the East Side Interceptor. Construction is
expected to begin in 2017. More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/East/NLkSamFlowDiversion.aspx.
• North Mercer Island Interceptor and Enatai Interceptor Upgrade project. This project is just
beginning; work on alternatives analysis is expected to begin in 2014. The project will increase
the capacity of the existing North Mercer Island Interceptor and Enatai Interceptor to meet the
RWSP design standard. The North Mercer Island and Enatai Interceptors serve areas in North
Mercer Island, the southwest portion of Bellevue, and the Town of Beaux Arts Village.
Construction is expected to begin in 2019. More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/East/NMIEnatai.aspx.
• Lake Hills and Northwest Lake Sammamish Interceptor Upgrade project. This project will
replace the existing Lake Hills Trunk and upgrade the Northwest Lake Sammamish Interceptor to
meet the RWSP conveyance design standard. The existing gravity pipelines are about 4.5 miles
long and are located in the City of Redmond. This project is just beginning; work on alternatives
analysis is expected to begin in 2014.
Decennial Flow Monitoring
As part of the CSI Program, the Decennial Flow Monitoring project began in 2009 and was completed in
2011. The project was carried out according to RWSP conveyance policies, which call for the Wastewater
Treatment Division to conduct systemwide flow monitoring in the separated conveyance system every
10 years to correspond with the federal census. The project collected flow data over two wet seasons.
RWSP 2013 Comprehensive Review 2-7
Chapter 2. RWSP Achievements in 2007−2013
Data collected from 235 flow meter locations will inform the CSI Program update that is under way and
is also available to local agencies for use in planning and designing their systems.
2015 CSI Program Update
Work on the 2015 CSI Program update began in 2013. The last update was completed in 2007. RWSP
policies call for regular program updates to verify, make adjustments to, or identify new conveyance
system needs. WTD will continue working with the Engineering and Planning Subcommittee of the
Metropolitan Water Pollution Abatement Advisory Committee (MWPAAC) and individual agencies to
complete the program update. Activities to complete the update include the following:
• Analyzing and applying new flow data and population forecasts to produce an updated list of
capacity needs and priorities
• Developing conceptual projects and planning-level cost estimates to meet capacity needs
• Prioritizing conceptual projects
More information on the CSI Program is available at
http://www.kingcounty.gov/environment/wastewater/CSI.aspx.
Reducing Infiltration and Inflow
I/I is water that enters the sewer system through cracked pipes, leaky manholes, or improperly
connected storm drains, downspouts, and sump pumps (Figure 2-7). Most inflow comes from
stormwater and most infiltration comes from groundwater. About 75 percent of the peak flow in the
County’s separated conveyance system is from I/I; 95 percent originates in local systems, primarily from
side sewers on private property.
Figure 2-7. Sources of Infiltration and Inflow
2-8 RWSP 2013 Comprehensive Review
Chapter 2. RWSP Achievements in 2007−2013
In 2007−2013, WTD continued to implement the Executive’s Recommended I/I Control Program that
was approved by the King County Council through Motion 12292 in May 2006. Implementation focused
on completing an initial I/I reduction project in the Skyway Water and Sewer District. The project
reached substantial completion in March 2012. It included replacing side sewers serving 302 residential
properties, over 90 manholes, and approximately 19,000 linear feet of 8-inch-diameter sewer main.
The purpose of the project was to determine whether and how it is possible to cost-effectively remove
enough I/I from the regional conveyance system to delay, reduce, or eliminate a planned CSI project.
The definition of cost-effectiveness focuses on regional benefit in terms of capital project costs. The
project was developed in consultation with MWPAAC’s Engineering and Planning Subcommittee during
the discussions that led to development of the recommended I/I Control Program.
One season of post-construction flow monitoring has been completed. Preliminary results indicate that
the project resulted in reducing peak flow by about 19 percent, which is less than anticipated. Reasons
for this result include the following: (1) properties may have had more sump pumps than anticipated, (2)
fewer parcels than planned underwent complete rehabilitation because of increasingly difficult field
conditions as work progressed into the wet season and more hardscape features than anticipated were
present on individual properties, and (3) the area that contributes I/I to the sewer basin appears to have
been larger than originally delineated. However, the Skyway initial I/I reduction project did provide
benefits including delaying the need for storage. WTD intends to conduct another wet-season of post-
construction flow monitoring to confirm or update the results of the project.
In accordance with the approved I/I Control Program, WTD will work with the Engineering and Planning
Subcommittee of MWPAAC in 2015 to develop recommendations for long-term I/I reduction and
control.
More information on the I/I Control Program is available at
http://www.kingcounty.gov/environment/wastewater/II.aspx.
Protecting Our Waters Program
WTD made significant progress in 2007−2013 to implement the County’s CSO Control Program, called
Protecting Our Waters. CSOs are discharges of wastewater and stormwater from combined sewers into
water bodies during heavy rainstorms when sewers are full. Combined sewers, which carry both
wastewater and stormwater, exist in many parts of older cities across the nation, including Seattle. To
protect treatment plants and avoid sewer backups into homes, businesses, and streets, combined
sewers in Seattle sometimes overflow into nearby water bodies. Although the wastewater in CSOs is
greatly diluted by stormwater, CSOs may be harmful to public health and aquatic life because they can
carry chemicals and disease-causing pathogens. The County began its CSO control efforts in the late
1970s.
The County is committed to controlling all its CSO sites by 2030. About one-half of its 38 CSO sites are
controlled. Projects are under way or planned to control the remaining uncontrolled CSOs.
A summary of the Protecting Our Waters Program’s achievements in 2007−2013 follows.
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Chapter 2. RWSP Achievements in 2007−2013
Control of Ballard CSO
Control of the Ballard CSO was incorporated into the Ballard Siphon Replacement project’s design and
construction. The project achieved substantial completion in 2013. The project included building a new
85-inch-diameter siphon pipe under Salmon Bay between the Ballard and Interbay areas of Seattle. The
new pipe replaced two 36-inch-diameter wooden stave pipes that have served the Ballard community
since the 1930s. The project may also result in reducing overflows at the 11th Ave NW CSO site.
Projects to Control CSOs along Puget Sound Beaches
Construction began on four projects to control CSOs along Puget Sound Beaches (Figure 2-8):
• The North Beach CSO control project is building an underground storage tank in the rights-of-
way in Northwest Blue Ridge Drive and Triton Drive Northwest in Seattle. The facility will store
excess flows during large storms when the North Beach Pump Station reaches maximum
capacity. Construction is expected to be complete in 2015. More information on the project is
available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/NBeachCSOStorage.aspx.
• The South Magnolia CSO control project is building an underground storage tank adjacent to
Smith Cove Park, south of the Magnolia Bridge in Seattle. The facility will store peak flows when
the South Magnolia Trunk reaches maximum capacity. Construction is expected to be complete
in 2015. More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/SMagnoliaCSOStorage.aspx
• The Murray CSO control project is building an underground storage tank beneath property
across the street from Seattle’s Lowman Beach Park. The facility will store peak flows when the
Murray Pump Station reaches maximum capacity. Construction is expected to complete in 2016.
More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/MurrayCSOStorage.aspx.
• The Barton CSO control project is constructing roadside rain gardens, a type of green
stormwater infrastructure (GSI) in the City of Seattle’s planting strips in the Sunrise Heights and
Westwood neighborhoods. Street runoff will be diverted away from storm drains and into the
vegetated swales. Once in the swales, the water will filter through soil to an underdrain, which
will take the water to a deep well for slow infiltration underground. Construction is expected to
be complete in 2015. More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/BartonCSO-GSI.aspx.
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Chapter 2. RWSP Achievements in 2007−2013
Figure 2-8. Location of the Puget Sound Beach CSO Control Projects
CSO Control Program Review and Plan Update
In accordance with RWSP policies, the CSO Control Program review and plan update was completed in
2012. As a result, in September 2012, the County Council approved an amendment to the County’s long-
term CSO control plan through Ordinance 17413. The plan includes nine projects to control the
remaining 14 uncontrolled CSOs by 2030 (Figure 2-9). The U.S. Environmental Protection Agency (EPA)
also approved the amended plan in 2013, and the plan is incorporated into the consent decree that the
County entered into with the U.S. Department of Justice, EPA, and Washington State Department of
Ecology (Ecology) in 2013. To date, the County is on schedule to meet all the milestones outlined in the
consent decree.
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Chapter 2. RWSP Achievements in 2007−2013
Figure 2-9. King County’s Long-Term CSO Control Plan Projects
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Chapter 2. RWSP Achievements in 2007−2013
Work began on three projects outlined in the Council-approved CSO control plan: Georgetown Wet
Weather Station to control the Brandon and South Michigan CSOs; Rainier Valley Wet Weather Storage
to control the Hanford #1 CSO, and the Highland Park and South Park green stormwater infrastructure
(GSI )project to help control the West Michigan and Terminal 115 CSOs.
• The Georgetown Wet Weather Treatment Station includes construction of a CSO wet-weather
treatment station between the Brandon Street and South Michigan Street Regulator Stations,
conveyance pipeline, and a new outfall structure to release the treated water into the Duwamish
Waterway. When constructed, the station will have the capacity to treat up to 66 million gallons
of combined rain and wastewater a day that would otherwise have discharged directly to the
Duwamish without treatment during storm events. Construction is expected to begin in 2017.
More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/BrandonMichiganCSO.aspx.
• The Rainier Valley Wet Weather Storage project will install a new sewer pipeline near the
intersection of Rainier Avenue South and Martin Luther King Boulevard South in Seattle to divert
flows to an existing pipe with extra capacity. Any excess flows from this area will be routed to a
new storage tank at the intersection of South Hanford Street and South 27th Avenue.
Construction is expected to begin in 2015. More information on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/HanfordCSO.aspx.
• The Highland Park and South Park GSI project is exploring the feasibility of reducing West
Michigan and Terminal 115 CSOs using GSI or a combination of GSI and storage for sewer
overflows. Based on street layouts and results of soils and groundwater testing, King County will
discuss options for GSI with the community. GSI construction is expected to begin in 2016, and if
needed, work on the storage pipe portion of the project would begin in 2019. More information
on the project is available at
http://www.kingcounty.gov/environment/wtd/Construction/Seattle/WMichT115CSO.aspx.
RainWise Rebate Program
Rain gardens and cisterns can help control stormwater that enters the combined sewer system. Through
a memorandum of agreement (MOA) with Seattle Public Utilities (SPU), WTD began offering
opportunities for residents to participate in the RainWise Rebate Program where there are potential
benefits to the County’s CSO control projects. The program pays for rain gardens and cisterns on private
property in some parts of the city and was started by SPU in 2010. Since then, over 250 rain gardens and
cisterns are now helping to control stormwater runoff and preventing CSOs. The MOA outlines the cost-
sharing and other responsibilities of each agency. More information on the RainWise program is
available at http://www.kingcounty.gov/environment/wastewater/CSO/BeRainwise.aspx.
Water Quality Assessment and Monitoring Study
Work began in 2013 on the Water Quality Assessment and Monitoring Study (assessment) that was
called for in Ordinance 17413. The purpose of the study is to examine how upcoming Protecting Our
Waters projects can be sequenced and integrated to optimize the investment being made in these
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Chapter 2. RWSP Achievements in 2007−2013
projects. In September 2013, the County Council approved the study’s scope of work through Motion
13966. The assessment will examine local water quality issues near King County CSOs in Elliott Bay, Lake
Union/Ship Canal, and the Duwamish River. Results from the assessment will be used to inform the next
CSO Control Program review and plan update, which is due to regulators in 2018. The goals of the
assessment are as follows:
• Provide information on how CSO control can work in conjunction with other water quality
projects to maximize water quality improvements
• Identify opportunities to lower the cost of CSO control
• Identify technologies that could potentially improve water quality such as GSI
• Establish baseline conditions for mandatory post-construction monitoring of CSO control
projects
More information on the assessment is available at
http://www.kingcounty.gov/environment/wastewater/CSO/WQstudy.aspx.
Implementing the Sediment Management Plan
As a part of RWSP implementation, WTD is carrying out a Sediment Management Plan (SMP) to
remediate contaminated sediments near CSO outfalls. Most of the contamination occurred in the early
to mid-1900s. The SMP addresses sediment contamination cleanups that are required under federal
Comprehensive Environmental Response, Compensation, and Liability Act (Superfund) and state Model
Toxic Control Act regulations. The SMP’s objectives are to repair potential environmental damage
through a timely, efficient, and economical process. The following activities were carried out as part of
implementing the SMP during 2007–2013:
• Completed cleanup of the former Denny Way CSO site off of Myrtle Edwards Park in Seattle and,
in 2008, began monitoring sediment quality (to be completed in 2018)
• Improved modeling to predict deposition of contaminants around CSO outfalls
• Completed post-construction monitoring of the Diagonal/Duwamish cleanup site
• Conducted sampling of sediments in the East Duwamish Waterway Superfund site and as part of
the East Waterway Group finalized the East Duwamish Waterway remedial investigation and
completed a draft feasibility study. The East Waterway Group is a partnership between the City
of Seattle, King County, and the Port of Seattle.
More information on the SMP is available at
http://www.kingcounty.gov/environment/wastewater/SedimentManagement.aspx .
Cleaning Up the Lower Duwamish Waterway Superfund Site
King County continues to work to improve water quality in the Lower Duwamish Waterway Superfund
site through actions such as controlling CSOs, restoring habitat, capping and removing sediments, and
controlling toxicants from industries and stormwater runoff. Since the 1960s, regional source control
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efforts have reduced flows of industrial waste and sewage into the Lower Duwamish by 98 percent, or
27 billion gallons per year.
The County is also partnering with the City of Seattle, the Port of Seattle, and the Boeing Company as
part of the Lower Duwamish Waterway Group (LDWG). The LDWG has been working with EPA and
Ecology since 2001 to study contamination and determine the best and most effective alternatives to
clean up the Lower Duwamish Waterway. During the 2007–2013 timeframe, the LDWG completed a
remedial investigation and feasibility study for the Lower Duwamish Waterway Superfund Site and
started a study to better understand who is eating contaminated seafood from the Duwamish River.
In 2013, EPA issued the Proposed Plan for the Lower Duwamish Waterway Superfund Site, which
presents a Preferred Alternative to clean up contamination in the in-waterway portion of the Lower
Duwamish Waterway Superfund site. EPA is expected to issue a Record of Decision in third quarter of
2014 to direct cleanup actions and long-term monitoring.
The County, in partnership with the LDWG, carried out engagement and outreach activities with
interested industries, businesses, residents, and environmental and community groups throughout the
efforts to develop the remedial investigation, the feasibility study, and on EPA’s proposed cleanup plan.
The process to allocate cleanup costs among potentially responsible parties, including King County, is
under way.
In addition, WTD’s Lower Duwamish Waterway Green Grants Program began providing grant funding in
2011 for air or water quality improvement projects, environmental education, and community outreach
efforts within the Duwamish River Valley. The funding supports projects that reduce air pollution,
prevent CSOs, and prevent pollution from going into the Duwamish River. Past projects have included
roadside rain gardens, outreach to businesses on how to implement best management practices to stop
stormwater pollution, an art installation that measures air quality, and wetland restoration.
More information on the County’s efforts to clean up the Lower Duwamish Waterway is available at
http://www.kingcounty.gov/environment/wastewater/Duwamish-waterway.aspx.
Creating Resources from Wastewater
RWSP policies provide guidance on beneficial uses for byproducts from wastewater treatment—
biosolids and digester gas from the solids treatment process and reclaimed water from the liquids
treatment process. This section provides information on achievements made in 2007−2013 through
WTD’s Biosolids Recycling Program, Energy Recovery and Efficiency Program, and Reclaimed Water
Program.
Biosolids Recycling Program
Biosolids are the nutrient-rich organic material produced by treating wastewater solids. After being
processed and treated, biosolids are beneficially used as a fertilizer and soil amendment in agriculture
and forestry or as an ingredient in compost. In 2007−2013, King County recycled 100 percent of its
biosolids for these uses; the description of uses for 2007−2012 is provided in each year’s RWSP annual
reports.
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Chapter 2. RWSP Achievements in 2007−2013
WTD launched the County’s biosolids brand, Loop®, in 2012. The development of the Loop brand is part
of a long-term strategic goal to increase public support and strengthen demand for biosolids. More
information on the benefits and uses of Loop is available at http://www.loopforyoursoil.com/.
In 2013, 115,801 wet tons of Loop biosolids were produced at the West Point, South, and Brightwater
treatment plants, all of which were recycled and used beneficially as a nutrient-rich soil amendment for
forestry and agricultural applications or was used to make compost. The sale of biosolids generated over
$188,000 in fertilizer revenue from customers.
The biosolids were used as a fertilizer andsoil amendment for a variety of applications:
• About 6,800 acres of dryland wheat in Douglas County as part of the Boulder Park Soil
Improvement Project
• About 2,600 acres of hops, orchards, and wheat at Natural Selection Farms in the Yakima Valley
• Over 600 acres of Douglas fir plantations on state forestlands and on Hancock’s Snoqualmie
Forest as part of the Mountains to Sound Greenway Biosolids Forestry Program
Highlights of other achievements for the Biosolids Recycling Program in 2007−2013 are as follows:
• Construction of the West Point Digestion Improvement project was completed. The project will
enhance the reliability of the West Point plant’s solids digestion system and reduce the risk of
digester upsets under current and future solids loading conditions.
• Progress was made on a project at the West Point Plant to upgrade and replace the screening
equipment that filters out trash and other debris. The project will meet the state’s biosolids
management rule requiring significant removal of manufactured inerts (trash and plastics) from
biosolids. Construction of the screening project is expected to be complete in late 2014.
• An analysis of alternative uses and market opportunities for biosolids was completed in 2009.
The analysis provided cost-benefit information for land application, composting, and alternative
energy production. The process confirmed that land application and composting of biosolids are
the most cost-effective and reliable options at this time. The report on the alternative uses and
market opportunities is available at
http://www.kingcounty.gov/environment/wastewater/Biosolids/DocumentsLinks.aspx.
• GroCo compost, which is made with Loop is now “Declare” certified, which meets Living Building
Challenge (LBC) standards. Declare offers LBC project teams a materials guide for product
specification. LBC is the built environment's most rigorous sustainability performance standard.
More information on the Declare label is available at http://www.declareproducts.com/.
Several research studies were conducted. Highlights from the studies are listed below.
• In 2008, WTD participated in a study through the Northwest Biosolids Management Association
to quantify the carbon sequestration benefits of using biosolids and other organic residuals as a
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Chapter 2. RWSP Achievements in 2007−2013
soil amendment for land application. Results showed a significant increase in carbon stored in
agricultural soils, indicating that use of biosolids as a soil amendment has the potential to
reduce the carbon footprint while helping secure the sustainability of agriculture in the state.
For example, the benefit of using Loop in 2012 offset over 42,000 tons of carbon dioxide
equivalents, which is similar to taking 8,000 cars off the road that year (Figure 2-10). The results
are similar for 2013. Because of investments in energy conservation, renewable energy
production and carbon and nutrient recycling, the WTD is 70 percent of the way to being
carbon-neutral in its operations.
Figure 2-10. WTD’s 2012 Carbon Impact
• In summer 2009, the County began collaborating on a carbon-sequestration demonstration
project in a borrow pit at Island Center Forest on Vashon Island.3 Researchers are evaluating the
ability of composted organic residuals (biosolids, food waste, and woody debris) to recover soil
quality by capturing and storing carbon, improving soil health, and enhancing vegetation growth
on this degraded site. Long-term monitoring in under way.
• In 2009, a biosolids research and demonstration garden was installed at South Treatment Plant.
University of Washington scientists studied the safety of vegetables grown in a sandy loam soil
mix and a biosolids compost soil mix. The research team noted that vegetables grown in the
biosolids compost mix were deemed safe and the growth was considered lush.
More information on the County’s Biosolids Recycling Program is available at
http://www.kingcounty.gov/environment/wastewater/Biosolids.aspx.
Energy Recovery and Efficiency Program
RWSP policies call for the County to use digester gas, an energy-rich methane gas naturally produced as
a byproduct of solids treatment, for energy and other beneficial purposes when it is cost-effective to do
so. In addition, the County’s Strategic Climate Action Plan includes energy goals to implement energy
efficiencies and increase renewable energy production.
3 A borrow pit is an area where material (usually soil, gravel or sand) has been dug for use at another location.
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Chapter 2. RWSP Achievements in 2007−2013
The South, West Point, and Brightwater treatment plants use digester gas to produce heat, electricity,
and natural gas. At South Plant, digester gas that is not used for in-plant purposes is “scrubbed” to the
quality required for pipeline natural gas and then sold to Puget Sound Energy.
A major achievement during 2007−2013 is the completion and startup of the Waste-to-Energy
cogeneration system at the West Point Plant. The cogeneration system creates electricity from the
facility’s digester gas and captures the heat generated from the influent pump engines. The system
reduces West Point’s demand for electricity supplied from the power grid, and will provide a significant
portion of West Point’s heat demand for most of the year. The cogeneration system, scheduled to be
online in 2014, will produce about 18,000 megawatt hours (MWh) of “green” electricity each year.
Seattle City Light will purchase power produced by the engines, including renewable energy credits. This
partnership will help Seattle City Light achieve its 15 percent renewable energy goal by 2020 in
accordance with Washington Initiative 937. The facility is expected to generate $1.4 million in annual
revenue to WTD from the sale of green electricity.
Other achievements during 2007−2013 include:
• Replacement of blowers at the West Point and South plants with more efficient blowers.
• WTD’s energy team conducts energy audits on facilities that consume over 5,000 million British
Thermal Units (MBtu) of annual energy. Results of the audits will inform future energy-efficiency
capital projects.
• In 2012, a request for information was advertised inviting local developers and commercial
owners to submit ideas for privately owned district energy systems that could extract and
recover heat from WTD’s conveyance system.
More information on WTD’s energy program is available at
http://www.kingcounty.gov/environment/wastewater/ResourceRecovery/Energy.aspx.
Reclaimed Water Program
RWSP water reuse policies provide guidance to King County on the development and implementation of
its Reclaimed Water Program. WTD has been safely producing and using reclaimed water since 1997.
Two major achievements in the Reclaimed Water Program occurred during 2007−2013 with the
completion and startup of the Carnation and Brightwater treatment plants. Both facilities produce and
distribute reclaimed water.
Reclaimed Water Planning Studies
WTD participated in several reclaimed water planning studies during this timeframe. In 2007, WTD
completed a preliminary analysis of reclaimed water options in the Green River Valley to answer
questions raised by the Cities of Auburn, Covington, Kent, Renton, and Tukwila. Information from the
study was incorporated into the reclaimed water comprehensive planning process that occurred in
2009–2012.
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Chapter 2. RWSP Achievements in 2007−2013
King County and the Covington Water District signed a memorandum of agreement in 2007 to jointly
fund and pursue a phased approach to explore opportunities for reclaimed water development in the
district’s service area. Results from this effort were incorporated into the reclaimed water
comprehensive planning process, described below.
In 2008–2009, WTD worked with the SPU on Seattle’s economic analysis of the potential for providing
reclaimed water from the Brightwater Treatment Plant to large irrigators and other potential users of
nonpotable water in north Seattle. Information from this analysis was incorporated into the reclaimed
water comprehensive planning process.
In 2009−2012, WTD initiated a reclaimed water comprehensive planning process to determine whether
and how King County should expand its existing Reclaimed Water Program over the next 30 years. WTD
worked closely with local water and sewer utilities throughout the process, and a database was
developed on potential reclaimed water uses in the region. WTD developed and analyzed three
conceptual strategies for reclaimed water satellite or skimming facilities to serve potential reclaimed
water uses.
Reclaimed Water Production and Use in 2013
As part of RWSP annual reports, information is provided on reclaimed water used each year for in-plant
or off-site purposes. Information for 2013 follows.
South Treatment Plant
South Plant produced 81.7 million gallons (MG) of reclaimed water in 2013. The majority of the water
was used at the plant for process water and landscape irrigation. If the reclaimed water were not
available for these uses, WTD would have to use potable water, which would have increased the
facility’s operational costs by $155,380 in 2013.
About 2.94 MG of reclaimed water was distributed and used off site by reclaimed water customers,
including the City of Tukwila. The city uses reclaimed water for irrigation of the Starfire Sports Complex
and wetland plants nursery, and for city public works uses such as street sweeping and sewer flushing.
West Point Treatment Plant
The West Point Plant produced 189.2 MG of reclaimed water in 2013. All of the reclaimed water
produced was used at the plant site for process water. If the reclaimed water were not available for
these uses, WTD would have to use potable water for such applications, which would have increased the
facility’s operational costs by $1,242,411 in 2013.
Carnation Treatment Plant
In 2013, the Carnation Plant discharged 31.93 MG of reclaimed water to enhance a wetland in the
County's Chinook Bend Natural Area.
Brightwater Treatment Plant
About 30.2 MG of reclaimed water from the Brightwater Plant was distributed to the Brightwater
Education and Community Center and the Willows Run Golf Course in 2013. The water was used for
irrigation, toilets/urinals, and public art. In addition, 336 MG of reclaimed water was produced and used
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Chapter 2. RWSP Achievements in 2007−2013
for process water at the plant. If the reclaimed water were not available for these uses, WTD would
have had to use potable water, which would have increased the facility’s operational costs by
$1,802,235 in 2013.
Protecting our Assets
It would cost more than $20 billion to build King County’s wastewater system from the ground up today,
and the value of existing facilities is estimated at about $6 billion. RWSP policies provide guidance for an
asset management program to maintain and repair equipment and facilities and to develop an asset
management plan. In addition, the Council-approved scope of work (Motion 13758) for the 2013 RWSP
comprehensive review report included adding information on assumptions regarding asset management
and replacement.
Maintaining the region’s wastewater assets is a high priority for WTD. The division’s Asset Management
Program oversees inspection of the regional treatment facilities and conveyance system, repairing and
replacing aging facilities, and developing plans to address ongoing system issues. The primary objectives
of the program are to manage the whole lifecycle of assets in a manner that minimizes the total costs of
owning, maintaining, and operating them; deliver a level of service that meets regulatory requirements
and ratepayer expectations; and fulfill WTD’s mission to protect public health and enhance the
environment by treating and reclaiming water, recycling solids, and generating energy. WTD continues
to update its asset management plans and practices. The assumptions, or principles, that guide WTD’s
Asset Management Program are as follows:
• Applying the principle that proper management of the region’s wastewater assets is
essential for public and environmental health and safety.
• Using Enterprise Asset Management (EAM) to standardize the management of assets across
sections, facilities, business units, and geographical locations. EAM integrates techniques for
control and optimization throughout asset lifecycles, including design, commissioning,
operations, and replacement. Effective EAM allows WTD to do the following:
o Maximize return on assets
o Balance costs and risks
o Improve asset decision making
o Comply with required regulations
o Increase asset service responses and enhance efficiency
o Lower total cost of ownership
• Maintaining an accurate asset inventory is essential for a successful asset management
program.
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Chapter 2. RWSP Achievements in 2007−2013
• Understanding criticality (the likelihood of failure [asset condition] and consequence of
failure) is key to managing risk and fulfilling WTD’s mission.
• Continually assessing and confirming criticality of an asset to ensure efficient allocation of
resources is of utmost importance and is an ongoing process.
• Ensuring good records management and ongoing tracking of asset performance provides for
condition-based maintenance and better decision making about the needs and life of an
asset
• Employing “Maintenance Best Practices” leads to better outcomes for facility operations
and ratepayers:
o Improved asset utilization and performance
o Reduced capital cost
o Reduced asset-related operating costs
o Extended life of asset
These principles form the basis of WTD’s Strategic Asset Management Plan (SAMP) that was updated in
2010. Because asset management tools evolve over time and lessons learned on optimizing asset use is
an ongoing process, WTD continues to update its SAMP; the next update is scheduled to be complete by
the end of 2015.
WTD’s facilities inspection team performs regularly scheduled condition assessments on the conveyance
system and facility structures. Results of the assessments and any rehabilitation recommendations are
reported in a Facilities Inspection Annual Work Plan. As of 2012, WTD’s closed-circuit television (CCTV)
crew has inspected a million lineal feet of pipe over 10 years.
In 2008, WTD completed a study on the vulnerability of major wastewater facilities to flooding from sea-
level rise. As effects of climate change continue to grow, it is important to assess the potential for
flooding at WTD’s facilities that are adjacent to tidally influenced water bodies. The study identified
these facilities and their potential for flooding, considering the effects of both sea-level rise and storm
surges, and then recommended the next steps in planning for this change. The study is available at
http://www.kingcounty.gov/environment/wastewater/CSI/Library/SeaLevelRise.aspx.
Ongoing and future activities to continually improve how WTD protects its assets include the following:
• Develop a tracking system in the computerized maintenance management system (CMMS) to
compile energy efficiency data to support asset refurbishment and replacement projects.
• Continue work to produce long-term capital restoration and replacement forecasts.
• Conduct a best practices assessment. WTD is reviewing other agencies’ best practices.
RWSP 2013 Comprehensive Review 2-21
Chapter 2. RWSP Achievements in 2007−2013
• Implement a resiliency and recovery. The program includes conducting a susceptibility review of
the region’s wastewater facilities with respect to their vulnerability to damage in the event of a
disaster, the potential extent of such damage, and ways to improve recoverability of affected
facilities immediately after a disaster.
• Complete the SAMP update.
More information on WTD’s asset management activities are available at
http://www.kingcounty.gov/environment/wtd/Construction/Assets.aspx.
2-22 RWSP 2013 Comprehensive Review
Chapter 3
Financial Stewardship
The RWSP financial policies guide the County on the long-term financing. The policies provide direction
for establishing annual sewer rates and capacity charges, and for allocating wastewater system costs
between existing and new customers. Appendix A provides information on how the RWSP financial
policies were implemented in 2007−2013.
This chapter describes how annual sewer rates and capacity charges are established, gives sewer rate
and capacity charge projections through 2030, and compares them to projections in previous RWSP
comprehensive review reports. The chapter also describes programs implemented in 2007−2013 to
increase efficiency and policy guidance on construction fund and emergency reserves.
Establishing Annual Sewer Rate and Capacity Charge
The RWSP calls for existing customers to pay a monthly sewer rate to cover the portion of the existing
and expanded system that serves them. New customers pay costs associated with the portion of the
existing system that serves them and costs associated with expanding the system to serve future
customers, in accordance with a fundamental principle of the RWSP that “growth pays for growth.”
The charges for new customers are collected through a combination of the monthly sewer rate and the
capacity charge. The capacity charge is designed to provide a means by which the growth customers
(new connections to the system) pay their equitable share of the cost of their service. The basic
approach is to identify (allocate) the costs of serving each customer group and then design rates and the
capacity charge so that each pay their equitable share.
At the request of the County Council’s Regional Water Quality Committee (RWQC), a Financial Policies
Work Group (FPWG) was formed in 2009 to review the RWSP financial policies. The FPWG was
comprised of staff representing MWPAAC, sewer districts, City of Seattle, City of Bellevue, the King
County Executive, and the King County Council. The FPWG reviewed the capacity charge methodology in
depth. Although the FPWG had lengthy discussions regarding how certain costs associated with growth
are allocated either to existing customers or current growth customers (those connecting between 2003
and 2030), there was no consensus on changing any of the allocations used to calculate the capacity
charge. The RWQC was briefed on the work of the FPWG during summer 2013. Based on the briefing,
the capacity charge discussion at RWQC has been tabled for now.
Factors that affect the sewer rate and capacity charge include the number of Residential Customer
Equivalents (RCEs), wastewater operating expenditures, capital program expenses, number of new
connections, and debt financing. In addition, these charges are affected by the allocation of capital
program costs between customers establishing new connections to the system and those with existing
connections. Figure 3-1 illustrates the relationship between the monthly rate and the capacity charge.
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Chapter 3. Financial Stewardship
Figure 3-1. Relationship Between the Monthly Sewer Rate and Capacity Charge
Residential Customer Equivalents
King County uses an RCE as the basic unit for charging local agencies for wastewater services. Agencies
are charged one RCE for each single detached housing unit, regardless of size or water consumption. For
multifamily dwellings and commercial and industrial establishments, agencies are charged on the basis
of water consumption. For each 750 cubic feet of water per month consumed, the agency is charged for
one RCE.
Local agencies employ a variety of means of allocating these costs to their customers. For example, in
the City of Seattle, the charge for all customers—single-family, multifamily, commercial, and industrial—
is based on water consumption. Other agencies charge per RCE.
Table 3-1 shows RCEs by category for 1994 to 2013. During this period, total RCEs increased by a little
over 59,000 relative to 1994 levels or an average annual percentage growth of 0.45 percent. This
aggregate change masks the underlying differences among the categories of customers. For example,
from 1994 to 2013, single-family residential RCEs increased by 90,354, which was partially offset by a
decline in commercial and multifamily RCEs of approximately 31,000. In addition, the recent recession
dampened RCE growth during the 2009 to 2012 period, with a 0.4 percent decrease in 2009. The 2013
growth of 1.3 percent is seen as a bounce back from the recession-induced low growth period of 2009
through 2012. Figure 3-2 shows the comparison of RCE forecasts for 2007 and for 2013.
It is assumed that RCEs will continue to grow beyond 2013 levels, increasing at approximately 0.43
percent annually through 2030. The County continually monitors for changes in underlying assumptions
and will adjust these projections accordingly.
The long-term forecast of RCEs is a trend projection intended to provide a conservative financial forecast
(relatively low, steady growth) for the County’s wastewater utility to avoid underestimating sewer rates,
especially in the near term. As such, it does not attempt to reflect swings in the business cycle or reflect
3-2 RWSP 2013 Comprehensive Review
Chapter 3. Financial Stewardship
the basis of capacity needs and timing. As recently shown, RCEs can be affected by short-term swings as
the result of the economic climate.
Table 3-1. Residential Customer Equivalents (1994–2013)
Year Single Family
Residential
% Change Commercial &
Multifamily
% Change Total % Change
1994 296,757 1.3% 362,300 -0.4% 659,057 0.4%
1995 299,963 1.1% 367,828 1.5% 667,791 1.3%
1996 303,292 1.1% 367,894 0.0% 671,186 0.5%
1997 307,340 1.3% 371,514 1.0% 678,854 1.1%
1998 310,878 1.2% 376,426 1.3% 687,304 1.2%
1999 315,878 1.6% 378,219 0.5% 694,097 1.0%
2000 320,117 1.3% 376,705 -0.4% 696,822 0.4%
2001 325,125 1.6% 377,235 0.1% 702,360 0.8%
2002 329,265 1.3% 355,830 -5.7% 685,095 -2.5%
2003 334,555 1.6% 350,578 -1.5% 685,133 0.0%
2004 342,582 2.4% 345,327 -1.5% 687,909 0.4%
2005 349,535 2.0% 340,282 -1.5% 689,817 0.3%
2006 357,115 2.2% 333,819 -1.9% 690,934 0.2%
2007 364,044 1.9% 338,902 1.5% 702,946 1.7%
2008 370,621 1.8% 336,225 -0.8% 706,846 0.6%
2009 375,513 1.3% 328,282 -2.4% 703,795 -0.4%
2010 378,148 0.7% 326,243 -0.6% 704,391 0.1%
2011 381,031 0.8% 326,247 0.0% 707,278 0.4%
2012 383,903 0.8% 324,991 -0.4% 708,894 0.2%
2013 387,111 0.8% 331,049 1.9% 718,160 1.3%
RWSP 2013 Comprehensive Review 3-3
Chapter 3. Financial Stewardship
Figure 3-2. 2007 and 2013 Residential Customer Equivalent Forecasts (1993 to 2030)
Sewer Rate and Capacity Charge Projections
Sewer Rate
Long-term projections of the monthly sewer rate are not strictly comparable to those presented each
year in the annual rate process. The rates presented during the annual rate process incorporate the
most up-to-date data and the assumption that not all of the capital improvement program (CIP) budget
will be expended during the year. Historically, in a given year, actual capital spending is 10 to 25 percent
less than budgeted for the entire program. This is largely because projects are delayed for a variety of
reasons, including permitting issues, unknown geotechnical conditions, and unforeseen construction
delays. Accounting for this actual spending lowers the proposed rate. However, long-term planning
assumes that 100 percent of the costs are incurred by completion. Consequently, the long-run rate
projections reflect an assumption that 100 percent of the annual CIP budget is expended each year.
Figure 3-3 presents the most current mid-term view of the original 1998 RWSP rate projections, the rate
projections from the RWSP 2006 Comprehensive Review, and the actual rates through 2014 (all rates
include inflation). Figure 3-4 presents long-term sewer rate projections from the RWSP 2006
Comprehensive Review and updated RWSP sewer rate projections with inflation (2002–2030) and
compares them with the 2013 long-term projections.
3-4 RWSP 2013 Comprehensive Review
Chapter 3. Financial Stewardship
Figure 3-3. Sewer Rate Projections with Inflation (2002–2014)
Figure 3-4. Sewer Rate Projections with Inflation (2002–2030)
$0.00
$10.00
$20.00
$30.00
$40.00
$50.00
$60.00
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Original RWSP Forecast
2006 RWSP Update Forecast
2013 Adopted Rate
Comparison of Monthly Wastewater Rate Projections
1998 Original RWSP, 2006 RWSP Update and 2013 Adopted Rate
(monthly rates with inflation)
Actual rates through $39.79
2014 rate
`
RWSP 2013 Comprehensive Review 3-5
Chapter 3. Financial Stewardship
Actual monthly sewer rates have closely tracked the long-run projections associated with the 2006
update through 2014. The main determinant of the pattern of monthly rates is the annual capital
spending patterns, as shown in Figure 3-5. This chart shows capital spending for the wastewater
program from 2000 to 2030. It highlights the relatively high amount of spending for the Brightwater
Treatment System during the 2003 to 2010 period, with peak capital expenditure in 2009 and 2010.
After completion of Brightwater construction, capital spending returned to a more normal long-run level
of approximately $175 to $200 million in 2013 dollars.
Figure 3-5. Annual Capital Spending for the Wastewater Treatment Division (2000 to 2030)
Capacity Charge
The increases in capital costs associated with new capacity have a direct and significant effect on the
capacity charge. This effect is shown in Table 3-2, which presents the 2003 to 2014 capacity charge for
both lump sum and monthly payments. The largest component of change in the capacity charge during
this period was in the capital cost of Brightwater. As Brightwater progressed and cost estimates
stabilized, increases in the capacity charge largely reflect the rate of inflation. Because Brightwater is
allocated exclusively as a growth cost, the impact to the capacity charge is direct.
0
50
100
150
200
250
300
$0
$100,000,000
$200,000,000
$300,000,000
$400,000,000
$500,000,000
$600,000,000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030
Total Capital Spending
without inflation in 2013 $
3-6 RWSP 2013 Comprehensive Review
Chapter 3. Financial Stewardship
Table 3-2. WTD Capacity Charge (2003−2014)
Year Monthly Charge Total Lump-Sum Paymenta Total When Paid Monthly
2003 $17.60 $2,197 $3,168
2004 $18.00 $2,247 $3,240
2005 $34.05 $4,251 $6,129
2006 $34.05 $4,251 $6,129
2007 $42.00 $5,196 $7,560
2008 $46.25 $5,721 $8,325
2009 $47.64 $5,893 $8,575
2010 $49.07 $6,070 $8,833
2011 $50.45 $6,241 $9,081
2012 $51.95 $6,427 $9,351
2013 $53.50 $6,618 $9,630
2014 $55.35 $6,847 $9,963
a.Current policy discounts lump sum payments at 3.2% percent.
Although total RCEs (new plus existing) have grown at a relatively slow rate recently, the number of
newly connecting customers has equaled or surpassed originally expected levels. While new connections
averaged more than 9,500 RCEs per year since the beginning of the capacity charge program in 1990,
they averaged approximately 10,000 per year between 2000 and 2013. This average masks some
volatility in that period, especially during the economic downturn of 2008 to 2013 when the average was
closer to 7,500 new connections per year. The forecast begins with a conservative assumption on a
recovery to 9,500 new connections in 2014 before moving to approximately 10,000 a year for 2015 to
2020, a level supported by longer-term demographic and employment trends for the County’s
wastewater service area. The projections decrease to approximately 9,600 per year after 2020,
reflecting a slowing in projected population growth.
Continuous Improvement Programs
Productivity Initiative Pilot Program
WTD’s Productivity Initiative Pilot Program was developed to identify and implement ways to increase
efficiency. This 10-year incentive program applied certain private-sector business practices, including the
establishment of an incentive-based cash payment to employees in the wastewater program, to reduce
RWSP 2013 Comprehensive Review 3-7
Chapter 3. Financial Stewardship
operating costs, increase productivity, and continue a high level of service and environmental protection
for WTD’s customers.
The pilot program ended in April 2011. The program generated nearly $84 million in savings for
ratepayers over its 10-year lifespan.
More information on the Productivity Initiative Pilot Program, including the comprehensive review
report of the program, is available at
http://www.kingcounty.gov/environment/wtd/About/Finances/PI.aspx.
Bright Ideas Program
WTD is committed to continuous improvement. As a follow-up to the Productivity Initiative, WTD
established an employee-initiated program called Bright Ideas. The program encourages creative
problem-solving throughout the organization and uses employees’ ideas to improve how WTD does
business. Since Bright Ideas was launched in September 2012, WTD employees have submitted more
than 550 ideas. It is expected that the program will result in over $400,000 in savings in 2014.
Policy Guidance on Construction Fund and Emergency Reserves
The King County Council adopted Ordinance 17480 in December 2012, amending the RWSP
comprehensive review reporting policies. The ordinance calls for including information related to policy
guidance on WTD’s construction fund and emergency reserves in RWSP comprehensive reviews.
Policy guidance on the construction fund and emergency reserves is provided in Motion 13798, which
was adopted by the County Council in December 2012. The development of the motion resulted from
the work conducted by the FPWG in its review of RWSP financial policies. The direction provided in the
motion continues to make sense and serve WTD’s ratepayers well. WTD will continue to review this
guidance as directed in the motion.
In regards to the construction fund and emergency reserves, the motion states:
2. Reserves in the Wastewater Treatment Division operating and capital budgets.
a. The current practice of maintaining a liquidity reserve of at least ten percent of
operating expenses plus five million dollars in the construction fund has been viewed
favorably by rating agencies and has improved bond ratings, and should therefore
continue.
b. The proposed financial plan for each fiscal year should include a minimum cash
balance, to be utilized for reserves, at the beginning of the year equal to or greater than
ten percent of operating expenses plus five million dollars in the construction fund.
c. If the cash balance or reserve has been utilized in the current or preceding year, the
financial plan will show how and when it will be restored to the minimum.
d. In addition to this minimum cash balance, the financial plan should include an
emergency capital reserve at the beginning of year with a minimum of fifteen million
3-8 RWSP 2013 Comprehensive Review
Chapter 3. Financial Stewardship
dollars to be used for unanticipated system repairs or equipment replacement in the
event of a natural disaster or some unforeseen system failure.
e. Interest earnings on the emergency capital reserve shall be available for operations.
f. If the emergency capital reserve has been utilized in the current or preceding year, the
financial plan will show how the capital reserve will be replenished to fifteen million
within five years.
g. As a part of each Regional Wastewater Services Plan review and update, the dollar
amounts for reserves stipulated in this motion should be reviewed to ensure they are
appropriate in future years.
RWSP 2013 Comprehensive Review 3-9
Chapter 3. Financial Stewardship
3-10 RWSP 2013 Comprehensive Review
Chapter 4
Forecasting Future Wastewater Treatment Plant Capacity Needs
A major component of the RWSP 2013 comprehensive review included evaluating and updating future
regional wastewater treatment capacity needs. This chapter summarizes this analysis, provides more
detail on methodology and findings, and discusses the findings as they relate to future treatment plant
capacity needs.
Summary
In general, WTD updates its treatment plant forecasts every 10 years using updated population and
employment forecasts provided by the Puget Sound Regional Council (PSRC). WTD also evaluates and
updates other key planning assumptions, such as water use, water conservation, and the service area
growth rate. The last major forecasting update occurred as part of the RWSP 2004 update and used
PSRC’s 2003 forecast. The results found that the difference in overall change between population
forecasts over the planning period and change in planning assumptions was insignificant with respect to
the wastewater system’s treatment capacity needs and confirmed the need and timing for the
Brightwater Treatment Plant and the anticipated expansion of South Treatment Plant in 2029.
For this review, WTD used PSRC’s 2013 Land Use Forecast as input for population and employment
numbers and worked closely with the Metropolitan Water Pollution Abatement Advisory Committee’s
(MWPAAC) Engineering and Planning Subcommittee (E&P Subcommittee) in May through December
2013 to update RWSP planning assumptions. WTD also met with individual agencies and consulted the
water and sewer comprehensive plans of several local agencies. This information along with operational
data from the treatment plants over the past several years was used to forecast treatment plant
capacity needs through 2060.
Key findings from the analysis are as follows:
• Regional population continues to increase.
• Treatment plant solids loadings will continue to grow in proportion with population growth.
• There was a 15 percent reduction in average wet-weather flow (AWWF) over the last decade,
which aligns with reduction in water use seen from 2000 to 2010. Because of this and projected
future water use and conservation, the AWWF capacity needs are less than forecast previously.
• Projections of future peak flows for the treatment plants are being developed as part of the
2015 Conveyance System Improvement Program update. Capacity requirements will be
reevaluated when these projections become available.
The analysis confirmed the benefits of having a three-plant regional system. Findings indicate that with
the Brightwater Plant, there is sufficient treatment plant capacity until the 2030s. Current forecasts
indicate that solids loadings capacity will be needed sooner than AWWF capacity at all three plants,
which could require additional equipment and digesters to handle the solids capacity needs. The
forecasts indicate that a full expansion at South Treatment Plant is unlikely to be needed in 2029 as
RWSP 2013 Comprehensive Review 4-1
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
previously projected. WTD will continue to monitor the factors and trends that affect treatment plant
capacity needs.
Methodology
WTD’s population and employment forecasts generally coincide with the most recent federal census
data. For this forecast, the current baseline year is 2010; the previous baseline year was 2000. A 50-year
planning horizon was used for this current forecasting effort.
The method used to forecast wastewater treatment plant flows and solids loadings (wasteloads) is to
multiply the population and employment forecasts by flow and wasteload factors representing average
volumes generated per person:
• AWWF has historically been used as the main indicator of treatment plant capacity needs. The
South Plant and Brightwater Plant service areas are served by separated sewer systems. AWWF
for these service areas is defined as the average of all flows during November through April. For
the West Point Plant, the AWWF is defined as the average of all non-storm flows during
November through April because the service area includes combined sewers and the plant has
wet weather treatment capacity above its secondary treatment capacity.
• Solids must be treated to ensure compliance with National Pollution Discharge Elimination
System (NPDES) permit limitations. Biological oxygen demand (BOD) and total suspended solids
(TSS) entering the plants are measured daily. Biosolids (Loop) leaving the plants are also
measured. The measurements are used in estimating future solids loading.
Peak flows to the treatment plants are also important in evaluating capacity needs. Peak flows represent
the highest combination of base flow and infiltration/inflow (I/I) expected to enter a wastewater system
during wet weather over a set time period (for example, 30-minute increments). The information
needed to forecast the peak flows is being generated as part of the 2015 Conveyance System
Improvement (CSI) Program update; therefore, peak flow forecasts for the treatment plants will be
generated following completion of the update.
Planning Assumptions
The planning assumptions used during this update compared to those used for the 2000 baseline
forecasts are shown in Table 4-1. WTD worked with MWPAAC’s E&P Subcommittee from May through
December 2013 to update these planning assumptions. In addition, WTD had discussions with individual
agencies, reviewed agency water and sewer comprehensive plans, and used flow monitoring and
treatment plant data to inform the update of the planning assumptions.
4-2 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Table 4-1. Previous and Updated Planning Assumptions
Category Previous Assumption Updated Assumption
Planning horizon 2050 50-year planning horizon (2060)
Extent of eventual service
area
Potentially sewerable areas in Urban
Growth Areas of King County’s
wastewater service area
Same
Future population
2003 Puget Sound Regional Council
(PSRC) forecast
2013 PSRC forecast
Water use Base Year 2000
Seattle residential: 55 gpcd
Other residential: 66 gpcd
Commercial: 33 gped
Industrial: 55 gped
Base Year 2010
Inside Seattlea
Residential: 46 gpcd
Commercial: 30 gped
Industrial: 61−68 gped
Outside Seattle
Residential: 54 gpcd
Commercial: 18 gped
Industrial: 45−56 gped
Water conservation
A 10% reduction in per-capita and per
employee water consumption between
2000 and 2010 and no additional
reduction after 2010
A 10% reduction in per-capita and per-employee
water consumption between 2010 and 2030 and
no additional reduction after 2030
Sewered area growth rate 90% of unsewered sewerable area in
2000 is sewered by 2030, 100% by 2050
100% of unsewered sewerable area in 2010 is
sewered by 2060, at a rate of 20% per decade
starting in 2010
Average wet weather I/I
degradation (treatment
plants)
Increase of 7% per decade up to a
maximum of 28%
No degradation
Design flow (separated
conveyance system)
20-year peak flow Same
Degradation of peak I/I
(separated conveyance
system)
Model basin peak I/I in year 2000 with
assumed increase of 7% per decade up
to a maximum of 28% (over 4 decades)
Model basin peak I/I in year 2010 with assumed
increase of 7% per decade through the planning
horizon
New system I/I (separated
conveyance system)
1,500 gpad with 7% degradation per
decade increase to approximately 2,000
gpad over 4 decades
2,000 gpad plus assumed I/I degradation (7%
per decade) through the planning horizon
gpcd = gallons per-capita per day; gped = gallons per employee per day; gpad = gallons per acre per day.
a Because of the large difference between industrial and commercial water usage inside and outside Seattle, the analysis used
separate employment usage factors for Seattle.
b The data did could not determine any apparent trend for AWWF I/I degradation rate.
RWSP 2013 Comprehensive Review 4-3
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Population and Employment Forecasts
WTD relies on population and employment forecasts from the Puget Sound Regional Council (PSRC) to
project flows in sewer model basins, which are delineations of the WTD service area. Model basins are
aggregated to forecast flows in treatment plant service areas.
For its latest flow projections, WTD is using the PSRC 2013 Land Use Forecast as input for population and
employment numbers. The 2013 Land Use Forecast was developed using PSRC’s new UrbanSim model.
The model forecasts growth for each year out to 2040 for residential populations and several
employment categories.
Figure 4-1 shows previous and current population projections for the whole WTD service area. Actual
population growth in sewered areas through 2010 is very close to the growth forecast as part of the
RWSP 2004 Update. The total residential population served by sewers is now projected to grow by 49
percent from 2010 to 2050 using the 2013 forecast compared to 45 percent for the same period using
the 2004 forecast. This population is predicted to grow by 8.6 percent between 2050 and 2060.
Commercial and industrial employment dropped slightly between 2000 and 2010; PSRC projects a
recovery in employment levels by 2020, with employment rising slightly above the 2004 forecast by
2040. Commercial employment is extrapolated to 2060 with an increase of 12 percent per decade, and
industrial employment is extrapolated with an increase of 3 percent per decade.
Figure 4-1. Previous and Current Population and Employment Projections for the WTD Service Area
Figure 4-2 shows the West Point, South, and Brightwater service areas. It was assumed in this analysis
that the service areas would remain the same throughout the planning period. Figures 4.3, 4-4, and 4-5
compare the previous and current population forecasts for each treatment plant service area.
Projections of sewered residential population are generated for each model basin using the assumed
4-4 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
sewered area growth rate shown in Table 4-1. All existing and future commercial and industrial
employees were assumed to be served by sewers.
Figure 4-2. King County’s Wastewater Treatment Service Areas
RWSP 2013 Comprehensive Review 4-5
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-3. Previous (2004) and Current (2013) Population and Employment Forecasts For West Point Service Area
Figure 4-4. Previous (2004) and Current (2013) Population and Employment Forecasts For South Plant Service Area
4-6 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-5. Previous (2004) and Current (2013) Population and Employment Forecasts For Brightwater Service Area
Average Wet Weather Flow Forecasts
Estimating Flow Factors for the Baseline Year
The process to forecast AWWF for each treatment plant begins with determining both the AWWF and
the average dry weather flow (ADWF) for the baseline year of 2010. Flow meters in the conveyance
system were used to estimate Brightwater flows prior to its startup.
The next step is to determine the portion of the flows attributable to base wastewater flow and to
infiltration and inflow (I/I). Base flow is estimated based on wet weather water usage.
WTD obtained winter water usage data from water purveyors in its service area. Actual residential
gallons per-capita per day (gpcd) of winter water usage for the years 2008 through 2012 were averaged
for each purveyor and further apportioned to each treatment plant basin using PSRC population data for
the period. Daily consumption rates were estimated for residential, commercial, and industrial
populations inside and outside Seattle because recent history shows that residential consumption is
lower and commercial/industrial consumption is higher in Seattle than in other areas. Because water
purveyors generally combine commercial and industrial per-employee daily usage (gped), WTD used
King County Industrial Waste Program records to estimate per-employee industrial water use (process
waste discharge plus the per-employee commercial daily usage).
Flow factors are the per-capita or per-employee daily flow to the wastewater system, estimated as the
daily consumption rates discussed previously. The updated flow factors are shown in Table 4-2. The flow
RWSP 2013 Comprehensive Review 4-7
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
factors for residential, commercial, and industrial water use and the 2010 population and employment
data were used to estimate base flow to the plants; the remaining measured flow is assumed to be I/I.
Table 4-2. Per-capita and Employee Flow Factors for 2010
Forecasting Future Flows
Most regional purveyors anticipate further reductions in per-capita water usage, as shown in Figure 4-6.
In addition, during discussions with the E&P Subcommittee, the Alderwood Water and Sewer District
indicated that it is updating its data and anticipates more water conservation than shown in Figure 4-6.
To accommodate these predictions, future base flow to the plants was forecast by multiplying the 2010
flow factors by the PRSC population forecasts assuming all flow factors would decrease by 10 percent
between 2010 and 2030 as the result of water conservation. The lower water consumption reduces the
amount of AWWF entering the plants. Average wet weather I/I is forecast to be the same as in 2010 for
the entire 50-year planning period because there was not any apparent trend in the data collected.
Figure 4-7 shows historical and projected AWWF from 1990 through 2060 for each treatment plant.
AWWF at West Point and South plants declined about 15 percent between 2000 and 2010−2011,
despite increased population. (The figure shows that some flows from West Point were temporarily
diverted to South Plant through the North Creek Pump Station until Brightwater came online.) This
decline was due in part to water conservation and in part to Brightwater beginning operations. The
AWWF is expected to slowly increase, even with increased water conservation, because of population
growth. South Plant AWWF is forecast to increase at a faster rate, which reflects the higher population
growth rate forecast for its service area.
West Point South Plant Brightwater
Inside
Seattle
Outside
Seattle
Inside
Seattle
Outside
Seattle Outside Seattle
Residential (gpcd) 46 54 46 54 54
Commercial (gped) 30 18 30 18 18
Industrial (gped) 61 49 68 56 45
Notes: gpcd = gallons per-capita per day; gped = gallons per employee per day; gpad = gallons per acre per day.
4-8 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-6. Regional Water Purveyor Predicted Water Usage Reductions from Water Conservation
RWSP 2013 Comprehensive Review 4-9
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-7. Historical and Forecasted Average Wet Weather Flow at West Point, South, and Brightwater Treatment Plants,
1990−2060
Wasteload Forecasts
Estimating Loading Factors for the Baseline Year
Solids loading to the treatment plants is directly related to population and employment. Biological
oxygen demand (BOD) and total suspended solids (TSS) are measured daily at each treatment plant. To
estimate existing (2010) wasteloads, the influent BOD and TSS measurements from 2007 through 2012
for each plant were averaged and adjusted for flow transfers to or from Brightwater. South Plant loads
included septage from septage haulers, solids from the Vashon and Carnation Treatment Plants, and
loadings from the SeaTac Airport deicing facility. West Point loadings included street washoff that enters
through the combined system.
Forecasting Future Loadings
Residential, commercial, and industrial loading factors (pounds per person per day) were determined for
BOD and TSS based on population forecasts and the 2010 wasteload averages. The daily per-employee
industrial loading factor was based on the Industrial Waste Program’s discharge and monitoring data
Flows from West
Point were
temporarily
diverted to South
Plant through the
North Creek Pump
Station when the
station came online
in 2000.
When Brightwater
came online, flows
treated at South
Plant and West Point
that are a part of
Brightwater’s service
area were sent to
Brightwater.
4-10 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
from 2008 through 2012. The loading factors were multiplied by population and employment forecasts
by decade through 2060. Separate daily loading factors (pounds per day) were determined for other
loads (septage, deicing, and street washoff). The future loading factor for septage was based on 2011
and 2012 daily loads (increased from the 2010 load because one septage receiver left the market in
2009). Figures 4-8 and 4-9 show actual and projected BOD and TSS loads for each treatment plant from
1990 through 2060. As population increases, the loadings to the treatments plants are forecast to
increase proportionately.
Figure 4-8. Historical and Forecasted Average BOD load at Treatment Plants, 1990−2060
RWSP 2013 Comprehensive Review 4-11
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-9. Historical and Forecasted Average TSS load at Treatment Plants, 1990−2060
Comparison of Future Flows, Loadings, and Capacities
WTD compared the AWWF and wasteload forecasts to treatment plant capacities to determine if
capacity could be exceeded in the 50-year planning period. Solids loadings appear to be a greater
determinant of capacity requirements than AWWF. Historically, AWWF has been used as a proxy for
treatment plant capacity. The nominal plant capacity based on AWWF no longer reflects the capacity
limitations of the treatment plants, mainly because of reduced water usage. Loadings continue to rise
with population growth, whereas AWWF may either decrease or rise more slowly because of the effects
of water conservation and commercial/industrial usage. This finding is consistent with trends in other
wastewater utilities throughout the country.
Figure 4-10 shows the actual and forecast wasteloads from 1985 through 2060 and the systemwide
capacities to treat BOD and TSS, both with and without the South Plant expansion around 2000 and the
start of Brightwater operation in 2011.
4-12 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-10. Comparison of Actual and Forecast Solids Loadings with Systemwide Treatment Capacities, 1980−2060
Comparison of forecast AWWF and solids loadings with capacity at the three treatments plants indicates
the benefits of a three-plant system and that the plants will have sufficient treatment capacity until at
least the 2030s:
• West Point Plant. Figure 4-11 shows that AWWF will not exceed design capacity at West Point
through 2060, whereas capacity to treat TSS may be exceeded by around 2030 and to treat BOD
about 10 years later.
• South Plant. Figure 4-12 shows that AWWF may be at capacity at South Plant in 2060 and that
the capacity to treat TSS will be exceeded by around 2035 and to treat BOD about 10 years later.
• Brightwater Plant. Figure 4-13 shows that AWWF may come close to reaching capacity at
Brightwater past 2060 and that BOD and TSS treatment capacities may be exceeded in the late
2030s with the addition of membrane cassettes and other associated equipment planned for
2020.
RWSP 2013 Comprehensive Review 4-13
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-11. Actual and Forecast AWWF and Solids Loadings Compared to
West Point Treatment Plant Capacities, 1990−2060
4-14 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-12. Actual and Forecast AWWF and Solids Loadings Compared
to South Treatment Plant Capacities, 1990−2060
RWSP 2013 Comprehensive Review 4-15
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Figure 4-13. Actual and Forecast AWWF and Solids Loadings Compared to
Brightwater Treatment Plant Capacities, 2010−2060
Implications for Future Planning
Actual population growth and water use rates could be more or less than projected. Factors such as the
economy and natural or manmade events such as climate change could affect projections. Regulatory
requirements could change; for example, nutrient removal requirements would likely require treatment
plant upgrades that could affect treatment capacity. WTD will continue its evaluations and will revise
forecasts as appropriate.
The analysis shows that with the addition of Brightwater, capacity at the three regional plants is
sufficient until the 2030s. The forecasts indicate that additional capacity may be needed in the 2030s to
meet the projected solids loadings. The required upgrades to expand the solids handling capacity may
be less extensive than a full treatment plant upgrade and may include the need for additional digester
capacity. WTD plans to conduct a study in 2015/2016 to explore options to meet future solids loadings
needs.
4-16 RWSP 2013 Comprehensive Review
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
Although system-wide AWWF has remained fairly stable since 1990 and per-capita water use is
expected to continue to decrease in the near future, growth in population is expected to result in
increased AWWF through 2060 (Figure 4-14). The analysis shows that capacity at the three regional
plants is expected to be sufficient to accommodate the increased AWWF for the next 40 years.
Projections of future peak flows for the treatment plants are being developed as part of the 2015 CSI
Program update. Capacity requirements will be reevaluated when these forecasts become available. Of
the factors that affect treatment plant capacity, peak flows are expected to have the greatest sensitivity
to future climate change. Current scientific knowledge and projections on how climate change is
expected to affect peak flows will be incorporated into a sensitivity evaluation as part of the peak flow
projections.
The 2015 CSI program update may identify flow transfers that may be needed based on future
conveyance capacity needs. WTD will reassess treatment plant flow forecasts if projects are identified
that will lead to flow transfers not accounted for in the 2013 forecasts.
Recently a septage hauler applied for an operating permit to treat waste at its facility rather than at
South Plant. Based on its hauling record, this could reduce septage loads at South Plant by a third, thus
reducing TSS loading by 4,700 pounds per day and BOD by 1,500 pounds per day. This represents about
2.5 percent of the solids loading at South Plant and would delay the need for additional solids loading
capacity at South Plant by about two years.
Figure 4-14. Historical and Projected Systemwide Average Wet Weather Flow
RWSP 2013 Comprehensive Review 4-17
Chapter 4. Forecasting Future Wastewater Treatment Plant Capacity Needs
4-18 RWSP 2013 Comprehensive Review
Chapter 5
Preparing for the Future
The RWSP was approved in 1999 and set a course for meeting the region’s wastewater needs through
2030. The timing of this RWSP comprehensive review represents the midway point of RWSP
implementation. To date, the RWSP has been implemented as planned and amended to adjust to
changing conditions or new information. The RWSP continues to protect water quality and the
environment and ensures sufficient wastewater treatment and conveyance capacity to keep pace with
population and employment growth.
Since adoption of the RWSP, several new trends and issues have emerged that influence wastewater
management. These include climate change, new information about chemicals of concern, increased use
and demand for the byproducts of wastewater treatment, sustainable building practices, technology
trends, and more stringent regulations.
In addition, county initiatives and priorities have evolved over time. For, example, the County adopted
its first strategic plan in 2010. The plan established the following priorities for all county departments:
• Improve customer service
• Build lasting regional partnerships
• Stabilize county finances
• Build a culture of performance and empower employees to work together as “One King County”
Other key county priorities include responding to the challenges of climate change and integrating
equity and social justice considerations into the County’s decisions and policies, practices, and methods
for engaging communities.
This chapter summarizes WTD activities under way to address these emerging issues and priorities.
Climate Change
Improving energy efficiency and reducing greenhouse gas emissions are important elements in
addressing climate change. WTD has an active energy program both to conserve and to generate
energy. The use of Loop® biosolids also helps reduce greenhouse gas emissions. Chapter 2 provides
more information on WTD’s energy and biosolids recycling program.
WTD incorporates sustainable building practices into new facilities. The division considers energy costs
and energy efficiencies in the planning, design, construction, and operation of its facilities. WTD has
started to use the Institute for Sustainable Infrastructure’s EnvisionTM certification criteria during project
design. Use of this assessment tool helps the project design team assess costs and benefits over the
project lifecycle, evaluate environmental benefits, use outcome-based objectives, and achieve higher
levels of sustainability. The tool is designed specifically for civil infrastructure projects such as roads,
airports, dams, and water and wastewater systems.
RWSP 2013 Comprehensive Review 5-1
Chapter 5. Preparing for the Future
Incorporating roadside rain gardens and other green stormwater infrastructure (GSI) into projects not
only helps reduce combined sewer overflows (CSOs) and the amount of untreated stormwater that finds
its way to surface water, it also facilitates natural processes that recharge groundwater, preserve base
flow in streams, moderate impacts to water and air temperature, and protect hydrologic and hydraulic
stability. WTD is committed to using GSI where technically feasible and cost-effective. See Chapter 2 for
more information on how GSI is being incorporated into the County’s Protecting Our Waters program.
WTD continues to implement the recommendations resulting from the study on the vulnerability of
major wastewater facilities to flooding from sea-level rise. Work includes incorporating projected rises
in sea level into the planning process for upgrades or rehabilitation of facilities located in areas affected
by tides and storm surges. Estimates of sea-level rise continue to evolve. WTD regularly reviews new
data and information to keep its projections current. As the effects of climate change (hotter
temperatures, more frequent droughts, and other effects) become more noticeable across the country,
there is concern that populations may shift to milder climates. WTD is including the potential for climate
migration in its planning for the future.
Regulatory Environment
RWSP policies provide guidance for the County’s participation in the development of water quality laws
and standards. The County regularly participates in the development of effective and reasonable
regulations.
The County participates on committees associated with the Washington State Department of Ecology
(Ecology) water quality related rulemaking processes and efforts to update water quality standards. For
example, the County is a member of Ecology’s “Delegate’s Table” that was formed in 2012 to provide
advice and perspective on the water quality standards rule-making process that is under way. In
addition, the County has been working closely with Ecology and the U.S. Environmental Protection
Agency in developing and evaluating Lower Duwamish Superfund cleanup options.
Nutrient Removal
One emerging area of concern for Ecology is algal growth, stimulated by nitrogen loadings to Puget
Sound. The loadings may be contributing to depression of dissolved oxygen (DO) levels in near-bottom
regions. In 2006, Ecology began a major study to determine the extent of low DO and how nitrogen from
a variety of sources affects DO levels. Wastewater treatment plants around the nation are under
growing pressure to remove nutrients. While it is not clear how Ecology will use the results of its studies
to establish future regulatory limits, WTD conducted two studies to evaluate the impacts of a range of
potential nitrogen limits on capital and operating costs at the South and West Point treatment plants.
The studies evaluated a variety of nitrogen removal technologies and used existing treatment plant data
and computer modeling to develop capital costs, operation and maintenance costs, and greenhouse gas
emissions for each regulatory scenario.
Results of the studies show that the costs of upgrading South Plant would range from approximately
$0.5 billion to $1 billion with an associated operating cost increase of $10 million to $33 million per year.
The estimated costs of upgrading the West Point Plant would be about $1 billion with an operating cost
5-2 RWSP 2013 Comprehensive Review
Chapter 5. Preparing for the Future
of $30 million per year. However, because of lack of available space, upgrading the West Point Plant to
remove nitrogen would most likely substantially reduce its treatment capacity.
Source Control
Source control is one of the most effective ways to keep pollutants from entering the wastewater
system and being discharged to water bodies. The King County Industrial Waste Program (KCIW)
regulates industrial wastewater discharged into the County wastewater system. KCIW works
cooperatively with more than 1,500 companies and facilities to protect surface water and biosolids
quality, the environment, public health, and the wastewater system. The program provides technical
assistance and ensures that industrial facilities treat wastewater for harmful substances before
discharging the wastewater to sanitary sewers. Since 2007, KCIW has worked with other agencies to
conduct pollution source control inspections at Lower Duwamish Waterway businesses as part of an
Ecology interagency coordination effort. More information on the County’s Industrial Waste Program is
available at http://www.kingcounty.gov/environment/wastewater/IndustrialWaste.aspx.
Chemicals of Concern
WTD continues to follow the emerging science and technology investigations of chemicals of concern
thought to be reaching the environment through wastewater or stormwater discharges. These include
(1) chemicals found in personal care products and pharmaceuticals that are suspected to be endocrine
disruptors or have other unintended effects on humans and/or wildlife and (2) other commonly used
chemicals such as plasticizers, flame-retardants, and surface coatings like Gor-Tex and Teflon.
Other Topics
The following are other issues that are important to WTD:
• Relabeling or banning of “disposable wipes” because they cause significant maintenance issues
in wastewater systems.
• Product stewardship efforts to reduce pollutants in wastewater and stormwater.
• Drug take-back programs by local governments or pharmaceutical companies to reduce
contamination of wastewater with unused and expired drugs. In 2013, King County’s Board of
Health passed a Rule & Regulation to create a drug take-back system for King County residents.
The program promotes the safe disposal of unused prescription and over-the-counter
medicines. It will be funded and operated by the drug manufacturers who produce the
medications. Under the new program, residents may dispose of unwanted medicines at
pharmacies and other secure locations across the county for no charge. The new law creates
one of only two such systems in the country.
Technology Trends
Certain technology trends are emerging in the industry, including decentralized systems, nutrient
recovery, energy recovery, and indirect and direct potable water reuse. WTD continues to monitor
technology trends and to consider pilot projects as appropriate. Information on these trends follows.
RWSP 2013 Comprehensive Review 5-3
Chapter 5. Preparing for the Future
Decentralized Wastewater Systems
The use of decentralized wastewater treatment systems is increasing. For some areas, decentralized
systems are the most sustainable and cost-effective solutions. Examples of decentralization are as
follows:
• Consolidated Utility District (CUD) of Rutherford County, Tennessee. The utility provides sewer
service to many of its outlying customers through an innovative system, often referred to as a
septic tank effluent pumping (STEP) system. Approximately 50 subdivisions contain a STEP
system, a recirculating sand filter, and a large effluent drip dispersal system, all of which are
owned and managed by the CUD. The system allows for high-density development
(subdivisions) in areas where city sewer service is not available or soil types are not conducive to
conventional septic tank and drain field lines. The 1,500-gallon septic tank is equipped with a
pump and control panel located at each residence for controlled discharge of wastewater to a
centralized wastewater collection system. For more information, see
http://www.cudrc.com/Departments/Waste-Water.aspx.
• Loudoun Water, in Loudoun County, Virginia. Loudon Water has adopted an integrated
approach to wastewater management that includes purchased capacity from a centralized
plant, a satellite water reclamation facility, and several small community cluster systems. The
approach has allowed Loudoun County to maintain its rural character and create a system in
which growth pays for growth. Developers design and construct cluster wastewater facilities to
Loudoun Water standards at their own cost and transfer ownership of the system to Loudoun
Water for continued maintenance. For more information, see http://www.loudounwater.org/.
• The Bullitt Center in Seattle, Washington. World Architecture News honored the Bullitt Center
as the “greenest commercial building in the world.” The Bullitt Center was built to achieve the
goals of the Living Building Challenge and demonstrate 365 continuous days of performance
that meet net zero energy and water. The center has a water and sewage processing system
that provides some waste product processing on site and uses hauling to avoid discharge to the
municipal sewage system. WTD supports the Bullitt Center’s efforts to achieve the Living
Building certification by taking the building’s liquid waste stream to the Carnation Treatment
Plant. At the Carnation Plant, the waste stream is treated and discharged to enhance a wetland
in the Chinook Bend Natural Area rather than being discharged to a water body. WTD also takes
the building’s solids from the composting toilets to make the GroCo commercial compost
product. GroCo compost obtained “Declare” certification through the partnership with the
Bullitt Center. For more information, see http://www.bullittcenter.org/.
Nutrient Recovery
Clean Water Services in Hillsboro, Oregon, opened the world’s largest municipal nutrient recovery
facility in 2012. The project is a public-private partnership with Ostara Nutrient Recovery Technologies
of Vancouver, Canada. The facility captures phosphorus in wastewater to produce 1,200 tons a year of
Crystal Green, a high value, slow-release fertilizer. The Ostara process is also being used in several
wastewater plants in Canada. More information is available at
5-4 RWSP 2013 Comprehensive Review
Chapter 5. Preparing for the Future
http://www.cleanwaterservices.org/AboutUs/WastewaterAndStormwater/TreatmentFacilities/RockCre
ekNutrientRecovery.aspx.
Energy Recovery
WTD continues to investigate means to improve and expand its ability to produce energy from
wastewater treatment. Two promising opportunities area as follows:
• WTD is assessing the potential of adding organic wastes (such as food waste) to the sewage
solids that are processed in anaerobic digesters at the South Treatment Plant. Recent WTD
studies of what is known as “grease co-digestion” have investigated the costs and potential
revenues associated with establishing a waste restaurant grease (brown grease) receiving
facility. Brown grease is typically processed in rendering facilities and/or disposed of in landfills
because there is a shortage of facilities that can cost-effectively convert the grease to energy.
When restaurant grease is mixed into anaerobic digesters, it can substantially increase the
production of valuable biogas that can be used to produce renewable energy. Numerous
wastewater treatment facilities have successfully implemented brown grease co-digestion
programs. In addition to continuing to assess the benefits of a facility at South Plant, WTD is
working with private entrepreneurs to determine if the private sector might be able to cost-
effectively convert this waste product into renewable energy.
• The South Plant biogas scrubber system currently processes biogas produced by the treatment
plant solids digestion system to convert it into high-quality bio-methane (natural gas). This bio-
methane is then injected into the nearby natural gas pipeline and sold to Puget Sound Energy.
However, elements of the gas management system are aging and will require replacement in
the near future. A study was conducted to assess the existing system of biogas recovery and
energy production to determine if it still provides the “best and highest” use the biogas. Results
from the study are expected in 2014.
Indirect and Direct Potable Reuse
Advances in water treatment technology allow for production of high-quality drinking water for indirect
and direct potable use. Two examples are as follows:
• In Texas, the Colorado River Municipal Water District is developing a direct potable reuse
project. The project will reclaim wastewater effluent from the City of Big Spring and process it
using advanced treatment technology. Approximately 1.8 million gallons per day of water from
the facility will be blended with other water from surface water reservoirs. More information on
this project is available at http://twri.tamu.edu/publications/txh2o/summer-2013/reclaiming-a-
valuable-clean-resource/.
• In California, the Orange County Water District and the Orange County Sanitation District jointly
funded the Groundwater Replenishment System (GWRS). The GWRS takes highly treated
wastewater that would have previously been discharged into the Pacific Ocean and purifies it
using a three-step advanced treatment process consisting of microfiltration, reverse osmosis,
and ultraviolet light with hydrogen peroxide. The purified water is injected into a seawater
RWSP 2013 Comprehensive Review 5-5
Chapter 5. Preparing for the Future
barrier and pumped to recharge basins where it naturally percolates into the groundwater
basin. More information on this system is available at http://www.gwrsystem.com/.
Building Equity and Opportunity
WTD strives to further the goals of the County’s Equity and Social Justice Initiative in all its work—from
planning through facility operations. In 2011, WTD conducted an analysis to compare historical capital
project cost data with King County demographic data (to determine whether demographics (race,
ethnicity, social status) affect project costs and schedule performance. The analysis used GIS (geographic
information systems) to map 133 historical capital projects to see how they related to minority and
income demographic conditions. When considering capital improvement, outreach, or planning
decisions, these maps help assess the potential impacts of new actions as they relate to current service
levels and spatial demographics. This analysis verified that the location of WTD facilities had no
discernable correlation to the race, ethnicity, or economic status of the host community. It further
confirms that facility locations are driven by hydraulics and topography–not any community-based
factors.
WTD has also reviewed how its facilities are assets in the neighborhoods where they are located in
comparison to neighborhood demographics. The information from this work is being used to improve
facilities in residential areas where any discrepancies in screening or other neighborhood enhancements
have been identified.
In addition, the WTD community outreach team shares information in multiple languages and uses other
techniques to reach people who might not have traditionally participated in these processes. WTD
provides career training and opportunities consistent with the Equity and Social Justice Initiative. In
order to continue to introduce youth to wastewater careers, the division has developed more contracts
with higher education organizations to provide work-study placements for students with financial aid
awards and to provide job-training opportunities to disadvantaged youth through King County
Worksource’s Work-to-Hire program.
5-6 RWSP 2013 Comprehensive Review
Chapter 6
Conclusions and Next Steps
This chapter summarizes conclusions from the review of RWSP implementation in 2007 through 2013
and next steps in continuing to implement the RWSP and protect the region’s water quality.
Conclusions
• Overall, implementation of the RWSP continues to protect the region’s water quality,
environment, and economy by providing dependable and high-quality wastewater treatment.
• The RWSP’s primary objective, completion of the Brightwater Treatment Plant, has been
achieved. The Brightwater Plant began operation in 2011 and is producing effluent, whose
quality exceeds conventional secondary treatment, and reclaimed water that is used for
irrigation in the Sammamish Valley.
• A major component of the RWSP 2013 comprehensive review included evaluating and updating
future regional wastewater treatment capacity needs. The review confirmed the benefits of
having a three-plant regional system. Findings indicate that with construction of the
Brightwater Plant, there is sufficient treatment plant capacity until the 2030s. Updated
forecasts indicate that a full expansion at South Treatment Plant is unlikely to be needed in
2029 as previously projected. WTD will continue to monitor the factors and trends that affect
treatment plant capacity needs.
• Actual population growth and water use rates could be more or less than projected. Of the
factors that affect treatment plant capacity, climate change is expected to have a significant
impact on future peak flows at treatment plants. WTD will track trends and climate change
impacts and projections over time.
• In accordance with RWSP conveyance and infiltration/inflow (I/I) policies, WTD completed five
conveyance system improvement (CSI) projects and one I/I reduction project between 2007 and
2013.
• RWSP policies provide guidance to find beneficial uses for byproducts from wastewater
treatment. WTD continues to create resources from the wastewater it treats in the form of
biosolids and digester gas from the solids treatment process and reclaimed water from the
liquids treatment process.
• WTD made significant progress in 2007−2013 to implement combined sewer overflow (CSO)
control projects under the Protecting Our Waters Program to control all its CSO sites by 2030.
About one-half of its 38 CSO sites are controlled to the Washington State standard of no more
than one overflow per year on average. Projects are under way or planned to control the
remaining uncontrolled CSOs by 2030.
RWSP 2013 Comprehensive Review 6-1
Chapter 6. Conclusions and Next Steps
• It would cost well over $20 billion to build King County’s wastewater system from the ground
up today, and the current value of existing facilities is about $6 billion. The primary objectives of
the Asset Management Program are to manage the whole lifecycle of a facility or asset; deliver
a level of service that meets regulatory requirements and ratepayer expectations; and fulfill
WTD’s mission to protect public health and enhance the environment by treating and
reclaiming water, recycling solids, and generating energy.
• WTD is committed to continuous improvement. It completed a 10-year pilot Productivity
Initiative Program in 2011 aimed at increasing efficiency. The program generated nearly $84
million in savings for ratepayers over its lifespan. Under WTD’s new Bright Ideas Program, WTD
employees have submitted more than 550 ideas to improve efficiencies that are expected to
result in over $400,000 in savings in 2014.
• RWSP comprehensive review reporting policies call for the inclusion of information on the
effectiveness of policy implementation. This information is provided in Appendix A.
Next Steps
• WTD will continue to implement the Protecting Our Waters Program to control the County’s'
remaining uncontrolled CSOs.
• WTD will conduct a study in 2015−2016 to explore options to meet future solids loadings needs
that might improve treatment plant efficiency and reduce the cost of improvements needed to
handle increased loadings over time.
• The CSI Program, which details capital projects necessary to meet the 20-year peak flow
standard, was last updated in 2007. Based on updated population and employment projections
released by the Puget Sound Regional Council in 2013, WTD will work to complete a CSI Program
update in 2015. Projections of future peak flows for the treatment plants will also be developed
as part of the update and capacity requirements will be reevaluated.
• In order to maintain accurate forecasts of wastewater system capacity needs, WTD will track
trends and climate change impacts over time and will continue to monitor flow data and work
with local agencies as they implement their land use and sewer plans in order to track actual
population growth and water use rates in relation to current projections.
• WTD’s first I/I reduction project intended to reduce or eliminate the need for a CSI project was
completed in 2013. The project followed recommendations contained in the I/I Control Program
approved by the Council in 2006. In accordance with the program, WTD will be working with
MWPAAC in 2015 to develop recommendations for long-term I/I reduction and control.
• WTD will be working with MWPAAC’s Engineering and Planning Subcommittee and the RWQC to
discuss policy implementation and effectiveness and any recommendations for policy
amendments. These discussions will help to inform the County Executive, who may recommend
policy changes in 2015.
6-2 RWSP 2013 Comprehensive Review
Chapter 6. Conclusions and Next Steps
• WTD’s Strategic Asset Management Plan (SAMP) was last updated in 2010. Optimizing asset
management practices is an ongoing process, and WTD will update the SAMP in December
2015.
• WTD will continue its efforts to be a state-of the-art, energy-efficient, lean, continually
improving agency. A cornerstone of this effort will be the ongoing Bright Ideas Program that
provides a means for employees to identify and seek approval for implementing efficiencies and
cost saving measures in the Division’s operations.
• WTD will continue to expand its ability to create resources from wastewater through facilities at
the West, South, and Brightwater plants by using digester gas to produce heat, electricity, and
natural gas; recycling 100 percent of biosolids produced through the treatment process; and
finding new customers and uses for reclaimed water.
RWSP 2013 Comprehensive Review 6-3
Chapter 6. Conclusions and Next Steps
6-4 RWSP 2013 Comprehensive Review
Appendix A
RWSP Policies Implementation
in 2007−2013
Appendix A. RWSP Policies Implementation in 2007−2013
Introduction
This appendix provides information on how RWSP policies were implemented in 2007−2013. The
appendix is in a similar format to the two previous RWSP comprehensive reviews.4 RWSP policies are
part of King County Code Chapter 28.86.
There are 13 sets of RWSP policies:
• Treatment Plant Policies (TPP)
• Conveyance Policies (CP)
• Infiltration and Inflow Policies (I/IP)
• Combined Sewer Overflow Control Policies (CSOCP)
• Biosolids Policies (BP)
• Water Reuse Policies (WRP)
• Wastewater Services Policies (WWSP)
• Water Quality Protection Policies (WQPP)
• Wastewater Planning Policies (WWPP)
• Environmental Mitigation Policies (EMP)
• Public Involvement Policies (PIP)
• Financial Policies (FP)
• Reporting Policies
The introductory material for each policy set and the column that states each policy are written exactly
as written in the King County Code, including punctuation and capitalization. The reader may notice
certain words that are not capitalized that are usually capitalized or vice versa. The King County Code
has its own style guide, and the policies reflect that guide. Any changes in policy made during
2007−2013 are noted in italics after either the introductory material or the policy.
The second column summarizes how each policy was implemented in 2007−2013. The information
reflects WTD’s review of each policy.
4 Previous RWSP comprehensive reviews are available at
http://www.kingcounty.gov/environment/wtd/Construction/planning/rwsp/Library/CompReview.aspx.
A-2 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Treatment Plant Policies
A. Explanatory material. The treatment plant policies are intended to guide the county in providing
treatment at its existing plants and in expanding treatment capacity through the year 2030. The policies
direct that secondary treatment will be provided to all base sanitary flows. The county will investigate
possible tertiary treatment with a freshwater outfall to facilitate water reuse. The policies also direct
how the county will provide the expanded treatment capacity necessary to handle the projected
increases in wastewater flows resulting from population and employment growth. The policies provide
for the construction of a new treatment plant (the Brightwater treatment plant) to handle flows in a
new north service area, expansion of the south treatment plant to handle additional south and east King
County flows and the reservation of capacity at the west treatment plant to handle Seattle flows and
CSOs. The potential for expansion at the west and south treatment plants will be retained for
unanticipated circumstances such as changes in regulations. The policies address goals for odor control
at treatment plants and direct that water reuse is to continue and potentially expand at treatment
plants.
Treatment Plant Policies How implemented in 2007−2013
TPP-1: King County shall provide secondary
treatment to all base sanitary flow delivered to
its treatment plants. Treatment beyond the
secondary level may be provided to meet water
quality standards and achieve other goals such
as furthering the water reuse program or
benefiting species listed under the ESA.
The County operates three regional treatment
plants—West Point, South, and Brightwater Treatment
Plants, two local treatment plants—Vashon and
Carnation Treatment Plants, and one large on-site
septic system (Beulah Cove/Park). The processes
used at all of the County’s treatment plants provide
secondary treatment.
The West Point and South Plants treat wastewater to
secondary treatment using an activated sludge
biological process. The Vashon Treatment Plant uses
an oxidation ditch system. The Brightwater and
Carnation Plants use membrane bioreactor
technology. The Beulah Cove/Park uses a septic
tank/trickling filter.
Reclaimed water is produced at the South, West
Point, Carnation, and Brightwater Plants. (See TPP-9
for information on the uses of reclaimed water
produced from these plants.)
TPP-2: King County shall provide additional
wastewater treatment capacity to serve
growing wastewater needs by constructing the
Brightwater treatment plant at the Route 9 site
north of the city of Woodinville and then
expanding the treatment capacity at the south
treatment plant. The west treatment plant shall
be maintained at its rated capacity of one
hundred thirty-three mgd. The south treatment
plant capacity shall be limited to that needed to
serve the eastside and south King County,
except for flows from the North Creek Diversion
project and the planned six-million-gallon
storage tank, or minor rerating to facilitate
Construction of the Brightwater Treatment System is
complete, and the system began full operations on
October 29, 2012.
The work to complete the RWSP 2013 comprehensive
review included updating key planning assumptions
and using updated population and employment
forecasts developed by the Puget Sound Regional
Council to forecast treatment plant average wet-
weather flow (AWWF) and solids loadings capacity
through 2060. Findings indicate that there is sufficient
AWWF and loadings capacity systemwide into the
2030s.
WTD will continue to examine assumptions and trends
RWSP 2013 Comprehensive Review A-3
Appendix A. RWSP Policies Implementation in 2007−2013
Treatment Plant Policies How implemented in 2007−2013
south or east county growth. The potential for
expansion at the west treatment plant and
south treatment plant should be retained for
unexpected circumstances which shall include,
but not be limited to, higher than anticipated
population growth, new facilities to implement
the CSO reduction program or new regulatory
requirements.
that could affect treatment plant capacity needs to
ensure optimal timing for any future capacity-related
capital investments.
(See Chapter 4 for more information on the process to
forecast treatment plant flows and loadings.)
TPP-3: Any changes in facilities of the west
treatment plant shall comply with the terms of
the West Point settlement agreement.
The County continues to be in compliance with the
terms of the 1991 West Point Settlement Agreement.
TPP-4: King County’s goal is to prevent and
control nuisance odor occurrences at all
treatment plants and associated conveyance
facilities and will carry out an odor prevention
program that goes beyond traditional odor
control. To achieve these goals, the following
policies shall be implemented:
1. Existing treatment facilities shall be
retrofit in a phased manner up to the
High/Existing Plant Retrofit odor prevention
level as defined in Table 1 of Attachment A to
Ordinance 14712, the odor prevention policy
recommendations dated March 18, 2003. This
level reflects what is currently defined as the
best in the country for retrofit treatment
facilities of a similar size. Odor prevention
systems will be employed as required to meet
the goal of preventing and controlling nuisance
odor occurrences;
2. Existing conveyance facilities that
pose nuisance odor problems shall be
retrofitted with odor prevention systems as
soon as such odors occur, subject to technical
and financial feasibility. All other existing
conveyance facilities shall be retrofitted with
odor control systems during the next facility
upgrade;
3. The executive shall phase odor
prevention systems implementing the tasks
that generate the greatest improvements first,
balancing benefit gained with cost, and report
to the council on the status of the odor
prevention program in the annual RWSP report
as outlined in K.C.C. 28.86.165;
4. New regional treatment facilities
shall be constructed with odor control systems
that are designed to meet the High/New Plant
odor prevention level as defined in Table 1 of
Attachment A to Ordinance 14712, the odor
prevention policy recommendations dated
March 18, 2003. This level reflects what is
currently defined as the best in the country for
TPP-4.1 Work associated with phased odor control
retrofits in 2007−2013 included the following:
• West Point Plant. Completed modifications to
the odor scrubber system. Operational
activities, such as cleaning process tanks
more frequently, were also implemented to
complement and improve the results of the
phased retrofits.
• South Plant. Completed installation of covers
for each first pass of the four aeration basins
and for the return activated sludge (RAS)
channel and added a new odor scrubber to
control emissions from the aeration basins
and the RAS channel. Operational activities,
such as more frequent inspections of the odor
scrubber system, were implemented to
complement and improve the results of the
phased retrofits. In addition, a formal
environmental management system (EMS)
was implemented for air emission sources
including odor control.
The retrofits and operational changes have served to
reduce nuisance odors at both West Point and South
Plants. WTD continues to evaluate the results of these
efforts to determine if any further actions are needed.
TPP-4.2: When odors are attributed to existing
conveyance facilities, measures are taken to control
and prevent those odors. These measures include
sealing manhole covers, adjusting chemicals, and
repairing or replacing odor control equipment.
Conveyance system improvement projects include
upgrades to odor control facilities as appropriate. For
example, odor control equipment was included as part
of the Hidden Lake Pump Station and Sewer
Replacement project that was completed in spring
2009 and as part of the Bellevue Pump Station
upgrade that was completed in 2011.
TPP-4.3: The schedule for phased improvements
follows the direction provided in this policy. RWSP
A-4 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Treatment Plant Policies How implemented in 2007−2013
new treatment facilities of a similar size;
5. New conveyance facilities serving
these new regional treatment facilities shall
also be constructed with odor control systems
as an integral part of their design;
6. Design standards will be developed
and maintained for odor control systems to
meet the county’s odor prevention and control
goals;
7. A comprehensive odor control and
prevention monitoring program for the county’s
wastewater treatment and conveyance facilities
will be developed. This program shall include
the use of near facility neighbor surveys and
tracking of odor complaints and responses to
complaints and shall consider development of
an odor prevention benchmarking and audit
program with peer utilities; and
8. New odor prevention and
measurement technologies will be assessed
and methods for pilot testing new technologies
identified when determined by the executive to
be necessary and appropriate for achieving the
goals of this policy.
annual reports include a status of the odor prevention
program.
TPP-4.4: The Brightwater Plant’s odor control system
was designed to meet the “best in the country for new
facilities” level, described in Attachment A to
Ordinance 14712. There have been no odors
attributed to the Brightwater Treatment Plant since it
began operating.
TPP-4.5: Odor control was incorporated into the
Brightwater conveyance system. There have been no
sewage-related odors attributed to Brightwater
conveyance facilities since they began operating.
There was one complaint in 2013 related to diesel
odors that emanated from the Brightwater Influent
Pump Station during testing of the pump station’s
generators in 2013. To resolve the situation, a project
is under way to install diesel oxidation catalyst units
on each generator exhaust system.
TPP-4.6: WTD continues to use the design standards
for the County’s odor control systems.
TPP-4.7: Surveys of businesses and residents that
are near-neighbors of the County’s regional treatment
plants are carried out every two years. The findings
provide feedback on odor sources and process
improvements that have reduced odor impacts.
Information on the surveys is available at
http://www.kingcounty.gov/environment/wtd/About/Sys
tem/NearNeighborSurvey.aspx.
In addition, WTD has procedures in place to log,
investigate, and track all odor complaints. WTD’s goal
is to respond to each complaint within two hours after
receiving a complaint.
WTD consults with peer utilities on odor control
technologies, lessons learned, and other related
information.
TPP-4.8: WTD keeps informed on new technologies
through participation in professional organizations and
technical conferences. No assessments or pilot
studies were conducted during 2007−2013.
TPP-5: King County shall undertake studies to
determine whether it is economically and
environmentally feasible to discharge
reclaimed water to systems such as the Lake
Washington and Lake Sammamish watersheds
including the Ballard Locks.
WTD developed and analyzed conceptual strategies
for discharging reclaimed water into Lake Washington
and additional reclaimed water uses in the Lake
Sammamish watershed as part of the reclaimed water
comprehensive planning process that took place in
2009–2012.
WTD will continue to monitor any changing conditions
or future opportunities for reclaimed water uses in
these watersheds.
RWSP 2013 Comprehensive Review A-5
Appendix A. RWSP Policies Implementation in 2007−2013
Treatment Plant Policies How implemented in 2007−2013
TPP-6: The county shall evaluate opportunities
in collaboration with adjacent utilities regarding
the transfer of flows between the county's
treatment facilities and treatment facilities
owned and operated by other wastewater
utilities in the region. The evaluation shall
include, but not be limited to, cost
environmental and community impacts, liability,
engineering feasibility, flexibility, impacts to
contractual and regulatory obligations and
consistency with the level of service provided
at the county owned and operated facilities.
King County and the City of Edmonds continued to
transfer wastewater flows between systems in
accordance with their interlocal agreement. The
agreement stipulates that an equivalent amount of
flow is transferred through the Lake Ballinger Pump
Station from Edmonds to King County’s West Point
system as is transferred to Edmonds from King
County’s Richmond Beach area. The transfers
occurred during the dry season.
An additional agreement was followed that sent the
first 6 mgd of the Lake Ballinger Pump Station flows to
Edmonds during the wet season until Brightwater
came fully online in 2012. This arrangement made use
of extra Edmonds treatment capacity and minimized
the risk of overflows into Lake Washington during
large storm events.
TPP-7: King County may explore the possibility
of constructing one or more satellite treatment
plants in order to produce reclaimed water. The
county may build these plants in cooperation
with a local community and provide the
community with reclaimed water through a
regional water supply agency. In order to
ensure integrated water resource planning, in
the interim period prior to the development of a
regional water supply plan, King County shall
consult and coordinate with regional water
suppliers to ensure that water reuse decisions
are consistent with regional water supply plans.
To ensure costs and benefits are shared
equally throughout the region, all reclaimed
water used in the community shall be
distributed through a municipal water supply or
regional water supply agency consistent with a
regional water supply plan.
In 2007, WTD completed a preliminary analysis of
reclaimed water options in the Green River Valley to
answer questions raised by the Cities of Auburn,
Covington, Kent, Renton, and Tukwila. Information
from the study was incorporated into the reclaimed
water comprehensive planning process that occurred
in 2009–2012.
King County and the Covington Water District signed
a Memorandum of Agreement in 2007 to jointly fund
and pursue a phased approach to explore
opportunities for reclaimed water development in the
district’s service area. Information from this effort was
incorporated into the reclaimed water comprehensive
planning process.
In 2008–2009, WTD worked with the Seattle Public
Utilities (SPU) on SPU’s economic analysis of the
potential for providing reclaimed water from the
Brightwater Treatment Plant to large irrigators and
other potential users of nonpotable water in north
Seattle. Information from this effort was incorporated
into the reclaimed water comprehensive planning
process.
WTD developed and analyzed three conceptual
strategies for reclaimed water satellite or skimming
facilities as part of the reclaimed water comprehensive
planning process. WTD will continue to monitor
changing conditions or future opportunities that could
result in further exploration of such facilities.
WTD worked closely with water utilities during the
reclaimed water comprehensive planning process and
will continue to coordinate with water utilities on future
opportunities.
TPP-8: King County shall continue water reuse
and explore opportunities for expanded use at
existing plants, and shall explore water reuse
WTD has been producing and using reclaimed water
since 1997 at the South and West Point plants. South
Plant uses its reclaimed water at the plant for process
A-6 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Treatment Plant Policies How implemented in 2007−2013
opportunities at all new treatment facilities. water and landscape irrigation. Some of the the
reclaimed water is distributed and used offsite for
irrigation or public works uses, such as sewer flushing
and street sweeping. All of the reclaimed water
produced at the West Point Plant is used at the plant
site for process water and landscape irrigation.
The Carnation Treatment Plant began operating in
2008. The facility produces and discharges reclaimed
water to enhance a wetland in the County's Chinook
Bend Natural Area.
The Brightwater Treatment System began full
operations in 2012. Brightwater produces reclaimed
water for use at the Brightwater Environmental and
Education Center for non-drinking purposes such as
toilet flushing and landscape irrigation. In summer
2013, Brightwater began distributing some of its
reclaimed water offsite for irrigation uses.
RWSP 2013 Comprehensive Review A-7
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Conveyance Policies
A. Explanatory material. The conveyance policies are intended to guide how major improvements to the
wastewater conveyance system, including building and upgrading the pipes and pump stations needed
to convey wastewater to the Brightwater treatment plant and building the outfall pipe from the
Brightwater treatment plant, will be accomplished. The policies also include guidance for other major
and minor conveyance improvements to accommodate increased flows in other parts of the service area
and to prevent improper discharges from the sanitary system.
Conveyance Policies How implemented in 2007–2013
CP-1: To protect public health and water
quality, King County shall plan, design and
construct county wastewater facilities to avoid
sanitary sewer overflows.
1. The twenty-year peak flow storm shall be
used as the design standard for the county’s
separated wastewater system.
2. Parameters developed by the wastewater
treatment division in consultation with the
metropolitan water pollution abatement
advisory committee shall be used to guide
project scheduling and prioritization for
separated wastewater system projects.
3. The south treatment plant effluent transfer
system shall be designed with a five-year
design storm standard. When effluent volumes
exceed the five-year design standard and
exceed the capacity of the south treatment
plant effluent transfer system, secondary
treated effluent from the south treatment plant
will be discharged to the Green/Duwamish river
until the flow subsides such that the flow can
be discharged through the south treatment
plant effluent transfer system.
CP-1.1: The 20-year peak flow storm is used as the
design standard for the County’s separated
wastewater system. All of the conveyance system
improvement (CSI) capital projects that were
implemented during the 2007−2013 period used this
standard as the basis for design of the project.
CP-1.2: The parameters developed with the
Metropolitan Water Pollution Abatement Advisory
Committee (MWPAAC) during the process to
complete the 2007 CSI Program Update continue to
guide CSI project scheduling and prioritization.
CP-1.3: Effluent volumes did not exceed the capacity
of the of the South Plant’s effluent transfer system
during 2007–2013.
CP-2: King County shall construct the
necessary wastewater conveyance facilities,
including, but not limited to pipelines, pumps
and regulators, to convey wastewater from
component agencies to the treatment plants for
treatment and to convey treated effluent to
water bodies for discharge. Conveyance
facilities shall be constructed during the
planning period of this plan to ensure that all
treatment plants can ultimately operate at their
rated capacities. No parallel eastside
interceptor shall be constructed. No parallel
Kenmore Interceptor shall be constructed.
Conveyance projects in 2007–2013 were
implemented following the prioritization that was
included in the 2007 CSI Program update. The
prioritization process was developed by WTD and
MWPAAC. The goal of the process is to phase
implementation of CSI projects to meet the most
pressing needs and continue to protect public health,
the environment, and ratepayers.
The completion of the Brightwater Treatment System
eliminates any need to parallel the Eastside
Interceptor or the Kenmore Lakeline.
A-8 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Conveyance Policies How implemented in 2007–2013
CP-3: King County shall periodically evaluate
population and employment growth
assumptions and development pattern
assumptions used to size conveyance facilities
to allow for flexibility to convey future flows that
may differ from previous estimates. The
following activities shall take place to confirm
assumptions and conveyance improvement
needs:
1. Field verification of wastewater flows and
conveyance component conditions prior to
implementation of regional conveyance capital
projects that are intended to expand capacity of
the system; and
2. Decennial flow monitoring to correspond with
the Federal Census conducted every ten years.
(Ordinance 16033, approved in March 2008,
amended this policy to provide direction on the
activities to undertake to confirm assumptions
and needs.)
WTD uses population and employment growth
projections from the Puget Sound Regional Council
(PSRC), along with other RWSP key planning
assumptions (see Chapter 4) in its efforts to forecast
flows and determine sizing and timing of capital
investments to meet conveyance or treatment
capacity needs.
CP-3.1: WTD completed field verification prior to
implementing CSI projects during the 2007−2013
period.
CP-3.2: The Decennial Flow Monitoring (DFM) project
was completed in 2011. Data was collected from 235
flow meters in the separated portion of the regional
wastewater service area. The data is being used to
prepare the 2015 CSI Program update and will inform
the prioritization, timing, and sizing of future CSI
projects. The data is also available to local agencies
for use in planning and designing their systems.
CP-4: The executive shall update the
conveyance system improvement program
every five years beginning in 2013 to ensure
the program remains current. The program
updates shall provide information on growth
patterns, rate of growth and flow projections
and report on how this information affects
previously identified conveyance needs. The
program updates shall also provide information
on changed or new conveyance needs
identified since the previous update.
(This policy was added through Ordinance
16033.)
WTD began work in 2013 to update the CSI program,
and the program update is expected to be complete in
2015. WTD is using PSRC’s 2013 population and
employment forecast data, WTD’s updated planning
assumptions (see Chapter 3), data from the DFM
project, and information from local agencies to verify
or update future needs for the separated conveyance
system.
CP-5: King County shall apply uniform criteria
throughout its service area for the financing,
development, ownership, operation,
maintenance, repair and replacement of all
conveyance facilities. The criteria shall include:
1. County ownership and operation of
permanent conveyance facilities that serve
natural drainage areas of greater than one
thousand acres;
2. Conformance to the county's
comprehensive water pollution abatement plan
and the Regional Wastewater Service Plan as
precondition of county ownership; and
3. A financial feasibility threshold governing
limitations of the county's financial contribution
to: development of a new interceptor or trunk
sewer; or acquisition of an interceptor or trunk
sewer constructed by a local agency. The
The acquisition of the Central Plateau Interceptor from
the City of Renton was the only acquisition that took
place in 2007–2013 in accordance with this policy.
RWSP 2013 Comprehensive Review A-9
Appendix A. RWSP Policies Implementation in 2007−2013
Conveyance Policies How implemented in 2007–2013
threshold, as specified in K.C.C. 28.84.080,
shall consider the capital costs that can be
supported by the existing customers in the
natural drainage area that would be served by
the new facility.
(This policy used to be CP-4. Ordinance 16033
moved it to CP-5; no other changes were made
to this policy.)
CP-6: King County shall closely integrate water
reuse planning and I/I study results with
planning for wastewater conveyance and
treatment facilities. King County shall consider
water conservation and demand management
assumptions developed by local utilities for
wastewater facility planning.
(This policy used to be CP-5. Ordinance 16033
moved it to CP-6; no other changes were made
to this policy.)
WTD implemented this policy in 2007−2013 through
the following activities:
• Assessed the effects of conceptual reclaimed
water strategies on planned conveyance
system projects in 2012 as part of the
reclaimed water comprehesnive planning
process. Findings indicated that the strategies
would not affect any planned conveyance
system improvements.
• Implemented the Skyway initial infiltration and
inflow (I/I) reduction project. Post-project flow
monitoring is under way, and results will be
incorporated into conveyance system
planning as appropriate.
• Updated the water conservation and water
use assumptions based on winter water use
data and the projections of future use from
local water utilites (see Chapter 4). WTD
worked closely with MWPAAC on the update
of the RWSP key planning assumptions. The
updated assumptions will be used to verify or
udpate the sizing and timing of any future
conveyance capacity needs.
CP-7: King County shall evaluate other
demand management alternatives to meet
identified conveyance needs, such as
infiltration and inflow (I/I) reduction, water
conservation, and reclaimed water facilities.
Factors such as operational, environmental
and financial impacts, costs and benefits, and
the net present value of alternatives shall be
included in the evaluation of all feasible
alternatives identified by the county.
(This policy was added through Ordinance
16033.)
The process to determine how best to meet an
identified conveyance need occurs during project
planning and predesign and includes consideration of
the alternatives and factors listed in this policy.
A-10 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Infiltration and Inflow Policies
A. Explanatory material. The I/I policies are intended to guide the county in working cooperatively with
component agencies to reduce the amount of I/I that flows into component agencies’ local collection
systems, thereby reducing the impact of I/I on the regional system’s capacity. This cooperative process
will assess levels of I/I in local conveyance systems and construct pilot projects and will evaluate the
cost-effectiveness and environmental costs and benefits of local collection system rehabilitation. The
executive will develop and recommend long-term measures to reduce existing and future levels of I/I
into local collection systems. Incentives for component agencies to meet the adopted target for I/I
reduction may include a surcharge.
Infiltration and Inflow (I/I) Policies How Implemented in 2007–2013
I/IP-1: King County is committed to controlling
I/I within its regional conveyance system and
shall rehabilitate portions of its regional
conveyance system to reduce I/I whenever the
cost of rehabilitation is less than the costs of
conveying and treating that flow or when
rehabilitation provides significant environmental
benefits to water quantity, water quality, stream
flows, wetlands or habitat for species listed
under the ESA.
The County’s Regional I/I Control Program was
approved by the King County Council in 2006 through
Motion 12292. The program calls for WTD to carry out
initial I/I reduction projects to test the cost-
effectiveness of I/I reduction on a larger scale than the
pilot projects that were completed in 2004.
WTD worked closely with MWPAAC to identfiy
potential initial I/I reduction project areas for further
analysis. As a result of the analysis, design efforts,
and budget limitations, WTD selected the Skyway
Initial I/I reduction project for implementation. The
project was managed and funded by King County in
partnership with the Skyway Water and Sewer District.
Construction was completed in 2013. Analysis of the
project’s results are under way. WTD will be working
closely with MWPAAC to develop recommendations
on the next steps regarding the County’s I/I control
program and policy updates.
I/IP-2: King County shall work cooperatively
with component agencies to reduce I/I in local
conveyance systems utilizing and evaluating I/I
pilot rehabilitation projects, and developing
draft local conveyance systems' design
guidelines, procedures and policies, including
inspection and enforcement standards.
Evaluations of the pilot rehabilitation projects
and a regional needs assessment of the
conveyance system and assessments of I/I
levels in each of the local sewer systems will
form the basis for identifying and reporting on
the options and the associated cost of
removing I/I and preventing future increases.
The executive shall submit to the council a
report on the options, capital costs and
environmental costs and benefits including but
not limited to those related to water quality,
groundwater inception, stream flows and
wetlands, and habitat of species listed under
the ESA. No later than December 31, 2005,
This policy was written to provide guidance to the I/I
reduction pilot program, which was completed in
2004. As a result of the 10 pilot projects, the
Executive’s recommended I/I control program was
developed in coordination with MWPAAC and
approved by the County Council through Motion
12292 in 2006.
RWSP 2013 Comprehensive Review A-11
Appendix A. RWSP Policies Implementation in 2007−2013
Infiltration and Inflow (I/I) Policies How Implemented in 2007–2013
utilizing the prior assessments and reports the
executive shall recommend target levels for I/I
reduction in local collection systems and
propose long-term measures to meet the
targets. These measures shall include, but not
be limited to, establishing new local
conveyance systems design standards,
implementing an enforcement program,
developing an incentive based cost sharing
program and establishing a surcharge
program. The overall goal for peak I/I reduction
in the service area should be thirty percent
from the peak twenty-year level identified in the
report. The county shall pay one hundred
percent of the cost of the assessments and
pilot projects.
I/IP-3: King County shall consider an I/I
surcharge, no later than June 30, 2006, on
component agencies that do not meet the
adopted target levels for I/I reduction in local
collection systems. The I/I surcharge should be
specifically designed to ensure the component
agencies’ compliance with the adopted target
levels. King County shall pursue changes to
component agency contracts if necessary or
implement other strategies in order to levy an
I/I surcharge.
One of the recommendations included in the 2006 I/I
control program was to not implement a surcharge on
local agencies.
As noted in I/IP-1, WTD will be working with MWPAAC
to develop recommendations on the next steps
regarding the County’s I/I program and policy updates.
A-12 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Combined Sewer Overflow Control Policies
A. Explanatory material. The CSO control policies are intended to guide the county in controlling CSO
discharges. Highest priority for controlling CSO discharges is directed at those that pose the greatest risk
to human health, particularly at bathing beaches, and environmental health, particularly those that
threaten species listed under ESA. The county will continue to work with federal, state and local
jurisdictions on regulations, permits and programs related to CSOs and stormwater. The county will also
continue its development of CSO programs and projects based on assessments of water quality and
contaminated sediments.
Note: In May 2013, the King County Council approved Ordinance 17587, which amended several of the
CSO control policies to ensure the policies are consistent with the 2012 Council-approved long-term CSO
Control Plan and consent decree that was negotiated in 2013 with the U.S. Environmental Protection
Agency (EPA) and the Washington State Department of Ecology (Ecology).
Combined Sewer Overflow Control Policies How Implemented in 2007–2013
CSOCP-1: King County shall plan to control its
CSO discharges by the end of 2030 to meet:
1. The state's CSO control standard of an
average of one untreated discharge per CSO
outfall per year based on a twenty-year moving
average, and
2. Conditions of National Pollutant
Discharge Elimination System permit
requirements;
3. conditions of the Environmental
Protection Agency/Washington state Department
of Ecology Consent Decree.
(Ordinance 17587 amended this policy to
include 2030 as the completion date to achieve
CSO control; define the state’s CSO control
standard; and reconfirm the County’s
commitment to meet permit requirements and
the conditions of the consent decree.)
The King County Council approved the County’s
amended long-term CSO control plan through
Ordinance 17413 in September 2012. The plan
includes a schedule to complete nine CSO control
projects by the end of 2030. EPA subsequently
approved the plan in March 2013. The project
schedule is also included in the consent decree that
was negotiated with EPA and Ecology in 2013.
CSOCP-2: King County shall continue to work
with state and federal agencies to develop
cost-effective regulations that protect water
quality. King County shall meet the
requirements of state and federal regulations
and agreements.
(This policy was amended by Ordinance
17587. The language in this policy had
previously been included as part of CSOCP-1.
The Engineering and Planning Subcommittee
of MWPAAC [E&P] recommended making this
The County continues to work with state and federal
agencies on regulations related to protecting water
quality. For example, the County is a member of
Ecology’s “Delegate’s Table” that was formed in 2012
to provide advice and perspective to Ecology on the
water quality standards rule-making process that is
under way. In addition, the County has been working
closely with Ecology and EPA in developing and
evaluating Lower Duwamish Superfund cleanup
options.
The County continues to meet all of its state and
RWSP 2013 Comprehensive Review A-13
Appendix A. RWSP Policies Implementation in 2007−2013
Combined Sewer Overflow Control Policies How Implemented in 2007–2013
a separate policy.) federal regulations and agreements.
CSOCP-3: Consistent with the Environmental
Protection Agency/Washington state
Department of Ecology Consent Decree and
the county's long-term CSO control plan as
approved through Ordinance 17413, King
County shall give the highest priority for control
of CSO discharges that have the highest
potential to impact:
1. Human health through contact with CSO
flows or fish consumption; or
2. Environmental health, such as in areas
where sediment remediation is under way or
anticipated or where there is potential to impact
species listed under ESA.
(Previously, this policy was CSOCP-2.
Ordinance 17587 amended this policy to add
language to be consistent with the approved
amendment to the County’s long-term CSO
plan and to better define “highest priority”.)
The CSO control project schedule that was approved
by the Council and EPA and included in the consent
decree reflects the priorities outlined in this policy.
CSOCP-4: Consistent with its legal authority, if
King County constructs new projects that would
separate stormwater from its combined system
that result in separated stormwater discharges
to waterways, the county shall coordinate with
the city of Seattle in the city's municipal
stormwater National Pollutant Discharge
Elimination System permit (MS4) process as
appropriate.
(Previously, this policy was CSOCP-3.
Ordinance 17587 amended this policy to clarify
that the policy provides guidance for new
projects.)
There were no new projects constructed in 2007–
2013 that corresponded to this policy.
CSOCP-5: King County's wastewater
conveyance and treatment facilities shall not be
designed to intercept, collect and treat new
sources of stormwater. However, King County
may evaluate benefits and impacts to the
county system from accepting stormwater from
the city of Seattle that is not currently in the
combined system and shall consider factors
including, but not limited to existing capacity,
benefits and costs to ratepayers and the
regional system, operational impacts, payment
to county for value of the use of available
capacity and for the costs of conveyance and
treatment of new sources of stormwater and
compliance with state and federal regulations
and commitments.
(Previously, this policy was CSOCP-4.
Ordinance 17587 amended the policy to clarify
The County’s facilities are not designed to intercept,
collect, or treat new sources of stormwater. During the
2007–2013 timeframe, there were no proposals from
the City of Seattle regarding additional stormwater to
WTD’s system.
A-14 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Combined Sewer Overflow Control Policies How Implemented in 2007–2013
that King County’s facilities shall not be
designed for new sources of stormwater and to
require the County to consider the benefits,
costs and impacts of accepting new sources of
stormwater from Seattle if such a request were
to occur.)
CSOCP-6: In accordance with King County's
industrial waste rules and regulations, including
K.C.C. 28.84.050.K.1 and 28.84.060, the
county shall accept contaminated stormwater
runoff from industrial sources and shall
establish a fee to capture the cost of
transporting and treating this stormwater.
Specific authorization for such discharge is
required.
(Previously, this policy was CSOCP-5.
Ordinance 17587 amended the policy to
ensure it is consistent with King County Code’s
definition of industrial waste and to
acknowledge that the policy is in accordance
with industrial waste rules and regulations.)
WTD’s Industrial Waste Program continues to
coordinate the approvals of and cost recovery for
industrial discharges.
CSOCP-7: King County shall consider
implementing green stormwater infrastructure
projects to control CSOs when results of
technical, engineering, and benefit/cost
analyses and modeling demonstrate it is a
viable and cost-effective CSO control method.
(Ordinance 17587 added this policy to assure
that the use of green stormwater infrastructure
to control CSOs would be based on analytical
results and modeling.)
The Barton CSO control project that is under way in
Seattle is a green stormwater infrastructure (GSI)
project. The project includes constructing bioretention
swales in the planter strips in the city right-of-way on
up to 15 blocks in the Sunrise Heights and Westwood
neighborhoods in West Seattle. The decision to use
GSI for this project was based on the results of
analyses listed in this policy. The project is expected
be complete by the end of 2015.
Four of the nine CSO control projects that were
approved through Ordinance 17413 have been
identified as projects that could benefit from GSI:
West Michigan/Terminal 115, University, Montlake,
and 11th Ave NW CSO control projects. The analyses
listed in this policy will be conducted prior to
implementing specific GSI projects.
CSOCP-8: King County shall consider
implementing joint CSO control projects with
the city of Seattle when it is cost-effective, is
within county legal authorities and can be
accomplished within the schedule outlined in
the Environmental Protection
Agency/Washington state Department of
Ecology Consent Decree and the county's
approved long-term CSO control plan.
(Previously, this policy was CSOCP-6
Ordinance 17587 amended the policy to
incorporate information on potential joint
projects with Seattle, consistent with the
consent decree and Council-approved
Three of the nine CSO control projects that were
approved through Ordinance 17413 are identified as
potential joint projects with Seattle to control both
agencies’ CSOs in the 3rd Ave W, University, and
Montlake CSO basins. Five small transfers of flows
from Seattle projects to the King County system have
also been identified; the City would reimburse the
County for any operation and maintenance (O&M)
costs associated with these flows.
The County and City continue to discuss the potential
for these joint projects. The City is expected to finalize
and submit its long-term CSO control plan to EPA and
Ecology in 2015.
RWSP 2013 Comprehensive Review A-15
Appendix A. RWSP Policies Implementation in 2007−2013
Combined Sewer Overflow Control Policies How Implemented in 2007–2013
amendment to the long-term CSO control
plan.)
CSOCP-9: King County shall implement its
long-range sediment management strategy to
address its portion of responsibility for
contaminated sediment locations associated
with county CSOs and other facilities and
properties. Where applicable, the county shall
implement and cost share sediment
remediation activities in partnership with other
public and private parties, including the
county's current agreement with the Lower
Duwamish Waterway Group, the Department of
Ecology and the Environmental Protection
Agency, under the federal Comprehensive
Environmental Response, Compensation and
Liability Act.
(Previously, this policy was CSOCP-7,
Ordinance 17587 moved the policy to CSOCP-
9.)
The County continues to work to improve water quality
in the Lower Duwamish Waterway through actions
such as reducing CSOs, restoring habitats, capping or
removing sediments, and controlling toxicants from
industries and stormwater runoff.
WTD continued to carry out its Sediment Management
Plan (SMP) to remediate contaminated sediments
near CSO outfalls. The following activities were
carried out as part of implementing the SMP during
2007–2013:
• Completed cleanup of the former Denny Way
CSO site off of Myrtle Edwards Park in
Seattle; monitoring of sediment quality began
in 2008 and will continue through 2018
• Developed a model to better predict
deposition of contaminants around CSO
outfalls
• Completed post-construction monitoring of the
Diagonal/Duwamish cleanup site
• Conducted sampling of sediments in the East
Duwamish Waterway Superfund site, finalized
the East Duwamish Waterway remedial
investigation, and completed a draft feasibility
study
The Lower Duwamish Waterway Group (LDWG)
consists of King County, the City of Seattle, the Port of
Seattle, and the Boeing Company. The LDWG has
been working with EPA and Ecology since 2001 to
study the contamination and determine the best and
most effective alternatives to clean up the Lower
Duwamish Waterway (LDW). During the 2007–2013
timeframe, the LDWG completed a remedial
investigation and feasibility study for the LDW
Superfund site and started a study to better
understand who is eating contaminated seafood from
the Duwamish River.
In 2013, EPA issued the Proposed Plan for the Lower
Duwamish Waterway Superfund Site, which presents
a preferred alternative to clean up contamination in
the in-waterway portion of the LDW Superfund site.
EPA is expected to issue a Record of Decision in third
quarter 2014 to direct cleanup actions and long-term
monitoring.
The County, in partnership with the LDWG, carried out
engagement and outreach activities with interested
industries, businesses, residents, and environmental
and community groups throughout development of the
remedial investigation, feasibility study, and EPA’s
proposed cleanup plan.
A-16 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Combined Sewer Overflow Control Policies How Implemented in 2007–2013
The process to allocate cleanup costs among
potential responsible parties (PRPs) is under way.
CSOCP-10: Consistent with the Environmental
Protection Agency/Washington state
Department of Ecology Consent Decree, King
County shall assess CSO control projects,
priorities and opportunities using the most
current studies and information available, for
each CSO Control Plan Amendment as
required by the Department of Ecology in the
National Pollutant Discharge Elimination
System permit renewal process.
(Previously, this policy was CSOCP-8.
Ordinance 17587 added language to be
consistent with the Council-approved long-
range CSO control plan and the consent
decree. In addition, the policy was split into two
policies – see CSOCP-11.)
For the 2012 CSO Control Program review and plan
amendment, WTD assessed available scientific
studies to identify information that could shape the
program. Studies relating to the LDW Superfund
cleanup efforts and to salmon health and recovery
informed the recommendation and schedule to
complete CSO control projects in LDW sooner than
planned in the 1999 RWSP CSO control schedule.
CSOCP-11: Before completion of an National
Pollutant Discharge Elimination System
required CSO Control Plan Amendment, the
executive shall submit a CSO program review
report to the council and RWQC. The purpose
of the review is to evaluate, at a minimum,
changes to regulations, new technologies,
existing CSO control performance, and human
and environmental health priorities that may
affect implementation of the CSO Control Plan.
Based on its consideration of the CSO program
review, RWQC may make recommendations to
the council for modifying or amending the CSO
program, including changing the sequencing of
CSO projects. Any future updates or
amendments to the county's long-term CSO
control plan are subject to Environmental
Protection Agency and Washington state
Department of Ecology approvals.
(Ordinance 17587 moved this portion of the
previous CSOCP-8, and added language to
indicate that EPA and Ecology must approve
any future CSO Control Plan Amendment.)
The County Executive submitted the 2012 CSO
Control Program review to the County Council in June
2012. The Council approved the program review and
schedule for the amended long-term CSO control plan
in September 2012. As required, the County’s 2012
long-term CSO control plan amendment was
submitted to Ecology and EPA in October 2012.
The next program review is scheduled to be submitted
to the County Council in 2017.
CSCOP-12: King County shall implement its
CSO control projects in accordance with the
Environmental Protection Agency/Washington
state Department of Ecology Consent Decree
and the schedule outlined in the county's
approved long-term CSO control plan.
(Ordinance 17587 added this policy to be
consistent with the Council-approved long-term
CSO control plan and Consent Decree.)
Compliance with the consent decree is a top priority
for the County. All the CSO control projects outlined in
the consent decree are on schedule to achieve their
critical milestones.
CSOCP-13: King County shall prepare a water Work on the Water Quality Assessment And
RWSP 2013 Comprehensive Review A-17
Appendix A. RWSP Policies Implementation in 2007−2013
Combined Sewer Overflow Control Policies How Implemented in 2007–2013
quality assessment and monitoring study,
consistent with the guidance provided in
Ordinance 17413 and other applicable legal
requirements, to inform the next combined
sewer overflow control program review in 2018.
(Ordinance 17587 added this policy to be
consistent with Ordinance 17413, which directs
the County Executive to conduct a water
quality assessment and monitoring study.)
Monitoring Study is under way. The scope of work for
the assessment and study was approved by the
County Council in September 2013. More information
is available at
http://www.kingcounty.gov/environment/wastewater/C
SO/WQstudy.aspx.
A-18 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Biosolids Policies
A. Explanatory material. The biosolids policies are intended to guide the county to continue to produce
and market class B biosolids. The county will also continue to evaluate alternative technologies so as to
produce the highest quality marketable biosolids. This would include technologies that produce class A
biosolids.
Biosolids Policies How Implemented in 2007–2013
BP-1: King County shall strive to achieve
beneficial use of wastewater solids. A
beneficial use can be any use that proves to be
environmentally safe, economically sound and
utilizes the advantageous qualities of the
material.
One hundred percent of King County’s Loop®
biosolids were used beneficially as a soil amendment
and fertilizer in agriculture and forestry or as an
ingredient in compost.
Loop production began at the Brightwater Treatment
Plant in late 2011.
BP-2: Biosolids-derived products should be
used as a soil amendment in landscaping
projects funded by King County.
Specifications for the Loop compost (GroCo) have
been added to King County’s standard procurement
documents for use in bids and contracts. GroCo was
used in landscaping at the Brightwater Treatment
Plant.
BP-3: King County shall consider new and
innovative technologies for wastewater solids
processing, energy recovery, and beneficial
uses brought forward by public or private
interests. King County shall seek to advance
the beneficial use of wastewater solids,
effluent, and methane gas through research
and demonstration projects.
Examples of efforts to meet this policy during 2007–
2013 are as follows:
• Through the Northwest Biosolids Management
Association (NBMA), WTD participates in
biosolids-related research studies. In 2008, a
research project was conducted to quantify the
carbon sequestration benefits of using biosolids
and other organic residuals as a soil amendment
for land application. Results showed a significant
increase in carbon stored in agricultural soils,
indicating that use of biosolids as a soil
amendment has the potential to reduce the
carbon footprint while helping secure the
sustainability of agriculture in the state. By
sequestering carbon and avoiding synthetic
fertilizers, the use of Loop offset over 42,000 tons
of carbon dioxide equivalents in 2012, which is
similar to taking 8,000 cars off the road.
• WTD issued a Request for Information in 2008 to
learn about options for supplementing,
strengthening, or diversifying the County’s
biosolids program. Findings showed that
generally no changes are needed at this time.
The current program captures energy by
producing biogas from digestion, helps reduce
atmospheric carbon by storing it in the soil,
provides fertilizer for crops, and is less expensive
than other options.
• In summer 2009, the County began collaborating
on a carbon-sequestration demonstration project
in a borrow pit at Island Center Forest on Vashon
Island. Researchers are evaluating the ability of
composted organic residuals (biosolids, food
waste, and woody debris) to recover soil quality
RWSP 2013 Comprehensive Review A-19
Appendix A. RWSP Policies Implementation in 2007−2013
Biosolids Policies How Implemented in 2007–2013
by capturing and storing carbon, improving soil
health, and enhancing vegetation growth.
• In 2009, a Loop research and demonstration
garden was installed at South Treatment Plant.
University of Washington scientists studied the
safety of vegetables grown in a sandy loam soil
mix and a biosolids compost soil mix. The
vegetables grown in the biosolids compost mix
were deemed safe and the growth was
considered lush.
• A request for information was submitted in 2012
inviting local developers and commerical owners
to submit ideas for privately owned district energy
systems that could extract and recover heat from
WTD’s conveyance system. The goal was to
gauge interest in the private sector about
investing in new technologies that would make
heat energy and possibly other forms of energy in
the wastewater system more widely
available.WTD is working with real estate
developers to demonstrate how their projects can
tap into this thermal energy asset.
BP-4: King County shall seek to maximize
program reliability and minimize risk by one or
more of the following:
1. maintaining reserve capacity to manage
approximately one hundred fifty percent of
projected volume of biosolids;
2. considering diverse technologies, end
products, and beneficial uses; or
3. pursuing contractual protections
including interlocal agreements, where
appropriate.
WTD recycles 100 percent of its biosolids for use in
forestry and on irrigated and dryland crops, and to
make compost. In accordance with this policy, the
biosolids program has permitted land, primarily in
Douglas County, to maintain site capacity for 150
percent of annual volume. This additional capacity has
allowed King County to recycle 100 percent of its
biosolids even when one or more of its projects have
temporarily reduced capacity. In addition, WTD has an
agreement with the City of Everett for temporary
storage for the County’s biosolids at the City’s
treatment plant, which mitigates the effects of winter
pass closures. When the passes reopen, the stored
bisolids would be taken to Douglas County.
The County continues to evaluate markets that would
provide additional site capacity and environmental
benefits and to investigate technologies that have the
potential to cost-effectively produce Class A biosolids.
Two requests for proposals were issued for
composting services. While no new facilities were
available, a new lower-cost, multi-year contract was
awarded to the County’s long-term contractor for
GroCo.
More information on how the County continues to
implement this policy is available in the Biosolids
Strategic Plan 2012–2016, which is available at
http://www.kingcounty.gov/environment/wastewater/Bi
osolids/DocumentsLinks.aspx.
BP-5: King County shall produce and use
biosolids in accordance with federal, state and
local regulations.
WTD continues to meet all regulatory requirements for
production and beneficial use of biosolids.
In accordance with an amendment to the state’s
biosolids management rule (WAC 173-308-205),
A-20 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Biosolids Policies How Implemented in 2007–2013
construction began in 2013 on the influent screenings
project at the West Point Treatment Plant and will be
completed in third quarter 2014. The project meets the
rule’s requirement for “significant removal” of
manufactured inerts (trash and plastics) from
biosolids. The amendment rule requires treatment
plants to screen these objects from the wastewater
stream with 3/8-inch or finer bar screens. The West
Point Plant currently has 5/8-inch screens.
BP-6: King County shall strive to produce the
highest quality biosolids economically and
practically achievable and shall continue efforts
to reduce trace metals in biosolids consistent
with 40 C.F.R. Part 503 pollutant concentration
levels (exceptional quality) for individual
metals. The county shall continue to provide
class B biosolids and also to explore
technologies that may enable the county to
generate class A biosolids cost-effectively or
because they have better marketability. Future
decisions about technology, transportation and
distribution shall be based on marketability of
biosolids products.
WTD’s biosolids are routinely monitored for metals,
conventional constituents (phosphorous, potassium,
and pH), microbes, and organic compounds. The
metal concentrations are well below the most
restrictive federal and state standards. Industrial
source control and pretreatment have reduced the
amount of metals in biosolids by 70–90 percent since
the 1980s.
WTD participated in studies on the fate and
degradation of trace organic compounds after land
application of biosolids. Compounds include
nonylphenol (a surfactant), ibubprofen, triclosan (an
antibacterial), and estrogens. These are found in
household cleaning products, personal care products,
and pharmaceuticals. All compounds degraded
quickly, and no movement in soil, leaching, or plant
uptake was observed.
WTD launched the County’s biosolids brand, Loop, in
2012. The development of the Loop brand is part of a
long-term strategic goal to increase public support and
strengthen demand for biosolids. More information on
the benefits and uses of Loop is available at
http://www.loopforyoursoil.com/.
WTD developed an inventory of organic residuals and
degraded lands managed by the County, with the
objective of partnering with other county agencies to
improve soils, sequester carbon, and reduce costs of
managing residuals. The demonstration project at the
Island Center Forest is a result of these efforts (see
BP-3).
BP-7: When biosolids derived products are
distributed outside the wastewater service
area, the county shall require that local
sponsors using the products secure any
permits required by the local government body.
The local sponsors outside of the County’s
wastewater service area who use biosolids are
responsible for securing local support and any
applicable permits relating to the use of biosolids.
BP-8: King County shall work cooperatively
with statewide organizations on biosolids
issues.
King County participates in local organizations and is
a founding member of the NBMA, whose purpose is to
share technical knowledge about biosolids
management between members and to provide
opportunities to work with university scientists; local,
state, and federal regulators; and the general public.
Through the NBMA, WTD works cooperatively with
RWSP 2013 Comprehensive Review A-21
Appendix A. RWSP Policies Implementation in 2007−2013
Biosolids Policies How Implemented in 2007–2013
regulatory officials, scientists, and other biosolids
managers on regulatory issues, education and
training, public information, and research and
demonstration.
BP-9: King County shall seek to minimize the
noise and odor impact associated with
processing, transporting and applying of
biosolids, consistent with constraints of
economic and environmental considerations
and giving due regard to neighboring
communities.
In 2011, a new 10-year hauling contract was awarded.
The new contract required an onboard tracking
system, in advance of federal requirements to monitor
both trucks and drivers.
During 2011 and 2012, the biosolids program began
replacing its fleet of haul trucks. The trucks are quieter
and meet new EPA 2010 nitrous oxide (N2O) emission
standards, lowering the N2O emissions to less than 1
percent of the emissions of the previous fleet.
Construction of the West Point Treatment Plant
Digestion System Improvements project was
completed in 2013. The project will enhance the
reliability of the West Point Plant’s solids digestion
system and reduce the risk of digester upsets under
current and future solids loading conditions. In
addition to affecting the quality of the biosolids, these
upsets could increase odor at the plant. The project
also included modifications to the blending storage
tank (Digester 6) to enable its use as an emergency
digester if needed.
WTD has procedures in place to log, investigate, and
track all odor complaints. WTD’s goal is to respond to
each complaint within two hours after receiving a
complaint. (See TPP-4 for more information on the
County’s odor goals.)
BP-10: Where cost-effective, King County shall
beneficially use methane produced at the
treatment plants for energy and other
purposes.
The South, West Point, and Brightwater Treatment
Plants use digester gas (methane) to produce heat,
electricity, and natural gas. At the South Treatment
Plant, digester gas that is not used for in-plant
purposes is “scrubbed” to the quality required for
pipeline natural gas and then sold to Puget Sound
Energy.
The new Waste-to-Energy cogeneration system that
came online at the West Point Plant in 2013 will
supply a source of green energy for plant operations
and for sale to Seattle City Light per an agreement
that was signed in 2009. The system will produce
about 18,000 megawatt hours of electricity per year,
which is the same amount of power used by 1,100
typical Pacific Northwest homes.
A-22 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Water Reuse Policies
A. Explanatory material. The water reuse policies are intended to guide the county in continuing to
develop its program to produce reclaimed water. The county will coordinate its program with regional
water supply plans and work with state agencies and local jurisdictions on opportunities for water reuse.
The county will implement pilot and demonstration projects. Additional projects shall be implemented
subject to economic and financial feasibility assessments, including assessing environmental benefits
and costs.
The water reuse policies, as in the treatment plant policies, intend that the county continue producing
reclaimed water at its treatment plants. The treatment plant policies also address the potential
construction of one or more satellite plants. These small plants would provide reclaimed water, with the
solids being transferred to the regional plants for processing.
Water Reuse Policies How Implemented in 2007–2013
WRP-1: King County shall actively pursue the
use of reclaimed water while protecting the
public health and safety and the environment.
The county shall facilitate the development of a
water reuse program to help meet the goals of
the county to preserve water supplies within
the region and to ensure that any reclaimed
water reintroduced into the environment will
protect the water quality of the receiving water
body and the aquatic environment.
WTD has been safely using reclaimed water since
1997 at the South and West Point treatment plants.
Some of the reclaimed water produced at the South
Plant is distributed and used off-site by reclaimed
water customers, including the City of Tukwila. Starfire
Sports uses reclaimed water for irrigation, and the City
uses it for street sweeping, sewer flushing, and other
public works uses.
In March 2009, the Carnation Treatment Plant started
discharging its Class A reclaimed water to enhance a
wetland in the Chinook Bend Natural Area.
The Brightwater Treatment Plant began producing
reclaimed water in 2012. Reclaimed water is used at
the Brightwater Environmental and Education Center
for non-drinking purposes, such as toilet flushing and
landscape irrigation. It is also used for in-plant uses.
In June 2013, reclaimed water from Brightwater was
distributed to Willows Run Golf Course for irrigation
purposes.
The County’s Reclaimed Water Program includes
customer support and and development, permit
compliance, and planning associated with reclaimed
water use from South, Carnation, and Brightwater
Plants.
The County carried out two studies during this
timeframe—a turf irrigation study and an ornamental
plant and food crop irrigation study—in partnership
with University of Washington researchers to develop
local, independent, best-available science about the
public health and environmental impacts of using
reclaimed water. Results of both studies confirmed
that that reclaimed water uses are safe for people and
the environment. More information on the reclaimed
water studies are available at
http://www.kingcounty.gov/environment/wastewater/R
RWSP 2013 Comprehensive Review A-23
Appendix A. RWSP Policies Implementation in 2007−2013
Water Reuse Policies How Implemented in 2007–2013
esourceRecovery/ReWater/WaterResearch.aspx.
Also, the County carried out a joint feasibility study
with the City of Bothell, which was completed in 2013.
The City has requested more information from the
County on customer interests and funding options.
WTD carried out a reclaimed water comprehensive
planning process during this timeframe. The County
worked with local jurisdictions, water supply agencies,
and interested parties in the effort. The planning effort
gathered informaton on potential uses for reclaimed
water now and over the next 30 years and the
different ways that that the County’s reclaimed water
program could serve potential uses for reclaimed
water.
WRP-2: By December 2007, the King County
executive shall prepare for review by council a
reclaimed water feasibility study as part of a
regional water supply plan which will include a
comprehensive financial business plan
including tasks and schedule for the
development of a water reuse program and a
process to coordinate with affected tribal and
local governments, the state and area citizens.
The reclaimed water feasibility study shall be
reviewed by the RWQC. At a minimum the
feasibility study shall comply with chapter 90.46
RCW and include:
1. Review of new technologies for
feasibility and cost effectiveness, that may be
applicable for future wastewater planning;
2. Review of revenue sources other than
the wastewater rate for distribution of reused
water;
3. Detailed review and an update of a
regional market analysis for reused water;
4. Review of possible environmental
benefits of reused water; and
5. Review of regional benefits of reused
water.
This policy has been fully implemented. The reclaimed
water feasibility study was issued in March 2008 and
reviewed by the Regional Water Quality Committee in
April 2008; the study is available at
http://www.kingcounty.gov/environment/wastewater/R
WCompPlan/Library/Feasibility.aspx.
WRP-3: Recycling and reusing reclaimed water
shall be investigated as a possible future
significant new source of water to enhance or
maintain fish runs, supply additional water for
the region’s nonpotable uses, preserve
environmental and aesthetic values and defer
the need to develop new potable water supply
projects.
The reclaimed water planning process collected
information on potential nonpotable consumptive and
environmental enhancement uses. Conceptual
strategies to provide reclaimed water for some of
these uses were developed and evaluated as a part of
the effort. The information gathered in the planning
effort will help inform any future reclaimed water
opportunities that may arise. Documentation from the
planning effort is available at
http://www.kingcounty.gov/environment/wastewater/R
WCompPlan/Library.aspx.
WRP-4: King County’s water reuse program WTD coordinated with water supply agencies during
A-24 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Water Reuse Policies How Implemented in 2007–2013
and projects shall be coordinated with the
regional water supply plans and regional basin
plans, in accordance with state and federal
standards. The coordination shall be done with
the affected water supply purveyors. Water
reuse must be coordinated with water
supply/resource purveyors to ensure that
resources are developed in a manner
complementary with each other to allow the
most effective management of resources in the
county.
the reclaimed water planning process. Although a
regional water supply plan has not been developed,
the County remains committed to coordinating with
water supply agencies on reclaimed water projects
and related issues.
WRP-5: King County shall implement
nonpotable projects on a case-by-case basis.
To evaluate nonpotable projects, King County
shall develop criteria which will include, but are
not limited to: capital, operation and
maintenance costs; cost recovery; potential
and proposed uses; rate and capacity charge
impacts; environmental benefits; fisheries
habitat maintenance and enhancement
potential; community and social benefits and
impacts; public education opportunities; risk
and liability; demonstration of new
technologies; and enhancing economic
development. A detailed financial analysis of
the overall costs and benefits of a water reuse
project shall include cost estimates for the
capital and operations associated with a
project, the anticipated or existing contracts for
purchases of reused water, including
agricultural and other potential uses,
anticipated costs for potable water when the
project becomes operational; and estimates
regarding recovery of capital costs from new
reused water customers versus costs to be
assumed by existing ratepayers and new
customers paying the capacity charge. Water
reuse projects that require major capital
funding shall be reviewed by RWQC and
approved by the council.
There were no new major projects implemented
during this timeframe. As opportunities arise, WTD will
evaluate potential reclaimed water projects using the
criteria in this policy prior to implementing any new
major reclaimed water projects.
WRP-6: King County shall work with local
water purveyors, including when the local
purveyors update their water comprehensive
plans, to evaluate the opportunities for water
reuse within their local service area.
WTD participates in discussions with individual water
agencies, jurisdictions, MWPAAC, and other entities
concerning reclaimed water opportunities.
In addition, King County Code 13.24.010 calls for
water comprehensive plans to include an evaluation of
reclaimed water opportunities, as required by RCW
90.46.120, and calls for sewer comprehensive plans
to discuss opportunities for reclaimed water, as
required under RCW 90.48.112 and 90.48.495. King
County’s Utilities and Technical Review Committee
(UTRC) serves as the technical review body for water
and sewer utilities' comprehensive plans and works
RWSP 2013 Comprehensive Review A-25
Appendix A. RWSP Policies Implementation in 2007−2013
Water Reuse Policies How Implemented in 2007–2013
with the utilities during review of their plans.
WRP-7: King County shall develop an active
water reuse public education and involvement
program to correspond with the development of
the water reuse program and be coordinated
with other water conservation education
programs.
Information on water conservation and reclaimed
water is incorporated into WTD’s education programs,
including the display at the Brightwater Education and
Community Center. WTD’s education programs
include treatment plant open houses, treatment plant
tours for schools and interested groups, and
information shared at public meetings, on websites,
and through social media. As part of its education
efforts, WTD reaches out to other education
programs, local wastewater and water supply
agencies, and community, environmental, and
business groups.
The information on how WTD implemented its Public
Involvement Policies in 2007–2013 provides more
information on WTD’s education and outreach
programs.
WRP-8: King County shall utilize a forum or
multiple forums to provide opportunities for
coordination and communication with the
Washington state Departments of Health and
Ecology, which have the principal state
regulatory roles in the planning, design and
construction of reuse facilities. The county shall
involve other parties on these forums, including
but not limited to, the Corps of Engineers,
Washington state Department of Fish and
Wildlife, National Marine Fisheries Service,
United States Fish and Wildlife Service,
regional water suppliers, tribal governments,
local water and wastewater districts, cities,
local health departments, watershed forums
and environmental and community groups.
This process is an ongoing element of the County’s
reclaimed water program. Agencies cited in WRP-8
are regular participants, along with the County, in
multiple processes and committees related to water
supply and environmental and public health issues.
Examples of WTD’s specific efforts during this
timeframe are as follows:
• Participated in Ecology’s effort on reclaimed
water rule making. The County was an active
member of Ecology’s Reclaimed Water Rule
Advisory Committee. The rule-making process
was suspended in 2010. The governor directed
state agencies to review all current and
anticipated rule-making and decide what could be
delayed.
• Worked closely with the groups listed in this
policy during the reclaimed water comprehensive
planning effort.
• Helped establish and is a board member of the
WaterReuse Association’s Pacific Northwest
Section. The new section will focus on local
legislative and regulatory issues in Washington,
Oregon, Idaho, and Alaska—and is the first
WateReuse section to include multiple states.
WRP-9: King County shall work, on a case-by-
case basis, with the Washington state
Departments of Health and Ecology on water
reuse projects including, but not limited to,
those that are not specifically cited in the 1997
Department of Health and Ecology Water
Reclamation and Reuse Standards.
King County works closely with the Washington State
Departments of Health and Ecology on the County’s
reclaimed water program, including the reclaimed
water permitting processes for South, Brightwater,
and Carnation treatment plants. South Plant’s
reclaimed water permit was renewed in 2009,
Carnation’s reclaimed water permit became effective
in 2009 and was renewed in 2013, and Brightwater’s
reclaimed water permit became effective in 2011.
A-26 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Water Reuse Policies How Implemented in 2007–2013
WRP-10: King County shall hold and maintain
the exclusive right to any reclaimed water
generated by the wastewater treatment plants
of King County.
The County continues to be in compliance with this
policy. The policy is in accordance with RCW
90.46.120, which states “The owner of a wastewater
treatment facility that is reclaiming water with a permit
issued under this chapter has the exclusive right to
any reclaimed water generated by the wastewater
treatment facility.”
WRP-11: King County’s water reuse program
projects shall not impair any existing water
rights unless compensation or mitigation for
such impairment is agreed to by the holder of
the affected water rights.
The County continues to be in compliance with this
policy. The policy is in accordance with RCW
90.46.130, which states “…facilities that reclaim water
under this chapter shall not impair any existing water
right downstream from any freshwater discharge
points of such facilities unless compensation or
mitigation for such impairment is agreed to by the
holder of the affected water right.”
WRP-12: King County shall retain the flexibility
to produce and distribute reclaimed water at all
treatment plants including retaining options to
add additional levels of treatment.
The County continues to look to expand customer
opportunities for distributing reclaimed water from
South and Brightwater treatment plants. All of the
reclaimed water from the Carnation Plant is used to
enhance a wetland at the Chinook Bend Natural Area.
Reclaimed water produced at Brightwater, South, and
West Point Plants is used for irrigation at the plant
sites and for in-plant purposes.
WRP-13: King County shall continue to
evaluate potential funding of pilot-scale and
water reuse projects, in whole or in part, from
the wastewater utility rate base.
The Reclaimed Water Feasibility Study included a
review of revenue sources for reclaimed water
distribution, and the reclaimed water comprehensive
planning process included discussions on ways to
fund future reclaimed water projects. The County’s
reclaimed water projects are currently funded through
the wastewater rate and reclaimed water customers.
WRP-14: King County shall complete an
economic and financial feasibility assessment,
including environmental benefits, of its water
reuse program. The assessment shall include
the analysis of marginal costs including
stranded costs and benefits to estimate
equitable cost splits between participating
governmental agencies and utilities. The
assessment shall also include a review of
existing and planned water and wastewater
facilities in an approved plan to ensure that
water reuse facilities are justified when any
resulting redundant capacity as well as other
factors are taken into account.
The feasibility study that was completed per WRP-2
addressed this policy.
In addition, the reclaimed water comprehensive
planning process included an economic and financial
feasibility assessment and an analysis of
environmental benefits of the conceptual strategies
that were developed as part of the process.
WRP-15: King County should pursue
development of a water reuse program to
discharge reclaimed water to reduce
freshwater consumption used in the operation
of the Ballard Locks as a priority water reuse
project.
This policy is similar to the guidance in TPP-5. WTD
developed and analyzed conceptual strategies for
discharging reclaimed water into Lake Washington
and additional reclaimed water uses in the Lake
Sammamish watershed as part of the reclaimed water
comprehensive planning process that took place in
2009–2012. Based on the analysis, it was determined
RWSP 2013 Comprehensive Review A-27
Appendix A. RWSP Policies Implementation in 2007−2013
Water Reuse Policies How Implemented in 2007–2013
to not pursue any of the strategies at this time.
WTD will continue to monitor changing conditions or
future opportunities that could result in additional
reclaimed water uses in these watersheds
A-28 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Wastewater Service Policies
A. Explanatory material. The wastewater services policies guide the county in both providing wastewater
services to its customers and maintaining the wastewater system in a cost-effective, environmentally
responsible manner. These policies shall also guide King County’s development and operation of
community treatment systems.
King County provides wholesale wastewater treatment and disposal service to component agencies. The
county’s wastewater service area boundary generally coincides with the boundaries of these component
agencies, including certain areas in Snohomish county and Pierce county. The county is to provide
wastewater services to areas within the respective urban growth boundaries and in rural areas only to
protect public health and safety, in conformance with state provisions and local growth management
act policies and regulations.
Wastewater Services Policies How Implemented in 2007–2013
WWSP-1: King County shall provide
wastewater services to fulfill the contractual
commitments to its component agency
customers in a manner that promotes
environmental stewardship, recognizes the
value of wastewater in the regional water
resource system and reflects a wise use of
public funds.
King County has long-term agreements to provide
sewage disposal and treatment services with 33 local
governments and one Indian Tribe.
Environmental stewardship is an important component
of the County’s wastewater treatment service; WTD’s
mission is to protect public health and enhance the
environment by treating and reclaiming water, recycling
solids, and generating energy. WTD’s vision of creating
resources from wastewater is carried out in recognition
of the overall value of wastewater.
WTD provides high-quality wastewater treatment in as
cost-effective manner as possible. The division
regularly evaluates projects in the planning and design
phases to identify potential cost-savings. WTD bonds
are highly rated and receive low interest rates.
WWSP-2: King County shall continue to foster
tribal relations as appropriate to structure
processes for joint water quality stewardship.
WTD regularly works with affected Tribal Governments
on its plans and projects. Activities with the Tribal
Governments during the 2007 to 2013 timeframe
include the following:
• Participating in workshops on environmental
priorities and CSO control technologies during the
2012 CSO Control Program review
• Holding meetings and discussions with staff from
area tribal governments during the reclaimed
water comprehensive planning process
• Working with the Puyallup Tribal Government to
address shellfish contamination of the
Quartermaster Harbor area of Vashon-Maury
Island and in other closed or restricted areas in the
Vashon-Maury Island area
• Working with the Suquamish and Tulalip Tribal
Governments to implement a shellfish program
enhancement effort in the Richmond Beach area
of north King County as part of the Brightwater
RWSP 2013 Comprehensive Review A-29
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Services Policies How Implemented in 2007–2013
mitigation program
• Working with the Muckleshoot Indian and
Suquamish Indian Governments in the decision
process for cleaning up Duwamish River
sediments and on improving equity and social
justice determinants
• Working with Muckleshoot Indian Tribe regarding
water or sewer plan reviews and approvals within
areas of interest to the tribe.
WWSP-3: King County shall not accept
additional wastewater directly from private
facilities within the boundaries of a component
agency without the prior written consent of
such component agency.
WTD has received no such requests from private
facilities since the adoption of the RWSP.
WWSP-4: King County’s wastewater service
area generally has been developed along
those boundaries adopted in the original
metropolitan Seattle sewerage and drainage
survey, substantive portions of which were
adopted as the county's comprehensive water
pollution abatement plan and amended. King
County's wastewater service area consists of
the service areas of the component agencies
with which a sewage disposal agreement has
been established (agreement for sewage
disposal, section 2) and the county's service
area boundary is the perimeter of these areas.
The service area boundary for sewer service
provided to Snohomish county and Pierce
county shall not exceed each county’s urban
growth boundary. The service area boundary
within King County shall be consistent with
countywide planning policy CO-14 and the King
County Comprehensive Plan which permit
sewer expansion in rural areas and resource
lands where needed to address specific health
and safety problems. To protect public health
and safety, the county may assume in
accordance with state procedures, the
ownership of existing sewer treatment and
conveyance facilities that have been
constructed by a sewer district organized under
state law.
The County’s wastewater service area boundary
remains consistent with this policy.
WWSP-5: Extensions of existing conveyance
facilities or construction of new conveyance
facilities must be consistent with King County’s
land use plans and policies, and certified by
potentially affected land use jurisdictions as
consistent with their adopted land use plans
and policies.
WTD evaluates its projects during the planning process
to ensure consistency with the County’s land use plans
and policies. WTD maintains and reviews up-to-date
local capital improvement plans for jurisdictions and
sewer districts in the County’s wastewater service area
and works closely with local jurisdictions through all
phases of a WTD project that is planned within their
jurisdiction.
A-30 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Services Policies How Implemented in 2007–2013
WWSP-6: King County shall operate and
maintain its facilities to protect public health
and the environment, comply with regulations
and improve services in a fiscally responsible
manner.
WTD’s mission is to protect public health and enhance
the environment by treating and reclaiming water,
recycling solids, and generating energy. Extensive
resources have been committed to maintaining the
integrity of the wastewater system and preventing
sanitary sewer overflows. The Industrial Waste and
Local Hazardous Waste Management programs work
to control pollutants at their sources and prevent those
pollutants from reaching the County’s treatment plants.
The King County Council’s review of WTD’s programs,
priorities, and costs during the annual rate setting
process and Council’s budget process provides
additional assurance that WTD is carrying out its
programs in a fiscally responsible manner.
WWSP-7: King County shall plan, design and
construct wastewater facilities in accordance
with standards established by regulatory
agencies and manuals of practice for
engineering.
WTD designs and constructs wastewater treatment
facilities to ensure that they fully comply or exceed
regulatory and permit requirements. WTD applies
science and engineering to planning, design, and
construction of facilities and follows industry-recognized
standards. As a result, the County’s wastewater system
exceeds the reliability standards of most major
metropolitan systems and has been able to absorb
record storm events in recent years with little effect on
public health and safety.
WTD participates in national organizations and
associations that address issues such as pumping
standards, treatment and odor control standards and
technologies, and predictive modeling tools.
In addition, WTD follows the guidelines in the Criteria
for Sewage Works Design manual. Ecology prepares
this manual, also known as the “Orange Book.” It
serves as a guide for the design of wastewater
collection, treatment, and reclamation systems and
addresses requirements that will lead to approvable
plans. WAC 173-240-040 requires that sewer plans and
specifications are reasonably consistent with the
Orange Book.
WWSP-8: King County shall construct, operate
and maintain facilities to prevent raw sewage
overflows and to contain overflows in the
combined collection system. In the event of a
raw sewage overflow, the county shall initiate a
rapid and coordinated response including
notification of public health agencies, the
media, the public and the affected jurisdiction.
Preserving public health and water quality shall
be the highest priority, to be implemented by
immediately initiating repairs or constructing
temporary diversion systems that return flow
back to the wastewater system.
Implementation of the RWSP ensures that adequate
wastewater capacity will be available when needed.
The various sections and work units of WTD coordinate
to assess needs and prioritize projects to prevent
overflows. WTD’s forecasting and demand-modeling
capabilities, in-field flow monitoring, and ongoing facility
inspections provide essential information to identify and
address capacity, operational, and maintenance needs.
WTD has established emergency response procedures
in the event of sewage overflows.
WWSP-9: To ensure the region’s multibillion-WTD’s formal and detailed Strategic Asset
RWSP 2013 Comprehensive Review A-31
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Services Policies How Implemented in 2007–2013
dollar investment in wastewater facilities, an
asset management program shall be
established that provides for appropriate
ongoing maintenance and repair of equipment
and facilities. The wastewater maintenance
budget, staffing levels and priorities shall be
developed to reflect the long-term useful life of
wastewater facilities as identified by the asset
management program.
Management Plan (SAMP) that was developed in 2006
was updated in 2010. The next update is scheduled for
2014. The focus of the SAMP is to balance lifecycle
costs and risks at the asset level. To optimize
stewardship of ratepayer dollars, minimize risk of asset
failure and comply with regulations WTD’s Asset
Management Program (AMP) is sustained at all levels
of the division through the Asset Management Steering
Committee (AMSC), Maintenance Best Practices
Steering Committee (MBPSC), Technical Standards
Committee (TSC) and the Computerized Maintenance
Management System (CMMS) Users Group.
WTD’s AMP strives to apply the whole life (cradle to
grave) approach to its assets. The focus is holistic,
starting with the development of technical standards
and predesign (what we build), project management
and engineering (how we build it), O&M (how we
operate and maintain it from commissioning through
decommissioning and disposal), and finance (how we
pay for it). The ability to measure and improve each
step of the asset management process is the function
of the Key Performance Indicator (KPI) Program, which
is currently being updated.
Another important element is tracking, scheduling, and
assessing asset management and performance over
the life of the asset. A high priority for WTD is to ensure
this essential information is kept current in its CMMS.
WWSP-10: The asset management program
shall establish a wastewater facilities assets
management plan, updated annually,
establishing replacement of worn, inefficient
and/or depreciated capital assets to ensure
continued reliability of the wastewater
infrastructure.
Regularly scheduled condition assessments are
performed on the conveyance system and facility
structures. Findings and rehabilitation
recommendations are reported in a facilities inspection
annual work plan and are tracked in CMMS.
The lifecycle of process equipment, facility structures,
and the conveyance system is managed under the
SAMP.
WWSP-11: King County shall design,
construct, operate and maintain its facilities to
meet or exceed regulatory requirements for air,
water and solids emissions as well as to
ensure worker, public and system safety.
WTD’s treatment plants continue to meet and. in most
cases, exceed permit requirements. In 2013, all of the
County’s treatment plants operated without any
violation of their NPDES permit effluent limits.
The Industrial Waste Program permits discharges into
the sewer that are not hazardous to workers and cause
no environmental harm.
For emergencies, WTD has procedures in place to
ensure worker, public, and system safety.
A-32 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Services Policies How Implemented in 2007–2013
WWSP-12: King County shall accept sewage,
septage and biosolids from outside its service
area provided that it is consistent with the King
County Comprehensive Plan or the
comprehensive plan of the source jurisdiction,
capacity is available and no operating
difficulties are created. The county shall
establish a rate to recover costs from accepting
sewage, septage and biosolids from outside its
service area.
Services are monitored for consistency with applicable
plans and to ensure they cause no adverse impact to
the wastewater system. A separate rate, based on
solids content, has been established to cover the costs
of processing deliveries of septage and biosolids at the
South Treatment Plant.
WWSP-13: King County shall identify the
potential for “liability protection” for component
agencies for unexpected costs associated with
water quality requirements.
This policy was developed in 1999, soon after Chinook
salmon was listed as a threatened species under the
Endangered Species Act. There was discussion that if
the County were to do a Habitat Conservation Plan
(HCP) for the entire wastewater service area, there
might be a way for the local agencies to achieve
“liability protection” under WTD’s HCP. WTD
discontinued the work on the HCP in April 2005 after
the first phase was completed.
WWSP-14: King County shall continue its long-
standing commitment to research and
development funding relating to water quality
and technologies for the wastewater system.
Examples of studies undertaken in this timeframe
include:
• Nitrogen Removal Study. WTD conducted two
studies to evaluate the impacts of a range of
potential nitrogen limits on capital and operating
costs at the South Treatment Plant and West Point
Treatment Plant. The studies evaluated a variety
of nitrogen removal technologies and used existing
treatment plant data and computer modeling to
develop capital costs, O&M costs and greenhouse
gas (GHG) emissions for each regulatory scenario.
Results of the studies show that the costs of
upgrading the South Treatment Plant would range
from approximately $0.5 billion to $1 billion with an
associated operating cost increase of $10 to $33
million per year. The estimated costs of upgrading
the West Point Treatment Plant is $1 billion with
an operating cost of $30 million per year.
Upgrading the West Point Plant to remove
nitrogen would substantially reduce its treatment
capacitybecause of lack of available space and
would therefore require construction of one or
more new treatment plants with a total design
capacity of 75–150 mgd.
• South Plant Biogas Utilization. The South Plant
biogas scrubber system currently processes
biogas produced by the solids digestion system to
convert it into high-quality bio-methane (natural
gas). This gas is then injected into the nearby
natural gas pipeline and sold to Puget Sound
Energy.
Critical elements of the biogas recovery and
RWSP 2013 Comprehensive Review A-33
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Services Policies How Implemented in 2007–2013
energy production system are aging and will
require replacement in the near future. A study
was conducted to assess the system to determine
if it still provides the best and highest use the
biogas. The study concluded that replacing the
gas scrubbing system with new technology and
upgrading the plant heating systems would resolve
substantial issues at a similar capital cost but
significantly lower lifecycle cost when compared to
the status quo alternative or other alternatives
evaluated (including internal combustion engine
generators).
• Grease Co-Digestion at South Plant. WTD has
been investigating the potential of adding organic
wastes (such as food waste) to the sewage solids
that are processed in anaerobic digesters (“co-
digestion”) at the South Plant. Recent WTD
studies have investigated the costs and potential
revenues associated with establishing a waste
restaurant grease (“brown grease”) receiving
facility. Brown grease is typically processed in
rendering facilities and/or disposed of in landfills.
There is a shortage of facilities that can cost-
effectively convert the grease to energy.
When restaurant grease is mixed into anaerobic
digesters, it can substantially increase the
production of valuable biogas that can be used to
produce renewable energy. Numerous wastewater
treatment facilities have successfully implemented
brown grease co-digestion programs. In addition to
continuing to assess the benefits of a facility at
South Plant, WTD is actively working with private
entrepreneurs to determine if the private sector
could cost-effectively convert this waste product
into renewable energy.
WWSP-15: King County will consider
development and operation of community
treatment systems under the following
circumstances:
1. The systems are necessary to alleviate
existing documented public health hazards or
water quality impairment;
2. Connections to public sewers tributary to
conventional wastewater treatment facilities are
not technically or economically feasible;
3. Installation of on-site septic systems is not
technically feasible;
4. Properties to be served by said systems are
within the jurisdiction and service area of a
local government authority authorized to
provide sewer service;
5. The local sewer service provider agrees to
own and operate the collection system tributary
The County continues to own and operate the Beulah
Park/Cove Treatment Facility on Vashon Island in
accordance with this policy.
A-34 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Services Policies How Implemented in 2007–2013
to the community treatment system;
6. Development of the community systems and
provision of sewer service are consistent with
all applicable utility and land use plans; and
Public sewer extensions shall be in compliance
with King County Comprehensive Plan Policy
F-313 as in effect on March 11, 1999.
RWSP 2013 Comprehensive Review A-35
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Water Quality Protection Policies
A. Explanatory materials. The water quality protection policies are intended to guide King County in
identifying and resolving regional water quality issues, protecting public and environmental health and
protecting the public’s investment in wastewater facilities and water resource management. Research
and analysis are required and will be used to evaluate water quality in county streams and other bodies
of water within the service district.
Water Quality Protection Policies How Implemented in 2007–2013
WQPP-1: King County shall participate in
identifying and resolving water quality issues
pertaining to public health and ecosystem
protection in the region to ensure that the
public's investment in wastewater facilities and
water resource management programs is
protected.
King County monitors the waters and sediments near
treatment plant and CSO outfalls to ensure compliance
with water quality regulations and to quickly identify and
resolve water quality issues.
King County’s Trouble Call Program responds to water
quality emergencies in King County. The primary role of
this program is to support WTD. The program also
investigates activities such as illegal spills, dump sites,
construction erosion and sediment control problems,
unknown discharges from outfalls, algal blooms, and
fish kills. The program’s mission is to respond,
investigate, and work cooperatively with agencies on
water quality complaints and emergency environmental
situations within the greater King County region. More
information on the program is available at
http://www.kingcounty.gov/environment/wlr/sections-
programs/environmental-lab/trouble-call.aspx.
WQPP-2: King County shall evaluate the
impacts and benefits of actions that affect the
quality of the region’s waters and identify
measures to meet and maintain water quality
standards.
WTD builds, operates, and maintains wastewater
facilities to ensure the County meets or exceeds water
quality regulations and standards, such as NPDES
discharge limitations. In 2007 through 2012, West Point
and South treatment plants received the National
Association of Clean Water Agencies (NACWA)
Platinum Peak Performance Award each year for
operating multiple consecutive years of compliance with
NPDES permit effluent limits.
The Vashon Treatment Plant received NACWA’s Silver
Peak Performance Award in 2010 and the Gold Award
in 2011 and 2012. NACWA’s Silver Awards are
presented to facilities with no more than five NPDES
violations in a year and Gold Awards are presented to
facilities with no NPDES permit effluent limit violations
in a year. In 2011, the Vashon Plant had one effluent
limit violation because of a pH exceedance that
occurred on December 12, and in 2012, the plant
earned Ecology’s “Outstanding Performance Award” for
meeting all the conditions of its NPDES permit with no
violations of any kind. The Vashon Plant met its
NPDES permit effluent requirements in 2007 through
2009.
The Carnation Treatment Plant received NACWA’s
Gold Award in 2010 and 2012, and the Silver Award in
2011. In 2011, the plant exceeded its reclaimed water
A-36 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Water Quality Protection Policies How Implemented in 2007–2013
permit instantaneous maximum turbidity limits on two
days in March.
All of the County’s treatment plants met their NPDES
permit effluent limits in 2013. At the time of publication
of this report, NACWA had not awarded its peak
performance awards for 2013.
The County’s CSO Control Program, Protecting Our
Waters, and amended long-term CSO control plan is
designed to protect water quality in the water bodies
where the County’s CSOs discharge. The County is on
schedule to meet all the milestones associated with its
CSO Control Program and consent decree to ensure all
the County’s CSOs are controlled by 2030. About one-
half of the County’s CSOs are controlled to the state
standard of one untreated overflow from each location
per year on average. Construction is under way on four
CSO control projects along Puget Sound beaches, and
work has begun on two CSO control projects in the
Lower Duwamish Waterway that were approved by the
County Council in 2012 as part of the County’s
amended long-term CSO control plan.
WQPP-3: King County shall forecast future
aquatic resource conditions that may affect
wastewater treatment decisions and work
cooperatively to identify cost-effective
alternatives to mitigate water quality problems
and enhance regional water quality.
King County routinely monitors and models the
condition of County water resources and uses
information from these efforts and from other programs
in the region to identify trends.
The Water Quality Assessment And Monitoring Study
that is under way and was approved through Ordinance
17413 aligns with this policy. The assessment is
examining local water quality concerns near King
County CSOs in Elliott Bay, Lake Union/Ship Canal,
and the Duwamish River.
WQPP-4: King County shall participate with its
regional partners to identify methods, plans
and programs to enhance water quality and
water resources in the region.
King County works with other entities in the region on
water quality monitoring and protection programs,
including cities, Tribes, and state and federal agencies.
The County monitoring data is routinely used by
Ecology when they present monitoring results in the
Puget Sound region.
The County continues to work with Ecology and local
jurisdictions on developing and implementing Total
Maximum Daily Loads for impaired surface waters and
to develop a more coordinated ambient monitoring
program.
Since 2008, multiple agencies and organizations,
including the County, are participating in a regional
stormwater monitoring coordination effort to ensure
cost efficiencies and avoid duplication in the monitoring
programs. The regional monitoring recommendations
have been incorporated into stormwater NPDES
permits for jurisdictions. The County also participates
on coordination committees regarding toxic chemical
monitoring, marine water quality monitoring, and
RWSP 2013 Comprehensive Review A-37
Appendix A. RWSP Policies Implementation in 2007−2013
Water Quality Protection Policies How Implemented in 2007–2013
freshwater monitoring.
The County continues to provide technical assistance
to the Puget Sound Partnership (PSP). The County
also participates in the South Central Caucus Group,
which is the local integrating organization (LIO), for
PSP’s South Central Puget Sound Action Area and the
Snohomish-Stillaguamish LIO, which is one of the LIOs
for the PSP’s Whidbey Action Area.
WQPP-5: The King County executive shall
implement a comprehensive water quality
monitoring program of streams and water
bodies that are or could be impacted by
influent, effluent, sanitary system overflows or
CSOs. The range of data to be gathered
should be based on water pollutants and
elements that scientific literature identifies as
variables of concern, what is needed to
substantiate the benefits of abating combined
sewer overflows and what is required by state
and federal agencies. The executive shall
submit summary reports and comprehensive
reviews of this information to the King County
council as outlined in K.C.C. 28.86.165.
A summary report on the County’s comprehensive
water quality monitoring program is provided in the
RWSP annual reports. Monitoring results are also
provided annually in the environmental indicator tab of
the County’s Department of Natural Resources and
Parks KingStat website at
http://your.kingcounty.gov/dnrp/measures/.
WQPP-6: King County shall implement and
maintain water quality, monitoring, evaluating
and reporting programs to support the national
pollutant discharge elimination system for
wastewater and other permit applications, and
ensure permit compliance.
King County has ongoing monitoring programs that
assess discharge quality for permit compliance.
Ambient water and sediment quality monitoring
provides background information and assists in
identifying any adverse impacts from wastewater
facilities. The specific programs that were under way in
this timeframe and support the regional wastewater
treatment system’s needs are as follows:
• Marine water quality monitoring, including routine
offshore and nearshore water quality, continuous
water quality, and sediment quality in King County’s
marine waters
• Lake Union, Lake Washington, and Lake
Sammamish water quality monitoring, including
routine water quality and continuous water quality
• Stream water quality monitoring in Water Resource
Inventory Areas (WRIAs) 8 (greater Lake
Washington watershed) and 9 (Green/Duwamish
watershed) and on Vashon Island, including routine
water quality, stream benthos (bottom-dwelling
organisms), and pollution source identification
• Streamflow and temperature monitoring in WRIAs 8
and 9
• Freshwater swimming beach monitoring in WRIAs 8
and 9
• Toxics and contaminant assessment in fish tissue in
Lake Washington and addressing new and emerging
A-38 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Water Quality Protection Policies How Implemented in 2007–2013
contaminants of concern
• Watershed impact assessment/management support
affecting the WTD service area.
In response to a proviso in the 2012 King County
Budget, a report on King County’s water quality
monitoring was provided to the King County Council in
April 2012. The report is available at
http://green.kingcounty.gov/WLR/Waterres/StreamsDat
a/pdf/King-County-WTD-Proviso-Final-4-18-12.pdf.
WQPP-7: King County shall actively participate
in the development of water quality laws,
standards and program development to ensure
cost-effective maintenance or enhancement of
environmental and public health.
The County regularly participates in the development of
effective and reasonable regulations, both on its own
and through professional organizations such as
NACWA, Water Environment Federation, Water Reuse
Association, and Pacific Northwest Clean Water
Association. The County participates in advisory
groups, contributes technical information, and reviews
and comments on proposals. County staff has also
been participating in nationwide discussions on
emerging chemicals of concerns.
The County participates on committees associated with
Ecology’s water quality related rule-making processes
and efforts to update water quality standards. For
example, the County is a member of Ecology’s
“Delegate’s Table” that was formed in 2012 to provide
advice and perspective to Ecology on the water quality
standards rule-making process that is under way. The
County also participated in Ecology’s reclaimed water
rule-making process, which was suspended in 2010. In
addition, the County has been working closely with
Ecology and the U.S. Environmental Protection Agency
(EPA) in developing and evaluating Lower Duwamish
Superfund cleanup options.
WQPP-8: King County shall assess the risk to
human health and the environment from
wastewater treatment and conveyance
activities, and use this information in evaluating
water pollution abatement control options.
Results of the water quality monitoring activities
described in WQPP-6 help to inform WTD of any risks
to public health and environment from its facilities.
WTD operates and maintains its facilities to ensure they
are operating well and meet or exceed permit and other
requirements that are designed to protect public health
and the environment.
In addition, during design and construction of
wastewater facilities, WTD works with the affected
communities and regulatory agencies to ensure
measures are taken to minimize adverse impacts to the
public or the environment during construction or
operations.
RWSP 2013 Comprehensive Review A-39
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Wastewater Planning Policies
A. Explanatory material. The wastewater planning policies are intended to guide the county in its long-
term comprehensive planning for design and construction of facilities that meet the wastewater needs
of customers within the service area.
Recognizing that the RWSP is a complex and dynamic comprehensive development guide that will
regularly need to be updated, the county will conduct annual reviews of plan implementation and its
consistency with policies, and of scientific, economic and technical information as well as periodic
comprehensive reviews of the assumptions on which the RWSP is based.
These policies also express the intent of the council to request that the RWQC continue review of the
conditions and assumptions that guide the implementation of the RWSP.
Wastewater Planning Policies How Implemented in 2007–2013
WWPP-1: King County shall plan
comprehensively to provide for the design and
construction of facilities that meet the
wastewater system needs of the service area
and shall coordinate with other local
jurisdictions to ensure that construction-related
disruption to neighborhoods is minimized.
WTD considers several factors to ensure
comprehensive wastewater planning. Flow monitoring
and facilities inspections provide key information
related to capacity, maintenance, and asset
replacement needs. WTD reviews population and
employment forecasts, water conservation and water
use assumptions, and rainfall data and then
incorporates updated information into its planning of
facilities. In addition, WTD reviews the comprehensive
plans of its local agencies and meets with
representatives of those agencies to confirm planning
assumptions as well as to coordinate construction
related activities.
WTD regularly works with permitting agencies, local
jurisdictions, and affected neighbors during the
planning, design, and construction of projects to
minimize construction related disruptions. Agreements
related to hours of construction, parking for
construction workers, noise control, and traffic control
measures often result from these efforts.
WWPP-2: In planning future wastewater
systems, King County shall make a long-term
assessment of wastewater system needs.
To protect public health and water quality, it is
essential to plan wastewater facilities before they are
needed. Current planning takes into account a 50-
year planning horizon from the base year 2010. This
means that 2060 represents the year that WTD
assumes that all the sewerable portions of the
County’s service area will be sewered. However, WTD
expects the population in its service area to continue
to increase after 2060. To ensure that existing and
planned facilities will meet future needs, the County
monitors population and employment forecasts,
comprehensive plans of the local agencies, the
potential for new regulations, new technologies, and
information relating to climate change.
WWPP-3: In planning for facilities, King County
shall work collaboratively with other
jurisdictions and look for opportunities to
WTD coordinates with local jurisdictions and agencies
during planning and implementation of projects.
Examples during the 2007−2013 timeframe are as
A-40 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Planning Policies How Implemented in 2007–2013
achieve cost-savings. follows:
• Update of RWSP planning assumptions. WTD
coordinated closely with the Engineering and
Planning Subcommittee of MWPAAC and
individual local agencies during the review and
update of the RWSP planning assumptions for
the RWSP 2013 comprehensive review.
• Skyway initial I/I reduction project. This project
was managed and funded by King County in
partnership with the Skyway Water and Sewer
District. As part of the cost-share agreement, the
project rehabilitated mains and manholes in the
project basin at the District's cost.
• Bellevue Influent Trunk project. This project
was completed in 2012. It included design and
construction of a new portion of the City of
Bellevue’s West Central Business District (CBD)
Trunk. Under a cost-share agreement, the City of
Bellevue covered the costs associated with the
improvements to the CBD Trunk and shared a
portion of the design, construction, and staff labor
costs.
• Ballard Siphon Replacement project.
Coordination within WTD also provides
opportunities for cost-savings. Control of the
Ballard CSO was incorporated into this project,
which was completed in 2013.
• Long-term CSO control plan. The County
worked closely with the City of Seattle during
development of the County’s amended long-term
CSO control plan, which was approved by the
County Council in September 2012. Three of the
nine CSO control projects that were approved are
identified as potential joint projects with Seattle to
control both agencies’ CSOs in the 3rd Ave W,
University, and Montlake CSO basins. Five small
transfers of flows from Seattle projects to the
King County system have also been identified;
the City would reimburse the County for any
O&M costs associated with these flows. The
County and City continue to discuss the potential
for these joint projects.
• RainWise. Over 250 rain gardens and cisterns
are now helping to control stormwater runoff and
preventing CSOs as part of the RainWise
Program in Seattle. Seattle Public Utilities (SPU)
started the successful program in 2010 to pay for
rain gardens and cisterns on private property in
some parts of the city. WTD is now also offering
the RainWise Program to homeowners through a
memorandum of agreement with the SPU; the
RWSP 2013 Comprehensive Review A-41
Appendix A. RWSP Policies Implementation in 2007−2013
Wastewater Planning Policies How Implemented in 2007–2013
agreement outlines the cost-sharing and other
responsibilities of each agency.
• Lower Duwamish Waterway Superfund
cleanup. The County is an active participant in
the Lower Duwamish Waterway Group (LDWG),
which consists of King County, the City of
Seattle, the Port of Seattle, and the Boeing
Company. The LDWG has been working with
EPA and Ecology since 2001 to study
contamination and determine the best and most
effective alternatives to clean up the LDW.
WWPP-4: Facility sizing shall take into account
the need to accommodate build-out population.
As noted in WWPP-2, current planning considers
needs over a 50-year planning horizon, through 2060.
The year 2060 represents when potentially sewerable
portions of the County’s service area are expected to
be sewered. WTD evaluated regional treatment plant
capacity needs through 2060 as part of the process to
complete the RWSP 2013 comprehensive review.
The 2015 CSI program update will evaluate and
identify separated conveyance system capacity needs
over a 50-year planning horizon, through 2060.
WWPP-5: RWSP review processes. King
County shall monitor the implementation of the
RWSP and conduct reviews of the RWSP as
outlined in K.C.C. 28.86.165.
During 2007−2013, RWSP annual reports were
submitted in accordance with the reporting policies
outlined in K.C.C. 28.86.165.
The RWSP 2013 comprehensive review has been
completed following the guidance provided in K.C.C.
28.86.165.
A-42 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Environmental Mitigation Policies
A. Explanatory material. The environmental mitigation policies are intended to guide King County in
working with communities to develop mitigation measures for environmental impacts from the
construction and operation of wastewater facilities. These policies also ensure that the siting and
mitigation processes for wastewater facilities are consistent with the Growth Management Act and the
state Environmental Policy Act.
Environmental Mitigation Policies How Implemented in 2007–2013
EMP-1: King County shall work with affected
communities to develop mitigation measures
for environmental impacts created by the
construction, operation, maintenance,
expansion or replacement of regional
wastewater facilities. These mitigation
measures shall:
1. Address the adverse environmental impacts
caused by the project;
2. Address the adverse environmental impacts
identified in the county’s environmental
documents; and
3. Be reasonable in terms of cost and
magnitude as measured against severity and
duration of impact.
During the planning, design and construction of
projects, WTD works with permitting and regulatory
agencies, local jurisdictions, tribes, and affected
businesses and residents to identify measures to
avoid and minimize environmental impacts that could
result from the construction, operation, maintenance,
and expansion or replacement of regional wastewater
facilities. Adverse environmental impacts and
associated mitigation are typically identified during
project review under the State Environmental Policy
Act and consultations or reviews required by local,
state and federal regulations (such as Endangered
Species Act and National Historic Preservation Act).
Examples of mitigation related activities that occurred
in 2007–2013 are as follows:
• Barton Pump Station Upgrade project.
Construction impacts associated with this project
include temporary closure of a Fauntleroy Ferry
Terminal toll collection lane and the release of
odorous air when the pump station wetwell was
exposed. To address these impacts, the County
worked with Washington State Ferries to develop
an operational strategy (such as closing the ferry
lane only during non-peak use times) and agreed
on traffic control plans to minimize impacts to
ferry traffic. To minimize odor impacts during
construction, an aboveground temporary odor
control unit will be located at the project site to
treat foul air from the wetwell. Following
construction, part of the site will be restored for
use as a street-end park containing a community-
maintained garden and artwork and providing
beach access. The County incorporated
community input into the landscaping plan for the
site and measures for protecting and replacing
artwork.
• Barton CSO Control project. The County
proposed construction rain of gardens, a low
impact development approach, for controlling
CSOs in the Barton basin rather than
constructing a large tank that would have had a
higher potential for adverse environmental
impacts. The County responded to community
RWSP 2013 Comprehensive Review A-43
Appendix A. RWSP Policies Implementation in 2007−2013
Environmental Mitigation Policies How Implemented in 2007–2013
concerns by reducing the number of proposed
curb extensions and locating rain gardens on one
side of the street instead of both to preserve
mature trees. The County is minimizing impacts
by phasing construction.
• Murray CSO Control project. Based on
community feedback received during predesign,
the County decided to locate the CSO storage
facility on private properties occupied by
residential buildings rather than in a public park.
Mitigation included compensation to property
owners for fair market value of the properties and
relocation benefits to eligible tenants. Project
design elements were developed by a
professional artist and landscape architect with
input by community members to address
concerns about potential aesthetic impacts.
Design elements include the provision of public
access to portions of the project site,
maintenance of Puget Sound views from publicly
accessible areas, finishes and landscaping that
have a more park-like than industrial feel, and
redesign of Beach Drive to discourage through-
traffic.
• North Beach CSO Control project. Based on
community feedback received during predesign
and design, the County located the CSO storage
facility below an existing street and configured it
so as to minimize impacts to residential and park
access during construction. A new permanent
aboveground ancillary equipment facility was
situated on the project site and designed so that
it would not block views of Puget Sound from
nearby residences. The County worked with the
City of Seattle on a street restoration plan to
ensure that the design addressed community’s
concerns. The City proposed new street lights,
but did not require them after the County
conveyed the community’s concerns about light
pollution in the residential area that currently has
unobstructed views of Puget Sound. The street
restoration plan also included reconfiguration of
the intersection in which the storage facility is
located to increase pedestrian and vehicle safety.
• Kent/Auburn Conveyance System
Improvement project. The County developed
traffic control plans for this trenched pipeline
installation project. The plans included traffic and
pedestrian detour routes, flaggers, notice to
businesses, residences, and a school of times
when construction would be nearby. The County
minimized the impact of trenching through a
school playground by performing the work during
A-44 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Environmental Mitigation Policies How Implemented in 2007–2013
the summer. A professional archaeologist
monitored activities in culturally sensitive project
areas.
EMP-2: Mitigation measures identified through
the state Environmental Policy Act process
shall be incorporated into design plans and
construction contracts to ensure full
compliance.
This policy is implemented for every project that
undergoes the SEPA review process. WTD
environmental planners prepare checklists and review
construction plans and specifications to make sure
mitigation measures are included in these documents.
Typical mitigation measures included in SEPA
checklists for WTD projects include the following:
• Temporary erosion and sedimentation control
measures during project construction
• Measures to minimize noise, such as mufflers or
sound barriers
• Landscaping and architectural features to help a
facility blend into the surrounding area
• Actions to minimize light and glare
• Construction traffic routing and parking plans
EMP-3: The siting process and mitigation for
new facilities shall be consistent with the
Growth Management Act and the state
Environmental Policy Act, as well as the lawful
requirements and conditions established by the
jurisdictions governing the permitting process.
Wastewater treatment facilities are considered
essential public facilities under the Growth
Management Act. WTD plans new facilities or
upgrades to existing facilities to ensure capacity is
available when needed.
Environmental, community, cost, right-of-way, and
regulatory considerations are included in the process
to site new wastewater facilities. WTD staff works with
permitting agencies and local jurisdictions to ensure
projects and facilities comply with applicable
requirements and conditions.
EMP-4: King County shall mitigate the long-
term and short-term impacts for wastewater
facilities in the communities in which they are
located. The county’s goal will be to construct
regional wastewater facilities that enhance the
quality of life in the region and in the local
community, and are not detrimental to the
quality of life in their vicinity.
King County is committed to being a good neighbor
with its wastewater facilities. The examples provided
in EMP-1 align with this policy.
RWSP 2013 Comprehensive Review A-45
Appendix A. RWSP Policies Implementation in 2007−2013
Environmental Mitigation Policies How Implemented in 2007–2013
EMP-5: King County shall enter into a
negotiated mitigation agreement with any
community that is adversely impacted by the
expansion or addition of major regional
wastewater conveyance and treatment
facilities. Such agreements shall be executed
in conjunction with the project permit review.
Mitigation shall be designed and implemented
in coordination with the local community, and
shall be at least ten percent of the costs
associated with the new facilities. For the south
treatment plant and for the new north treatment
plant, a target for mitigation shall be at least ten
percent of individual project costs, or a
cumulative total of ten million dollars for each
plant, whichever is greater, provided that
mitigation funded through wastewater revenues
is consistent with: chapter 35.58 RCW; Section
230.10.10 of the King County Charter;
agreements for sewage disposal entered into
between King County and component
agencies; and other applicable county
ordinance and state law restrictions.
This policy was written with the construction of a new
third regional treatment system (now known as the
Brightwater Treatment System) and the anticipated
full future expansion of the South Plant in mind.
The Brightwater systemwide mitigation package that
has been implemented complied with this policy.
A-46 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Public Involvement Policies
A. Explanatory material. The public involvement policies are intended to guide the county in maintaining
public information and education programs and to engage the public and component agencies in
planning, designing and operating decisions that affect them.
Public Involvement Policies How Implemented in 2007−2013
PIP-1: King County shall maintain public
information/education programs and engage
the public and component agencies of local
sewer service in the planning, designing and
operating decisions affecting them.
WTD holds monthly meetings MWPAAC to share
information with local agencies on programs and
projects that are at various stages of planning and
implementation.
WTD routinely engages public officials and residents
in the planning and decision-making process for its
projects and programs. Here are some examples of
how the public influenced WTD decisions:
• With the help of a group of educators who raised
more than $1 million, the Brightwater Center
achieved platinum LEED status. The Brightwater
Center is an environmental education and
community center built to replace a grange hall
on the Brightwater site.
• 53rd Avenue Pump Station improvements were
designed to expand the facility underground in
order to maintain neighborhood views.
• As part of the Ravenna Creek Pipe Extension,
WTD removed invasive weeds and replaced
native plants in some areas around the Ravenna
Creek Daylighting Project in the south end of
Ravenna Park.
• Neighbors of the Murray Pump Station worked
with WTD designers to minimize the “industrial
facility” feel, encourage views of Puget Sound,
discourage through-traffic on Beach Drive, and
enhance continuous space between Lowman
Beach Park and the facility site.
• WTD responded to a West Seattle community’s
concerns by minimizing the number of blocks and
the number of parking spaces required for a GSI
project. Neighbors have input on street trees and
many want a rain garden on their own property.
• MWPAAC participated in the process to amend
the CSO control plan in 2012. Members also
provided significant input on the proposed CSO
control policy updates that were developed to be
consistent with the CSO control plan and the
CSO consent decree. These CSO control policies
were approved by the King County Council in
May 2013.
• Industrial waste customers provided advice on
policies, procedures, and program priorities
RWSP 2013 Comprehensive Review A-47
Appendix A. RWSP Policies Implementation in 2007−2013
Public Involvement Policies How Implemented in 2007−2013
through an advisory committee, customer survey,
and program workshops.
PIP-2: King County shall develop public
information and education programs to support
county wastewater programs and shall lay the
groundwork for public understanding of and
involvement in specific programs.
WTD places high importance on educating the public
regarding the wastewater system, projects and
services. Innovations in 2007−2013 include the
following:
• WTD’s website transitioned to a new domain
www.kingcounty.gov in 2007−2008 and was
improved to make it more user-friendly and
informative. The website includes information on
the county’s wastewater system and process,
programs planned for the future, projects in
design and construction, and the sewer rate and
the capacity charge.
• The status of King County and Seattle CSOs is
now on the web in real time. King County worked
with Seattle in 2011 to bring its overflow
information into the County’s website in order to
streamline the public’s access to the information.
http://www.kingcounty.gov/environment/wastewat
er/CSOstatus.aspx
• The King County Equity and Social Justice
Ordinance (launched as in initiative in 2008) has
shaped the way WTD implements the public
involvement policies. Information is being
provided in multiple languages, and other
techniques are being used to reach people who
might not have traditionally participated in these
processes.
• WTD has been expanding its use of social media
tools to include Facebook, Twitter, U-tube,
Vimeo, and Flickr.
Ongoing activities from 2007−2013 include the
following:
• Public information and outreach: web pages,
open houses, information booths, displays,
speakers bureau, wastewater treatment facility
tours, and education partnerships.
• Two-way dialogue: briefings, 24-hour hotlines,
advisory groups, public meetings, canvassing
neighborhoods with fliers, newsletters, mailings,
response to inquiries, on-line forms.
• Response to odor complaints within two hours.
• Response to over 15,000 customer calls every
year from ratepayers about the monthly sewer
and capacity charge rates.
• Outreach to industrial businesses regarding
federal and King County pretreatment
regulations, policies, and procedures: meetings,
A-48 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Public Involvement Policies How Implemented in 2007−2013
newsletters, fact sheets and web page with easy
access to tools and forms.
• Media relations to keep local news media
informed about WTD projects and programs that
affect the neighborhoods they serve and provide
general information on the wastewater system.
See PIP-5 for more information on WTD’s educational
programs.
PIP-3: King County shall involve public officials
and citizens of affected jurisdictions early and
actively in the planning and decision-making
process for capital projects.
A public involvement initial needs assessment is
conducted at the beginning of every WTD capital
project to assess opportunities for early and active
involvement. The assessment is used to tailor public
involvement plans for specific projects.
Examples of how early, active involvement shaped
capital projects are as follows:
• Public officials and the public had many
opportunities to comment on and shape the 2012
CSO Control Program review. Information was
available through briefings, presentations, and
workshops; in public libraries; and on the W eb.
Materials were available in five languages.
http://www.kingcounty.gov/environment/wastewat
er/CSO/ProgramReview.aspx
• Our Duwamish is a website designed to provide
one location for information on all the services
King County provides in the Duwamish area and
links to opportunities to comment on EPA’s
Superfund cleanup plan.
http://www.kingcounty.gov/environment/watershe
ds/green-river/OurDuwamish.aspx
• In 2013, outreach was under way in the
Duwamish area, where WTD has large CSO
control projects (Brandon-Michigan, Hanford)
planned over the next several years. While
continuing to maintain existing relationships,
WTD is also reaching out to diverse community
leaders, offering treatment plant tours to area
schools, and developing multi-lingual tools to help
implement these projects.
PIP-4: King County shall inform affected
residents and businesses in advance of capital
construction projects.
WTD construction teams include community relations
experts to inform affected residents and businesses in
advance of capital construction projects and respond
to questions and concerns. Typical activities include
pre-construction meetings, fliers, web updates, signs,
direct on-the-ground contact, and 24-hour project
hotlines. Procedures are in place to document and
track questions, concerns, or complaints, and ensure
prompt response. Lessons-learned evaluations are
conducted to identify what has worked and to apply
the lessons to other projects.
RWSP 2013 Comprehensive Review A-49
Appendix A. RWSP Policies Implementation in 2007−2013
Public Involvement Policies How Implemented in 2007−2013
This website explains how WTD works with the public
throughout the stages of a capital project from
planning to construction to operation.
http://www.kingcounty.gov/environment/wtd/Constructi
on/phases.aspx
WTD provides construction information in multiple
languages to reach everyone in affected
neighborhoods. For example, construction information
was provided in Russian and English during the
Bellevue Influent Trunk project (completed in 2012).
http://www.kingcounty.gov/environment/wtd/Constructi
on/Completed/BellevueInfluentTrunk.aspx
In 2012, routine construction specifications were
updated so that solutions to some typical community
impacts are automatically included when a contract is
bid. This ensures all communities have the same level
of consideration and improves service for everyone,
including communities who may have linguistic or
other challenges communicating with the County.
PIP-5: King County shall disseminate
information and provide education to the
general public, private sector and
governmental agencies regarding the status,
needs and potential future of the region's water
resources.
WTD reached significant information and education
milestones between 2007−2013:
• A new partnership with Cascadia Community
College began in 2012 to provide training for
future treatment plant operators.
http://www.cascadia.edu/programs/degrees/water
quality.aspx
• In 2011, WTD celebrated the Brightwater Grand
opening. More than 2000 people (general public;
private sector and governmental agencies)
attended the event and learned about the status
and potential future of the region’s water
resources.
• In 2011, the Brightwater Center opened and
began offering significant programming about
water resources through educational partnerships
with IslandW ood and other organizations. The
center includes an interactive display hall. In the
first year of operation the center reached
approximately 4,000 4th−8th graders in school
programs, 300 participants in family programs,
and 150 teachers in professional development
workshops.
• King County’s new biosolids brand Loop® was
introduced to the public at the 2012 Flower and
Garden Show. King County biosolids have been
a key ingredient in compost available at the show
for decades.
• Since 2010, King County, Seattle University and
the Salvation Army Renton Food Bank have
partnered on a five-year community farm project
A-50 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Public Involvement Policies How Implemented in 2007−2013
located on an acre of the South Treatment Plant,
demonstrating the use of GroCo compost made
with Loop biosolids and increasing public
understanding of the benefits of nutrient
recycling.
http://www.kingcounty.gov/environment/wtd/Educ
ation/SouthPlant/RRdemoprojects.aspx
Continuing programs include the following:
• Treatment plant tours. Over 3,000 students and
hundreds of other interested parties annually
learn the importance of water conservation and
the process of wastewater treatment by touring a
treatment plant.
• Treatment plant open houses. Members of the
public are invited to tour the Brightwater
Treatment Plant one Saturday every month.
Tours at other treatment plants are scheduled
each year in conjunction with World Water Day
(March) and World Toilet Day (November) and
upon request. All of these events feature water
conservation, water quality, and wastewater
treatment information.
Key educational materials include the following:
• Let’s Talk Trash brochures and posters.
These materials, designed to prevent trash in the
wastewater system, are available in six
languages.
http://www.kingcounty.gov/environment/wtd/Educ
ation/ThingsYouCanDo/TalkTrash.aspx
• Ratepayer report. This is a detailed report for
the general public about the services WTD
provides. It is updated each time the rate is
changed.
http://www.kingcounty.gov/environment/wtd/Abou
t/Finances/RatePayerReport.aspx
• New materials describing the quality and
effectiveness of Loop biosolids are available at
http://www.loopforyoursoil.com/.
PIP-6: King County shall actively solicit and
incorporate public opinions throughout the
implementation of its comprehensive plan.
The activities described in PIP-1 through PIP-5
illustrate how WTD keeps people informed and
involved in the projects and programs associated with
implementing the RWSP.
WTD solicits public feedback and opinion in its the bi-
annual water quality surveys, bi-annual surveys of
near neighbors of the regional treatment plants,
capital project surveys, public meetings, open houses,
and informational booths. Opportunities for public
comment are also provided via WTD project websites,
emails, letters, and phone calls.
RWSP 2013 Comprehensive Review A-51
Appendix A. RWSP Policies Implementation in 2007−2013
Public Involvement Policies How Implemented in 2007−2013
PIP-7: Beginning January 1, 2001, King County
shall implement a public awareness and
education program regarding the
environmental impacts and costs to wastewater
rate payers of I/I in the local and regional
conveyance systems.
WTD’s I/I website provides detailed information on I/I,
how it is found and fixed, and what people can do to
help.
http://www.kingcounty.gov/environment/wastewater/II.
aspx
WTD serves as a clearinghouse regarding information
on technologies related to I/I reduction; this
information is made available to MWPAAC members.
From 2007−2012, members of the Skyway community
participated in intensive public involvement associated
with construction of a pilot I/I project.
http://www.kingcounty.gov/environment/wastewater/II/
InitialProjects/Skyway.aspx .
Meetings, newsletters, door-to-door fliers, and
response to complaints and inquiries included
education about the impacts of I/I on the wastewater
system. Community members in Bellevue and
Issaquah received significant I/I information until
Skyway was selected for the pilot project.
A post-construction survey of Skyway residents
illustrated a high level of understanding of the I/I
problem. The survey showed that 61 of 63
respondents (97 percent) recalled getting information
about the project before it began, and 62 of the 63
respondents (98.5 percent) understood the purpose of
the project and the benefit to the area.
PIP-8: King County shall support regional water
supply agencies and water purveyors in their
public education campaign on the need and
ways to conserve water. King County should
promote pilot projects that support homeowner
water conservation in coordination with water
suppliers and purveyors, emphasizing
strategies and technologies that reduce
wastewater.
Water conservation is a key theme for all of WTD’s
outreach and education efforts, including Brightwater
Center activities, open houses, informational booths,
public meetings, and school outreach. It is embedded
in a number of the “things you can do” to protect the
environment featured on the web site.
http://www.kingcounty.gov/environment/wtd/Education
/ThingsYouCanDo.aspx
Water conservation is a major theme in the
Brightwater Center displays, including signs informing
visitors about the use of reclaimed water on site.
Because Brightwater is in its service area, Cross
Valley Water District had input on the displays
developed for the center.
A-52 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Financial Policies
A. Under the provisions of the King County Charter and RCW 35.58.200, these financial policies are
hereby adopted and declared to be the principal financial policies of the comprehensive water pollution
abatement plan for King County, adopted by the Municipality of Metropolitan Seattle (Metro) in
Resolution No. 23, as amended, and the RWSP, a supplement to the plan.
B. Explanatory material.
1. Financial forecast and budget. Policies FP-1 through FP-10 are intended to guide the county in the
areas of prudent financial forecasting and budget planning and are included to ensure the financial
security and bonding capacity for the wastewater system. This set of policies also addresses the county’s
legal and contractual commitments regarding the use of sewer revenues to pay for sewer expenses.
2. Debt financing and borrowing. Policies FP-11 through FP-14 are intended to guide the county in
financing the wastewater system capital program. These policies direct that capital costs be spread over
time to keep rates more stable for ratepayers by the county issuing bonds. A smaller share of annual
capital costs will be funded directly from sewer rates and sewer revenues and capacity charges.
3. Collecting revenue. Policies FP-15 through FP-17 are intended to guide King County in establishing
annual sewer rates and approving wastewater system capital improvement and operating budgets.
Monthly sewer rates, which are the primary source of revenue for the county’s regional wastewater
system, are to be uniformly assessed on all customers. Customers with new connections to the
wastewater system will pay an additional capacity charge. The amount of that charge is set by the
council, within the constraints of state law.
4. Community treatment systems. Policy FP-18 is intended to guide the county in the financial
management of community treatment systems.
Financial Policies How Implemented in 2007–2013
FP-1: The county shall maintain for the
wastewater system a multiyear financial
forecast and cash-flow projection of six years
or more, estimating service growth, operating
expenses, capital needs, reserves and debt
service. The financial forecast shall be
submitted by the executive with the annual
sewer rate ordinance.
A six-year financial plan is submitted each year with
the WTD sewer rate proposal and again with the
annual budget proposal. The financial plan is also
updated for each new bond issue or bond refunding.
FP-2: If the operations component of the
proposed annual wastewater system budget
increases by more than the reasonable cost of
the addition of new facilities, increased flows,
new programs authorized by the council, and
inflation, or if revenues decline below the
financial forecast estimate, a feasible
alternative spending plan shall be presented, at
the next quarterly budget report, to the council
by the executive identifying steps to reduce
cost increases.
There were no occurrences of the situation described
in FP-2 in 2007–2013, nor are any anticipated for the
near-term. If such a situation were to occur, this policy
would be implemented.
RWSP 2013 Comprehensive Review A-53
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
FP-3: The executive shall maintain an ongoing
program of reviewing business practices and
potential cost-effective technologies and
strategies for savings and efficiencies; the
results shall be reported in the annual budget
submittal and in an annual report to the
RWQC.
Results of WTD’s Productivity Initiative Pilot Program,
a 10-year incentive program, was reported annually in
RWSP annual reports. In addition, an annual report
was submitted to the King County Council. The pilot
program ended in April 2011. The program generated
nearly $84 million in savings for ratepayers.
As part of WTD’s continuous improvement efforts and
the Executive’s Efficiency Initiative, WTD has
implemented a Bright Ideas program, which
encourages creative problem-solving throughout the
organization and uses employees’ ideas to improve
how WTD does business. Information on this program
is included as part of the annual sewer rate submittal
to the King County Council.
FP-4: New technologies or changes in practice
that differ significantly from existing
technologies or practices shall be reported to
the council and RWQC with projected costs
prior to implementation and shall also be
summarized in the RWSP annual report.
No major changes in wastewater technologies or
practices were implemented during this timeframe.
FP-5: Significant new capital and operational
initiatives proposed by the Executive that are
not within the scope of the current RWSP nor
included in the RWSP, or are required by new
state or federal regulations will be reviewed by
the RWQC and approved by the council to
ensure due diligence review of potential
impacts to major capital projects' schedules,
including Brightwater, the bond rating or the
sewer rate and capacity charge.
All capital and operational costs are reviewed as part
of the annual budget adoption process. No initiatives
of this type were included in either the capital or
operating budget requests in this timeframe.
Brightwater began full operations on October 29,
2012.
FP-6: The county shall maintain for the
wastewater system a prudent minimum cash
balance for reserves, including but not limited
to, cash flow and potential future liabilities. The
cash balance shall be approved by the council
in the annual sewer rate ordinance.
Since 2007, the bond ratings of the wastewater
system have been upgraded. The rating from Moody’s
has been upgraded twice from A1 to Aa2 and the
rating from Standard’s and Poor’s has been upgraded
once from AA to AA+.
FP-7: Unless otherwise directed by the council
by motion, the King County department of
natural resources and parks or its successor
agency shall charge a fee that recovers all
direct and indirect costs for any services
related to the wastewater system provided to
other public or private organizations.
All work performed by WTD for other public or private
organizations has required the recovery of all direct
and indirect costs.
FP-8: Water quality improvement activities,
programs and projects, in addition to those that
are functions of sewage treatment, may be
eligible for funding assistance from sewer rate
revenues after consideration of criteria and
limitations suggested by the metropolitan water
pollution abatement advisory committee, and, if
The 1.5 percent of annual operating budget limit on
“Culver” funds had been strictly adhered to when such
funding was approved in the annual rate process. This
funding was eliminated from the 2011, 2012, 2013,
and 2014 rate submittals.
As part of the 2015 rate submittal, the County
Executive has proposed the start-up of “Our Waters”
A-54 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
deemed eligible, shall be limited to one and
one half percent of the annual wastewater
system operating budget. An annual report on
activities, programs and projects funded will be
made to the RWQC. Alternative methods of
providing a similar level of funding assistance
for water quality improvement activities shall be
transmitted to the RWQC and the council within
seven months of policy adoption.
program, which, if approved and implemented, would
adhere to this policy.
FP-9: The calculation of general government
overhead to be charged to the wastewater
system shall be based on a methodology that
provides for the equitable distribution of
overhead costs throughout county government.
Estimated overhead charges shall be
calculated in a fair and consistent manner,
utilizing a methodology that best matches the
estimated cost of the services provided to the
actual overhead charge. The overall allocation
formula and any subsequent modifications will
be reported to the RWQC.
Overhead costs of King County general government
are allocated by the Executive budget office to all
parts of the County on a consistent basis.
FP-10: The assets of the wastewater system
are pledged to be used for the exclusive benefit
of the wastewater system including operating
expenses, debt service payments, asset
assignment and the capital program associated
therewith. The system shall be fully reimbursed
for the value associated with any use or
transfer of such assets for other county
government purposes. The executive shall
provide reports to the RWQC pertaining to any
significant transfers of assets for other county
government purposes in advance of and
subsequent to any such transfers.
No assets were transferred outside of WTD in 2007–
2013.
FP-11: The county shall structure bond
covenants to ensure a prudent budget
standard.
Bond covenants are strictly followed, monitored, and
revised to maintain prudent and conservative
standards. Outstanding bonds are constantly
monitored for refunding opportunities to lower interest
rates/debt service.
See FP-6 regarding the upgrading of WTD’s bond
ratings since 2007.
FP-12: King County should structure the term
of its borrowings to match the expected useful
life of the assets to be funded.
In 2007, WTD increased the term of bonds issued to
40 years. In addition to moderating the impact to
current sewer rates, this provides a better match
between the life of the facilities and the debt financing
their construction.
FP-13: The wastewater system’s capital
program shall be financed predominantly by
annual staged issues of long-term general
obligation or sewer revenue bonds, provided
WTD capital expenditures are predominantly funded
by the issuance of Sewer Revenue Bonds. Between
2007 and 2013, County General Obligation Bonds
have not been a significant portion of new debt
RWSP 2013 Comprehensive Review A-55
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
that:
All available sources of grants are
utilized to offset targeted program costs;
Funds available after operations and
reserves are provided for shall be used for the
capital program; excess funds accumulated in
reserves may also be used for capital;
Consideration is given to competing
demands for use of the county’s overall general
obligation debt capacity; and
Consideration is given to the overall
level of debt financing that can be sustained
over the long term given the size of the future
capital programs, potential impacts on credit
ratings, and other relevant factors such as
intergenerational rate equity and the types of
projects appropriately financed with long-term
debt.
issuances. Significant bond refundings occurred
between 2011 and 2012. All refinanced revenue
bonds have been refunded with new revenue bonds
with the same term and at least a present value
savings of 5 percent. In some cases, refinanced
general obligation bonds have been refunded with
new revenue bonds with the same term and at least a
present value savings of 5 percent.
FP-14: To achieve a better maturity matching
of assets and liabilities, thereby reducing
interest rate risk, short-term, variable rate
borrowing shall be used to fund a portion of the
capital program, provided that:
Outstanding short-term, variable rate
debt comprises no more than twenty percent of
total outstanding revenue bonds and general
obligation bonds; and
Appropriate liquidity is available to
protect the day-to-day operations of the
system.
(Ordinance 17492, approved in December
2012, amended this policy to add the words
“variable rate”, and changed the percent
amount of allowable outstanding short term,
variable debt to comprise twenty [previously it
was fifteen] percent of total outstanding
revenue bonds and general obligation bonds.)
Short-term variable (junior lien) debt is targeted for no
more than approximately 20 percent of the total debt
issued. Year-end liquidity reserves are targeted at 10
percent of the year’s operating expense total plus $5
million.
FP-15: King County shall charge its customers
sewer rates and capacity charges sufficient to
cover the costs of constructing and operating its
wastewater system. Revenues shall be sufficient
to maintain capital assets in sound working
condition, providing for maintenance and
rehabilitation of facilities so that total system
costs are minimized while continuing to provide
reliable, high quality service and maintaining
high water quality standards.
1. Existing and new sewer customers
shall each contribute to the cost of the
King County maintains a uniform monthly sewer rate in
accordance with this policy.
The sewer rate is set on an annual basis such that,
given projections of other revenues and costs, the
revenue requirements for providing wastewater
services are met.
The rate stabilization reserve allows for excess
revenues generated in an earlier year to be treated as
operating revenues for the subsequent year. These
revenues therefore can be applied directly to debt
coverage requirements in the subsequent year,
allowing for a reduction of the sewer rate in that
subsequent year. The use and planned use of the rate
stablization funds are included in annual the rate
A-56 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
wastewater system as follows:
a. Existing customers shall pay
through the monthly sewer rate for the portion of
the existing and expanded conveyance and
treatment system that serves existing
customers.
b. New customers shall pay costs
associated with the portion of the existing
wastewater conveyance and treatment system
that serves new customers and costs associated
with expanding the system to serve new
customers. New customers shall pay these
costs through a combination of the monthly
sewer rate and the capacity charge. Such rates
and charges shall be designated to have growth
pay for growth.
2. Sewer rate. King County shall
maintain a uniform monthly sewer rate
expressed as charges per residential customer
equivalent for all customers.
a. Sewer rates shall be designed to
generate revenue sufficient to cover, at a
minimum, all costs of system operation and
maintenance and all capital costs incurred to
serve existing customers.
b. King County should attempt to adopt
a multiyear sewer rate to provide stable costs to
sewer customers. If a multiyear rate is
established and when permitted upon the
retirement by the county of certain outstanding
sewer revenue bonds, a rate stabilization
reserve account shall be created to ensure that
adequate funds are available to sustain the rate
through completion of the rate cycle. An annual
report on the use of funds from this rate
stabilization account shall be provided annually
to the RWQC.
c. The executive, in consultation with
the RWQC, shall propose for council adoption
policies to ensure that adequate debt service
coverage and emergency reserves are
established and periodically reviewed.
3. Capacity charge. The amount of the
capacity charge shall be a uniform charge, shall
be approved annually and shall not exceed the
transmittal financial plan and the annual budget
financial plan as required by Governmental Accounting
Standards Board (GASB) accounting standards.
Information on the rate stabilization account is
included in the annual sewer rate briefing to the
Regional Water Quality Committee.
The debt service coverage minimum is based on
meeting two ratios, 1.25 on parity debt (revenue and
general obligation bonds) and a target of 1.15 on all
debt.
The capacity charge is based on the methodology
listed in this policy.
RWSP 2013 Comprehensive Review A-57
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
cost of capital facilities necessary to serve new
customers. The methodology that shall be
applied to set the capacity charge is set forth in
FP-15.3.a.
a. The capacity charge shall be based
on allocating the total cost of the wastewater
system (net of grants and other non rate
revenues) to existing and new customers as
prescribed in this subsection. The total system
cost includes the costs to operate, maintain, and
expand the wastewater system over the life of
the RWSP. Total estimated revenues from the
uniform monthly rate from all customers and
capacity charge payments from new customers,
together with estimated non rate revenues, shall
equal the estimated total system costs. The
capacity charge calculation is represented as
follows:
Capacity = [Total system costs — rate revenue
Charge from existing customers] — Rate revenue
from new customers
_________________________________
Number of new customers
where:
(1) total system costs (net of grants
and other non rate revenues) minus rate
revenue from existing customers equals costs
allocated to new customers.
(2) costs allocated to new customers
minus rate revenue from new customers equals
the total revenue to be recovered through the
capacity charge.
(3) total capacity charge revenue
requirements divided by the total number of new
customers equals the amount of the capacity
charge to be paid by each new customer.
b. The capacity charge may be paid by
new customers in a single payment or as a
monthly charge at the rate established by the
council. The county shall establish a monthly
capacity charge by dividing that amount by one
hundred eighty (twelve monthly payments per
A-58 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
year for fifteen years). The executive shall
transmit for council adoption an ordinance to
adjust the discount rate for lump sum payment.
The executive shall also transmit for council
adoption an ordinance to adjust the monthly
capacity charge to reflect the county's average
cost of money if the capacity charge is paid over
time.
c. King County shall pursue changes in
state law to enable the county to require
payment of the capacity charge in a single
payment.
d. The capacity charge shall be set
such that each new customer shall pay an equal
share of the costs of facilities allocated to new
customers, regardless of what year the
customer connects to the system. The capacity
charge shall be based upon the costs, customer
growth and related financial assumptions used
for the Regional Wastewater Services Plan
adopted by Ordinance 13680 as such
assumptions may be updated. Customer growth
and projected costs, including inflation, shall be
updated every three years beginning in 2003.
e. The county should periodically
review the capacity charge to ensure that the
actual costs of system expansion to serve new
customers are reflected in the charge. All
reasonable steps should be taken to coordinate
the imposition, collection of and accounting for
rates and charges with component agencies to
reduce redundant program overhead costs.
f. Existing customers shall pay the
monthly capacity charge established at the time
they connected to the system as currently
enacted by K.C.C. 28.84.055. New customers
shall pay the capacity charge established at the
time they connect to the system.
g. To ensure that the capacity charge
will not exceed the costs of facilities needed to
serve new customers, costs assigned and
allocated to new customers shall be at a
minimum ninety five percent of the projected
capital costs of new and existing treatment,
conveyance and biosolids capacity needed to
serve new customers.
RWSP 2013 Comprehensive Review A-59
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
h. Costs assigned and allocated to
existing customers shall include the capital cost
of existing and future treatment, conveyance
and biosolids capacity used by existing
customers, and the capital costs of assessing
and reducing infiltration and inflow related to the
use of the existing conveyance and treatment
capacity.
i. Capital costs of combined sewer
overflow control shall be paid by existing and
new customers based on their average
proportionate share of total customers over the
life of the RWSP.
j. Operations and maintenance costs
shall be paid by existing and new customers in
the uniform monthly rate based on their annual
proportionate share of total customers.
k. Any costs not allocated in FP-15.3
f., g., h., i. and j. shall be paid by existing and
new customers in the sewer rate.
l. Upon implementation of these
explicit policies, the Seattle combined sewer
overflow benefit charge shall be discontinued.
4. Based on an analysis of residential
water consumption, as of December 13, 1999,
King County uses a factor of seven hundred fifty
cubic feet per month to convert water
consumption of volume-based customers to
residential customer equivalents for billing
purposes. King County shall periodically review
the appropriateness of this factor to ensure that
all accounts pay their fair share of the cost of the
wastewater system.
FP-16: The executive shall prepare and submit
to the council a report in support of the
proposed monthly sewer rates for the next
year, including the following information:
Key assumptions: key financial
assumptions such as inflation, bond interest
rates, investment income, size and timing of
bond issues, and the considerations underlying
the projection of future growth in residential
customer equivalents;
Significant financial projections: all key
projections, including the annual projection of
operating and capital costs, debt service
All key assumptions, significant financial projections,
historical results, and policy options are provided as
part of the annual sewer rate submittal letter and
attachments.
A-60 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Financial Policies How Implemented in 2007–2013
coverage, cash balances, revenue
requirements, revenue projections and a
discussion of significant factors that impact the
degree of uncertainty associated with the
projections;
Historical data: a discussion of the accuracy of
the projections of costs and revenues from
previous recent budgets, and
Policy options: calculations or
analyses, or both, of the effect of certain policy
options on the overall revenue requirement.
These options should include alternative capital
program accomplishment percentages
(including a ninety percent, a ninety-five
percent and a one hundred percent
accomplishment rate), and the rate shall be
selected that most accurately matches
historical performance in accomplishing the
capital program and that shall not negatively
impair the bond rating.
FP-17: Expenditures from the wastewater
revenues to correct water pollution problems
caused by septic systems shall occur only if
such expenditures financially benefit
wastewater system current customers when
the additional monthly sewer rate revenues
from these added customers are considered.
No expenditures from the wastewater revenue were
used for these purposes in 2007−2013.
FP-18: The cost of community treatment
systems developed and operated in
accordance with WWSP-15 would not be
subsidized by the remaining ratepayers of the
county’s wastewater treatment system.
This policy has been adhered to since the adoption of
the RWSP.
RWSP 2013 Comprehensive Review A-61
Appendix A. RWSP Policies Implementation in 2007−2013
RWSP Reporting Policies
A. The executive shall review the implementation of the RWSP on a regular basis and submit the
following reports to council and the RWQC:
Reporting Policies How Implemented in 2004–2006
A. Regional wastewater services plan annual
report. The executive shall submit a written
report to the council and RWQC in September
each year until the facilities identified in the
RWSP are operational. This report, covering
the previous year's implementation, will provide
the following:
1. A summary of activities for each major
component of the RWSP, including treatment,
conveyance, infiltration and inflow, combined
sewer overflows, water reuse, biosolids and
highlights of research and development
projects underway and proposed for the
coming year;
2. Details on each active RWSP project in the
capital budget, including a project summary,
project highlights, project issues, upcoming
activities, schedules, an expenditures summary
including staff labor and miscellaneous
services, a description of adjustments to costs
and schedule and a status of the projects
contracts;
3. A status of the odor prevention program,
including a listing and summary of odor
complaints received and progress on
implementing odor prevention policies and
projects;
4. A summary of the previous year's results for
the comprehensive water quality monitoring
program;
5. A review of the plan elements, including
water pollution abatement, water quality, water
reclamation, Endangered Species Act
compliance, biosolids management and
variability of quality over time, wastewater
public health problems, compliance with other
agency regulations and agreements, to ensure
it reflects current conditions; and
6. An update of anticipated RWSP program
costs through the year 2030
The RWSP annual reports are submitted to the King
County Council in September to cover the previous
year’s implementation and include information on the
items listed in 1 through 6 of this policy. The King
County Executive has transmitted an annual report to
the King County Council every year since 2000.
B.1. Comprehensive regional wastewater
services plan review. The executive shall
submit a written report to council and RWQC
that provides a comprehensive review of the
RWSP. The report will review the following:
The RWSP 2013 Comprehensive Review is the third
RWSP comprehensive review and covers
implementation of the RWSP from 2007 through 2013.
The report has been prepared following the guidance in
this policy.
A-62 RWSP 2013 Comprehensive Review
Appendix A. RWSP Policies Implementation in 2007−2013
Reporting Policies How Implemented in 2004–2006
a. assumptions on the rate and location of
growth, the rate of septic conversions and the
effectiveness of water conservation efforts;
b. phasing and size of facilities; and
c. effectiveness of RWSP policies
implementation, for infiltration and inflow
reduction, water reuse, biosolids, CSO
abatement, water quality protection,
environmental mitigation and public
involvement;
d. policy guidance for the construction fund
and the emergency capital reserves
2. The next comprehensive regional
wastewater services plan review is due in June
2014. Subsequent reports will be prepared
every three to five years as established by the
council and RWQC following their review of the
current report. The specific due date will be
based upon the availability of necessary
information, the completion of key milestones,
and the time needed to collect and analyze
data. The executive may recommend policy
changes based on the findings of the report
and other information from changing
regulations, new technologies or emerging or
relevant factors;
3. The comprehensive regional wastewater
services plan review will include all elements of
the RWSP annual report, replacing it for that
year.
(Ordinance 17480, which was approved in
December 2012, amended this policy to
include “policy guidance for the construction
fund and the emergency capital reserves” in
RWSP comprehensive reviews, and
established the due date for this
Comprehensive Review Report.)
C. Operational master plan. The RWSP
Operational Master Plan that was adopted by
council in December 1999 shall be updated on
a regular basis in conjunction with policy
revisions to the RWSP.
In accordance with Motion 13758, the King County
Executive submitted to the County Council a report on
options to provide summary information on WTD’s
long-range capital program. The report was submitted
in August 2013.
RWSP 2013 Comprehensive Review A-63
Appendix B
Odor Prevention and Control Program
Appendix B. Odor Prevention and Control Program
Odor Prevention and Control Program
RWSP policies provide direction on implementing an Odor Prevention and Control Program at all
wastewater treatment plants and associated conveyance facilities that goes beyond traditional odor
control. RWSP policies also call for including a summary of odor complaints in annual reports.
WTD received and investigated 49 odor complaints in 2013. When investigating an odor complaint, the
source is not always identifiable. For example, some complaints received are in areas where there are
no WTD facilities. Of the 56 complaints received, 25 were determined to be attributable to WTD
facilities. The breakdown is shown in Table 1. No odor complaints were attributed to the Brightwater,
South, Vashon, and Carnation treatment plants. Complaints attributable to WTD facilities were resolved
through replacing carbon in odor control facilities, using chemical solutions, sealing manhole covers,
replacing equipment such as fan belts, and restoring power after a power outage.
Table1. Odor Complaints in 2013
Location Complaints Received Complaints Attributed
to WTD Facilities
South Treatment Plant 3 0
South Plant conveyance facilities 25 19
West Point Treatment Plant 10 1
West Point conveyance facilities 14 4
Brightwater Treatment Plant 1 0
Brightwater conveyance facilities 3 1a
Vashon Treatment Plant 0 0
Carnation Treatment Plant 0 0
Total 56 25
a There were no sewage-related odors attributed to Brightwater conveyance facilities since they began operating.
This complaint was related to diesel odors that emanated from the Brightwater Influent Pump Station during testing of
the pump station’s generators in 2013. To resolve the situation, a project is under way to install diesel oxidation
catalyst units on each generator exhaust system.
Odor complaints in 2007−2012 can be found in the RWSP annual reports at
http://www.kingcounty.gov/environment/wtd/Construction/planning/rwsp/Library/AnnualReport.aspx.
More information on the Odor Prevention and Control Program is available at
http://www.kingcounty.gov/environment/wtd/Response/OdorControl/GoodNeighbor.aspx.
B-2 RWSP 2013 Comprehensive Review
Appendix C
Water Quality and Sediment Monitoring in 2013
Appendix B. Odor Prevention and Control Program
Water Quality and Sediment Monitoring in 2013
To protect public health and King County’s significant investment in water quality improvements, the
County regularly monitors treatment plant effluent, marine water, fresh water, and sediments. The
parameters used to assess a water body’s health under Washington State Water Quality Standards are
fecal coliform bacteria, dissolved oxygen, temperature, pH, nutrients, turbidity, and a variety of
chemical compounds. Monitoring results for the previous year are presented as environmental
indicators on the County’s Department of Natural Resources and Parks KingStat website at
http://your.kingcounty.gov/dnrp/measures/. Overall water and sediment quality conditions observed in
2013 were largely consistent with those observed in 2012 and in previous years. Key findings in 2013
include the following:
• Treatment plant effluent consistently met permit requirements.
• Waters in most urban streams are frequently warmer than Washington State temperature
standards allow, have more bacteria than the standards allow, and occasionally do not have as
much oxygen as required by state standards.
• The health of streams, as measured by the diversity and abundance of the community of
organisms that live on the stream bottom, is generally not as good in urban areas.
• Two beaches in Lake Sammamish and six beaches in Lake Washington had incidents of high
bacteria that did not meet state standards. These events were brief and did not result in beach
closures.
• With the exception of two stations in Quartermaster Harbor, marine water quality throughout
the Puget Sound Central Basin was at a low level of concern in 2013. Level of concern rankings in
Quartermaster Harbor were moderate and high due to low dissolved oxygen and dissolved
inorganic nitrogen values during the late summer and early fall months.
• There were no exceedances of the standards for fecal coliform bacteria levels at the County’s
treatment plant marine outfalls in 2013.
In addition, investigations to locate sources of bacteria in Juanita Creek, Thornton Creek, Boise Creek
and the stormwater drainage infrastructure in White Center continued in 2013. When sources are
identified, staff works with other entities, such as county and local stormwater programs, local sewer
districts, and Public Health−Seattle & King County, to ensure identified sources are controlled.
Data and reports are available at the Water and Land Resources Division’s Science and Technical
Support Section website at http://www.kingcounty.gov/environment/wlr/sections-programs/science-
section/doing-science.aspx.
Water quality and sediment monitoring reports for 2007−2012 can be found in the RWSP annual reports
at
http://www.kingcounty.gov/environment/wtd/Construction/planning/rwsp/Library/AnnualReport.aspx.
C-2 RWSP 2013 Comprehensive Review
June 29, 2010 - FINAL i
pw://Carollo/Documents/Client/WA/King County/7683E00/Deliverables/Final Report/TOC.docx
KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE
SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE
PROGRAM DEVELOPMENT
(SOUTH PLANT NITROGEN REMOVAL STUDY)
TABLE OF CONTENTS
EXECUTIVE SUMMARY
Page No.
ES.1 INTRODUCTION ............................................................................................... ES-1
ES.2 SOUTH PLANT NITROGEN REMOVAL - CURRENT CONFIGURATION ......... ES-1
ES.3 SOUTH PLANT NITROGEN REMOVAL SCENARIOS ...................................... ES-2
ES.4 SOUTH PLANT NITROGEN REMOVAL EFFECT ON RECLAIMED WATER
PRODUCTION ................................................................................................... ES-7
ES.5 FINDINGS AND CONCLUSIONS .................................................................... ES-10
CHAPTER 1 SOUTH PLANT NITROGEN REMOVAL - CURRENT CONFIGURATION
1.1 INTRODUCTION .................................................................................................. 1-1
1.2 BACKGROUND .................................................................................................... 1-2
1.2.1 Description of Existing Plant ...................................................................... 1-2
1.2.2 Summary of Current NPDES Permit .......................................................... 1-5
1.3 NITROGEN LIMIT SCENARIOS ........................................................................... 1-6
1.4 FLOW AND LOAD BASIS ..................................................................................... 1-6
1.5 NITROGEN REMOVAL CAPACITY ANALYSIS .................................................... 1-7
1.5.1 Data Analysis ............................................................................................ 1-9
1.5.2 Model Calibration .................................................................................... 1-18
1.5.3 Modeling Results TIN 8 ........................................................................... 1-18
1.5.4 Modeling Results TIN 3 ........................................................................... 1-21
1.6 CONCLUSIONS.................................................................................................. 1-23
CHAPTER 2 SOUTH PLANT NITROGEN REMOVAL SCENARIOS
2.1 INTRODUCTION .................................................................................................. 2-1
2.2 ALTERNATIVES SCREENING ............................................................................. 2-1
2.2.1 Nitrogen Removal Alternatives .................................................................. 2-1
2.2.2 Initial Alternatives Screening Results ....................................................... 2-14
2.2.3 Nitrogen Removal Alternatives Analysis .................................................. 2-14
2.3 ALTERNATIVES EVALUATION .......................................................................... 2-28
2.4 ALTERNATIVES SUBJECT TO MORE DETAILED ANALYSIS .......................... 2-31
2.4.1 Necessary Equipment ............................................................................. 2-31
2.4.2 Site layout ............................................................................................... 2-34
2.4.3 Cost .................................................................................................... 2-34
2.4.4 Sensitivity Analysis .................................................................................. 2-37
2.5 GREENHOUSE GAS COMPARISON ................................................................. 2-45
2.5.1 Overview ................................................................................................. 2-45
2.5.2 Background ............................................................................................. 2-47
June 29, 2010 - FINAL ii
pw://Carollo/Documents/Client/WA/King County/7683E00/Deliverables/Final Report/TOC.docx
2.5.3 Methodology ............................................................................................ 2-47
2.5.4 Categories and Sources of GHG Emissions ............................................ 2-48
2.5.5 Estimate of GHG Emissions in Terms of “CO2 Equivalents” .................... 2-48
2.5.6 Description of GHG Emissions Estimates ................................................ 2-49
2.5.7 Direct GHG Emissions ............................................................................. 2-49
2.5.8 Indirect GHG Emissions .......................................................................... 2-51
2.5.9 Summary of GHG Emissions Estimates .................................................. 2-52
2.6 FINDINGS AND CONCLUSIONS ....................................................................... 2-55
CHAPTER 3 SOUTH PLANT NITROGEN REMOVAL EFFECT ON
RECLAIMED WATER PRODUCTION
3.1 INTRODUCTION .................................................................................................. 3-1
3.2 SUMMARY OF RECLAIMED WATER STANDARDS ........................................... 3-1
3.3 RECLAIMED WATER EVALUATION .................................................................... 3-4
3.3.1 Reclaimed Water Effects ........................................................................... 3-4
3.3.2 Reclaimed Water Options Costs ................................................................ 3-7
3.3.3 Other Effects ............................................................................................. 3-8
3.4 CONCLUSIONS.................................................................................................... 3-8
LIST OF APPENDICES
APPENDIX A - Evaluation Criteria
APPENDIX B - Cost Assumptions and Summaries
LIST OF TABLES
Table ES.1 8 mg/L TIN (Summer-only) Alternative Footprint Analysis ...................... ES-3
Table ES.2 3 mg/L TIN (Year-round) Alternative Foot Print Analysis ........................ ES-3
Table ES.3 8 mg/L TIN (Summer-only) Scoring Matrix .............................................. ES-4
Table ES.4 3 mg/L TIN (Year-round) Scoring Matrix ................................................. ES-5
Table ES.5 Estimate Summary for 8 mg/L TIN (Summer-only) Permit Level
Upgrade to the STP ................................................................................ ES-6
Table ES.6 Estimate Summary for 3 mg/L TIN (Year-round) Permit Level Upgrade
to the STP .............................................................................................. ES-6
Table ES.7 Summary of Relative Reclaimed Water Cost Effects ............................ ES-10
Table 1.1 Current NPDES Permit Summary .............................................................. 1-5
Table 1.2 Design Influent Flow and Loads ................................................................ 1-7
Table 1.3 Current Configuration – TIN 8 mg/L Scenario Modeling Results .............. 1-20
Table 1.4 Current Configuration – TIN 3 mg/L Scenario Modeling Results .............. 1-23
Table 2.1 Nitrogen Removal Alternatives .................................................................. 2-2
Table 2.2 8 mg/L TIN (Summer-only) Alternative Footprint Analysis ....................... 2-21
Table 2.3 3 mg/L TIN (Year-round) Alternative Foot Print Analysis ......................... 2-28
Table 2.4 8 mg/L TIN (Summer-only) Scoring Matrix ............................................... 2-30
Table 2.5 3 mg/L TIN (Year-round) Scoring Matrix .................................................. 2-31
Table 2.6 Estimate Summary for 8 mg/L TIN (Summer-only) Permit Level
Upgrade to the STP ................................................................................. 2-36
Table 2.7 Estimate Summary for 3 mg/L TIN (Year-round) Permit Level Upgrade
to the STP ............................................................................................... 2-36
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Table 2.8 Greenhouse Gases and Global Warming Potentials ................................ 2-49
Table 2.9 Estimated Annual Total Metric Tons of Carbon Dioxide Equivalent
Emission.................................................................................................. 2-53
Table 3.1 Definitions of Reclaimed Water ................................................................. 3-2
Table 3.2 Summary of Reclaimed Water Uses Requiring Nitrogen Removal............. 3-3
Table 3.3 Summary of Relative Reclaimed Water Costs Effects ............................... 3-7
Table 3.4 Summary of Other Relative Reclaimed Water Effects................................ 3-8
LIST OF FIGURES
Figure ES.1 GHG Comparison ................................................................................... ES-8
Figure 1.1 STP Process Flow Schematic ................................................................... 1-3
Figure 1.2 STP Arial Photograph ................................................................................ 1-4
Figure 1.3 Process Schematic for STP BioWin Model ................................................ 1-8
Figure 1.4 Raw Sewage Flow for the Period from 2005 to 2009 ............................... 1-10
Figure 1.5 Raw Sewage Loading Data for the Period from 2005 to 2009 ................. 1-11
Figure 1.6 SVI Data for the Period from 2007 to 2009 .............................................. 1-12
Figure 1.7 Settleability Data from 2003 Tests Compared to Standard SVI-Based
Formulas ................................................................................................. 1-13
Figure 1.8 Temperature Data for the Period from 2005 to 2009 ............................... 1-15
Figure 1.9 SRT Data for the Period from 2005 to 2009 ............................................. 1-16
Figure 1.10 Washout Aerobic SRT Values for Nitrifier Organisms .............................. 1-17
Figure 1.11 MLE Schematic ....................................................................................... 1-19
Figure 1.12 Bardenpho Schematic ............................................................................. 1-22
Figure 2.1 MLE Schematic ......................................................................................... 2-4
Figure 2.2 Bardenpho Schematic ............................................................................... 2-6
Figure 2.3 Step Feed Schematic ................................................................................ 2-7
Figure 2.4 BAF/DNF Schematic ................................................................................. 2-9
Figure 2.5 Examples of Media Used in MBBR and IFAS Processes ......................... 2-10
Figure 2.6 MLE IFAS Schematic .............................................................................. 2-11
Figure 2.7 Centrate Reaeration Schematic ............................................................... 2-13
Figure 2.8 MLE Footprint 8 mg/L TIN (Summer only) ............................................... 2-16
Figure 2.9 MLE – MBR 8 mg/L TIN (Summer only) Footprint ................................... 2-17
Figure 2.10 MLE – IFAS 8 mg/L TIN (Summer only) Footprint (Conservative
Sizing) ..................................................................................................... 2-18
Figure 2.11 MLE – IFAS 8 mg/L TIN (Summer only) Footprint (Aggressive Sizing) .... 2-19
Figure 2.12 BAF/DNF 8 mg/L TIN (Summer only) Footprint ....................................... 2-20
Figure 2.13 Bardenpho 3 mg/L TIN (Year round) Footprint......................................... 2-22
Figure 2.14 Bardenpho-MBR 3 mg/L TIN (Year round) Footprint ............................... 2-23
Figure 2.15 Bardenpho-IFAS 3 mg/L TIN (Year round) Footprint Conservative
Sizing ...................................................................................................... 2-25
Figure 2.16 Bardenpho-IFAS 3 mg/L TIN (Year round) Footprint Aggressive Sizing .. 2-26
Figure 2.17 BAF/DNF 3 mg/L TIN (Year round) Footprint ........................................... 2-27
Figure 2.18 BioWin Schematic – 8 mg/L Permit Level ................................................ 2-38
Figure 2.19 BioWin Schematic – 3 mg/L (Year round) Permit Level ........................... 2-39
Figure 2.20 Dynamic Influent Flow and Concentration 8 mg/L TIN (Summer only)
Permit Level ............................................................................................ 2-41
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Figure 2.21 Dynamic Influent Flow and Concentration 3 mg/L TIN (Year round)
Permit Level ............................................................................................ 2-42
Figure 2.22 Dynamic Effluent Flow and Concentration 8 mg/L TIN (Summer only)
Permit Level ............................................................................................ 2-43
Figure 2.23 Dynamic Effluent Flow and Concentration 3 mg/L TIN (Year round)
Permit Level ............................................................................................ 2-44
Figure 2.24 State Point Diagram for Bardenpho BNR................................................. 2-46
Figure 2.25 GHG Comparison .................................................................................... 2-54
Figure 3.1 Site Requirements for 98 mgd of Conventional Filtration ........................... 3-5
Figure 3.2 Site Requirements for 36 mgd of Conventional Filtration ........................... 3-6
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ABBREVIATIONS
AACE Association for the Advancement of Civil Engineering
AB32 Assembly Bill 32
BAF Biological Aerated Filter
BNR Biological Nitrogen Removal
BOD5 Biochemical Oxygen Demand (5-day)
C Celsius
CARB California Air Resources Board
CAS Conventional Activated Sludge
CCAR GRP California Climate Action Registry General Reporting Protocol
cfm Cubic Feet per Minute
CH4 Methane
County King County
CO2 Carbon Dioxide
CO2e Equivalent CO2
DAFT Dissolved Air Flotation Thickener
DIN Dissolved Inorganic Nitrogen
DNF Denitrifying Filter
DO Dissolved Oxygen
Ecology Department of Ecology
EPA Environmental Protection Agency
fbf Filterable BOD5 Fraction
fvu Non-biodegradable Volatile Fraction
GHG Greenhouse Gas
gpd Gallons per Day
gpd/sf Gallons per Day per Square Foot
GWP Global Warming Potential
HOCI Hypochlorite
IFAS Integrated Fixed Film Activated Sludge
IPCC International Panel on Climate Change
LOTT Lacey, Olympia, Tumwater, Thurston County
MBBR Moving Bed Bioreactor
MBR Membrane Bioreactor
MG Million Gallons
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mg/L Milligrams per Liter
mgd Million Gallons per Day
mL/g Milliliter per Gram
MLE Modified Ludzak-Ettinger
MCLG Maximum Containment Limit Goal
MLR Mixed Liquor Return
MLSS Mixed Liquor Suspended Solids
N Nitrogen
N2O Nitrous Oxide
NH4+ Ammonium Ion
NDN Nitrification/Denitrification
NH4MgPO4 6H2O Ammonium Magnesium Phosphate
NO3- Nitrate Ion
NPDES National Pollutant Discharge Elimination System
NR Nitrogen Removal
O&M Operation and Maintenance
POTW Publically Owned Treatment Works
ppd Pounds per Day
ppd/kcf Pounds per Day per Thousand Cubic Feet
ppd/sf Pounds per Day per Square Foot
RAS Return Activated Sludge
SF Square Foot
SRT Solids Residence Time
STP South Treatment Plant
SVI Sludge Volume Index
TIN Total Inorganic Nitrogen
TKN Total Kjeldahl Nitrogen
TSS Total Suspended Solids
U.S. United States
WAS Waste Activated Sludge
WERF Water Environment Research Foundation
WWTP Wastewater Treatment Plant
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Executive Summary
ES.1 INTRODUCTION
According to the Washington State Department of Ecology (Ecology 2008b), portions of
South Puget Sound do not meet Washington State water quality standards for dissolved
oxygen (DO). Ecology is concerned that algal growth stimulated by nitrogen loadings to
Puget Sound is causing DO depression in near-bottom regions. In 2006 Ecology began a
major study to determine the extent of low DO and how nitrogen from a variety of sources
affects DO levels. While it is not clear how Ecology will use the results of its studies to
establish future regulatory limits, King County (County) has undertaken this project to
evaluate potential effects of future nitrogen removal requirements for the King County South
Treatment Plant (STP).
This report is divided into three chapters. Chapter 1 describes project assumptions and
evaluates how much flow the existing STP could process if required to comply with a
summer seasonal limit of 8-milligrams per liter (mg/L) TIN (Total Inorganic Nitrogen) or an
annual limit of 3-mg/L TIN and what modifications would be required for nitrogen removal.
Chapter 2 evaluates the potential effects (e.g., tankage, footprint, cost, greenhouse gas
emissions) to the STP if it were required to meet the assumed seasonal or year-round limit
while maintaining its current rated capacity (144-million gallons per day (mgd) max month
year-round and 98-mgd max month during summer). Chapter 3 evaluates the effects that
implementing nitrogen removal would have on reclaimed water production at the STP.
ES.2 SOUTH PLANT NITROGEN REMOVAL - CURRENT
CONFIGURATION
A project team was assembled to evaluate the effects of potential future nitrogen limits on
the capacity of the STP. A full-plant model was developed and calibrated to operating data
collected at the plant. The project team decided upon two effluent nitrogen scenarios
representing potential permitting scenarios: (1) a summer effluent limit of 8 mg/L TIN and
(2) a year-round effluent limit of 3 mg/L TIN. As part of a project workshop, the project team
also decided that the capacity rating of the current plant to meet the two target nitrogen
effluent scenarios would be determined with one aeration basin and one secondary clarifier
out of service.
Based on these assumptions, the modeled capacity of the current STP to meet the summer
effluent limit of 8 mg/L TIN is 36 mgd. This capacity rating was based on operating the
existing aeration basins in a Modified Ludzak-Ettinger (MLE) configuration. To meet this
effluent limit, minor modifications would be needed at the current plant including the
addition of baffle walls, mixed liquor return (MLR) pumps and a chemical delivery system.
However, major construction would be needed (onsite or offsite) to meet the current
maximum summer month flow of 98 mgd and replace the 62 mgd of capacity lost as a
result of the nitrogen removal modifications.
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Based on the assumptions established in the first workshop, the modeled capacity of the
current STP to meet the year-round effluent limit of 3 mg/L TIN was determined to be 30
mgd. This capacity rating was based on operating the existing aeration basins in a
Bardenpho configuration. To meet this effluent limit, minor modifications would be needed
at the current plant including the addition of baffle walls, MLR pumps and a chemical
delivery system. However, construction would be needed (onsite or offsite) to meet the
current maximum month flow of 144 mgd and replace the 114 mgd of capacity lost as a
result of the nitrogen removal modifications.
ES.3 SOUTH PLANT NITROGEN REMOVAL SCENARIOS
There are four general classes of nitrogen removal alternatives:
• Land-based
• Aquatic
• Chemical
• Biological
At the first workshop on October 1, 2009, a variety of potential alternatives within each of
the classes was considered and four biological nitrogen removal alternatives were selected
for further evaluation for each nitrogen removal scenario. These selected alternatives
represent a range of biological alternatives including suspended growth, attached growth
and hybrid processes. For the 8 mg/L TIN (summer-only) scenario, the selected processes
were: 1) MLE, 2) MLE – membrane bioreactor (MBR), 3) MLE – integrated fixed-film
activated sludge (IFAS) and 4) biological aerated filter (BAF) / denitrifying filter (DNF). For
the 3 mg/L TIN (year-round) scenario, the selected processes were: 1) Bardenpho, 2)
Bardenpho – MBR, 3) Bardenpho – IFAS, and 4) BAF/DNF. For each representative
alternative, side stream treatment was evaluated to determine whether additional treatment
could reduce the footprint and cost of the alternative.
The four selected alternatives for each nitrogen limit scenario were evaluated to determine
a relative cost and footprint for each alternative. Tables ES.1 and ES.2 summarize the
footprint effects of each alternative for the effluent limit scenario of 8 mg/L TIN during the
summer and 3 mg/L TIN year round, respectively. Footprint estimates are primarily for
comparative purposes, and do not currently account for other features that can consume
land area such as roads, odor control, and ancillary equipment.
The MLE alternative requires the greatest footprint and provides very little space for the
plant to expand to treat future flows or to respond to future changes in effluent quality
requirements while the BAF-DNF and MLE-MBR alternatives provide the most available
space for future expansion. The MLE-IFAS alternative could be very attractive from a
footprint standpoint if the most aggressive of the manufacturer’s performance and design
criteria could be confirmed.
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The Bardenpho alternative requires the greatest footprint and does not fit on the site while
the BAF-DNF and Bardenpho-MBR alternatives provide the most available space for future
expansion. The Bardenpho-IFAS alternative could be very attractive from a footprint
standpoint if the aggressive version of manufacturer’s claims and assumed packing
densities could be confirmed.
Table ES.1 8 mg/L TIN (Summer-only) Alternative Footprint Analysis
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
MLE MLE-MBR MLE-IFAS
(A)(1)
MLE-IFAS
(C)(2) BAF / DNF
Total added basins, sf(3) 359,900 107,700 39,900 191,600 100,700
Full buildout capacity
assuming no expansion on
the biosolids site, mgd(1)
144 270 360 210 270
(1) IFAS A stands for the aggressive sizing of IFAS.
Notes:
(2) IFAS C stands for the conservative sizing of IFAS.
(3) Capacity ratings are based on maximum month flows during the summer months. The
maximum month flow capacity of the current plant for summer flows is 98 mgd. The assumed
density of aeration basins is based on the proposed STP site buildout layout provided by the
County. No extra allowances were made for roads or ancillary facilities.
Table ES.2 3 mg/L TIN (Year-round) Alternative Foot Print Analysis
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Bardenpho Bardenpho
- MBR
Bardenpho
- IFAS (A)(1)
Bardenpho
- IFAS (C)(2)
BAF /
DNF
Total added basins, sf 1,009,100 293,700 80,300 505,900 183,300
Full buildout capacity
assuming no
expansion on the
biosolids site, mgd(3)
TL(4) 170 300 TL(4) 240
(1) IFAS A stands for the aggressive sizing of IFAS.
Notes:
(2) IFAS C stands for the conservative sizing of IFAS.
(3) Capacity ratings are based on maximum month flows. The maximum month flow capacity of
the current plant is 144 mgd. The assumed density of aeration basins is based on the
proposed STP site buildout layout provided by the County. No extra allowances were made for
roads or ancillary facilities.
(4) TL = estimated foot print is too large and does not fit on the site.
Based on team input from the first workshop, the four alternatives for each nutrient limit
scenario were evaluated based on the following cost and non-cost criteria: (1) onsite capital
costs, (2) operation and maintenance (O&M) costs, (3) risk, (4) future flexibility, (5) footprint,
(6) energy, (7) odor, (8) compatibility with existing processes, (9) biosolids quality, and (10)
reclaimed water quality/quantity. Each of these criteria was scored from 1 (low) to 3 (high).
The weighting for each criterion was established by the team at the second workshop on
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December 15, 2009. Tables ES.3 and ES.4 present the weighted results for each effluent
limit scenario. Based on this analysis, the two leading alternatives for both effluent limit
scenarios were the MBR and BAF/DNF. The County decided to select the MBR system as
the representative alternative for both effluent limit scenarios. The team concluded that the
BAF/DNF system should also be considered in more detail at a facility planning or pre-
design level. Since aggressive IFAS sizing potentially offers a very competitive alternative,
the County may want to consider pilot testing to determine the optimum kinetic parameters
and packing densities.
Table ES.3 8 mg/L TIN (Summer-only) Scoring Matrix
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Score
Criteria Weight MLE MBR IFAS A(1) IFAS C(2) BAF
Onsite Capital Cost 1 3 2 3 1 3
O&M Cost 1 3 1 2 2 2
Risk 2 3 3 0(3) 1 2
Future Flexibility 2 1 3 3 1 3
Footprint 3 1 3 3 2 3
Energy 2 3 2 3 1 2
Odor 1 2 2 2 2 2
Compatibility with existing processes 1 3 3 3 3 3
Biosolids Quality 1 2 2 2 2 2
Reclaimed Water Quality/Quantity 1 1 3 2 2 2
Un-weighted Total 22 24 F(4) 17 24
Weighted Total 31 38 F(4) 24 37
(1) IFAS A stands for the aggressive sizing of IFAS.
Notes:
(2) IFAS C stands for the conservative sizing of IFAS.
(3) The aggressive IFAS sizing was determined to be too risky based on the manufacturer’s lack of
sufficiently demonstrated approach to tank sizing. The County may want to consider pilot
testing to further support this consideration.
(4) A score of a “0” on any of the criteria results in a failure of that alternative.
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Table ES.4 3 mg/L TIN (Year-round) Scoring Matrix
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Score
Criteria Weight MBR IFAS A(1) IFAS C(2) BAF
Onsite Capital Cost 1 2 3 3 2
O&M Cost 1 1 1 3 2
Risk 2 3 0(3) 1 2
Footprint 3 2 3 0(4) 2
Energy 2 1 3 2 2
Odor 1 2 2 2 2
Compatibility with existing processes 1 3 3 3 3
Biosolids Quality 1 2 2 2 2
Reclaimed Water Quality/Quantity 1 3 2 1 2
Un-weighted Total 19 F(5) F(5) 19
Weighted Total 27 F(5) F(5) 27
(1) IFAS A stands for the aggressive sizing of IFAS.
Notes:
(2) IFAS C stands for the conservative sizing of IFAS.
(3) The aggressive IFAS sizing was deemed to be too risky based on the manufacturer’s lack of an
adequate explanation for tank sizing. This alternative should be pilot tested before further
consideration.
(4) The conservative sizing of IFAS was given a “0” for footprint since this alternative did not fit on
the site.
(5) A score of a “0” on any of the criteria results in a failure of that alternative.
Tables ES.5 and ES.6 present summaries of estimated costs for upgrade of the STP to
provide for nitrogen removal for the two potential permit levels. The estimates include the
cost of odor control covers and equipment for the reactor tanks. The cost estimates were
based on a preliminary quantity estimate for excavation and concrete for new tanks and
estimated cost for new equipment. To these direct costs were added allowances for piping
and miscellaneous mechanical equipment, electrical equipment, instrumentation, site work,
contingency, general conditions, contractor overhead, and profit, sales tax, allied costs
(planning, design, construction management, permits, etc.). O&M costs were estimated
based on an Environmental Protection Agency (EPA) database for unit process labor,
estimated power requirements and chemical consumption, and allowances for structural
and equipment maintenance. Costs were indexed to estimated unit prices for March 15,
2010. The expected accuracy range for this type of estimate is defined by the Association
for the Advancement of Cost Engineering (AACE) as a Level - 5 Order of Magnitude
Estimate and has an expected accuracy range of +50 to -30 percent. The tables present
summaries of costs for major project elements in five columns:
1. Costs for conventional activated sludge (CAS) operation
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South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater Treatment Division
Treatment Element CAS
MLE
Upgrade
MLE
MBR
Total BNR
Upgrade Difference
Present Worth Cost, $ Million
Capital Cost(1) $0 $105 $425 $530 $530
Operation and Maintenance(2) $25 $46 $129 $176 $149
Total Present Worth $25 $151 $554 $706 $679
(1) Capital cost includes construction cost, contingency (40%), tax, and allied costs (costs of planning, engineering, construction
management, permitting, legal and other associated costs (45%)). All costs are in March 2010 dollars.
Notes:
(2) Present worth O&M values were calculated assuming a 3% discount rate over a 20-year period on calculated current yearly O&M costs.
Table ES.6 Estimate Summary for 3 mg/L TIN (Year-round) Permit Level Upgrade to the STP
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater Treatment Division
Treatment Element CAS
Bardenpho
Upgrade
Bardenpho
MBR
Total BNR
Upgrade Difference
Present Worth Cost, $ Million
Capital Cost (1) $0 $188 $779 $967 $959
Operation and Maintenance(2) $25 $128 $394 $522 $475
Total Present Worth $25 $316 $1,173 $1,489 $1,434
(1) Capital cost includes construction cost, contingency (40%), tax, and allied costs (costs of planning, engineering, construction
management, permitting, legal and other associated costs (45%)). All costs are in March 2010 dollars.
Notes:
(2) Present worth O&M values were calculated assuming a 3% discount rate over a 20-year period on calculated current yearly O&M costs.
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2. Upgrade of the existing CAS to provide for biological nitrogen removal (BNR)
3. New Parallel MBR BNR facilities
4. The total estimated cost for the BNR upgrade
5. The difference in cost between the BNR upgrade and the cost of operation of the
existing CAS
The greenhouse gas (GHG) emissions of the representative alternative for each permit
scenario were compared against the current mode of operation at the STP. A summary of
the results of the GHG analysis for the project is presented in Figure ES.1. This figure
presents a bar chart representing the total estimated annual production of carbon dioxide
(CO2) equivalents for the three process alternatives:
1. CAS
2. BNR with an effluent permit goal of 8 mg/L TIN for the six summer months of the year
by conversion of the existing aeration tanks to an MLE process with treatment of the
remaining flow by MLE MBR. Operation in CAS the remainder of the year.
3. BNR with an effluent permit goal of 3 mg/L TIN (year-round) by conversion of the
existing aeration tanks to a Bardenpho process with treatment of the remaining flow
by Bardenpho MBR.
The results indicate that the effect of a summer-only effluent permit level of 8 mg/L TIN
would be approximately two thirds more GHG emissions compared to secondary treatment
at the STP. Imposition of a 3 mg/L TIN year-round limit would result in approximately three
times more emissions of equivalent GHGs. The primary sources of increased GHG
emissions are process nitrous oxide (N2O) and purchased electricity.
ES.4 SOUTH PLANT NITROGEN REMOVAL EFFECT ON
RECLAIMED WATER PRODUCTION
The STP currently provides secondary treatment for up to 144 mgd of flow on a maximum
month basis for discharge to Puget Sound. Substantial removal of ammonia is not
achieved. Reclaimed water filtration facilities for up to 1.5 mgd of secondary effluent are
available using coagulation, flocculation, sand filtration, and disinfection. Implementation of
BNR at the STP could have a significant effect on reclaimed water availability, potential
customers, and quality, depending on the technology selected.
The current flow of the STP during the summer season when reclaimed water could be
potentially useful for irrigation is approximately 98 mgd. Coagulation, flocculation, and
filtration would be required to implement production of 98 mgd of reclaimed water from the
current non-nitrified secondary effluent. Assuming typical detention times and loading
ratios, approximately 38,000 square foot (sf) of coagulation, flocculation, and filtration
facilities would be required. In calculating effects, current capacity of 1.5 mgd was ignored.
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GHG COMPARISON
FIGURE ES.1
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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The MLE – MBR alternative for operation for an 8 mg/L TIN permit level during the summer
would produce up to 62 mgd of MBR effluent water during the summer that would
substantially meet the requirements for Class A reclaimed water. To produce reclaimed
water equaling the full current dry weather flow of 98 mgd, sand filtration of 36 mgd from the
existing secondary clarifiers would be needed resulting in a requirement of approximately
13,000 sf of coagulation, flocculation, and filtration facilities.
The Bardenpho – MBR upgrade strategy would produce up to 114 mgd of MBR effluent
year round that would substantially meet the requirements of Class A reclaimed water. This
means that during the summer season, the STP could treat the full summer flow through
the MBRs, if BNR were implemented.
Table ES.7 compares the costs of reclaimed water production for the full 98 mgd summer
flow for the current non-nitrified secondary effluent to the requirements for additional
filtration assuming nitrogen removal upgrade by a parallel MBR process for either the
8 mg/L (summer only) or the 3 mg/L (year-round) TIN permit level. As shown in Table ES.7,
there would be no additional cost to implement reclaimed water production for the full
summer flow of 98 mgd if the 3 mg/L (year-round) TIN permit limit project is implemented.
Table ES.7 shows that the cost of implementing reclaimed water by conventional filtration is
approximately $104 million in present worth capital and operating and maintenance costs. If
a 3 mg/L (year-round) TIN permit limit project using parallel MBR were implemented, this
cost would be avoided.
The relative present worth cost of implementing 36 mgd of reclaimed water production for
non-nitrified effluent would be approximately $45 million. This would represent a savings of
approximately $45 million over providing full summer reclaimed water production today from
non-nitrified STP effluent. This relative savings in reclaimed water production would be
realized if the 8 mg/L (summer-only) parallel MBR project were implemented.
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Table ES.7 Summary of Relative Reclaimed Water Cost Effects
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Treatment Process Current Approach.
Non-nitrified
Secondary
Effluent. No new
facilities.
Summer only.
8 mg/l TIN Summer
Limit
Parallel MLE-MBR
Processes
3 mg/l TIN All-year
Limit
Add’l Sand Filtration
Req’d
98 mgd sand filters MLE
Effluent
36 mgd
sand
filters
MBR
Effluent
62 mgd -
no sand
filters
MBR Effluent
114 mgd – no sand
filters
Capital Cost $57M $23M $0 $0
Annual O&M Cost $3.1M/yr $1.4M/yr $0 $0
Disinfection Assumed equal cost for all alternatives.
Present Worth O&M(1) $47M $22M $0
Total Present Worth $104M $45M $0
(1) Present worth O&M values calculated assuming a 3% discount rate over a 20-year
period on calculated current yearly O&M costs.
Notes:
ES.5 FINDINGS AND CONCLUSIONS
The principle findings and conclusions of this report are the following:
1. At a project workshop two potential nitrogen removal permit requirements were
determined to bracket potential permit limits that could be applied by the Department
of Ecology in response to South Puget Sound water quality studies: 1) a “least
stringent” potential effluent limit of 8 mg/L TIN for the summer months only and 2) a
“most stringent” potential limit of 3 mg/L TIN year-round.
2. Based on assumptions developed at project workshops, the modeled capacity of the
current STP, with minor modifications, to meet the “least stringent” summer effluent
limit was 36 mgd. Major modifications that would be needed would be construction of
a new treatment plant to treat the remainder of the summer flow (approximately 62
mgd).
3. The modeled capacity of the current STP to meet, with minor modifications, the “most
stringent” year-round effluent limit was 30 mgd. Major modifications that would be
needed would be construction of a new treatment plant to treat the remainder of the
flow (approximately 114 mgd).
4. A large number of potential nitrogen removal alternatives were considered for each
potential permit scenario and reduced to four for each permit scenario. Potential
effects of each of these upgrade strategies were estimated using a series of criteria
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including capital cost, O&M cost, risk, flexibility, footprint, energy, odor generation
potential, compatibility with existing processes, effect on biosolids quantity, and the
amount and quality of reclaimed water produced. Each of these criteria were scored
from 1 (low) to 3 (high) and tallied to determine the ranking. The final ranking
indicated that for the 8 mg/L TIN (summer-only) permit level, the most promising
upgrade strategy would be to upgrade the existing CAS process at the STP to
provide for anoxic and aerobic treatment in two stages by a MLE process and to
construct a parallel nitrogen removing MBR process to treat the remainder of the flow.
For the 3 mg/L TIN (year-round) discharge alternative a similar strategy was selected,
but using a four-stage anoxic and aerobic process (the Bardenpho process). It was
concluded that two other processes, BAF/DNF and IFAS processes, were potentially
cost-effective and have similar enough other effects that they should be considered
for pilot testing in the future.
5. The incremental present worth cost for upgrade of the STP to meet an 8 mg/L TIN
permit level during the summer months is estimated at approximately $680 million
more than continuing operation of secondary treatment over the next twenty years.
The estimated incremental present worth cost for upgrade of the STP to meet a 3
mg/L TIN (year-round) permit level is approximately $1,430 million more than the cost
of continuing with secondary treatment.
6. It was concluded that meeting an 8 mg/L TIN summer permit level would result in
nearly two thirds more GHG emissions from the STP compared to the currently-used
CAS process and that a 3 mg/L TIN year-round permit level would result in
approximately three times more GHG emissions compared to continuing with
secondary treatment at the STP.
7. If BNR were implemented at the STP, between 36 and 98 mgd of effluent would be
made available that would be suitable for reclaimed water use. Assuming that the
costs of production of this water were required for BNR in any case, this water would
be available for reclaimed use at a relative savings over the costs of production of the
water using conventional gravity sand filtration. Cost savings would be in the range of
$45 to $104 million, depending on the level of nitrogen removal implemented. There
would also be a savings in land area of between one quarter and one acre and a
savings of a small amount in electricity consumption and GHG emissions, compared
to production of the same amount of reclaimed water using media filtration if BNR
treatment facilities were not available.
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Chapter 1
SOUTH PLANT NITROGEN REMOVAL -
CURRENT CONFIGURATION
1.1 INTRODUCTION
According to the Washington State Department of Ecology (Ecology 2008b), portions of
South Puget Sound do not meet Washington State water quality standards for dissolved
oxygen (DO). Ecology is concerned that algal growth stimulated by nitrogen loadings to
Puget Sound is causing DO depressions in near-bottom regions. The form of nitrogen of
greatest interest to Ecology is dissolved inorganic nitrogen (DIN), which is the sum of
nitrate, nitrite, and ammonium. In 2006 Ecology began a major study to determine the
extent of low DO and how nitrogen from a variety of sources affects DO levels. The primary
concern was with South Puget Sound below the Tacoma Narrows, but because it was
thought that circulation of nitrogen from the north could cause low DO effects, the Central
Puget Sound area north of the Tacoma Narrows and south of Edmonds was included in the
study. All of King County’s wastewater treatment plants (WWTP) discharge to the Central
Puget Sound. The scope of work for the Ecology study includes data collection, developing
hydrodynamic and water quality models, and simulating alternative management scenarios.
To date Ecology has completed data collection and hydrodynamic modeling. The last
elements of Ecology’s scope of work are being completed in 2010. Ecology produced two
significant conclusions from its data collection effort (Ecology, 2008a):
• Nitrogen is the main pollutant that causes low dissolved oxygen levels.
• In September 2007, wastewater treatment plants contributed 80 percent of the
watershed DIN load to South Puget Sound (nitrogen loads in late summer are
particularly important because this is when DO levels are the lowest). Because of the
greater population density in the Central Puget Sound study area, the sum of WWTP
DIN loadings from the combined Central and South Puget Sound area contributed
over 90 percent of the watershed DIN load to the combined Central and South Puget
Sound.
Results of the hydrodynamic modeling are available as an external review draft (Ecology,
2009). These results conclude that “Based on predicted dilution levels derived from water
column maximum dye concentrations during September 16-30, 2007, dye from South and
Central Puget Sound exchanges through the Tacoma Narrows (Figure ES-7). Therefore,
we cannot rule out the influence of Central Puget Sound sources on South Puget Sound
water quality. However, the results are not sufficient to rule in an influence either given the
complexity of nutrient transport and transformation within marine environments. The water
quality model is needed to quantify the link between sources and water quality
impairments.” Results of the water quality transport modeling are expected in 2010.
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With this background King County (the County) undertook the current project to “determine
the effectiveness and costs of a range of treatment scenarios designed to reduce nitrogen
discharged by the South Treatment Plant (STP)” (from scope of work for King County
Contract E00025E07). An initial project team workshop was conducted on October 1, 2009
where the project assumptions were established.
Three memoranda were produced as part of this project. The first memorandum evaluated
how much flow the existing STP could process if required to comply with two different levels
of nitrogen removal and what modifications would be required for each. The second
memorandum evaluated the potential effects on the STP (in terms of additional tankage,
footprint, cost, and greenhouse gas emissions) if it were required to meet the assumed
seasonal or year-round limit while maintaining its current rated capacity (144-million gallons
per day (mgd) max month year-round and 98-mgd max month during summer). The third
memorandum evaluated effects on the reclaimed water program for the County. These
three memoranda have been incorporated, respectively, into Chapters 1, 2, and 3 of this
report.
The purpose of this first chapter is to describe the process used to determine target effluent
nitrogen limits and the re-rated capacity of the current STP to meet these target nitrogen
limits.
1.2 BACKGROUND
1.2.1 Description of Existing Plant
The STP was built in 1965 on a 94 acre site in Renton, Washington. The plant has been
modified several times since 1965; a schematic of the current plant and an aerial overview
are shown in Figures 1.1 and 1.2.
Wastewater enters the plant through the Eastside and South Interceptors. Rags and paper
are removed through coarse bar screens and grit is removed in pre-aerated grit tanks.
Screened, degritted wastewater flows to 12 primary clarifiers, where approximately 60
percent of total suspended solids (TSS) are removed. Primary clarifier effluent flows by
gravity to four aeration basins.
The aeration basins are operated in a plug flow mode and wastewater, mixed with return
activated sludge (RAS) flows through the basin in a serpentine manner. The first one-eighth
of each basin is not aerated and acts as selector, limiting growth of filamentous bacteria.
Mixed liquor suspended solids (MLSS) are clarified in 24 secondary clarifiers. Secondary
effluent is disinfected in chlorine contact channels using a hypochlorite solution prior to
discharge in the Puget Sound.
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STP PROCESS FLOW SCHEMATIC
FIGURE 1.1
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT
THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE
WATER REUSE PROGRAM DEVELOPMENT
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STP AERIAL PHOTOGRAPH
FIGURE 1.2
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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1.2.2 Summary of Current NPDES Permit
The STP’s current National Pollution Discharge Elimination System (NPDES) permit was
issued in 2009 and expires in 2014. The permit is summarized in Table 1.1 for the plant’s
main Puget Sound outfall. The current STP permit does not regulate effluent nitrogen but it
does require the plant to monitor the final effluent for total ammonia (concentration and
load), nitrate-nitrite, and total Kjeldahl nitrogen (TKN) concentration, monthly.
Table 1.1 Current NPDES Permit Summary
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Parameter Average Monthly(1) Average Weekly(2)
BOD5
30 mg/L, 36,000 ppd, 85%
removal of influent BOD5 45 mg/L 54,000 ppd
TSS
30 mg/L, 36,000 ppd, 85%
removal of influent TSS 45 mg/L, 54,000 ppd
Fecal Coliform Bacteria(3) 200/100 mL 400/100 mL
pH(4)
Daily minimum is equal to or greater than 6.0 and the daily
maximum is less than or equal to 9.0
Parameter Average Monthly(1) Maximum Daily(5)
Total Residual Chlorine 0.5 mg/L 0.75 mg/L
Notes:
(1) Average monthly effluent limit means the highest allowable average of daily discharges over a
calendar month. To calculate the discharge value to compare to the limit, you add the value of
each daily discharge measured during a calendar month and divide this sum by the total
number of daily discharge measured. See footnote 3 for fecal coliform calculations.
(2) Average weekly discharge limitation means the highest allowable average of “daily
discharges” over a calendar week, calculated as the sum of all “daily discharges” measured
during a calendar week divided by the number of “daily discharges” measured during that
week. See footnote 3 for fecal coliform calculations.
(3) To calculate the average monthly and average weekly values for fecal coliforms, you must use
the geometric mean. Ecology gives directions to calculate this value in publication No. 04-10-
020, Information Manual for Treatment Plant Operators.
(4) Indicates the range of permitted values. The Permittee must report the instantaneous
maximum and minimum pH monthly. Do not average pH values.
(5) Maximum daily effluent limit means the highest allowable daily discharge. The daily discharge
means the discharge of a pollutant measured during a calendar day. The daily discharge is
the average measurement of the pollutant over the day. This does not apply to pH.
The current permit lists plant flows and loads:
• Maximum month design flow of 144 mgd
• Peak instantaneous design flow of 325 mgd
• Maximum month five day biochemical oxygen demand (BOD5) loading of 251,000
pounds per day (ppd)
• Maximum month TSS loading of 235,000 ppd
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1.3 NITROGEN LIMIT SCENARIOS
This section describes the process used to determine target nitrogen limits for use in project
nitrogen removal scenarios. The nitrogen concentration in WWTP effluent is regulated to
either protect human health or the environment. Since nitrate in drinking water can be
responsible for the “blue baby syndrome”, the Environmental Protection Agency (EPA) has
set a maximum contaminant limit goal (MCLG) of 10 milligrams per liter (mg/L) for nitrate
(measured as nitrogen) in public drinking water supplies. From the perspective of effects on
the human environment: since nitrogen can limit algal growth, decreasing effluent nitrogen
concentration can improve the quality of the receiving water. The Lacey, Olympia,
Tumwater, Thurston County (LOTT) Budd Inlet Treatment Plant in Olympia was the first
large treatment plant discharging to Puget Sound to be given a nitrogen limit. This plant is
limited to an average summer (for two periods from April through October) total inorganic
nitrogen (TIN) concentration of 3 mg/L. TIN is defined as is the sum of ammonia, nitrate,
and nitrite (TIN and DIN are the same). Several plants in Florida are now facing potential
total nitrogen limits of less than 1 mg/L.
A summer season permit limit would be less stringent, in the sense that the limit could be
met with smaller tank volumes and fewer other effects, than a maximum month limit (or
even a maximum day limit) that was enforced year-round. This is because biological
nitrification, typically a key step in nitrogen removal, is slower in cold temperatures. The
extreme range of possible limits for total inorganic nitrogen based on this background would
be from 1 mg/L (most stringent) to 10 mg/L TIN (least stringent) in terms of numerical value.
From a compliance period perspective: a limit imposed as an average over the entire year
would be least stringent and a maximum month (or even maximum day) limit imposed in the
coldest months of the year would be the most stringent.
Based on these considerations, two permit scenarios were selected at the first project
workshop on October 1, 2009 (Carollo Engineers, 2009a). The two permit scenarios given
below represent the least and most stringent permit scenarios that workshop participants
felt could reasonably be requested by Ecology, respectively:
1. Summer-season (May 1 through October 31) limit of 8 mg/L TIN
2. Year-round limit of 3 mg/L TIN imposed in the coldest month
1.4 FLOW AND LOAD BASIS
The work documented in this report evaluated the capacity of the existing STP treatment
system and modifications to the existing system necessary to provide nitrogen removal for
the design maximum month flow of 144 mgd. This corresponds to the rated maximum
month flow from the current NPDES permit. The BOD5, TSS, and ammonia loads that
correspond to this flow were taken from Brown and Caldwell (2004) and from STP plant
records for the year 2007. These are summarized in Table 1.2.
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The design year-round maximum month flow and loads from Brown and Caldwell (2004)
were used to evaluate the permit scenario of a year-round limit of 3 mg/L TIN. To evaluate
the 8 mg/L (summer-only) TIN limit scenario maximum summer month flows and loads
during the design year were determined from the Brown and Caldwell (2004) values using
peak factors from the STP record for the years 2006 through 2008. These values are also
summarized in Table 1.2.
Table 1.2 Design Influent Flow and Loads
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Description
Current Annual
Average
Design Summer
Maximum Month
Design Year-round
Maximum Month(1)
Flow, mgd 85 98 144
BOD5, ppd 164,000 231,000 251,000
TSS, ppd 168,000 221,000 235,000
NH4-N, ppd 16,300 26,200 23,600
Notes:
(1) Brown and Caldwell (2004)
1.5 NITROGEN REMOVAL CAPACITY ANALYSIS
Treatment plant models were developed by Carollo for this report and calibrated to existing
plant data to evaluate the capacity of the existing plant to meet the two effluent permit
scenarios defined above. As part of the work, Carollo prepared two models; a steady state
model using Biotran, a proprietary Carollo spreadsheet model, and BioWin, commercial
process analysis software from Envirosim. Both models included primary treatment,
activated sludge reactors, secondary sedimentation tanks, solids thickening, digestion, and
dewatering unit process and return flows. Figure 1.3 presents a schematic of the model
developed in BioWin.
These calibrated models were used to define the capacity of the current treatment plant
(with minor modifications) to meet the summer season limit of 8 mg/L of TIN and the year
round limit of 3 mg/L of TIN. The analysis of the current treatment plant described in this
report was based on maximum month flows and loads. For our analysis we assumed that
one aeration basin and one secondary clarifier was out of service. This was a decision of
the October 1, 2009 workshop. The analysis assumed that 23 out of the 24 clarifiers would
be in service, even at the reduced flows required to meet the more stringent effluent limits.
This assumption allows operation at higher MLSS concentrations while still maintaining the
current solids loading rates on the clarifiers. This section describes the analysis of the STP
data, the model calibration process, and the model results for the two effluent scenarios.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 1.3.doc
PROCESS SCHEMATIC FOR STP BIOWIN MODEL
FIGURE 1.3
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
Anaerobic Pass 1 Aerobic Pass 2 Aerobic Pass 3 Aerobic Pass 4 Aerobic Pass 1 Effluent
Digesters 1- 4 Storage Digester
Sludge Disposal
Cl2 Contact
Screened Sewage
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1.5.1 Data Analysis
In preparation for the model analysis, operating data for the period from 2005 through 2009
were reviewed. Figure 1.4 presents a time-series graph of influent flow at the STP for the
period. A full year of data for 2007 was taken as representative of the period and was used
for calibration of the Biotran model. The average and maximum month flows for 2007 were
76.5 mgd and approximately 120 mgd, respectively.
Influent BOD5 loadings in 2007 averaged approximately 165,000 ppd with a maximum
month average of approximately 195,000 ppd. The maximum month TSS load has
historically been approximately the same as the maximum month BOD5 load. Daily influent
loadings for the entire period are shown in Figure 1.5.
Three key parameters are especially important for successful activated sludge operation
and model calibration: sludge settleability, temperature, and solids residence time (SRT).
The data analysis for these three parameters is summarized in the sections below.
1.5.1.1 Sludge Settleability
The sludge volume index (SVI) gives an indication of sludge settling rates, which are
important for solids capture in the secondary sedimentation tanks. SVI values for STP have
mostly been below 150 milliliter per gram (mL/g) with several excursions as high as 250
mL/g in the last two years. Figure 1.6 shows a time-series plot of SVI data since 2007.
Solids settling capacity can be calculated based on settling tests, or estimated from a
statistically-derived formula. Brown and Caldwell (2004) included settling velocity data from
tests in March and August of 2003. These data are compared in Figure 1.7 to data
calculated using the Daigger and Pitman equations (Daigger, 1995 and Pittman, 1985) and
using the default settling parameters from BioWin. The graph shows the calculated solids
flux capacity in pounds of solids per square foot of clarifier cross-section per day (ppd/sf).
The solids flux rate based on the Daigger equation lies between the two values measured
in 2003. For the initial modeling, the BioWin default values were used, but the effect of
settleability on performance was considered in a sensitivity evaluation presented in the
Chapter 2.
1.5.1.2 Temperature
Temperature affects biological growth and sludge settling. In general, for higher
temperatures, growth rates and oxygen consumption in the activated sludge process
increase, and settling rates may also increase as a result of lower fluid viscosity. At lower
temperatures biological growth slows.
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RAW SEWAGE FLOW FOR THE PERIOD
FROM 2005 TO 2009
FIGURE 1.4
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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RAW SEWAGE LOADING DATA FOR THE PERIOD
FROM 2005 TO 2009
FIGURE 1.5
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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SVI DATA FOR THE PERIOD FROM 2007 TO 2009
FIGURE 1.6
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 1.7.doc
SETTLEABILITY DATA FROM 2003 TESTS COMPARED TO
STANDARD SVI-BASED FORMULAS
FIGURE 1.7
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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Influent temperature data from 2005 through 2009 provided by the County were evaluated
to determine the minimum 30-day running average summer (May 1 through October 31)
temperature and the minimum 30-day running average year-round temperature. These data
are shown in Figure 1.8. Based on the four years of data a minimum month summer
temperature of 13.9 degrees Celsius (C) and a minimum month year-round temperature of
11.4 C were selected for use in the project.
1.5.1.3 Solids Residence Time
The SRT of the activated sludge system is a key parameter for model calibration as it
determines bacterial growth rates, which in turn determine oxygen consumption and sludge
production for the system. Figure 1.9 presents data for aeration basin total SRT provided by
the County. The SRT varied from a minimum of 2.1 days to a maximum of 5.8 days over
the period of the data. The models used for this study were calibrated to the average total
SRT during the 2007 calibration time period of 3.5 days.
A key group of organisms for this evaluation are the nitrifiers. These organisms are
sensitive to temperature as is illustrated in Figure 1.10. This graph shows the washout, or
minimum, SRT for the nitrifiers as predicted by Jenkins, et al. 2004. At the minimum
summer temperature of approximately 14 C, nitrifying organisms are washed out of the
system when the aerobic SRT is less that approximately 6 days. At the minimum year-
round temperature of approximately 11 C, the nitrifying organisms are washed out of the
system when the aerobic SRT is less than approximately 12 days. With one-eighth of the
existing aeration tanks operated anaerobically, only seven-eighths of the total SRT count
towards aerobic SRT. In other words, for the total average SRT of 3.5 days maintained in
the STP during 2007 the aerobic SRT would have been approximately 3.1 days.
The summer nitrification temperature estimate presented in Figure 1.8 can be compared to
the STP’s full-scale nitrification testing experience. During the summer of 2000 the STP
was operated at a 10 to 14 day total SRT with one-eighth of the basin unaerated (resulting
in an aerobic SRT of 9 to 12 days) and the RAS rate at maximum flow. During this period
the plant was able to operate with good nitrification and secondary effluent ammonia
concentrations less than 1 mg/L and reasonably good denitrification; with secondary
effluent nitrate concentrations in the range of 10 to 15 mg/L.
Based on this full-scale experience, modeling in BioWin and Biotran, and the minimum
SRTs listed in Figure 1.6, the target aerobic SRT for the summer effluent scenario of 8
mg/L TIN was 9 days and the target aerobic SRT of the year-round effluent scenario of 3
mg/L TIN was 13 days.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 1.8.doc
TEMPERATURE DATA FOR THE PERIOD FROM 2005 TO 2009
FIGURE 1.8
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND
THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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SRT DATA FOR THE PERIOD FROM 2005 TO 2009
FIGURE 1.9
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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WASHOUT AEROBIC SRT VALUES FOR NITRIFIER ORGANISMS
FIGURE 1.10
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND
THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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1.5.2 Model Calibration
The “South Plant Peak Flow Management Report” (Carollo Engineers, 2010) described
three different approaches to the BioW in model calibration as summarized below:
1. The default values from BioWin for raw sewage
2. The values from Biotran calibrated to 2007 STP data
3. Values assumed in the 2000 Brown and Caldwell evaluation
The Peak Flow Management Report found little difference between the three different
calibration approaches. Based on this finding, the second calibration approach, using 2007
STP data, was used to calibrate the model for this study. Data received from the County for
the year 2007 was used to match primary organics removal, the amount of solids produced
in waste activated sludge (WAS), and the recorded solids residence time for the average
mixed liquor suspended solids for the period. Two primary parameters were used to
produce the calibration: the apparent filterable BOD5 fraction (filterable BOD5 fraction (fbf) =
0.415) and the non-biodegradable volatile suspended solids (non-biodegradable volatile
fraction (fvu) = 0.15). These values were used to produce wastewater characteristic ratios
for the raw wastewater. These characteristic ratios were in turn used as input to a BioWin
model of the entire STP.
1.5.3 Modeling Results TIN 8
Based on the calibrated BioWin model and an assumed aerobic SRT of 9 days, the
secondary effluent scenario of 8 mg/L TIN can be met with a reduced maximum summer
month flow of 36 mgd (or 37 percent of the design maximum summer month flow of 98
mgd). This scenario assumes one aeration basin and one secondary clarifier out of service
as decided in the October 1, 2009 workshop. For this scenario the activated sludge basins
would be operated in a Modified Ludzak-Ettinger (MLE) configuration shown in Figure 1.11.
With this configuration, the entire first pass would be unaerated, increasing the unaerated
fraction form 12.5 percent to 25 percent. The unaerated fraction would serve as the anoxic
zone where in the bacteria would convert nitrate to nitrogen gas. Additional nitrate would be
returned to the anoxic zone by a mixed liquor return (MLR) pump. Based on the modeling
the optimal flow rate for this pump would be 360 percent of the influent flow. The remaining
75 percent of the activated sludge basin would be aerated. It is in this portion of the basin
that nitrifying bacteria would convert ammonia to nitrate.
In the absence of oxygen, denitrifying bacteria use nitrate as an oxygen source. The MLE
configuration is considered a pre-anoxic denitrification process, since the denitrification
process precedes the nitrification process. This is an optimal configuration for denitrification
because the denitrification process occurs in the zone with the highest BOD5 concentration.
However, when denitrification processes follow primary clarification, the BOD5 available
from the wastewater can limit the extent of denitrification.
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MLE SCHEMATIC
FIGURE 1.11
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
June 29, 2010 - FINAL 1-20
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It is generally thought that a BOD5 to TKN ratio of at least 4 is required for denitrification
(Randall et al., 1992). The BOD5 to TKN ratio of the STP primary effluent is approximately
equal to the minimum ratio. Through modeling it was determined that for the STP without
an external carbon source, a 50 percent anoxic zone size would be required. Since this
severely limits the capacity of the system, if was assumed that the anoxic zone size would
be limited to 25 percent and an external carbon source in the form of methanol would be
used. Table 1.3 summarizes the modeling results for this scenario.
To meet the TIN limit of 8 mg/L, the following modifications would be needed to the existing
plant:
• Added baffle wall at the end of the first pass
• Mixed liquor return pumps capable of delivering 360 percent of the influent flow
• Methanol delivery system and methanol storage
• Additional diffusers to the second pass of the aeration basins
• Additional plant capacity for the remainder of the design year flow (or 62 mgd
maximum summer month). This will be addressed in the subsequent chapter.
Table 1.3 Current Configuration – TIN 8 mg/L Scenario Modeling Results
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Value
Design Maximum Summer Month Flow 36 mgd
Aeration Basins
Aeration Basins in Service 3
Unaerated Fraction 25%
RAS Rate 58%
MLR Rate 360%
MLSS Concentration 3,700 mg/L
Aeration Air Requirement 40,000 scfm
Methanol Feed
Flow Rate 1,400 gpd
COD Load 13,900 ppd COD
Secondary Clarification
Secondary Clarifiers in Service 23
Secondary Effluent
Ammonia 0.2 mg/L
Nitrate 7.5 mg/L
Nitrite 0.07 mg/L
TIN 7.8 mg/L
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1.5.4 Modeling Results TIN 3
Based on the calibrated BioWin model and an assumed aerobic SRT of 13 days, the
secondary effluent scenario of 3 mg/L TIN can be met with a reduced maximum month flow
of 30 mgd (or 21 percent of the design maximum month flow of 144 mgd). This capacity
rating assumes one aeration basin and one secondary clarifier out of service, as decided at
the October 1, 2009 workshop. For this scenario the activated sludge basins would be
operated in a Bardenpho configuration shown in Figure 1.12. With this configuration, the
entire first pass would be unaerated, the second and third passes would be aerated, 80
percent of the fourth pass would be unaerated, and 20 percent of the fourth pass would be
aerated.
This process would increase the unaerated fraction form 12.5 percent to 45 percent. The
Bardenpho process incorporates both pre-anoxic and post-anoxic denitrification. The first
two zones (or the first three passes at STP) would function very similarly to the MLE
process described above. The last two zones (or the last pass at STP) are polishing zones
that, combined with an external carbon source, can reduce the residual TIN to values less
than 3 mg/L. Table 1.4 summarizes the modeling results for this scenario.
To meet the TIN limit of 3 mg/L, the following modifications would be needed to the existing
plant:
• Three additional baffle walls, one at the end of the first pass and the second and third
in the fourth pass
• Mixed liquor return pumps capable of delivering 350 percent of the influent flow
• Methanol delivery system and methanol storage
• Additional plant capacity for the remainder of the design year flow (or 114 mgd
maximum summer month). This will be addressed in the subsequent chapter.
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BARDENPHO SCHEMATIC
FIGURE 1.12
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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Table 1.4 Current Configuration – TIN 3 mg/L Scenario Modeling Results
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Value
Design Maximum Summer Month Flow 30 mgd
Aeration Basins
Aeration Basins in Service 3
Unaerated Fraction 45%
RAS Rate 100%
MLR Rate 350%
MLSS Concentration 3,700 mg/L
Aeration Air Requirement 20,500 scfm
Methanol Feed
Flow Rate 150 gpd
COD Load 1,500 ppd COD
Secondary Clarification
Secondary Clarifiers in Service 23
Secondary Effluent
Ammonia 0.4 mg/L
Nitrate 2.15 mg/L
Nitrite 0.1 mg/L
TIN 2.65 mg/L
1.6 CONCLUSIONS
This project was initiated based on the South Puget Sound Study findings which suggest
that the South Puget Sound may have excess nitrogen. A project team was assembled to
evaluate the impacts of potential future nitrogen limits on the capacity of the STP. A full-
plant model was developed and calibrated to operating data collected at the plant. The
project team decided on two effluent nitrogen scenarios representing the anticipated “least
stringent” and “most stringent” permitting scenarios at the October 1, 2009 workshop. At
this workshop, the project team also decided that the capacity rating of the current plant to
meet the two target nitrogen effluent scenarios would be determined with one aeration
basin and one secondary clarifier out of service.
Based on these assumptions, the modeled capacity of the current STP to meet the “least
stringent” summer effluent limit of 8 mg/L TIN was 36 mgd. To meet this effluent limit, minor
modifications would be needed at the current plant including the addition of baffle walls,
MLR pumps and a chemical delivery system. Major modifications that would be needed
would be the construction of a new treatment plant to treat the remainder of the summer
flow (approximately 62 mgd).
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Based on these assumptions, the modeled capacity of the current STP to meet the “most
stringent” year-round effluent limit of 3 mg/L TIN was 30 mgd. To meet this effluent limit,
minor modifications would be needed at the current plant including the addition of baffle
walls, MLR pumps and a chemical delivery system. Major modifications that would be
needed would be the construction of a new treatment plant to treat the remainder of the
flow (approximately 114 mgd). Chapter 2 addresses alternatives to treat the entire flow to
the two target effluent nitrogen limits.
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Chapter 2
SOUTH PLANT NITROGEN REMOVAL SCENARIOS
2.1 INTRODUCTION
Chapter 1 described project assumptions and evaluated how much flow the existing South
Treatment Plant (STP) could process if required to comply with a summer seasonal limit of
8-milligrams per liter (mg/L) total inorganic nitrogen (TIN) or an annual limit of 3-mg/L TIN
and what modifications would be required for nitrogen removal. This chapter (Chapter 2)
describes potential effects on to the STP (e.g., tankage, footprint, cost, greenhouse gas
emissions) if it were required to meet the assumed seasonal or year-round limit while
maintaining its current rated capacity (144-million gallons per day (mgd) max month year-
round and 98-mgd max month during summer).
Four nitrogen (N) removal alternatives were selected for evaluation under each assumed
permit limit. Two representative alternatives, one each for the seasonal limit and annual
limit, were subsequently selected for a more detailed cost estimate, sensitivity analysis, and
sustainability analysis. The cost estimates are considered to be order of magnitude
estimates, i.e., in the +50 to -30 percent accuracy range.
The representative alternative in each case was the approach that best met the weighted
evaluation criteria developed by the project team for each nitrogen removal scenario. It is
intended to be a “representative” approach by which the costs and effects of implementing
nitrogen removal at South Plant can be assessed.
2.2 ALTERNATIVES SCREENING
2.2.1 Nitrogen Removal Alternatives
Table 2.1 summarizes four different classes of nitrogen removal alternatives. These were
the four classes of alternatives discussed at the first project workshop (Carollo, 2009a). At
the workshop a large number of possible treatment scenarios for nitrogen removal were
considered and screened by consensus of the meeting to a narrower range of alternatives
as discussed below.
2.2.1.1 Land-based Alternatives
Land-based alternatives rely on anoxic wetting and aerobic drying cycles to convert
ammonia to nitrate and nitrate to nitrogen gas. The nitrifying and denitrifying organisms are
present in both the wastewater and the soil communities. All of these alternatives are land
intensive and would not fit on the available site at STP. It is not likely that any of these
alternatives could reliably meet either of the two selected effluent permit levels for TIN.
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Table 2.1 Nitrogen Removal Alternatives
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Land Based Aquatic Chemical Biological
Infiltration Basins Wetlands Ion Exchange Suspended Growth
Overland Flow Wetlands Ion Exchange Suspended Growth
Spray Irrigation Floating Aquatic
Plants
Crystallization
Breakpoint
Chlorination
Hybrid
Side Stream
2.2.1.2 Aquatic Alternatives
Aquatic alternatives rely on aerobic biological processes to convert ammonia to nitrate and
anoxic biological processes to convert nitrate to nitrogen gas. As with the land-based
alternatives, these processes are land intensive and would not fit on the available site at
STP. Furthermore, experience with these systems elsewhere indicates that they would not
likely be able to reliably meet either of the two effluent limit scenarios.
2.2.1.3 Chemical Alternatives
Chemical alternatives rely on changes to effluent quality through chemical reactions. This
section summarizes these processes.
In ion exchange treatment systems the ammonium ion (NH4+) and the nitrate ion (NO3-)
displace ions on a natural or synthetic ion exchange resin. Clinoptilolite is one of the most
frequently used resins, due to its high affinity for ammonium and it’s relatively low cost.
In air stripping, nitrogen - specifically, ammonia - can be stripped from the wastewater into
the atmosphere by passing air through the wastewater. To ensure effective N removal, lime
or caustic are typically added to raise the wastewater pH above pH 10.5-11. The high pH
converts most of the ammonia species in wastewater to the molecular NH3 form, which is
volatile. In general, this process requires large quantities of chemical, which produce large
quantities of chemical sludge, and is less effective at the relatively low wastewater
temperatures of the STP than it would be in a warmer climate. A draw back of air stripping
is that while ammonia is removed from the water it is added to the atmosphere, potentially
contributing to air pollution.
Crystallization is the process by which nitrogen and phosphorus are removed through the
formation of crystals such as struvite (ammonium magnesium phosphate -
NH4MgPO4·6H2O). The Ostara Company produces struvite as a fertilizer in a proprietary
fluidized bed reactor. This process is ideally suited as a side stream treatment on the
anaerobic digester return stream for treatment plants employing biological phosphorus
removal. Ammonia removal by struvite formation is usually limited by available phosphorus.
Typical ammonia removal through this process ranges from 10 to 15 percent. Since
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phosphorus removal is not required in the scenarios considered for this report, struvite
crystallization was not considered further for the STP.
Breakpoint chlorination is the process by which sufficient chlorine is added to stepwise
oxidize ammonium to chloramines and finally to nitrogen gas, as summarized in the
following reaction:
2NH4+ + 2HOCl 2NH2Cl + HOCl NHCl2 + NOH N2(gas) + HOCl + HCl
(This reaction is not balanced and does not show H2O and H+)
As demonstrated in the above reaction, approximately 1.5 moles of hypochlorite (HOCI) are
required for every mole of ammonium reduced. For the STP with an average effluent
ammonia concentration of 30 milligrams per liter (mg/L), this process would require
hypochlorite doses of approximately 200 mg/L. For comparison, the current hypochlorite
dose for disinfection at the STP is about 2-2.5 mg/L with an annual product cost around
$370,000. If breakpoint chlorination were implemented at the STP, additional costs would
need to be incurred for alkalinity replacement. As is shown in the above reaction,
breakpoint chlorination produces an acid which would cause the pH to decrease without an
alkalinity supplement.
None of the chemical alternatives were selected for further evaluation due to their high
operating costs and low effectiveness at temperatures typical of the Pacific Northwest.
2.2.1.4 Biological Alternatives
Biological nitrogen removal (BNR) alternatives can be divided into four basic groups:
suspended growth, attached growth, hybrid (both suspended and attached growth), and
side stream treatment. These alternatives can be coupled with a clarifier as shown in Figure
2.1 or with a membrane filter to operate as a membrane bioreactor (MBR) process. The
current STP secondary process is a suspended growth, conventional activated sludge
(CAS) process with clarifiers.
2.2.1.4.1 Suspended Growth Alternatives
In the suspended growth nitrogen removal alternatives, the nitrifying and denitrifying
organisms are suspended in the activated sludge mixed liquor. Examples of feasible
suspended growth processes are the Modified Ludzak-Ettinger (MLE), Bardenpho, and step
feed configurations with alternating anoxic and aerobic zones. This section briefly describes
each of these configurations.
A schematic of an MLE configuration is shown in Figure 2.1. The MLE process includes an
unaerated zone followed by an aerated zone with mixed liquor return (MLR) flow (in the
range of 200 to 500 percent of the influent flow) from the aerated zone back to the anoxic
zone. In the unaerated, anoxic zone denitrifying bacteria convert nitrate to nitrogen gas and
in the aerobic zone, the nitrifying organisms convert ammonia to nitrate. This configuration
is considered a pre-anoxic denitrification process, since the denitrification process precedes
the nitrification process.
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MLE SCHEMATIC
FIGURE 2.1
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
June 29, 2010 - FINAL 2-5
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This is an optimal configuration for denitrification because the denitrification process occurs
in the zone with the highest food or five-day biochemical oxygen demand (BOD5)
concentration. However, when denitrification processes follow primary clarification, the
BOD5 available from the wastewater can limit the extent of denitrification and an external
carbon source (methanol is the most common carbon source used currently) could be
required for effective nitrogen removal. The efficiency of the MLE process depends on the
carbon to nitrogen ratio of the aeration basin influent, the MLR flow rate, and the size of the
anoxic zone. Generally, this process cannot meet TIN limits below 5 mg/L and in most
situations is better suited to meet a TIN limit in the range of 8 to 12 mg/L. This process can
be coupled with a clarifier as shown in Figure 2.1 or with a membrane filter and operated as
a MLE MBR process.
A schematic of a Bardenpho configuration is shown in Figure 2.2. This is a four-zone
process with an initial anoxic zone, followed by an aerobic zone, which is followed by
another anoxic zone and a final aerobic zone. This process also includes a MLR from the
second zone to the first zone, typically in the range of 200 to 500 percent of the influent
flow. The Bardenpho process incorporates both pre-anoxic and post-anoxic denitrification.
The first two zones function identically to the MLE process described above. The last two
zones are polishing zones that, combined with an external carbon source, can reduce the
residual TIN to values less than 3 mg/L. This process can be coupled with a clarifier as
shown in Figure 2.2 or with a membrane filter and operated as a Bardenpho MBR process.
A step feed configuration includes multiple anoxic and aerobic zones with the activated
sludge influent split between each of the anoxic zones and the return activated sludge
(RAS) directed to the first anoxic zone. A schematic of the step feed process is shown in
Figure 2.3. This process is very similar to the MLE configuration, except that instead of a
MLR stream, the nitrate rich effluent from the aerobic zone proceeds to an anoxic zone.
The step feed process typically obtains comparable ammonia removal and better nitrogen
removal than a plug flow process with the same flow and tank volume. This occurs because
the split feed dilutes the mixed liquor suspended solids (MLSS) as it travels through the
aeration basin, permitting a higher solids inventory to be maintained for a given clarifier flow
rate. Conversely, a step feed process of the same volume can accommodate a higher flow
for a given degree of nitrogen removal, but with higher effluent ammonia concentrations.
Step feed can be combined with a post-anoxic zone in the last pass to meet low effluent
TIN limits.
2.2.1.4.2 Attached Growth Alternatives
In attached growth nitrogen removal processes, the nitrifying and denitrifying bacteria are
attached to solid media. Attached growth nitrogen removal alternatives include stationary
bed, trickling filter, and moving bed applications.
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BARDENPHO SCHEMATIC
FIGURE 2.2
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.3.docx
STEP FEED SCHEMATIC
FIGURE 2.3
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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Examples of the stationary bed process are the biological aerated filter (BAF) and the
denitrifying filter (DNF). Generally, BAFs are used exclusively for nitrification followed by a
DNF for denitrification. In these filters, biomass grows on expanded shale media or
polystyrene pellets, and usually, no additional clarification or filtration is required. Both the
BAF and DNF follow the CAS process. The initial DNFs were single media, downflow, deep
bed filters. Many DNFs are now being marketed by the BAF manufacturers that are upflow
reactors. If filtration is not required, these upflow DNFs can be more highly loaded than the
downflow counterparts. DNFs require a source of carbon; usually methanol is added. This
process can provide nearly complete denitrification. A schematic of a BAF/DNF process for
the STP is shown in Figure 2.4.
In trickling filters, wastewater is distributed over solid media which were originally rocks and
are now almost exclusively a plastic cross flow media. The trickling filter process can
provide nitrification with the denitrification process occurring in a separate DNF.
The moving bed bioreactor (MBBR) is a reactor tank containing random media upon which
microorganism growth is facilitated by aeration. Existing activated sludge basins could be
retrofitted to MBBR basins. The media generally consists of plastic wagon wheels or
sponges as illustrated in Figure 2.5.
2.2.1.4.3 Hybrid Alternatives
A hybrid process combines suspended growth with attached growth. The main hybrid
alternative for nitrogen removal is the integrated fixed film activated sludge (IFAS) process.
In an IFAS process, plastic media, ropes, or sponges are added to an aeration tank to
provide surfaces upon which bacteria attach and grow with the intent of increasing the
overall biomass inventory in the aeration tank (see Figure 2.5 for media examples). An
IFAS process is configured like an activated sludge process with RAS introduced into the
first reactor tank in the process. Biomass growing on the media allows for greater nitrogen
removal with no increase in the overall aeration basin or clarifier volume. Most IFAS media
systems are proprietary, but there are many suppliers, allowing competitive selection of
IFAS media and equipment. The IFAS system differs from the previously discussed MBBR
system in that it incorporates both fixed film processes (the biofilm growing on the media)
with suspended growth processes through the RAS recycle.
Most IFAS systems only add media to aerobic zones; however, at least one supplier has
some experience with the use of fixed media in anoxic zones. The IFAS process can be
configured in either the MLE configuration or the Bardenpho configuration to add nitrogen
removal capacity to existing aeration basins. The IFAS process requires intermediate
screens and/or internal recirculation pumping at the end of the aeration basin to keep the
media evenly distributed in the reactor. A schematic of an MLE IFAS alternative for the STP
is shown in Figure 2.6.
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BAF/DNF SCHEMATIC
FIGURE 2.4
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.5.docx
EXAMPLES OF MEDIA USED IN
MBBR AND IFAS PROCESSES
FIGURE 2.5
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.6.docx
MLE IFAS SCHEMATIC
FIGURE 2.6
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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2.2.1.4.4 Side stream Alternatives
Solids treatment processes, including the anaerobic digestion process employed at the
STP, usually generate return flows, or side streams, rich in nutrients. In anaerobic digestion
carbonaceous components of the treated sludge stream are converted to methane gas.
Mineralized nutrients like nitrogen and phosphorus compounds remain in the liquid stream
that is returned to the main liquids treatment process in the side stream flow from sludge
dewatering.
A number of processes, many of them proprietary, have been developed for treatment of
ammonia-rich side streams from solids processing facilities. These include the Sharon®
process, which operates by encouraging a special pathway for nitrogen removal: instead of
employing the normal, four-stepped, process of conversion of ammonia to nitrite and then
to nitrate and from nitrate to nitrite and then to nitrogen gas, this process proceeds at
elevated temperature to encourage a two-step conversion from ammonia to nitrite and from
nitrite directly to nitrogen gas. A full-scale installation of a Sharon® process recently was
constructed in New York City.
Another proprietary process, Anammox®, employs special bacteria that oxidize ammonia
using nitrite and nitrate as electron acceptors. This process, which doesn’t require oxygen,
operates at elevated temperature and requires strict control of pH. It operates at high (30-
50 day) solids residence time (SRT). It can be operated with Sharon®. This process has
been operated only at bench scale to date in the United States (U.S.). The first full-scale
Anammox® plant was started up in the Netherlands in 2002 and several are installed for
operation in Europe.
The InNitri® process provides nitrification of side stream flows and employs what is called
bioaugmentation to return a stream of waste nitrifying organism to the main activated
sludge treatment system to increase the number of viable organisms there. Although
developed over ten years ago, currently there are no full-scale InNitri® installations. Two
applications have progressed to pilot scale in the U.S., which has led to one full-scale
installation currently being bid for construction.
Perhaps the most fundamental side stream treatment alternative is centrate reaeration. A
schematic of this alternative is shown in Figure 2.7. In this alternative the ammonia-rich
centrate is combined with the high-suspended solids concentration RAS stream in a
separate basin, where the high ammonia concentrations yield faster transformation rates of
ammonia to nitrate. Nitrifiers grown in the side stream reactor are returned to the liquid
stream nitrification process. An alternate configuration is to locate the treatment tank
directly on the centrate return stream. This side stream treatment process can be used with
a nitrogen removal alternative to add capacity. Centrate reaeration was selected at the
workshop to serve as the representative process for side stream treatment.
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CENTRATE REAERATION SCHEMATIC
FIGURE 2.7
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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2.2.2 Initial Alternatives Screening Results
At the first workshop in October 2009, four nitrogen removal alternatives were selected for
further evaluation for each nitrogen removal scenario. These selected alternatives
represent a range of different biological alternatives including suspended growth, attached
growth, and hybrid processes. For the 8 mg/L TIN (summer-only) scenario, the selected
processes were:
• MLE
• MLE – MBR
• MLE – IFAS
• BAF/DNF
For the 3 mg/L TIN (year-round) scenario, the selected processes were:
• Bardenpho
• Bardenpho – MBR
• Bardenpho – IFAS
• BAF/DNF
The following section discusses initial evaluation of these alternatives and selection of a
representative alternative for each nitrogen removal permit scenario for a more detailed
evaluation. For each representative alternative, side stream treatment was evaluated to
determine whether additional treatment could reduce the footprint and cost of the
alternative.
2.2.3 Nitrogen Removal Alternatives Analysis
The four selected alternatives for each nitrogen limit scenario were evaluated to determine
a relative cost and footprint for each alternative. This section summarizes these findings.
2.2.3.1 8 mg/L TIN (summer-only) Scenario
For each of the alternatives evaluated under the 8 mg/L TIN (summer-only) scenarios,
except for the BAF/DNF alternative, it was assumed that the aeration basins would operate
with a 9-day aerobic SRT during maximum summer month flows (98 mgd) with one basin
out of service. Additionally, it was assumed that new aeration tanks would be the same side
water depth as the current tanks.
For the MLE alternative, nine new aeration tanks with a total volume of 42 million gallons
(MG ) would be required in addition to the existing four aeration tanks. The existing four
tanks would provide a capacity of 30 mgd (assuming one tank out of service) and the
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additional nine aeration tanks would provide an additional 68-mgd capacity. All of the
aeration tanks (existing and new) would require baffles, mixers, mixed liquor return pumps
and methanol storage and dosing equipment. No additional clarifiers would be required.
The capacity of the existing plant would be less than the de-rated capacity described in
Chapter 1 because this alternative assumes that all the summer maximum month flow is
directed to the existing clarifiers, while the capacity rating in Chapter 1 assumed only 30-40
mgd through the existing clarifiers. This higher flow results in a decreased MLSS
concentration and reduces the capacity of the existing plant to meet projected growth
consistent with the Regional Wastewater Services Plan or to respond to future, more
restrictive, effluent standards. This alternative would fit on the site but would leave no room
for expansion. Figure 2.8 provides a schematic of the footprint of this alternative.
For the MLE-MBR alternative, two new aeration tanks and 11 new membrane tanks would
be built with a capacity for 62 mgd of maximum month flow. This new MBR facility would be
operated as a separate, parallel secondary process. The two new MBR aeration tanks (with
a volume of 4.7 MG each) would have a greater capacity than the CAS aeration tanks
because the membranes can perform at a very concentrated MLSS concentration
compared to the clarifiers. The existing aeration tanks and clarifiers would be modified for
the MLE process, and have a capacity of 36 mgd assuming one aeration tank out of
service. No additional clarifiers would be required. As is shown in Figure 2.9, this alternative
would fit on the site and would retain room for expansion to meet projected growth.
In the MLE-IFAS alternative, the existing aeration basins would be converted to IFAS
basins. Depending on manufacturer’s claims and assumed packing densities, (between 1 to
5) new aeration basins would be required with a volume of 4.7 MG each. This alternative
would fit on the site as is shown in Figures 2.10 and 2.11.
For the BAF/DNF alternative, the existing plant would be operated in the same manner as it
is currently operated, resulting in no change in capacity. To achieve the 8 mg/L TIN
(summer-only) limit, 25 BAF units and 14 DNF units would be added. This sizing was based
on an ammonia loading rate of 60 pounds per day per thousand cubic foot (ppd/kcf) of filter
volume for nitrification and 120 ppd/kcf of nitrate loading for denitrification. Methanol
addition would be required at the DNF. This alternative fits on the site and allows for
expansion as is shown in Figure 2.12.
Table 2.2 summarizes the footprint requirements of each alternative. Footprint estimates
are primarily for comparative purposes and do not currently account for other features that
can consume footprint such as roads, odor control, and ancillary equipment. The MLE
alternative requires the greatest footprint and provides very little space for the plant to
expand to treat future flows or to respond to future changes in effluent quality requirements
while the BAF/DNF and MLE-MBR alternatives provide the most available space for future
expansion. The MLE-IFAS alternative could be very attractive from a footprint standpoint if
the most aggressive of the manufacturer’s performance and design criteria could be
confirmed.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.8.docx
MLE FOOTPRINT 8 MG/L TIN (SUMMER ONLY)
FIGURE 2.8
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New Aeration
Basins
Existing aeration
basins modified with
new baffle walls,
mixers and diffusers
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.9.docx
MLE – MBR 8 MG/L TIN (SUMMER ONLY) FOOTPRINT
FIGURE 2.9
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New
Aeration
Basins
New
Membrane
Tanks
New aeration basins
modified with baffle
walls, diffusers and
mixers
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.10.docx
MLE – IFAS FOOTPRINT 8 MG/L TIN (SUMMER ONLY)
(CONSERVATIVE SIZING)
FIGURE 2.10
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New Aeration
Basins with
IFAS media
Existing basins
modified with baffle
walls, diffusers and
mixers along with IFAS
media
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.11.docx
MLE – IFAS FOOTPRINT 8 MG/L TIN (SUMMER ONLY)
(AGGRESSIVE SIZING)
FIGURE 2.11
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New Aeration
Basins, with IFAS
media
Existing aeration
basins modified with
new baffle walls,
mixers and diffusers
along with IFAS media
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.12.docx
BAF/DNF 8 MG/L TIN (SUMMER ONLY) FOOTPRINT
FIGURE 2.12
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
DAF
DNF
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Table 2.2 8 mg/L TIN (Summer-only) Alternative Footprint Analysis
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
MLE MLE-MBR MLE-IFAS BAF / DNF
Total added basins, acres 8.3 2.5 .9 to 4.4 2.3
Approximate full-buildout
capacity assuming no
expansion on the biosolids
site(1)
144 mgd 270 mgd 210 – 360 mgd 270 mgd
Notes:
(1) Capacity ratings are based on maximum month flows during the summer months. The
maximum month flow capacity of the current plant for summer flows is 98 mgd. The assumed
density of aeration basins is based on the proposed STP site buildout layout provided by the
County. No extra allowances were made for roads or ancillary facilities.
2.2.3.2 3 mg/L TIN (Year-round) Scenario
For the first three of the 3 mg/L TIN (year-round) scenarios (excluding the BAF/DNF
alternative), it was assumed that the aeration basins would operate at a 13-day aerobic
SRT during the maximum month loads and flows (144 mgd) with one basin out of service.
Modification of the existing aeration tanks would be required for each of these three
alternatives. Methanol addition would be required for all four alternatives.
For the Bardenpho alternative, 24 new aeration tanks (each with a volume of 4.6 MG) and
four new secondary clarifiers would be required in addition to the existing four aeration
tanks and 24 clarifiers. Once modified, the existing four tanks would provide a capacity of
17 mgd (assuming one aeration tank is out of service) and the additional 24 aeration tanks
would provide an additional capacity of 127 mgd. All of the aeration tanks would require
baffles, mixers, MLR pumps, and methanol storage and dosing equipment. The capacity of
the existing plant is less than the de-rated capacity described in Chapter 1 because this
alternative assumes that all the maximum month flow is directed to the existing clarifiers,
while the capacity rating in Chapter 1 assumed only 30 mgd through the existing clarifiers.
This higher flow results in a decreased MLSS concentration and reduces the capacity of the
existing plant. This does not fit within the available site area. Figure 2.13 provides a
schematic of the footprint impact of this alternative.
For the Bardenpho MBR alternative, the existing plant would be de-rated to approximately
30 mgd and a parallel MBR plant would be added consisting of seven new aeration tanks
(with a total volume of 25 MG) and 20 new membrane tanks. Membrane tank sizing was
based on continuous 20 degree flux rates of 15 gallons per day per square foot (gpd/sf) of
membrane area. As is shown in Figure 2.14, this alternative fits on the site and allows room
for minimal expansion. In this design the existing activated sludge system would handle
peak flow rates. It was assumed that the peak flows up to 242 mgd would pass through the
existing activated sludge clarifiers while the MBR process was operated at a constant flow
of approximately 114 mgd.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.13.docx
BARDENPHO 3 MG/L TIN (YEAR ROUND) FOOTPRINT
FIGURE 2.13
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New
Aeration
Basins
Existing aeration
basins modified with
new baffle walls,
mixers and diffusers
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.14.docx
BARDENPHO - MBR 3 MG/L TIN
(YEAR ROUND) FOOTPRINT
FIGURE 2.14
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New
Aeration
Basins
Membrane
Tanks
Existing aeration basins
modified with baffle
walls, mixers and
diffusers
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The adequacy of any nutrient removal scheme depends on the interplay between loading
and regulatory requirements. The Bardenpho MBR alternative was sized on the assumption
that nitrogen removal requirements would be met over a maximum month of loading. The
analysis was based on steady state modeling in Carollo’s Biotran program and in the
commercial model BioWin, but a sensitivity analysis was performed in BioWin to investigate
the effects of dynamic loading.
In the Bardenpho-IFAS alternative, the existing aeration basins would be converted to IFAS
basins. Depending on manufacturer’s claims and assumed packing densities, between 2 to
16 new aeration basins (with a volume of 4.4 MG each) would be required. An initial
conservative sizing for IFAS using random media was based on the default packing density
from the BioWin media reactor of 25 percent. Subsequent communication from the random
media manufacturer indicated that densities up to 65 percent could be used. For the
conservative sizing assumption (using the 25 percent packing density), four new secondary
clarifiers were assumed to allow the plant to run at a higher MLSS concentration. As is
shown in Figure 2.15, the conservative sizing assumption would not fit on the site.
However, a Bardenpho IFAS alternative would fit on the site assuming the aggressive
sizing assumption shown in Figure 2.16. The aggressive sizing was based on the
assumption that an effective MLSS concentration in the existing aeration tanks could be
maintained by use of sponge media of approximately 8,500 mg/L, including both free and
embedded biomass. This assumption has been based on experience at one operating
facility in the U.S. Sizing for this alternative by the manufacturer assumed 10,000 gpd of
methanol use, approximately three times the amount required for the Bardenpho MBR
alternative.
For the BAF/DNF alternative, the existing plant would be operated in the same manner as it
is currently operated, resulting in no change in capacity. To achieve the 3 mg/L TIN (year-
round) limit, 52 BAF units and 19 DNF units would be added. This sizing was based on a
loading rate of 28 ppd/kcf for nitrification and 98 ppd/kcf of nitrate loading for denitrification.
Methanol addition would be required for the DNF. Peak hydraulic flows of 242 mgd would
be handled through the existing plant as they currently are, with up to 144 mgd going to the
BAF and DNF and the remaining flow going to effluent. This alternative fits on the site and
allows for minimal expansion as is shown in Figure 2.17.
Table 2.3 summarizes the footprint requirements of each alternative. Footprint estimates
are primarily for comparative purposes and do not account for additional features that can
consume footprint such as roads, odor control, and ancillary equipment, etc. The
Bardenpho alternative requires the greatest footprint and does not fit on the site while the
BAF/DNF and Bardenpho-MBR alternatives provide the most available space for future
expansion. The Bardenpho-IFAS alternative could be very attractive from a footprint
standpoint if the aggressive version of manufacturer’s claims and assumed packing
densities could be confirmed.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.15.docx
BARDENPHO - IFAS 3 MG/L TIN (YEAR ROUND)
FOOTPRINT CONSERVATIVE SIZING
FIGURE 2.15
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New Aeration
Basins, with IFAS
media
IFAS media added to
existing basins, along
with baffle walls, new
diffusers and mixers
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.16.docx
BARDENPHO - IFAS 3 MG/L TIN (YEAR-ROUND)
FOOTPRINT AGGRESSIVE SIZING
FIGURE 2.16
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT
PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
New aeration basins
with IFAS media and
baffle walls
Existing aeration basins
modified with baffle walls,
mixers, new diffusers and
IFAS media
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.17.docx BAF/DNF 3 MG/L TIN (YEAR-ROUND) FOOTPRINT FIGURE 2.17 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT DNF BAF
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Table 2.3 3 mg/L TIN (Year-round) Alternative Foot Print Analysis
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Bardenpho Bardenpho-
MBR
Bardenpho-
IFAS BAF / DNF
Total added basins, acres 23.2 6.7 1.8 – 11.6 4.3
Full buildout capacity
assuming no expansion
on the biosolids site(1)
TL(2) 170 mgd TL - 300 mgd 240 mgd
Notes:
(1) Capacity ratings are based on maximum month flows. The maximum month flow capacity of
the current plant is 144 mgd. The assumed density of aeration basins is based on the
proposed STP site buildout layout provided by the County. No extra allowances were made for
roads or ancillary facilities.
(2) TL = estimated foot print is too large and does not fit on the site.
2.3 ALTERNATIVES EVALUATION
Based on team input from the first workshop, the four alternatives for each nitrogen limit
scenario were evaluated based on the following cost and non-cost criteria:
• Onsite capital costs: Approximate planning level capital costs were estimated for
construction of facilities on the STP site. Treatment of future flows off-site was not
considered. Capital costs included construction costs and appropriate additional
allowances for contingency, allied cost, sales tax, and other anticipated ancillary
costs. Costs were indexed to estimated unit prices for March 15, 2010. The expected
accuracy range for this type of estimate is defined by the Association for the
Advancement of Cost Engineering (AACE) as a Level - 5 Order of Magnitude
Estimate and has an expected accuracy range of +50 to -30 percent. Cost
assumptions are summarized in Appendix B.
• Operation and Maintenance (O&M) costs: Approximate O&M costs were considered
based on average annual flows and loads for a midpoint flow. The midpoint flow was
established as the average between the 2007 average annual flow of 84.9 mgd and
the estimated 108 mgd average annual flow associated with the maximum month
design capacity of 144 mgd. The costs were therefore based on an average annual
flow of 96.5 mgd. O&M costs included: labor, energy, and chemical costs and
allowances for structural maintenance and equipment replacement. O&M costs were
estimated based on an Environmental Protection Agency (EPA) database for unit
process labor, estimated power requirements and chemical consumption, and
allowances for structural and equipment maintenance.
• Risk: Risk was defined in reference to the County’s familiarity with the process and
the number of worldwide installations.
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• Future Flexibility: Future flexibility was only considered for the 8 mg/L TIN (summer-
only) effluent scenario and was defined as the ability of the selected process to meet
a future 3 mg/L TIN (year-round) limit.
• Footprint: An approximate process footprint for each alternative was determined
based on the area required for new process tanks. No allowances were made for
ancillary facilities.
• Energy: Energy use was estimated for each alternative based on factors such as
estimated blower demand, pumping, and membrane air scour needs.
• Odor: The odor production potential of each alternative was qualitatively compared to
the other alternatives for each nitrogen limit scenario.
• Compatibility with existing processes: The compatibility with existing processes was
defined as whether or not the selected process would result in stranding of significant
assets, such as secondary clarifiers.
• Biosolids Quality: The biosolids quality (nitrogen and phosphorus content) was
qualitatively compared for each alternative to adversely impact on the beneficial use
of biosolids.
• Reclaimed water quality/quantity: Both reclaimed water quality and quantity were
compared for each alternative. Aspects of this comparison included whether the
alternative produced an easily filterable effluent and whether the alternative left room
on the site for future reclaimed water filters.
Each of these criteria was scored from 1 (low) to 3 (high) based on scoring definitions
provided in Appendix A. The weighting for each criterion was established by the team at the
second workshop. Criterion weights for capital and O&M costs were maintained at a weight
of 1 since workshop participants did not want cost factors to overshadow evaluation of other
factors. Table 2.4 and 2.5 present the weighted results for each effluent limit scenarios.
Based on this analysis, the two leading alternatives for both effluent limit scenarios were the
MBR and BAF/DNF. The County decided to select the MBR system as the representative
alternative for both effluent limit scenarios. The team concluded that the BAF/DNF system
should be considered in more detail at a facility planning or pre-design level. Since
aggressive IFAS sizing potentially offers a very competitive alternative, the County may
want to consider pilot testing to determine the optimum kinetic parameters and packing
densities.
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Table 2.4 8 mg/L TIN (Summer-only) Scoring Matrix
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Score
Criteria Weight MLE MBR IFAS A(1) IFAS C(2) BAF
Onsite Capital Cost 1 3 2 3 1 3
O&M Cost 1 3 1 2 2 2
Risk 2 3 3 0(3) 1 2
Future Flexibility 2 1 3 3 1 3
Footprint 3 1 3 3 2 3
Energy 2 3 2 3 1 2
Odor 1 2 2 2 2 2
Compatibility with existing processes 1 3 3 3 3 3
Biosolids Quality 1 2 2 2 2 2
Reclaimed Water Quality/Quantity 1 1 3 2 2 2
Un-weighted Total 22 24 F(4) 17 24
Weighted Total 31 38 F(4) 24 37
Notes:
(1) IFAS A stands for the aggressive sizing of IFAS.
(2) IFAS C stands for the conservative sizing of IFAS.
(3) The aggressive IFAS sizing was determined to be too risky based on the manufacturer’s lack of
sufficiently demonstrated approach to tank sizing. The County may want to consider pilot
testing to further support this consideration.
(4) A score of a “0” on any of the criteria results in a failure of that alternative.
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Table 2.5 3 mg/L TIN (Year-round) Scoring Matrix
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Score
Criteria Weight MBR IFAS A(1) IFAS C(2) BAF
Onsite Capital Cost 1 2 3 3 2
O&M Cost 1 1 1 3 2
Risk 2 3 0(3) 1 2
Footprint 3 2 3 0(4) 2
Energy 2 1 3 2 2
Odor 1 2 2 2 2
Compatibility with existing processes 1 3 3 3 3
Biosolids Quality 1 2 2 2 2
Reclaimed Water Quality/Quantity 1 3 2 1 2
Un-weighted Total 19 F(5) F(5) 19
Weighted Total 27 F(5) F(5) 27
Notes:
(1) IFAS A stands for the aggressive sizing of IFAS.
(2) IFAS C stands for the conservative sizing of IFAS.
(3) The aggressive IFAS sizing was deemed to be too risky based on the manufacturer’s lack of an
adequate explanation for tank sizing. This alternative should be pilot tested before further
consideration.
(4) The conservative sizing of IFAS was given a “0” for footprint since this alternative did not fit on
the site.
(5) A score of a “0” on any of the criteria results in a failure of that alternative.
2.4 ALTERNATIVES SUBJECT TO MORE DETAILED ANALYSIS
2.4.1 Necessary Equipment
Two alternatives, one each for the seasonal limit and annual limit, were selected for a more
detailed cost estimate, sensitivity analysis, and sustainability analysis:
• 8 mg/L TIN summer permit level: Parallel MLE/MLE MBR process
• 3 mg/L TIN (year-round) permit level: Parallel Bardenpho/Bardenpho MBR process
Significant elements of each alternative are summarized below.
2.4.1.1 8 mg/L TIN (summer-only) permit level: Parallel MLE/MLE MBR process
In this alternative the existing activated sludge aeration tanks and clarifiers would be
retained. The aeration tanks would be modified to provide for internal recycle of mixed
liquor to unaerated zones, which would be operated in anoxic mode for denitrification,
rather than in the current anaerobic mode for encouragement of phosphorus accumulating
organisms for settleability control. Methanol feed equipment would be provided to support
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denitrification. The existing tanks and clarifier would be de-rated to a maximum month
capacity of 36 mgd for operation during the summer months for nitrogen removal. A parallel
MBR process would be constructed to provide nitrogen removal for the summer months for
the remaining flow. With a maximum month flow of 98 mgd during the summer, the parallel
MBR process would be designed for a maximum month summer flow of 62 mgd. Winter
season operation of the MLE-MBR facilities and the existing facilities will need to be
addressed during any design phase. These considerations should include further
evaluation of existing facilities needed to control settleability during winter operation so
peak storm flows could be properly processed. It was assumed that MBR facilities would
only be operated during the summer months for nitrogen removal. For calculation of effects
it was assumed that the MBR facilities would be operated for a total of seven months per
year, allowing for three weeks of startup operation and one week of shut-down operation for
each six-month summer season. It was assumed that the MBR tanks would be drained and
cleaned and remain out of service during the winter. Major elements of each upgrade
include:
MLE BNR upgrade of existing aeration tanks:
• Installation of internal recycle pumps and piping
• Odor control covers for the aeration tanks
• Odor treatment equipment
• Installation of additional mixers in the first stage of the aeration tanks
• Modifications to the aeration tank air diffuser grids
Parallel MLE BNR MBR process:
• New unaerated and aerated aeration tanks
• Mixers and diffusers
• Odor control covers for the reactor tanks
• Odor treatment equipment
• New blowers
• New membrane tanks
• New membrane equipment building
• Chemical feed equipment and building (including methanol)
• MBR tank odor control covering
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• MBR tank roof
• Membranes and support equipment
2.4.1.2 3 mg/L TIN (year-round) permit level: Parallel Bardenpho/Bardenpho MBR
process
In this alternative the existing activated sludge aeration tanks and clarifiers would be
retained. The aeration tanks would be modified to provide for internal recycle of mixed
liquor to unaerated zones, which would be operated in anoxic mode for denitrification. In
addition, aerobic zones of the existing aeration tanks would be converted to unaerated
zones. Methanol feed would be provided. The modified existing tanks and clarifiers would
be de-rated to a maximum month capacity of 30 mgd for operation year round for nitrogen
removal. A parallel MBR process would be constructed to provide nitrogen removal year
round for the remaining flow. With a maximum month flow of 144 mgd to the STP, the
parallel MBR process would be designed for a maximum month flow of 114 mgd while 30
mgd is treated by the modified existing tanks. It is anticipated that this parallel design would
accommodate the current peak hour secondary flow rating of 242 mgd. During peak storm
events, 114-mgd would be directed to the MBR process and 128 mgd would be treated
through the existing system modified for Bardenpho operation. Major elements of each
upgrade include:
Bardenpho BNR upgrade of existing aeration tanks:
• Installation of internal recycle pumps and piping
• Odor control covers for the aeration tanks
• Odor treatment equipment
• Installation of additional mixers in the first and third stages of the aeration tanks
• Additional baffle walls
• Modifications to the aeration tank air diffuser grids
Parallel Bardenpho BNR MBR process:
• New unaerated and aerated aeration tanks
• Mixers and diffusers
• Odor control covers for the reactor tanks
• Odor treatment equipment
• New blowers
• New membrane tanks
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• New membrane equipment building
• Chemical feed building
• MBR tank odor control covering
• MBR tank roof
• Membranes and support equipment
2.4.2 Site layout
The proposed site layouts for the representative alternatives are presented in Figures 2.9
and 2.14.
2.4.3 Cost
Following selection of representative alternatives, the preliminary cost estimates prepared
for the alternatives screening were adjusted to reflect factors not considered in the
preliminary screening, such as odor control covering and treatment costs. The cost
estimates were based on a preliminary quantity estimate for excavation and concrete for
new tanks and estimated cost for new equipment. To these direct costs were added
allowances for piping and miscellaneous mechanical equipment, electrical equipment,
instrumentation, site work, contingency, general conditions, contractor overhead ,and profit,
sales tax, allied costs (planning, design, construction management, permits, etc.). O&M
costs were estimated based on an Environmental Protection Agency (EPA) database for
unit process labor, estimated power requirements and chemical consumption, and
allowances for structural and equipment maintenance. Costs were indexed to estimated
unit prices for March 15, 2010. The expected accuracy range for this type of estimate is
defined by the Association for the Advancement of Cost Engineering (AACE) as a Level -5
Order of Magnitude Estimate and has an expected accuracy range of +50 to -30 percent.
Cost assumptions are summarized in Appendix B.
Tables 2.6 and 2.7 present summaries of estimated costs for upgrade of the STP to provide
for nitrogen removal for the two potential permit levels. The estimates include the cost of
odor control covers and equipment for the reactor tanks. The existing CAS process does
not currently have complete odor control covers and treatment for the aeration tanks, but
the tanks are under a current upgrade to provide this. Costs for provision of these were
therefore not included. The tables present summaries of costs for major project elements in
five columns:
• Operation of the existing CAS
• Upgrade of the existing CAS to provide for BNR
• New Parallel MBR BNR facilities
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• The total estimated cost for the BNR upgrade
• The difference in cost between the BNR upgrade and the cost of the existing CAS
The differential present worth cost for nitrogen removal (column 6 in Tables 2.6 and 2.7) is
the present worth cost of the nitrogen removal upgrade (column 3 in Tables 2.6 and 2.7)
plus the present worth cost of the parallel MBR facilities (column 4 in Tables 2.6 and 2.7)
minus the present worth cost of CAS (column 2 in Tables 2.6 and 2.7). The estimated total
incremental present worth cost (including both incremental capital costs and incremental
operating costs) for upgrade of the STP to an 8 mg/L TIN summer discharge permit level is
approximately $680 million. The estimated incremental present worth cost for upgrade to
meet the requirements of a 3 mg/L TIN (year-round) discharge permit limit is approximately
$1,430 million.
The costs shown in the table are estimated costs for the unit processes shown based on
process calculations by Carollo Engineers. As a comparison of capital costs, the lump sum
construction cost for the aeration tanks for the new Brightwater Treatment Plant was
approximately $50 million for a design capacity of 36 mgd or approximately $1.40 per gallon
of max month flow capacity. The estimated construction cost from the current cost estimate
for the MBR aeration tanks for the 3 mg/L year-round permit limit was approximately $200
million without contingency but including all other allowances or approximately the same
unit cost as Brightwater for 144 mgd of capacity. The estimated operating cost from the
STP budget for secondary treatment power is in the range of $1.5 to $2.0 million dollars per
year. For comparison, the estimated total annual operating and maintenance cost in the
current estimate for secondary treatment for the future year intermediate between current
flows and design flows (89 mgd average flow) is $1.8 million per year including
approximately $1.3 million for power,and $600,000 per year for labor. In the current
estimate, O&M cost for structural and equipment maintenance and replacement were
based on a percentage allowance of capital cost. Since the capital cost estimates were not
available for the existing operation these costs were not included in the estimated O&M
costs for CAS. It is estimated that operating costs would increase to a total of almost $15
million annually for the 8 mg/L TIN (summer-only) permit limit and $35 million annually for
the 3 mg/L TIN (year-round) permit limit based on a similar distribution of costs for labor,
power, odor control, and structural and equipment maintenance.
June 29, 2010 - FINAL 2-36 pw://Carollo/Documents/Client/WA/King County/7683E00/Deliverables/Final Report/Ch02.docx Table 2.6 Estimate Summary for 8 mg/L TIN (Summer-only) Permit Level Upgrade to the STP
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater Treatment Division
Treatment Element CAS
MLE
Upgrade
MLE
MBR
Total BNR
Upgrade Difference
Present Worth Cost, $ Million
Capital Cost(1) $0 $105 $425 $530 $530
Operation and Maintenance(2) $25 $46 $129 $176 $149
Total Present Worth $25 $151 $554 $706 $679
Notes:
(1) Capital cost includes construction cost, contingency, tax, and allied costs (costs of planning, engineering, construction management,
permitting, legal and other associated costs). All costs are in March 2010 dollars.
(2) Present worth O&M values were calculated assuming a 3% discount rate over a 20-year period on calculated current yearly O&M costs.
Table 2.7 Estimate Summary for 3 mg/L TIN (Year-round) Permit Level Upgrade to the STP
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater Treatment Division
Treatment Element CAS
Bardenpho
Upgrade
Bardenpho
MBR
Total BNR
Upgrade Difference
Present Worth Cost, $ Million
Capital Cost (1) $0 $188 $779 $967 $958
Operation and Maintenance(2) $25 $128 $394 $522 $475
Total Present Worth $25 $316 $1,173 $1,489 $1,434
Notes:
(1) Capital cost includes construction cost, contingency, tax, and allied costs (costs of planning, engineering, construction management,
permitting, legal and other associated costs. All costs are in March 2010 dollars.
(2) Present worth O&M values were calculated assuming a 3% discount rate over a 20-year period on calculated current yearly O&M costs.
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2.4.4 Sensitivity Analysis
Following selection of representative alternatives for each permit level, a sensitivity analysis
was performed to determine the response of the representative alternative to potential
changes in conditions of operation from assumed conditions. Sensitivity was investigated in
three areas:
1. Sensitivity to dynamic loadings including dewatering schedule
2. Sensitivity to excursions in sludge volume index (SVI)
3. Sensitivity to loss of aeration blowers
These sensitivity factors were selected during the first project workshop in October 2009. In
addition to sensitivity to dewatering schedule, consideration of the effects of side stream
treatment on nitrogen removal was also included as part of the sensitivity analysis for
dynamic loading.
2.4.4.1 Sensitivity to Dynamic Loading
In order to determine sensitivity of the representative alternatives to dynamic loading two
different sources of dynamic instability were considered:
1. Dynamic influent loading
2. Dynamic dewatering return flows
Preliminary analysis of process alternatives was based on steady state modeling of unit
processes using both Carollo’s Biotran spreadsheet and the commercial software BioWin.
In steady state modeling, maximum month loadings are identified based on plant records
and peaking factors are used to estimate dynamic loading effects. For the current analysis,
dynamic models were developed to represent potential effects of diurnal variation in
loadings from both the influent sewer and from dewatering return flows. Diurnal variation in
flow and loading was assumed based on Carollo sampling and flow measurement for
Central Contra Costa Sanitary District in California, a King County peer agency. To simulate
the impact of dewatering schedule on potential nitrogen removal, two potential schedules
were modeled:
1. Seven days per week and eight hours per day
2. Seven days per week and centrate flow equalization
A schematic of the recommended configuration developed in BioWin for the 8 mg/L TIN
(summer-only) permit level is shown in Figure 2.18. A schematic for the recommended
configuration for the 3 mg/L TIN (year-round) permit level is presented in Figure 2.19.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.18.docx Anoxic Pass 1aAerobic Pass 2Aerobic Pass 3Aerobic Pass 4Anoxic Pass 1bEffluentDigesters 1- 4Storage DigesterSludge DisposalMethanolCOD InfluentMBRReaeration BIOWIN SCHEMATIC – 8 MG/L (SUMMER ONLY) PERMIT LEVEL FIGURE 2.18 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTUREWATER REUSE PROGRAMDEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.19.docx Anoxic 1Aerobic 3Aerobic 4Anoxic 2EffluentDigesters 1- 4Storage DigesterSludge DisposalMethanolScreened SewageAnoxic 5Membrane TankReaerationEQ BIOWIN SCHEMATIC – 3 MG/L (YEAR ROUND) PERMIT LEVEL FIGURE 2.19 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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Assumed influent flow and concentration variation for the two permit levels are shown in
Figures 2.20 and 2.21. Predicted dynamic TIN effluent concentrations are shown on
Figures 2.22 and 2.23, respectively for the 8 mg/L (summer-only) and 3 mg/L (year-round)
permit level. Simulations were conducted for the new MBR units which would be
constructed in parallel to existing units upgraded as discussed for nitrogen removal. It is
anticipated that dynamic behavior of the conventional nitrogen removal units would be
similar to that of the new parallel MBR units. For each permit level, simulations were
performed under three different scenarios:
• No centrate reaeration or centrate equalization
• Centrate reaeration but no equalization
• With both equalization and reaeration of centrate
For the 8 mg/L TIN (summer-only) permit level it was found that neither centrate reaeration
nor equalization were required to keep the average effluent TIN under 8 mg/L, but that
without centrate reaeration and equalization there were peak hourly excursions above the 8
mg/L TIN level. A compromise configuration with centrate reaeration but without
equalization is shown in the figures and was assumed in calculating costs. Different
locations for the centrate equalization tank were investigated: on the dewatering return line,
on the RAS line, and on the return line from the dissolved air flotation thickener (DAFT)
tanks. Location of the centrate equalization tank on the centrate line indicated the lowest
overall plant effluent TIN. An internal recycle configuration was initially explored for the 8
mg/L TIN (summer-only) permit level, but the modeling indicated that separate recycle
beyond the recycle from the membrane tank was not required to control TIN to the 8 mg/L
permit level. Likewise, use of a de-aeration tank on the return flow pipe from the membrane
tank did not significantly improve effluent TIN performance.
For the 3 mg/L TIN (year-round) permit level the modeling indicated that both centrate
reaeration and equalization would be required to keep the average effluent TIN comfortably
under the 3 mg/L TIN (year-round) level. Even with both features, however, peak hourly
excursions above the permit level were seen in the simulation. It was found that an internal
recycle system with up to 600 percent recycle ratio, in addition to the 400 percent recycle
flow from the membrane tanks, was required to keep effluent TIN levels under the 3 mg/L
TIN (year-round) level.
2.4.4.2 Sensitivity to excursions in SVI
The selected alternatives for nitrogen removal both include membrane separation of
biological treatment solids, rather than gravity tanks as used in the current plant. Thus,
sludge settleability is not a significant issue for the parallel MBR stream. Variations in SVI
would continue to affect the upgraded activated sludge system, but since existing facilities
have been de-rated significantly for nitrogen removal, overflow rates on secondary
sedimentation tanks would be much lower than under current operation.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.20.docx Dynamic InfluentCOD Influent FlowCOD Influent Total Carbonaceous BODCOD Influent Total suspended solidsCOD Influent Total Kjeldahl NitrogenDATE9/10/20099/9/20099/9/20099/9/20099/9/20099/8/20099/8/20099/8/20099/8/2009CONC. (mgN/L)240220200180160140120100806040200Flow (mgd)80706050403020100 DYNAMIC INFLUENT FLOW AND CONCENTRATION 8 MG/L TIN (SUMMER ONLY) PERMIT LEVEL FIGURE 2.20 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.21.docx Dynamic Influent Flow and ConcentrationCOD Influent FlowCOD Influent Total Carbonaceous BODCOD Influent Total suspended solidsCOD Influent Total Kjeldahl NitrogenDATE9/10/20099/9/20099/9/20099/9/20099/9/20099/8/20099/8/20099/8/20099/8/2009CONC. (mgN/L)240220200180160140120100806040200Flow (mgd)1501401301201101009080706050403020100 DYNAMIC INFLUENT FLOW AND CONCENTRATION 3 MG/L TIN (YEAR ROUND) PERMIT LEVEL FIGURE 2.21 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.22.docx Dynamic EffluentEffluent Filtered Carbonaceous BODEffluent Total suspended solidsEffluent Ammonia NEffluent Nitrite + NitrateEffluent Total inorganic NEffluent Total NDATE9/10/20099/9/20099/9/20099/9/20099/9/20099/8/20099/8/20099/8/20099/8/2009CONC. (mg/L)11109876543210 DYNAMIC EFFLUENT FLOW AND CONCENTRATION 8 MG/L TIN (SUMMER ONLY) PERMIT LEVEL FIGURE 2.22 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.23.docx Dynamic Effluent ConcentrationsEffluent Filtered Carbonaceous BODEffluent Total Carbonaceous BODEffluent Ammonia NEffluent Nitrite + NitrateEffluent Total inorganic NEffluent Total NDATE9/10/20099/9/20099/9/20099/9/20099/9/20099/8/20099/8/20099/8/20099/8/2009CONC. (mgP/L)76543210 DYNAMIC EFFLUENT FLOW AND CONCENTRATION 3 MG/L TIN (YEAR ROUND) PERMIT LEVEL FIGURE 2.23 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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Figure 2.24 presents a state point diagram for secondary clarifiers based on operation in a
Bardenpho configuration using existing secondary sedimentation tanks. The state point
diagram compares the operating conditions for solids loading to the theoretical settling flux
in pounds per day per square foot (ppd/sf) of tank area as a function of MLSS
concentration.
Under the conditions required, the overflow rate on the tanks would be less than 150
gallons per day per square foot (gpd/sf) with a MLSS concentration of 3,000 mg/L. The
state point diagram reflects an estimate of settling characteristics assuming an operating
SVI of approximately 150 milliliters per gram (mL/g). The diagram was prepared with a peak
factor to the Bardenpho BNR system of 3.0 at peak wet weather flow. The diagram
indicates sufficient capacity under these conditions. Calculations based on generic models
for the relationship relating settling velocity to SVI indicate that the tanks could operate with
a MLSS concentration of 3,000 mg/L at a peak flow up to approximately 65 mgd with SVI
values over 200 mL/g.
2.4.4.3 Sensitivity to loss of aeration blowers
The current blower capacity of the STP is 195,000 cubic feet per minute (cfm), provided by
10 units of various sizes. The capacity of the largest unit is 23,300 cfm, so the capacity of
the system with the largest unit out of service would be 171,000 cfm. The estimated
maximum month aeration demand for BNR operation of the existing four aeration tanks is
less than 20,000 cfm, so there would be sufficient blower capacity for operation of the
existing tanks, assuming new blower capacity were provided for the parallel MBR tanks.
Required blower capacity is less than current demands because flow would be off-loaded
from existing tanks by new parallel MBR tanks in the event that nitrogen removal were
required, even though the oxygen demands for BNR exceed that required for carbonaceous
treatment. If blower capacity from the existing blower system were used to meet part of the
demand for parallel MBR aeration, then adequate standby capacity would need to be
provided by additional blowers.
2.5 GREENHOUSE GAS COMPARISON
2.5.1 Overview
Effects of nitrogen removal upgrades on generation of greenhouse gas (GHG) emissions
from the STP were evaluated. This section provides an estimate of GHG emissions of the
existing system compared to those that would be expected if the STP were required to
remove nitrogen to the two different permit levels identified above.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 2.24.docx 05101520253001,0002,0003,0004,0005,0006,0007,0008,0009,00010,00011,00012,000Solids Flux (ppd/sf)State Point DiagramSettling Flux80% AlertMLSSDaily AverageDiurnal PeakWet-W Peak STATE POINT DIAGRAM FOR BARDENPHO BNR FIGURE 2.24 KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON FUTURE WATER REUSE PROGRAM DEVELOPMENT
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2.5.2 Background
The State of California adopted the Global Warming Solutions Act of 2006 (also known as
Assembly Bill 32 (AB 32)) in September of 2006. This Act is the first regulatory program in
the U.S. that will require many public and private agencies statewide to reduce GHG
emissions to 1990 levels by 2020 and 80 percent below 1990 levels by 2050. Currently,
there is no specific mandate for reduction that applies to publicly owned treatment works
(POTWs); however, the California Air Resources Board (CARB) has stated that POTWs
could be included in the near future and early voluntary reporting is recommended. Due to
the absence of any specific guidance based in Washington State law, the procedures and
methodologies which have been implemented in California were used to develop an
estimate of GHG emissions associated with nitrogen removal upgrade at the STP.
The estimates use the methodologies presented in and recommended by the California
Climate Action Registry General Reporting Protocol (CCAR GRP), a set of measuring
standards and protocols aligned with the international GHG Protocol Initiative and adapted
to California. AB 32 recommends using this protocol “where appropriate and to the
maximum extent feasible.” Agencies that choose to participate in the CCAR process will not
be required to significantly alter their reporting except as determined by CARB for
compliance purposes.
Emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) GHG
emissions were estimated. These gases are relevant to and comprise the majority of GHG
emissions generated from treatment of wastewater. The estimated annual GHG emissions
from the operation of the CAS process at the STP are compared to emissions from
operation of unit processes required to remove nitrogen. In general, annual GHG emissions
are a function of the flow treated, the influent water quality, and the treatment processes
used. A description of the calculation methodology is provided in the following section. The
GHG estimates provided are for secondary and nitrogen removal processes and solids
handling.
2.5.3 Methodology
The development of GHG emissions estimates requires a set of “boundary” conditions to
define the life cycle stages, the unit processes, and the time frame that is included in the
analysis. For this inventory, both construction and operations effects were considered.
These included:
• Construction of new tanks and equipment for BNR processes
• Operation of the CAS process compared to BNR processes
• Production and hauling of chemicals consumed for treatment (this includes methanol
required for nitrogen removal)
• Production and hauling of replacement materials consumed for treatment (this
included membranes required for MBR treatment)
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• Production and hauling of materials for construction of new tanks and equipment
2.5.4 Categories and Sources of GHG Emissions
There are two categories of emissions, direct and indirect, that were identified and
evaluated:
• Direct Emissions: Direct emissions are those resulting from sources owned or
controlled by the County, such as stationary combustion sources, mobile combustion
sources, and treatment unit processes. For this inventory, this includes treatment unit
process emissions, and N2O emissions from effluent discharge.
• Indirect Emissions: Indirect emissions are those originating from the actions of the
agency, but produced by sources owned or controlled by another entity. For this
inventory, this includes: production of purchased electricity for the operation of the
facility, manufacturing of chemicals and replacement materials used to treat the
wastewater, and transport of the chemicals and replacement materials to the facility.
2.5.5 Estimate of GHG Emissions in Terms of “CO2 Equivalents”
The major sources of GHG emissions were identified and categorized, and appropriate
emission factors were determined. The data was then transferred into Carollo’s GHG
emissions inventory model to calculate the quantities of CO2, CH4, and N2O emissions
generated from each source. Major sources included:
• Electricity Consumption (kilowatt-hours (kWh)) multiplied by Emission Factor
• Vehicle Fuel Consumption (gallons or miles traveled) multiplied by Emission Factor
• Chemical or Material Produced (unit weight) multiplied by Specific Energy (unit
energy per unit weight of material or chemical) multiplied by Emission Factor
Emissions were converted into carbon dioxide equivalent (CO2e) emissions. The major
GHG in the atmosphere is CO2. Other GHGs differ in their ability to absorb heat in the
atmosphere. For example, CH4 has 21 times the capacity to absorb heat relative to CO2
over a 100-year time horizon, so it is considered to have a global warming potential (GWP)
of 21. N2O has 310 times the capacity to absorb heat over a 100-year time horizon having a
GWP of 310. Therefore, a pound of emissions of CO2 has much less climatic impact than a
pound of CH4 or N2O, but typically CO2 is emitted in such large quantities compared to the
other two GHGs that it dominates the final result. CO2e emissions are calculated by
multiplying the amount of emissions of a particular GHG by its GWP (see Table 2.8).
Example:
What is the CO2e of one ton of CH4 emissions?
1 ton CH4 x 21 (GWP, tons CO2e/tons of CH4 emitted) = 21 tons CO2e
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Table 2.8 Greenhouse Gases and Global Warming Potentials
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Greenhouse Gas GWP(1) (Unit Mass CO2e/Unit Mass of GHG Emitted)
CO2 1
CH4 21
N2O 310
Notes:
(1) GWPs are from the Intergovernmental Panel on Climate Change Second Assessment
Report (1996) for a 100-year time horizon. These GWPs are still used today by
international convention and the U.S. to maintain the value of the CO2 “currency,” and
are used in this inventory to maintain consistency with international practice.
2.5.6 Description of GHG Emissions Estimates
This section provides a summary of the system being evaluated, a brief description of types
of annual GHG emissions considered in this analysis, and the sources of information used.
The system to be evaluated is defined as the construction of new nitrogen removal facilities
for the STP and subsequent operations compared to operation of the existing STP without
significant nitrogen removal. Liquids stream treatment processes included in the analysis
were: CAS aeration tanks, nitrogen removing activated sludge aeration tanks, and
membrane tanks. The GHG emission effects of other treatment processes at the STP,
including influent screening, grit removal, primary treatment, secondary sedimentation, and
disinfection were considered to be largely unaffected by addition of nitrogen removal and
therefore not included in the analysis. Solids handling unit processes considered include:
anaerobic digestion and truck transport of solids for disposal. The STP has sludge
thickening and dewatering processes, but the GHG effects of these were considered to be
similar for both conventional and nitrogen removal alternatives and were therefore not
included in the analysis.
2.5.7 Direct GHG Emissions
2.5.7.1 Process Emissions
GHG emissions are not only generated due to the energy consumed for operating the STP.
CH4 and N2O are also emitted as a by-product of wastewater treatment processes.
2.5.7.1.1 Methane
Wastewater from domestic and industrial sources is treated to remove soluble organic
matter, suspended solids, pathogenic organisms, and chemical contaminants. Soluble
organic matter is removed using biological processes in which microorganisms consume
the organic matter for cell maintenance and growth. The resulting biosolids are removed
from the effluent prior to discharge to the receiving water. At the STP microorganisms
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biodegrade the soluble organic material under both anaerobic and aerobic conditions.
Anaerobic conditions can generate CH4 emissions, but its unlikely that any significant CH4
production is taking place in the STP anaerobic selector tanks. Methane formation requires
continuously anaerobic conditions with cell growth times exceeding four days. The STP
liquid stream anaerobic zones have a solids residence time of less than one day and are
immediately followed by aerobic zones; it is therefore unlikely that methane-forming
bacteria have any significant growth in this system. This assumption was verified by multi-
species modeling of biological growth in the tanks. The modeling predicted that there would
be essentially no growth of methanogenic bacteria in the STP liquids treatment process.
The STP has anaerobic digesters, which generate significant quantities of CH4. In 2007,
approximately 11 percent of digester gas at the STP was flared. Of the remaining 89
percent of the gas, approximately 16 percent was used for digester heating, 16 percent was
used on-site to produce electricity (co-gen) and the remainder (57 percent) was sold as fuel
to Puget Sound Energy. There may be some fugitive emissions of CH4 from the STP
anaerobic digesters, but there is no reason to think that there would be significant
differences between conventional and nitrogen removing activated sludge processes in
their tendency to produce fugitive emissions of CH4. Nitrogen removing activated sludge
processes would be expected to generate less volatile waste solids due to the longer solids
residence times used in treatment, but there is no reason to think that the amount of gas
flared would be different with nitrogen removal in the liquid process. Therefore, CH4
process emissions were not included in the analysis.
2.5.7.1.2 Nitrous Oxide
N2O emissions are estimated by methodologies adapted from the 2006 International Panel
on Climate Change (IPCC) Guidelines for National GHG Inventories and Section 8.2 of the
U.S. EPA document, GHG Emissions and Sinks (1990-2006). These methodologies identify
that N2O emissions are generated at:
1. Centralized wastewater treatment plants (WWTPs) without nitrification/denitrification
(NDN)
2. Centralized WWTPs with NDN
3. From effluent discharged to receiving aquatic environments
Since NDN treatment is the central topic of this report, estimates of N2O emissions are of
significant importance. To identify the impact of implementing nitrogen removal by NDN at
the STP, emissions of CAS treatment without NDN were compared to estimated emissions
in the future with NDN. Estimates of N2O emissions generated are dependent on the
population (industrial and domestic) served by the treatment plant and the measured
average daily total nitrogen load discharged from the STP.
2.5.7.2 On-site Stationary Combustion
Stationary combustion refers to the combustion of fuels to produce electricity, heat, or
motive (mechanical) power using equipment in a fixed location. Typical stationary
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combustion units at WWTPs include boilers, flares, turbines, furnaces, and internal
combustion engines. It is estimated that approximately 11 percent of STP digester gas is
currently flared and approximately 16 percent of the remainder is currently used for digester
heating. It is possible that BNR liquid stream treatment could result in less digester gas
flaring because of the relatively smaller amount of waste solids production compared to
CAS, but because digester flaring could be independent of total gas production, stationary
combustion GHG effects were not included in the analysis.
2.5.8 Indirect GHG Emissions
2.5.8.1 Operation of Treatment Facilities
GHG emissions estimates from the operation of the treatment facilities are based on the
total annual electricity demand (kWh per year). Annual energy demands were estimated
using Carollo models for wastewater treatment for CAS treatment compared to models of
operation of existing facilities in a modified configuration for nitrogen removal combined with
MBRs configured for nitrogen removal. This is typically the most significant source of GHG
emissions for WWTPs.
2.5.8.2 Chemical Production
The CCAR GRP considers energy required for the production of chemicals consumed in
treatment processes to be outside the boundary of this type of inventory. However, in order
to provide a more complete analysis of the effects imposed by the existing system, the
energy consumed for chemical production is included in this inventory. The energy used per
unit chemical consumed was calculated using conversion factors from Owen (1982). The
only chemical considered in this analysis was methanol, which is required for nitrogen
removal at the STP, but not for CAS treatment. Annual chemical consumption was based
on estimates from Carollo’s biological process modeling.
2.5.8.3 Replacement Material Production
The CCAR GRP also considers energy required for the production/replacement of spent
materials used in treatment processes to be outside the boundary of this type of inventory.
However, in order to provide a more complete analysis of the effects imposed by the
existing system, the energy consumed for material production was included in this
inventory. The energy used per unit mass of material consumed was calculated using
conversion factors from Owen (1982). The replacement material production considered the
membrane replacement estimated from Carollo modeling. No other material replacement
values were estimated.
2.5.8.4 Chemical Handling
Estimates of GHG emissions generated from the transport of chemicals were based on the
type of truck used, the type of fuel consumed, and the distance from the chemical’s
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distribution center. The chemical handling considered the methanol consumption for BNR
and citric acid consumption for membrane cleaning estimated from Carollo modeling.
2.5.8.5 Solids Handling
Estimates of GHG emissions generated from the transport of grit and biosolids are based
on the type of truck used, the type of fuel consumed, and the distance to the disposal site.
Carollo used data estimated from Carollo models for sludge production of CAS compared to
nitrogen removal alternatives. Estimates for fuel consumption were based on the disposal
of biosolids to the Boulder Park site in Eastern Washington.
2.5.8.6 Replacement Material Handling
Estimates of GHG emissions generated from the transport of replacement materials are
based on the type of truck used, the type of fuel consumed, and the distance from the
material’s distribution center and disposal site (an Eastern Washington land fill). Carollo
applied assumptions for the truck type and fuel type consumed. The only replacement
material estimated was membranes for the BNR alternatives.
2.5.8.7 Construction Materials
Estimates for the indirect GHG emissions from production and transport of construction
materials for new MBR BNR facilities were estimated from quantity estimates for
construction using factors for conversion to GHG emissions.
2.5.8.8 Offsets
Offsets in this analysis are those emissions that were once generated from the
consumption of purchased electricity, but are now avoided (or are no longer emitted) since
the energy is now supplied by a renewable energy source. This analysis included estimated
differences in production of digester gas which is scrubbed and sold to the Puget Sound
Energy.
2.5.9 Summary of GHG Emissions Estimates
A summary of the results of the GHG analysis for the project is presented in Table 2.9 and
Figure 2.25. The table shows the cumulative emissions estimated for each alternative in
each category of GHG emission. The figure presents a bar chart representing the total
estimate annual production of CO2e for the three process alternatives:
• CAS
• BNR with an effluent permit goal of 8 mg/L TIN for the six summer months of the year
by conversion of the existing aeration tanks to an MLE process with treatment of the
remaining flow by MLE MB (Operation in CAS the remainder of the year)
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• BNR with an effluent permit goal of 3 mg/L TIN (year-round) by conversion of the
existing aeration tanks to a Bardenpho process with treatment of the remaining flow
by Bardenpho MBR
The results indicate that the impact of a summer-only effluent permit level of 8 mg/L TIN
would result in an approximately two thirds more GHG emissions than for secondary
treatment at the STP. A 3 mg/L TIN year-round limit would than result in approximately
three times more emissions of equivalent GHG emissions. The primary sources of
increased GHG emissions are process N2O and purchased electricity. Table 2.9 also shows
the number of vehicles that would need to be added to the Puget Sound region to have an
equivalent impact on regional GHG emissions as addition of either of the two nitrogen
removal permit scenarios. It is seen that implementation of the 8 mg/L (summer-only)
permit level would have the equivalent impact of adding 1,200 vehicles to the Puget Sound
region, while implementing the 3 mg/L year round permit limit would be equivalent to adding
nearly 4,000 vehicles to the region.
Table 2.9 Estimated Annual Total Metric Tons of Carbon Dioxide Equivalent
Emission
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Emission Type
CAS
MLE / MBR
(Summer TIN
= 8 mg/L)
Bardenpho /
MBR (Year
Round TIN = 3
mg/L)
Direct
Process N2O 1,106 2,420 2,420
N2O Effluent Discharge 38 13 6
Indirect
Offsets (Avoided Emissions) -1,396 -1,100 -1,246
Purchased Electricity 7,255 11,615 22,264
Construction Material Production 0 11 37
Chemical Production 0 93 1,739
Replacement Material Production 0 93 237
Construction Handling 0 6 22
Solids Handling 1,698 1,292 1,515
Chemicals Handling 0 19 49
Replacements Handling 0 5 13
Total 8,700 14,468 27,055
Relative Value (%) 100% 166% 311%
Equivalent Number of Vehicles1 1,582 2,782 5,302
Relative Number of Vehicles 0 1,200 3,720
Notes:
(1) Based on EPA estimate of 5.5 metric tons of annual CO2 equivalent emissions for an average
vehicle (http://www.epa.gov/oms/climate/420f05004.htm).
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2.6 FINDINGS AND CONCLUSIONS
This chapter has presented results of evaluations undertaken to determine the effects of an
effluent permit requirement for nitrogen removal at the STP. Two different potential permit
requirements have been assessed:
• 8 mg/L TIN for the summer period
• 3 mg/L TIN year round
The estimated costs and other effects of meeting each of these potential future permit
requirements were compared to continuation of the current practice of CAS operation to
meet a secondary treatment permit for discharge to Puget Sound. A wide range of potential
alternatives were considered and screened to four final alternatives for each permit level.
Costs of each of these upgrade strategies were estimated using a series of criteria
including capital cost, O&M cost, risk, flexibility, footprint, energy, odor generation potential,
compatibility with existing processes, impact on biosolids quantity, and the amount and
quality of reclaimed water produced. The final ranking indicated that for the 8 mg/L TIN
(summer-only) permit level, the most promising upgrade strategy would be to upgrade the
existing CAS process at the STP to provide for anoxic and aerobic treatment in two
treatment stages by a MLE process and to construct a parallel nitrogen removing MBR
process to treat the remainder of the flow. For the 3 mg/L TIN (year-round) discharge
alternative a similar strategy was selected, but using a four-stage anoxic and aerobic
process (the Bardenpho process). It was concluded that two other processes, BAF/DNF
and IFAS processes, were potentially cost-effective and have similar enough other effects
that they should be considered further in the future.
A sensitivity analysis was conducted to evaluate potential effects of diurnal loading variation
and variation in the schedule of sludge dewatering operations, variation in activated sludge
settleability, and the impact of air blower outage on nitrogen removal. It is concluded that
sludge dewatering return flow equalization and treatment would be necessary to ensure
meeting a 3 mg/L TIN (year-round) permit limit, but that equalization would be less
necessary with the 8 mg/L TIN (summer-only) permit limit. It was concluded that variation in
sludge settleability would have less impact on the MBR process selected than is
experienced today with the CAS process for secondary treatment. It was assumed that
additional aeration blowers would be constructed for new MBR treatment facilities at the
STP and that sufficient redundancy would be constructed to provide for blower outage.
The incremental present worth cost for upgrade of the STP to meet an 8 mg/L TIN permit
level during the summer months is estimated at a present worth cost of approximately $680
million more than continuing operation of secondary treatment over the next twenty years.
The estimated incremental present worth cost for upgrade to meet a 3 mg/L TIN (year-
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round) permit level is in approximately $1,430 million more than the cost of continuing with
secondary treatment.
In addition to evaluation of incremental present worth costs, an estimate of GHG emissions
was conducted. It was concluded that meeting an 8 mg/L TIN summer permit level would
result in nearly two thirds more GHG emissions from the STP compared to the currently-
used CAS process and that a 3 mg/L TIN year-round permit level would result in
approximately three times more GHG emissions compared to continuing with secondary
treatment at the STP. The primary sources of increased GHG emissions were estimated
increases in purchased electricity and N2O released during nitrogen removal treatment.
Addition of these treatment technologies to the STP would have a similar GHG effect to
addition of between 1,000 and 4,000 vehicles to the Puget Sound region, depending on the
permit level implemented.
The most significant conclusions from this analysis were:
• The incremental present worth cost for upgrade of the STP to meet an 8 mg/L TIN
permit level during the summer months is estimated at a present worth cost of
approximately $680 million more than continuing operation of secondary treatment
over the next twenty years.
• The estimated incremental present worth cost for upgrade to meet a 3 mg/L TIN
(year-round) permit level is in approximately $1,430 million more than the cost of
continuing with secondary treatment.
• Meeting an 8 mg/L TIN summer permit level would result in nearly two thirds more
GHG emissions from the STP compared to the currently-used CAS process.
• Meeting a 3 mg/L TIN year-round permit level would result in approximately three
times more GHG emissions compared to continuing with secondary treatment.
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Chapter 3
SOUTH PLANT NITROGEN REMOVAL
EFFECT ON RECLAIMED WATER PRODUCTION
3.1 INTRODUCTION
The South Treatment Plant (STP) currently performs secondary treatment for up to 144
million gallons per day (mgd) of flow on a maximum month basis for discharge to Puget
Sound. Substantial removal of ammonia is not achieved. Reclaimed water filtration facilities
for up to 1.5 mgd of secondary effluent are currently available. Implementation of nitrogen
removal at the STP could have a significant effect on reclaimed water availability, potential
customers, and quality, depending on the technology selected.
Previous chapters presented analysis used a basis for the information contained herein.
Chapter 1 reported development of two target permit levels for nitrogen removal:
• 8 mg/L total inorganic nitrogen (TIN) from May through October
• 3 mg/L TIN year-round
Chapter 2 reported results of a screening of a wide range of potential nitrogen removal
treatment scenarios to one potential technology for each permit level as follows:
• Parallel Modified Ludzack-Ettinger (MLE) – membrane bioreactor (MBR) process for
the 8 milligrams per liter (mg/L) summer TIN limit
• Parallel Bardenpho – MBR process for the 3 mg/L year round TIN limit
This chapter discusses potential effects of the selected alternative on reclaimed water
production and compared to the cost of implementing reclaimed water production for the
current, non-nitrified effluent.
3.2 SUMMARY OF RECLAIMED WATER STANDARDS
The legislative basis for reclaimed water regulation in the State of Washington is contained
90.46 RCW - Reclaimed Water Use. The current Water Reclamation and Reuse Standards
(Standards) date from 1997 and have been prepared jointly by the Department of Health
(DOH) and the Department of Ecology (Ecology) (See DOH and Ecology 1997). These
standards define reclaimed water in four classes based on quality as summarized in Table
3.1. Nitrogen removal is not required in general for any of the four classes, but is required
for specific uses. Uses mentioning nitrogen removal in the Water Reclamation and Reuse
Standards are summarized in Table 3.2.
Current standards are under review. New rules are expected by December 2010. This
analysis is based on the current regulations.
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Table 3.1 Definitions of Reclaimed Water
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
"Reclaimed water" means water derived in any part from wastewater with a domestic wastewater
component that has been adequately and reliably treated, so that it can be used for beneficial
purposes. Reclaimed water is not considered a wastewater.
"Class A Reclaimed Water" means reclaimed water that, at a minimum, is at all times an oxidized,
coagulated, filtered, disinfected wastewater. The wastewater shall be considered adequately
disinfected if the median number of total coliform organisms in the wastewater after disinfection does
not exceed 2.2 per 100 milliliters, as determined from the bacteriological results of the last 7 days for
which analyses have been completed, and the number of total coliform organisms does not exceed
23 per 100 milliliters in any sample.
"Class B Reclaimed Water" means reclaimed water that, at a minimum, is at all times an oxidized,
disinfected wastewater. The wastewater shall be considered adequately disinfected if the median
number of total coliform organisms in the wastewater after disinfection does not exceed 2.2 per 100
milliliters, as determined from the bacteriological results of the last 7 days for which analyses have
been completed, and the number of total coliform organisms does not exceed 23 per 100 milliliters in
any sample.
"Class C Reclaimed Water" means reclaimed water that, at a minimum, is at all times an oxidized,
disinfected wastewater. The wastewater shall be considered adequately disinfected if the median
number of total coliform organisms in the wastewater after disinfection does not exceed 23 per 100
milliliters, as determined from the bacteriological results of the last 7 days for which analyses have
been completed, and the number of total coliform organisms does not exceed 240 per 100 milliliters
in any sample.
"Class D Reclaimed Water" means reclaimed water that, at a minimum, is at all times an oxidized,
disinfected wastewater. The wastewater shall be considered adequately disinfected if the median
number of total coliform organisms in the wastewater after disinfection does not exceed 240 per 100
milliliters, as determined from the bacteriological results of the last 7 days for which analyses have
been completed.
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Table 3.2 Summary of Reclaimed Water Uses Requiring Nitrogen Removal
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Intended Use Nitrogen Removal Requirement
Groundwater Recharge by Surface
Percolation
The secondary treatment process to provide
oxidized wastewater shall include an
additional step to reduce nitrogen
Direct Recharge to Potable Ground Water Total nitrogen ≤10 mg/L as N
Discharge to Wetlands Total Kjeldahl nitrogen (as nitrogen) 3 mg/L
Non-restricted Recreational Impoundments Nitrogen removal to reduce levels of
phosphorus and/or nitrogen is
recommended
The Standards give the following requirement for disinfection:
Where chlorine is used as the disinfectant in the treatment process a
minimum chlorine residual of at least 1 mg/L after a contact time of at least 30
minutes is required. (DOH and Ecology, September 1997, Section I, Article 9,
Section 5 [a])
This requirement does not explicitly state whether the chlorine residual should be measured
as free or total chlorine.
Since the reclaimed water standards were issued in 1997, the design manual for
wastewater treatment plants, the Criteria for Sewage Works Design (Orange Book), has
been updated and a revised issue released in 2006. The Orange Book guidelines for
chlorine disinfection requirements have changed in this revised manual and now state:
When using chlorine as the disinfectant, state reclaimed water standards
require a minimum CT of 30, based on a minimum free available chlorine
residual of 1.0 mg/L after a t10 contact time of at least 30 minutes. The basis
for using this method is disinfection requirements developed for the safe
drinking water act.
An alternate approach is to provide a CT of 450 based on a total chlorine
residual of at least 5 mg/L after a modal contact time of at least 90 minutes.
Note this approach may not provide the same level of pathogen inactivation
as well the first. This approach, used in the state of California, prescribe a
level of disinfection to provide essentially pathogen free water (Ecology,
October 2006, E1-4.5.1 B).
The new Rule limits the contact time (CT) to 30 mg/L-min based on a free chlorine residual
and a T10 CT. The new draft standards “permit an alternative CT measurement such as total
chlorine residual and a modal T value it if is demonstrated to the satisfaction of the
departments that the alternative disinfection process provides an equivalent degree of
human health and environmental protection.”
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3.3 RECLAIMED WATER EVALUATION
3.3.1 Reclaimed Water Effects
The current flow of the STP during the summer season when reclaimed water could be
potentially used for irrigation is approximately 98 mgd. Coagulation, flocculation, and
filtration or membrane filtration would be required to implement production of 98 mgd of
reclaimed water from the current non-nitrified secondary effluent. Assuming a typical rapid
mix detention time of 1 second, flocculation detention time of 20 minutes, and a maximum
month hydraulic loading rate of 4 gallons per minute per square foot (gpm/sf) for the rapid
sand filters, a total of approximately 38,000 square foot (sf) of coagulation, flocculation, and
filtration facilities would be required. This sizing assumes two standby units out of a total of
45. Figure 3.1 shows how these facilities could fit on the existing site. The capacity of the
existing filtration units was not included in the current analysis.
The MLE – MBR alternative for operation for an 8 mg/L TIN permit level during the May
through October period would produce up to 62 mgd of MBR effluent water during the
summer that would substantially meet the requirements for Class A reclaimed water. To
produce reclaimed water equaling the full current dry weather flow of 98 mgd, sand filtration
of 36 mgd from the existing secondary clarifiers would be needed. Assuming rapid mix
detention time of 1 second, flocculation detention time of 20 minutes, and a maximum
month hydraulic loading rate of 4 gpm/sf for the rapid sand filters, a total of approximately
13,000 sf of coagulation, flocculation, and filtration facilities would be required with one unit
out of 17 out of service. Figure 3.2 shows how these facilities could fit on the existing site.
The Bardenpho – MBR upgrade strategy would produce up to 114 mgd of MBR effluent
year round that would substantially meet the requirements of Class A reclaimed water. This
means that the STP could provide reclaimed water for almost the entire average wet
weather design flow if the 3 mg/L TIN year-round alternative were implemented.
To achieve Class A reclaimed water standards for disinfection, additional chlorine contact
basin volume would likely be required to achieve the 30 minute T10 CT. However, this
requirement would be the same for the 8 mg/L TIN summer effluent scenario, the 3 mg/L
TIN year round effluent scenario, and production of reclaimed water from the current plant
(non-nitrified effluent). Disinfection with a substantially nitrified effluent following membrane
filtration may require chloramination. However, due to the higher quality water, the required
chlorine dose may decrease from what would be required following filtration of the non-
nitrified effluent. Since the effects of nitrogen removal with a MBR system on the chemical
requirements of disinfection are unknown without pilot-scale testing, it has been assumed
that costs and other effects of the disinfection system for all scenarios are equal.
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 3.1.docx
SITE REQUIREMENTS FOR 98 MGD OF CONVENTIONAL FILTRATION
FIGURE 3.1
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON
FUTURE WATER REUSE PROGRAM DEVELOPMENT
pw:\\Carollo\Documents\Client\WA\King County\7683E00\Deliverables\Final Report\Fig 3.2.docx
SITE REQUIREMENTS FOR 33 MGD OF CONVENTIONAL FILTRATION
FIGURE 3.2
KING COUNTY DEPARTMENT OF NATURAL
RESOURCES AND PARKS
ASSESSMENT OF POTENTIAL NITROGEN REMOVAL TECHNOLOGIES AT THE SOUTH TREATMENT PLANT AND THEIR IMPACT ON
FUTURE WATER REUSE PROGRAM DEVELOPMENT
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3.3.2 Reclaimed Water Options Costs
Table 3.3 compares the planning level costs of reclaimed water production for the full 98
mgd summer flow for the current non-nitrified secondary effluent to the requirements for
additional filtration assuming nitrogen removal upgrade by a parallel MBR process for either
the 8 mg/L (summer only) or the 3 mg/L (year-round) TIN permit level. As shown in Table
3.3, there would be no additional cost to implement reclaimed water production for the full
summer flow of 98 mgd if the 3 mg/L (year-round) TIN permit limit project is implemented.
Table 3.3 shows that the cost of implementing reclaimed water by conventional filtration is
approximately $104 million in present worth capital and operating and maintenance costs. If
a 3 mg/L (year-round) TIN permit limit project using parallel MBR were implemented, this
cost would be avoided.
The planning level present worth cost of implementing 36 mgd of reclaimed water
production for non-nitrified effluent would be approximately $45 million. This would
represent a savings of approximately $59 million over providing full summer reclaimed
water production today from non-nitrified STP effluent. This relative savings in reclaimed
water production would be realized if the 8 mg/L (summer-only) parallel MBR project were
implemented.
Table 3.3 Summary of Relative Reclaimed Water Costs Effects
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Treatment Process Current
Approach.
Non-nitrified
Secondary
Effluent. No
new facilities.
Summer only.
8 mg/l TIN Summer Limit
Parallel MLE-MBR
Processes
3 mg/l TIN All-
year Limit
Add’l Sand Filtration
Req’d
98 mgd sand
filters
MLE
Effluent
36 mgd
sand filters
MBR Effluent
62 mgd - no
sand filters
MBR Effluent
114 mgd – no
sand filters
Capital Cost $57M $23M $0 $0
Annual O&M Cost $3.1M/yr $1.4M/yr $0 $0
Disinfection Assumed equal cost for all alternatives.
Present Worth O&M $47M $22M $0
Total Present Worth $104M $45M $0
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3.3.3 Other Effects
In addition to economic effect, there would be other effects of implementing either an 8
mg/L (summer-only) or a 3 mg/L (year-round) TIN effluent permit limit project on potential
reclaimed water production. Key effects include additional land use, energy consumption,
and greenhouse gas (GHG) consumption. They are summarized in Table 3.4.
Table 3.4 Summary of Other Relative Reclaimed Water Effects
South Plant Nitrogen Removal Study
King County Department of Natural Resources and Parks Wastewater
Treatment Division
Element Current Approach
Non-nitrified
Secondary Effluent
(98 mgd treated)
8 mg/L TIN
Summer Effluent
Limit, Parallel
MLE-MBR
(36 mgd treated)
3 mg/L TIM Year-
round Effluent
Limit, Parallel
Bardenpho-MBR
(0 mgd treated)
Impact
Land area (sf) 38,000 13,000 0
Energy consumption
(kWh/year) 200,000
85,000
0
GHG Emissions
(metric tons of
annual eCO2) 300 100
0
3.4 CONCLUSIONS
The selected alternatives for implementation of nitrogen removal at the STP include
membrane filtration of a portion of the final effluent for two different flows depending on the
permit level for nitrogen removal required. This presents an opportunity for reclaimed water
use. If nitrogen removal were implemented at the STP, between 36 and 98 mgd of effluent
would be made available that would be suitable for reclaimed water use. Assuming that the
costs of production of this water were required for nitrogen removal in any case, this water
would be available for reclaimed use at a relative savings over the costs of production of
the water using conventional gravity sand filtration. Cost savings would be in the range of
$45 to $104 million, depending on the level of nitrogen removal required. There would also
be a savings in land area of between one quarter and one acre and a savings of a small
amount in electricity consumption and GHG emissions, compared to production of the same
amount of reclaimed water using media filtration if nitrogen removal treatment facilities were
not available.
REFERENCES
Brown and Caldwell (July 2004), South Plant Capacity and Re-rating Evaluation, Final
Draft.
Carollo Engineers (2010) South Plant Peak Flow Management Report.
Carollo Engineers (2009a) Project Kickoff Meeting Minutes, Conference Date, October 1,
2009.
Carollo Engineers (2009b) Alternative Selection Meeting Minutes, Conference Date,
December 15, 2009.
C. W. Randall, J. L. Barnard, H. D. Stensel. (1992) Design and Retrofit of Wastewater
Treatment Plants for Biological Nutrient Removal, Technomic Publishing Company, Inc.;
Lancaster.
Daigger, Glenn T. (1995) Development of refined clarifier operating diagrams using an
updated settling characteristics database, Water Environment Research, Volume 67,
Number 1.
Jenkins, David et. al. (2004) Manual on the Causes and Control of Activated Sludge
Bulking, Foaming, and Other Solids Separation Problems, IWA Publishing, 3rd Edition.
Owen, William F. (1982) Energy in Wastewater Treatment, Prentice-Hall.
Pittman, A.R. (1985) Settling of Nutrient Removal Activated Sludge, Wat. Sci. Tech., Vol.
17, Amsterdam, pg. 493-504.
State of Washington Department of Ecology (November 2008a) South Puget Sound
Dissolved Oxygen Study, Key Findings on Nitrogen Sources from the Data Report,
Publication No. 08-10-099.
State of Washington Department of Ecology (December 2008b) South Puget Sound
Dissolved Oxygen Study Interim Data Report, Publication No. 08-03-037.
State of Washington Department of Ecology (2009) EXTERNAL REVIEW DRAFT – 10-15-
09, South Puget Sound Dissolved Oxygen Study—South and Central Puget Sound Water
Circulation Model Development and Calibration, Publication No. 09-03-0xx.
U.S. EPA (April 15, 2010), Inventory of U.S. Greenhouse Gas Emissions and Sinks; 1990-
2008.
Washington State Department of Health and Washington State Department of Ecology
(September 1997) Water Reclamation and Reuse Standards.
Washington State Department of Ecology, Water Quality Program (October 2006) Criteria
for Sewage Works Design.
APPENDIX A
EVALUATION CRITERIA
Criteria MBR IFAS Linpor IFAS Kruger BAF
Capital Cost > 1.25 X lowest cost = 2 lowest cost = 3 < 1.25 x lowest = 3 > 1.25 X lowest cost = 2
1.37 1.00 1.24 1.48
O&M Cost, PW > 1.5 x lowest = 1 > 1.5 x lowest = 1 lowest = 3 < 1.5 x lowest = 2
1.58 1.50 1.00 1.41
Risk County familiar with
process. Brightwater will
be of a similar size range
= 3
County not familiar with
process. No US
installations of a similar
size = 1
County not familiar with
process. No US
installations of a similar
size = 1
County not familiar with
process. 1 US installation
of a similar size, 1
additional planned for
2010 = 1
Footprint, sf < 1.5 x lowest = 2 Lowest impact = 3 > 1.5 x lowest = 1 < 1.5 x lowest = 2
607,429 425,880 849,221 560,030
1.43 1.00 1.99 1.31
Energy > 1.5 x lowest = 1 Lowest = 3 < 1.5 x lowest = 2 < 1.5 x lowest = 2
1.69 1.00 1.30 1.49
Odor All processes equally
odoriforous
All processes equally
odoriforous
All processes equally
odoriforous
All processes equally
odoriforous
Compatibility with
existing processes
No stranded assetts No stranded assetts No stranded assetts No stranded assetts
Biosolids Quality Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
RW Quality Reclaimed water quality
effluent = 3
Nitrifying system, better
effluent = 2
nitrifying system, better
effluent, no room for filters
= 1
Nonnitrifying system = 1
TIN 3 Score Reasoning
Criteria MLE MBR IFAS Linpoor IFAS Kaldness BAF
Capital Cost Lowest capital cost = 3 < 2 X lowest cost = 2 < 1.25 X lowest = 3 > 2 X lowest = 1 < 2 X lowest = 2
1.00 1.72 1.15 2.11 1.73
O&M Cost, PW Lowest cost = 3 > 2 X lowest cost = 1 < 2 x lowest = 2 < 2 x lowest = 2 < 2 x lowest = 2
1.00 2.11 1.72 1.69 1.77
Risk Very similar to existing
process. County familiar
with process. Numerous
US installations in size
range = 3
County familiar with
process. Brightwater will
be of a similar size range
= 3
County not familiar with
process. No US
installations of a similar
size = 1
County not familiar with
process. No US
installations of a similar
size = 1
County not familiar with
process. 1 US installation
of a similar size, 1
additional planned for
2010 = 1
Future Flexibility Cannot meet future limit
of 3 mg/L = 1
Can meet future limit of 3
mg/L = 3
Can meet future limit of 3
mg/L = 3
Cannot meet future limit of
3 mg/L = 1
Can meet future limit of 3
mg/L = 3
Footprint, sf > 1.5 x lowest alternative
= 1
< 1.25 x lowest alternative
= 3
Lowest impact = 3 > 1.25 X lowest = 2 < 1.25 x lowest
alternative = 3
725,935 438,148 383,196 500,016 457,745
1.89 1.14 1.00 1.30 1.19
Energy Lowest energy use = 3 < 1.5 x lowest = 2 < 1.25 x = 3 > 1.5 x lowest = 1 < 1.5 x lowest = 2
1.00 1.26 1.10 1.71 1.34
Odor All processes equally
odoriforous
All processes equally
odoriforous
All processes equally
odoriforous
All processes equally
odoriforous
All processes equally
odoriforous
Compatibility with
existing processes
No stranded assetts No stranded assetts No stranded assetts No stranded assetts No stranded assetts
Biosolids Quality Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 3
Nitrogen removed by N2
gas evoluation, some N
lost from biosolids = 2
RW Quality Nitrifying system, better
effluent quality, but no
room on site for more
filters = 1
Reclaimed water quality
effluent = 3
Nitrifying system, better
effluent = 2
Nitrifying system, better
effluent = 3
Nonnitrifying system = 1
TIN 8 Score Reasoning
APPENDIX B
COST ASSUMPTIONS AND SUMMARIES
Client:
Project:
Subject: Cost Assumptions
Cost Assumptions
By :RWS
Estimate Cost Base :3/15/2010
Bordered Cells are
Input Cells
Item Value
Period of analysis, years 20
Discount rate, %3.0%
Construction Escalation rate, %6.0%
Mid-Point Construction date 15-Mar-10
Operations labor rate, $/hr $50
Diesel oil cost, $/gal $3.00
Power cost, $/kwh $0.07
Biosolids Management, $ / wet ton (with trucking)$50.00
Chemical Cost, $/lb
Chlorine $0.62
Sulfur Dioxide $0.19
Citric Acid $0.50
Alum $0.10
Ferric Chloride $0.35
Sodium hypochlorite $0.90
Methanol $0.33
Cationic Polymer $1.60
Structural Annual Replacement Cost, %2%
Equipment Annual Replacement Cost, %4%
Contingency, %40%
Allied Costs (Planning, Design, CM, Permits, etc.)45%
Sales tax, %10.0%
ENR Cost Index 10350
Present Worth Factor 14.87747
King County
Nutrient Removal Analysis - 3
mg/L Year-round TIN
Cost Comparison of Treatment AlternativesKing CountyNutrient Removal Analysis - 8 mg/L Summer TIN (98 mgd Max Month Flow)Treatment Element CAS MLE MLE MBR Total NR Cost DifferenceCapital Cost, $Fine Screening $0 $11,000,000 $11,000,000 $11,000,000CAS Aeration Tanks $0 $0 $0BNR Reactor Tanks $0 $105,200,000 $105,200,000 $105,200,000MBR Reactor Tanks $0 $179,600,000 $179,600,000 $179,600,000MBR Membrane Tanks and Equipment $0 $227,800,000 $227,800,000 $227,800,000Centrate Treatment Tanks $0 $6,300,000 $6,300,000 $6,300,000Total Project Cost $0 $105,000,000 $425,000,000 $530,000,000 $530,000,000Design Max Month Flow (mgd) 98 33 65 98 98Unit Project Cost ($/gpd) $0.00 $3.18 $6.54 $5.41 $5.41Operation and Maintenance Cost, $/yearFine Screening $0 $0 $660,000 $660,000 $660,000CAS Aeration Tanks $1,730,000 $721,000 $0 $721,000 -$1,009,000BNR Reactor Tanks $0 $2,390,000 $0 $2,390,000 $2,390,000MBR Reactor Tanks $0 $0 $2,870,000 $2,870,000 $2,870,000MBR Membrane Tanks and Equipment $0 $0 $4,920,000 $4,920,000 $4,920,000Centrate Treatment Tanks $0 $0 $200,000 $200,000 $200,000Total $1,700,000 $3,100,000 $8,700,000 $11,800,000 $10,000,000Present Worth Cost, $ MillionCapital $0 $105 $425 $530 $530Operation and Maintenance $25 $46 $129 $176 $149Total Present Present Worth $25 $151 $554 $706 $679
Cost Comparison of Treatment AlternativesKing CountyNutrient Removal Analysis - 3 mg/L Year-round TIN (144 mgd Max Month Flow)Treatment ElementCAS Bardenpho Upgrade Bardenpho MBRTotal NR UpgradeDifferenceCapital Cost, $Fine Screening$0$14,100,000 $14,100,000 $14,100,000CAS Aeration Tanks$0$0$0BNR Reactor Tanks $0 $179,800,000$179,800,000 $179,800,000BNR Secondary Sed Tanks$0 $8,300,000$8,300,000MBR Reactor Tanks$0$385,300,000 $385,300,000 $385,300,000MBR Membrane Tanks and Equipment$0$367,600,000 $367,600,000 $367,600,000Centrate Treatment Tanks$0$12,100,000 $12,100,000 $12,100,000Total Project Cost$0 $188,000,000 $779,000,000 $967,000,000 $959,000,000Design Flow, mgd14430114144144Unit Project Cost ($/gpd)$0.00$6.27$6.83$6.72$6.66Operation and Maintenance Cost, $/yearFine Screening$1,315,000 $1,315,000 $1,315,000CAS Aeration Tanks$1,840,000$0 -$1,840,000BNR Reactor Tanks$7,212,000$7,212,000 $7,212,000BNR Secondary Sed Tanks$1,367,000$1,367,000MBR Reactor Tanks$11,764,000 $11,764,000 $11,764,000MBR Membrane Tanks and Equipment$13,013,000 $13,013,000 $13,013,000Centrate Treatment Tanks$410,000 $410,000 $410,000Total$1,800,000 $8,600,000 $26,500,000 $35,100,000 $31,900,000Present Worth, $ MillionCapital$0$188$779$967$959Operation and Maintenance$27$128$394$522$475Total Present Worth$27$316$1,173 $1,489 $1,434