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HIGHLANDS 435 PRESSURE ZONE
RESERVOIRS
Prepared for:
CITY OF RENTON
10555 Grady Way
5th Floor
Renton, WA 98055
REN 113.104.01.104
Prepared by:
RH2 ENGINEERING, INC.
November 2015
TECHNICAL INFORMATION REPORT
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CITY OF RENTON
HIGHLANDS 435 PRESSURE ZONE RESERVOIRS
TECHNICAL INFORMATION REPORT
NOVEMBER 2015
Prepared by: RH2 Engineering, Inc.
Prepared for: the City of Renton
Note: This Technical Information Report was completed under the direct supervision of the following
Licensed Professional Engineers registered in the State of Washington.
Date Signed: 11/12/15
Date Signed: 11/12/15
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City of Renton
Highlands 435 Pressure Zone Reservoirs Project TIR
Table of Contents
Section 1 – Project Overview ..................................................................................................... 1
General ....................................................................................................................................................... 1
Section 2 – Conditions and Requirements Summary ............................................................... 1
Core Requirement No. 1 – Discharge at the Natural Location ......................................................... 2
Core Requirement No. 2 – Off-site Analysis ........................................................................................ 2
Core Requirement No. 3 – Flow Control ............................................................................................. 2
Core Requirement No. 4 – Conveyance System .................................................................................. 2
Core Requirement No. 5 – Erosion and Sediment Control ............................................................... 2
Core Requirement No. 6 – Operation and Maintenance .................................................................... 3
Core Requirement No. 7 – Financial Guarantees and Liability ......................................................... 3
Core Requirement No. 8 – Water Quality ............................................................................................ 3
Special Requirement No. 1 – Other Adopted Area-Specific Requirements .................................... 4
Special Requirement No. 2 – Flood Hazard Area Delineation .......................................................... 4
Special Requirement No. 3 – Flood Protection Facilities ................................................................... 4
Special Requirement No. 4 – Source Controls ..................................................................................... 5
Special Requirement No. 5 – Oil Control ............................................................................................. 5
Special Requirement No. 6 – Aquifer Protection Area ....................................................................... 5
Section 3 – Off-site Analysis ...................................................................................................... 5
Task 1 – Study Area Definition and Maps ............................................................................................ 5
Task 2 – Resource Review ....................................................................................................................... 5
Task 3 – Field Inspection ........................................................................................................................ 6
Task 4 – Drainage System Description and Problem Descriptions .................................................. 6
Task 5 – Mitigation of Existing or Potential Problems ....................................................................... 7
Section 4 – Flow Control and Water Quality Analysis and Design ........................................... 7
Johns Creek Basin TDA Existing Site Hydrology (Part A) ................................................................ 7
Johns Creek Basin TDA Developed Site Hydrology (Part B)............................................................ 8
Honey Creek Basin TDA Developed Site Hydrology (Part B) .......................................................... 9
Johns Creek Basin TDA Performance Standards (Part C) ............................................................... 11
Honey Creek TDA Performance Standards (Part C) ........................................................................ 11
Johns Creek Basin TDA Flow Control System (Part D) .................................................................. 11
Honey Creek Basin TDA Flow Control System (Part D) ................................................................ 12
Water Quality System (Part E) .............................................................................................................. 13
Section 5 – Conveyance System Analysis and Design ............................................................ 13
Section 6 – Special Reports and Studies .................................................................................. 14
Section 7 – Other Permits ........................................................................................................ 14
Section 8 – CSWPPP Analysis and Design ............................................................................. 15
ESC Plan Analysis and Design (Part A) .............................................................................................. 15
Stormwater Pollution Prevention and Spill (SWPPS) Plan (Part B) ................................................ 18
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Section 9 – Bond Quantities, Facility Summaries and Declaration of Covenant ................... 24
Section 10 – Operations and Maintenance Manual ................................................................ 24
APPENDICES
Appendix A – Worksheet and Forms
Appendix B – Geo Report
Appendix C – Threshold Discharge Areas
Appendix D – Salmon Habitat Projects WRIA 8
Appendix E – Downstream Analysis
Appendix F – Resource Review
Appendix G – Flow Control BMPs
Appendix H – KCRTS Modeling
Appendix I – Existing and Proposed Conveyance Systems Backwater Analyses (To be provided at
Utility Construction Permit submittal)
Appendix J – CSWPPP Sample Forms (To be provided at Utility Construction Permit submittal)
Appendix K – Stormwater Pollution Prevention and Spill Plan BMPs (To be provided at Utility
Construction Permit submittal)
Appendix L – Operations and Maintenance Manual (To be provided at Utility Construction Permit
submittal)
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SECTION 1 – PROJECT OVERVIEW
GENERAL
The City of Renton (City) owns and operates a potable water reservoir site in a residential area
off Northeast 12th Street between Monroe Avenue Northeast and Pierce Place Northeast. The
City desires to redevelop the site to remove the existing reservoirs and appurtenant structures
that have reached the end of their useful life, and reconstruct new potable water reservoirs
and appurtenant structures that will maximize the usability of the site for potable water storage
and renew the useful life of the facilities. It is expected that the improvements at the project
site will be constructed in phases over many years. This Technical Information Report (TIR)
addresses construction of the phase 1 reservoir and includes planning-level information for
future stormwater system expansion for phase 2.
The project site is on a lot commonly known by the City as 3410 Northeast 12th Street, Renton,
Washington. The parcel number is 0423059186. The area of the site is approximately 4.7 acres.
Currently, only the southern half of the site has been developed with potable water reservoirs
and associated water infrastructure. Under phase 1 of the proposed project, the northern half
of the site will be developed to construct a new 6.3-million-gallon reservoir.
The site has two Threshold Discharge Areas (TDAs). A TIR worksheet has been prepared for
each of the two TDAs for this project (Figures 1a and 1b in Appendix A). A Vicinity Map
showing the proposed site is included in Appendix A as Figure 2. The site is at a localized
highpoint, therefore, the upstream tributary area to the project site is negligible. A Soil Survey
Map from the Natural Resources Conservation Service has been included as Figure 4 of
Appendix A and indicates that on-site soils are Alderwood gravelly sandy loam, which is
classified as Hydrologic Soil Group (HSG) ‘C.’ In addition, ZZA Terracon prepared a
Geotechnical Report, dated January 19, 2009, which provides additional and site-specific
information regarding the on-site soils (Appendix B).
This TIR is intended to demonstrate compliance with the City of Renton Amendments to the King
County Surface Water Design Manual, February 2010 Edition, and the applicable sections of the
King County Surface Water Design Manual, 2009 Edition, (hereinafter collectively referred to as
the RKCSWDM) for the proposed project. Since the project will be constructed in phases
over many years, this TIR will demonstrate compliance for the current proposed project
improvements for phase 1. If additional or alternative stormwater management standards are
implemented at a future date after preparation of this TIR, and they will affect the results of
this TIR, it can be amended at such time to ensure compliance with the City of Renton
standards.
SECTION 2 – CONDITIONS AND REQUIREMENTS SUMMARY
In reviewing RKCSWDM Section 1.1.2 – Drainage Review Types and Requirements, and
Figure 1.1.2.A – Flow Chart for Determining Type of Drainage Review Required, the
following criteria have been considered:
The project is not a single-family residence.
The project is a redevelopment that proposes to add or replace more than 2,000 square
feet (sf) of impervious surface.
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The project will not result in 50 acres or more of new impervious surface.
Based on this rationale, the project will be subject to Full Drainage Review.
CORE REQUIREMENT NO. 1 – DISCHARGE AT THE NATURAL LOCATION
The existing site has two natural discharge locations and two TDAs. Approximately 60 percent
of the project site is tributary to the Johns Creek Basin and the remaining 40 percent is
tributary to the Honey Creek Basin. Appendix C contains information regarding the
delineation of the TDAs. The project does not propose to divert flows from either natural
discharge location, nor from the TDAs.
CORE REQUIREMENT NO. 2 – OFF-SITE ANALYSIS
An in-depth off-site analysis was performed for the project site and is detailed in Section 3 of
this TIR.
CORE REQUIREMENT NO. 3 – FLOW CONTROL
The project site is tributary to two drainage basins. The project is not exempt from Core
Requirement No. 3. In accordance with the RKCSWDM Flow Control Map, Reference 11a,
the area of the project site that is tributary to the Johns Creek Basin is subject to the Peak Rate
Flow Control Standard – Matching Existing, and the area of the project site that is tributary
to the Honey Creek Basin is subject to Flow Control Duration Standard – Matching Forested.
In the Johns Creek Basin, phase 1 of the project proposes to:
Add 0.89 acres of new impervious surface; and
Add or replace 0.16 acres of landscaped or lawn area.
In reviewing the requirements of RKCSWDM Section 1.2.3.1.A – Peak Rate Flow Control
Areas, the 0.76 acres of new impervious surface and 0.16 acres of landscaped/lawn area are
considered Target Surfaces.
In the Honey Creek Basin, the project proposes to:
Add 0.89 acres of new impervious surface; and
Add or replace 0.11 acres of landscaped or lawn area.
In reviewing the requirements of RKCSWDM Section 1.2.3.1.B – Flow Control Duration
Standard Areas, the 0.89 acres of new impervious surface and the 0.11 acres of
landscaped/lawn area are considered Target Surfaces.
CORE REQUIREMENT NO. 4 – CONVEYANCE SYSTEM
The project proposes to install a conveyance system for collecting and discharging water from
the project site. The proposed conveyance system will be designed to convey and contain the
25-year design storm event. The final design of the conveyance system and calculations will
be prepared at the time of the Utility Construction Permit application.
CORE REQUIREMENT NO. 5 – EROSION AND SEDIMENT CONTROL
A temporary erosion and sedimentation control (TESC) plan will be developed and included
as the erosion and sedimentation control (ESC) plan of the plan set for Phase 1 of the project
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at the time of the Utility Construction Permit application. Additional phases of the project will
require development of site-specific ESC plans as the details of those phases are developed.
A Construction Stormwater Pollution Prevention Plan is included in Section 8.
CORE REQUIREMENT NO. 6 – OPERATION AND MAINTENANCE
Section 10 includes information regarding the Operations and Maintenance (O&M) Manual.
The drainage facilities are proposed to be maintained by the City.
CORE REQUIREMENT NO. 7 – FINANCIAL GUARANTEES AND LIABILITY
In accordance with RKCSWDM Section 1.2.7 – Core Requirement No. 7 – Financial
Guarantees and Liability, all persons constructing any surface water facilities are required to
post with the City a bond, assignment of funds, or certified check. For this project, the City’s
Water Department requests that this requirement be waived, consistent with RCW 35.21.470,
which states:
A city or town may not require any state agency or unit of local government to secure
the performance of a permit requirement with a surety bond or other financial security
device, including cash or assigned account, as a condition of issuing a permit to that
unit of local government for a building construction project.
As used in this section, "building construction project" includes, in addition to its usual
meaning, associated landscaping, street alteration, pedestrian or vehicular access
alteration, or other amenities or alterations necessarily associated with the project.
CORE REQUIREMENT NO. 8 – WATER QUALITY
In accordance with Definitions in the RKCSWDM, the proposed project does not contain
pollution-generating surfaces, as described below:
Refer to page 1-4 of the RKCSWDM.
Pollution-generating impervious surface (PGIS) means an impervious surface considered
to be a significant source of pollutants in stormwater runoff. Such surfaces include those that
are subject to vehicular use2 or storage of erodible or leachable materials, wastes, or chemicals,
and that receive direct rainfall or the run-on or blow-in of rainfall. Metal roofs are also
considered to be PGIS unless they are treated to prevent leaching.
Footnote 2 is defined as:
Subject to vehicular use means the surface, whether paved or not, is regularly-used by
motor vehicles. The following surfaces are considered regularly-used by motor
vehicles: roads, unvegetated road shoulders, bike lanes within or not separated from
the traveled lane of a roadway, driveways, parking lots, unfenced firelanes, diesel
equipment storage yards, and airport runways. The following surfaces are not
considered regularly-used by motor vehicles: road shoulders primarily used for
emergency parking, paved bicycle pathways, bicycle lanes adjacent to unpaved or
paved road shoulders primarily used for emergency parking, fenced firelanes, and
infrequently-used maintenance access roads.
TIR Comment: The reservoir roofs will be constructed with concrete material that is not
leachable. The paved roads on the project site are infrequently used by the City’s Water
Department and not regularly-used by motor vehicles.
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Refer to Page 1-4 of the RKCSWDM.
Pollution-generating pervious surface (PGPS) means a non-impervious surface
considered to be a significant source of pollutants in surface and stormwater runoff.
Such surfaces include those subject to use of pesticides and fertilizers, loss of soil, or
the use or storage of erodible or leachable materials, wastes, or chemicals. Such
surfaces include, but are not limited to, the lawn and landscaped areas of residential or
commercial land uses, golf courses, parks, sports fields, and City-standard grassed
modular grid pavement.
TIR Comment: The City’s Water Department mows the grass areas of the project site in its
exiting condition and will continue to do so in the redeveloped condition. The Water
Department does not propose to use pesticides and fertilizers for maintenance of grass or
other pervious areas.
Since the proposed project does not contain pollution-generating surfaces, water quality
treatment is not required.
SPECIAL REQUIREMENT NO. 1 – OTHER ADOPTED AREA-SPECIFIC REQUIREMENTS
A Master Drainage Plan is not known to exist for the project site.
A Basin Plan is not known to exist for the project site.
A Salmon Habitat Plan exists for the project site and is titled, the Lake
Washington/Cedar/Sammamish Watershed, also known as Water Resource Inventory Area
(WRIA) 8. The project site is located specifically in the Lake Washington sub-basin of WRIA
8.1
The Salmon Habitat Plan for the Lake Washington sub-basin contains specific salmon
recovery projects, although none appear to be in the vicinity of the potable water system
project. Appendix D contains a map of salmon recovery projects.
A Stormwater Compliance Plan is not known to exist that would affect the project site.
A Flood Hazard Reduction Plan is not known to exist that would affect the project site.
A Shared Facility Drainage Plan is not known to exist that would affect the project site.
SPECIAL REQUIREMENT NO. 2 – FLOOD HAZARD AREA DELINEATION
The proposed project site is not directly adjacent to a stream, lake, wetland, or closed
depression, and, therefore, does not warrant delineation of the 100-year flood plain.
SPECIAL REQUIREMENT NO. 3 – FLOOD PROTECTION FACILITIES
The proposed project will not rely on an existing flood protection facility for protection against
hazards posed by erosion or inundation, nor will it construct a new flood protection facility.
1 Additional information can be found online at
http://www.govlink.org/watersheds/8/activities-partners/default.aspx#map.
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SPECIAL REQUIREMENT NO. 4 – SOURCE CONTROLS
The proposed project does not require a commercial building permit nor a commercial site
development permit; therefore, in accordance with RKCSWDM Section 1.3.4 (page 1-73), this
special requirement is not applicable.
SPECIAL REQUIREMENT NO. 5 – OIL CONTROL
The proposed project site is not considered high-use; therefore, this special requirement does
not apply.
SPECIAL REQUIREMENT NO. 6 – AQUIFER PROTECTION AREA
The proposed project site lies within Aquifer Protection Area Zone 2 and the Cedar Valley
Sole Source Aquifer Project Review Area, as identified on the Groundwater Protection Areas
in the City map. The project does not propose to construct pollution-generating surfaces;
therefore, a stormwater liner is not anticipated to be required.
SECTION 3 – OFF-SITE ANALYSIS
TASK 1 – STUDY AREA DEFINITION AND MAPS
The Downstream Analysis Map Series is included in Appendix E. Appendix E also contains
maps that demarcate the downstream flow path for a distance of 1 mile.
TASK 2 – RESOURCE REVIEW
Basin Plan – A basin plan is not known to exist for the project site.
Sensitive Areas Folio –Appendix F contains the following maps:
Sensitive Slopes: There are some sensitive slopes (greater than 25-percent and less than
or equal to 40-percent) on the project site and downstream of the project site. There
are protected slopes (greater than 40-percent and less than or equal to 90-percent)
downstream of the project site adjacent to Honey Creek.
Landslide: There are slopes downstream of the project site that are at moderate risk
for landslide.
Honey Creek is a Class-3 stream that is downstream of the project site, and runoff
from part of the site is tributary to Honey Creek.
There are no mapped wetlands on the project site, but there is one mapped wetland
downstream of the project site and associated with Honey Creek.
There is mapped erosion associated with the banks of Honey Creek downstream of
the project site.
City maps do not show the site and downstream areas being in Special Flood Hazard
Areas (100-year flood) nor Other Flood Areas (Zone X - 500-year flood).
The project site and downstream area do not show any mapped coal-mine hazards.
The project site lies within Aquifer Protection Area Zone 2 and the Cedar Valley Sole
Source Aquifer Project Review Area.
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Section 303d List – Appendix F contains a Washington State Department of Ecology
(Ecology) map indicating that downstream of the project site for the Johns Creek Basin, Lake
Washington is listed for bacteria and total phosphorus. In the Honey Creek Basin, Honey
Creek is tributary to May Creek, which is listed for bacteria, dissolved oxygen, mercury, pH,
and ammonia-N.
TASK 3 – FIELD INSPECTION
A Level-1 inspection and site visit was conducted on September 10, 2014. The temperature
was 71 degrees Fahrenheit, and sunny, with 0.00 inches of precipitation. It had rained 0.05
inches 2 days earlier on September 8, 2014. The downstream conveyance system was inspected
for both the Johns Creek Basin and Honey Creek Basin TDAs. Overall, no drainage issues
were observed, and all drainage systems were free-flowing. Land use, impervious surfaces,
topography, pipe sizes, drainage structures, and relevant critical areas were verified to the
extent possible as displayed in the study area maps and other relevant figures.
TASK 4 – DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS
The 435 Pressure Zone Reservoirs project site is divided into two TDAs. The two TDAs are
shown in the map in Appendix C, and downstream flow paths are shown in Appendix E.
JOHNS CREEK BASIN TDA DOWNSTREAM ALIGNMENT
The Johns Creek Basin TDA discharges off the northwest corner under historic conditions.
Currently, stormwater sheet flows off the site and is tributary to the downstream property (a
retirement residence) where it is collected in an on-site stormwater conveyance system and
underground facilities. The stormwater system routes the stormwater away from its historic
flow path to the Johns Creek Basin and instead routes it east and north for discharge to Honey
Creek, which would technically be a basin transfer at the time the development was
constructed. See the as-built plan for the retirement residence in Appendix E, which
identifies the basin transfer. For the purposes of the downstream analysis of the Johns Creek
Basin TDA, the historic flow path was followed, as shown in Appendix E.
There are currently no known, existing, or potential drainage systems problems reported from
the City, local owners, or observed during the field inspection for the Johns Creek Basin TDA.
HONEY CREEK BASIN TDA DOWNSTREAM ALIGNMENT
The Honey Creek Basin TDA discharges off the northeast corner of the project site via a
10-inch concrete pipe after being collected on-site using existing catch basins and a collection
system. From the northeast corner of the site, runoff travels due north in a 12-inch concrete
pipe to the south edge of NE Sunset Boulevard. Runoff then travels under NE Sunset
Boulevard via an 18-inch concrete pipe that discharges at a culvert outfall approximately
70 feet north of NE Sunset Boulevard. Runoff then travels in a channel in a northeasterly
direction. The culvert outfall and channel show signs of minor erosion and incising for
approximately 100 feet before reaching a more heavily-vegetated area (Appendix E). RH2
Engineering, Inc., (RH2) staff were not able to field-verify the remainder of the downstream
data due to heavy vegetation growth and systems primarily on private properties; therefore,
RH2 relied on the available data from the City’s online geographic information system (GIS)
mapping application. The channel is approximately 325 feet in length, from the 18-inch culvert
outfall to a point where it enters a 24-inch culvert pipe that continues to flow in the northeast
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direction through a series of pipes and catch basins before outfalling to another channel
approximately 80 to 90 feet from the edge of Honey Creek. Flow travels the 80 to 90 feet in a
channel and then becomes tributary to Honey Creek. Honey Creek then flows in a
northwesterly direction for approximately 1 mile before it becomes tributary to May Creek,
which eventually discharges into Lake Washington.
There are currently no known existing or potential drainage system problems reported from
the City, local owners, or observed during the field inspection for the Honey Creek Basin
TDA.
Parcels, pipe sizes, and approximate general slopes for both downstream alignments are shown
in the Off-site Analysis Drainage System Table and on project maps (Appendix E).
TASK 5 – MITIGATION OF EXISTING OR POTENTIAL PROBLEMS
A review of the information for the project site found no potential or existing drainage or
water quality problems beyond the minor erosion and incising of the outfall and channel
downstream of the 18-inch concrete pipe north of NE Sunset Boulevard. With the detention
standard of Flow Control Duration Standard – Matching Forested, it is anticipated that these
downstream conditions will decrease erosion/incising under developed conditions.
SECTION 4 – FLOW CONTROL AND WATER QUALITY ANALYSIS AND DESIGN
JOHNS CREEK BASIN TDA EXISTING SITE HYDROLOGY (PART A)
The Existing Site Plan is included in the plan set. The site is developed with potable water
reservoirs and appurtenant facilities along with gravel maintenance access roads. There are
some trees on the site, as shown in the existing site plan. As previously mentioned, the site has
two TDAs. The basins have been delineated in the maps in Appendix C. As mentioned in
the Off-site Analysis Section above, the property downstream of the Highlands Reservoir site
constructed a conveyance system that routes all runoff from the Highlands Reservoir site to
the Honey Creek Basin, technically resulting in a basin transfer. The proposed project seeks
to correct that and restore historic flow patterns. Because the site is at a localized highpoint,
the upstream tributary area to the project site is negligible.
Flow Control Best Management Practices (BMPs) are required for the project site per
RKCSWDM Section 1.2.3.3 since the project is subject to Core Requirement No. 3. The
proposed project is a non-subdivision project making improvements on an individual site/lot,
therefore, implementation of Flow Control BMPs shall be in accordance with the “Individual
Lot BMP Requirements” in Section 5.2.1 of the RKCSWDM. The site is more than 22,000 sf
and will have more than 45 percent impervious, therefore, it is considered a Large Lot High
Impervious site, and subject to RKCSWDM Section 5.2.1.2 – Large Lot High Impervious
BMP Requirements.
The criteria in the RKCSWDM for full dispersion was reviewed. Full dispersion was eliminated
from consideration since the existing site is developed with grass and not native vegetation. In
addition, it did not seem reasonable that the grassed areas could provide a sufficient hydrologic
response equivalent to full dispersion.
Since full dispersion is not feasible, the project’s target impervious surfaces are proposed to
be mitigated using low impact development techniques. The project has an impervious surface
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coverage of more than 65 percent; therefore, flow control BMPs must be applied to an
impervious area equal to at least 10 percent of the site/lot or 20 percent of the target
impervious surface, whichever is less. The following paragraphs detail the target impervious
surfaces and application of flow control BMPs by TDA.
JOHNS CREEK BASIN TDA DEVELOPED SITE HYDROLOGY (PART B)
The existing surface conditions are approximately 50 percent grass and 50 percent trees
(forested). The Flow Control Standard for the Johns Creek Basin is Peak Rate Flow Control
Standard – Match Existing. The Target Surfaces per RKCSWDM Section 1.2.3.1.A are the
new pervious and new impervious surfaces. Replaced impervious and replaced pervious
surfaces are not target surfaces. Tables 1, and 2 summarize the surface areas for modeling in
the King County Runoff Time Series (KCRTS). The “Model As…” part of Table 1 indicates
whether the surface was modeled as predeveloped (predev.tsf), developed (dev.tsf) or bypass
(bypass.tsf). The table identifies small areas that bypass the storm detention facilities because
of infeasibility to convey the runoff to the proposed storm detention facilities. Additionally,
the modeling identifies areas of the proposed access road around the reservoir that will be
retained and infiltrated slowly, as described in detail later in this section of the Report.
Table 1 – Johns Creek TDA Model As…
Stormwater Areas
Area
(ac) Predev.tsf Dev.tsf Bypass.tsf
Site & Project Site to Vault/Pump
Proposed Impervious to Vault
0.72 50% TG, 50% TF IMP --
Existing Impervious to Vault
0.48 IMP IMP --
Existing Pervious to Vault
1.02 TG TG --
Project Site to Bypass
Proposed Access Road to Infiltration
0.13 -- -- --
Proposed Pervious to Bypass
0.13 50% TG, 50% TF -- TG
Proposed Sidewalk to Bypass
0.04 TG -- IMP
Proposed Frontage Planter Strip to Bypass
0.03 TG -- TG
Notes: TG = Till Grass, TF = Till Forest, IMP = Impervious
Flow control BMPs must be applied to an impervious area equal to at least 10 percent of the
site/lot or 20 percent of the target impervious surface, whichever is less (Table 2). The target
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impervious surfaces in Table 1 are the Proposed Impervious to Vault, Proposed Access Road
to Infiltration, and Proposed Sidewalk to Bypass.
Table 2 – Flow Control BMP Calculations
Area Area (ac)
Johns Creek Basin TDA in Site 3.06
Target Impervious in Johns Creek Basin TDA 0.89
20 percent of Johns Creek Basin TDA 0.612
10 percent of Target Impervious 0.09
Area for Flow Control BMPs 0.09
The project proposes to accommodate the flow control BMP standard through the use of
infiltration into the soils below the access road subgrade for 0.13 acres of access road around
the proposed reservoir, thereby exceeding the minimum 0.09 acres required. The BMP will act
as permeable pavement but use traditional asphalt with a permeable subgrade instead. The
water will be allowed to sheet flow to the edge of the roadway and collect in a gravel trench
that is connected to the permeable subgrade, allowing water to infiltrate to the existing soils
beneath the pavement. The Geotechnical Report prepared by ZZA-Terracon (Appendix B)
indicates the soils below the topsoil are 2 to 5 feet of loose to medium density silty sand, which
is then underlain by dense to very dense sand with varying amounts of silt and gravel. In
reviewing the sieve analyses for Borings B-2 and B-4, which are generally the closest to the
project improvements, the project D10 size (10 percent of the material passing the sieve size
listed) would be 0.05 millimeters. Using guidance from Ecology’s Stormwater Management
Manual for Western Washington, 2012 Edition, the infiltration rate for this soil is 0.73 inches per
hour. The pavement was modeled using KCRTS and was determined that this method would
indeed infiltrate all stormwater from the proposed impervious roadway. Based on the area of
flow control BMPs calculations, it was determined that 0.09 acres are required to be infiltrated.
This resulted in 262 linear feet of a 15-foot-wide road, constructed with the permeable
subgrade for the Johns Creek Basin TDA. The areas where this road section will be used are
shown on the site plan in Appendix G. The calculations and typical road sections are also
found in Appendix G.
The project proposes to connect any proposed roof downspouts using a perforated pipe
connection.
HONEY CREEK BASIN TDA DEVELOPED SITE HYDROLOGY (PART B)
The Flow Control Standard for the Honey Creek Basin is Flow Control Duration Standard
Matching Forested Site Conditions. The Target Surfaces per RKCSWDM Section 1.2.3.1.A
are the new pervious and impervious surfaces and replaced impervious surface. Tables 4, 5,
and 6 summarize the surface areas for modeling in the King County Runoff Time Series
(KCRTS).
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Table 3 - Honey Creek TDA Model As…
Stormwater Areas
Area
(ac) Predev.tsf Dev.tsf Bypass.tsf
Proposed Impervious to Vault
0.76 TF IMP --
Existing Impervious to Vault
0.79 IMP IMP --
Existing Pervious to Vault
0.33 TG TG --
Project Site to Bypass
Proposed Access Road to Infiltration
0.11 -- -- --
Proposed Pervious to Bypass
0.10 TF -- TG
Proposed Sidewalk & Driveway to Bypass
0.02 TF -- IMP
Proposed Frontage Planter Strip to Bypass
0.01 TF -- TG
Flow control BMPs must be applied to an impervious area equal to at least 10 percent of the
site/lot or 20 percent of the target impervious surface, whichever is less (Table 4). The target
impervious surfaces in Table 3 are the Proposed Impervious to Vault, Proposed Access Road
to Infiltration, and Proposed Sidewalk & Driveway to Bypass.
Table 4 – Flow Control BMP Calculations
Area Area (ac)
Honey Creek Basin TDA in Site 1.84
Target Impervious in Honey Creek Basin TDA 0.89
20 percent of Honey Creek TDA 0.368
10 percent of Target Impervious 0.089
Area for Flow Control BMPs 0.089
The project proposes to accommodate the flow control BMP standard through the use of
infiltration into the soils below the access road subgrade for 0.11 acres of access road around
the proposed reservoir, thereby exceeding the minimum 0.09 acres required. The BMP will act
as permeable pavement but use traditional asphalt with a permeable subgrade instead. The
water will be allowed to sheet flow to the edge of the roadway and collect in a gravel trench
that is connected to the permeable subgrade, allowing water to infiltrate to the existing soils
beneath the pavement. A Geotechnical Report prepared by ZZA-Terracon (Appendix B)
indicates the soils below the topsoil are 2 to 5 feet of loose to medium density silty sand, which
is then underlain by dense to very dense sand with varying amounts of silt and gravel. In
reviewing the sieve analyses for Borings B-2 and B-4, which are generally the closest to the
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project improvements, the project D10 size (10 percent of the material passing the sieve size
listed) would be 0.05 millimeters. Using guidance from Ecology’s Stormwater Management
Manual for Western Washington the infiltration rate for this soil is 0.73 inches per hour. The
pavement was modeled using KCRTS and was determined that this method would indeed
infiltrate all stormwater from the proposed impervious roadway. Based on the area of flow
control BMPs calculations it was determined that 0.079 acres was required to be infiltrated.
This resulted in 230 linear feet of a 15-foot-wide road constructed with the permeable
subgrade for the Honey Creek Basin TDA. The areas where this road section will be used are
shown on the site plan in Appendix G. The calculations and typical road sections are also
found in Appendix G.
The project proposes to connect any proposed roof downspouts using a perforated pipe
connection.
JOHNS CREEK BASIN TDA PERFORMANCE STANDARDS (PART C)
The area specific Flow Control Standard is Peak Rate Flow Control Standard – Match
Existing.
The proposed project does not contain pollution-generating surfaces and, therefore, water
quality control facilities are not proposed.
HONEY CREEK TDA PERFORMANCE STANDARDS (PART C)
The area specific Flow Control Standard is Flow Control Duration Standard – Matching
Forested Site Conditions.
The proposed project does not contain pollution-generating surfaces and, therefore, water
quality control facilities are not proposed.
JOHNS CREEK BASIN TDA FLOW CONTROL SYSTEM (PART D)
A flow control facility is proposed for this project in the form of a detention vault. The
City’sWater Department staff were unsuccessful in obtaining an easement from downstream
property owners to route a storm pipe across their property for connecting to the storm system
in Sunset Boulevard. As such, a pump will be included in the proposed detention vault that
will pump the stormwater from the vault up to the gravity system in NE 12th Street which will
combine with the Sunset Boulevard storm system further downstream in the system. It is
anticipated that the pumped system will restore the historic flow patterns of the site by
discharging to Johns Creek instead of maintaining the basin transfer to Honey Creek that was
created by the retirement residence development north of the project site (as described above
in the Off-site Analysis section). It is expected that the pump will be equipped with a variable
frequency drive (VFD) which will include monitoring of the vault level to match the stage-
discharge performance of the outlet structure designed in KCRTS. The pump will discharge
to a private catch basin located on the project site near NE 12th Street, which will in-turn be
connected to the gravity-conveyance system located within NE 12th Street. Specific details and
specifications for the pump will be developed at the Utility Construction Permit application
submittal stage.
A proposed gravity conveyance system will be constructed in NE 12th Street to convey
stormwater to the west and to eventually connect to the existing gravity storm system in NE
12th Street, south of Monroe Avenue. The proposed gravity system will be designed and the
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existing downstream systems analyzed at the time of Utility Construction Permit application.
Refer to Appendix E, which contains a map showing the proposed pressure force main pipe
and downstream flow path for the stormwater pump discharge.
Frontage improvements are also required for the proposed project, including the addition of
curb and gutter, planter strip and sidewalk. The frontage improvements include traditional
curb/gutter with sidewalks sloped toward the road, and are not easily directed to the storm
detention facility because of hydraulics. As such, for the purposes of modeling, it was assumed
that runoff from the new impervious surfaces of the sidewalk and the plater strip could not
be routed to the detention facility and therefore were modeled as bypass areas.
ALTERNATE FOR FRONTAGE SURFACE WATER MANAGEMENT
At the time of Utility Construction Permit application, the City Water Department may elect
to incorporate additional low-impact development techniques for the proposed frontage
improvements. The curb and gutter may incorporate curb cuts allowing stormwater to flow
off the roadway and into the adjacent planter strip. The planter strip will act as a swale allowing
water to filter and partially infiltrate. Any excess stormwater that cannot infiltrate will then
flow over the proposed sidewalk, which can be sloped to drain toward the site for dispersion
on the site. This would mimic the existing conditions wherein the existing road runoff sheet
flows onto the site tends to disperse into the existing grass surfaces without any defined
channelized flow. Appendix G contains the frontage improvement details. The asphalt
pavement along the frontage is existing and no new or replaced impervious surfaces are
proposed for the driving lanes; therefore, the asphalt is not subject to detention or water
quality treatment requirements because it already exists. However, some level of treatment and
dispersion could be achieved by allowing the road runoff to disperse and infiltrate through the
planter strip. The proposed sidewalk for the frontage improvements is a new impervious
surface. Basic dispersion could be considered as a flow control BMP, thus the dispersed
impervious area (sidewalk) could be modeled as 50 percent impervious and 50 percent grass
in the KCRTS modeling software as per KCSWD Table 1.2.3.C. Due to the planter strip being
the same cover as existing conditions, there will be no change in peak flow from this area and
it was modeled as such. Appendix H contains the KCRTS Calculations.
Flow Control BMPs are proposed in the form of infiltrating road base for the target
impervious surface (described above).
HONEY CREEK BASIN TDA FLOW CONTROL SYSTEM (PART D)
A flow control facility is proposed for this project in the form of a detention vault.
Stormwater detention has been sized to meet Flow Control Duration Standard – Matching
Forested Site Conditions. Frontage improvements are also required for the proposed project,
including the addition of curb and gutter, planter strip, and sidewalk. The frontage
improvements include traditional curb/gutter with sidewalks sloped toward the road and are
not easily directed to the storm detention facility because of hydraulics. As such, for the
purposes of modeling, it was assumed that runoff from the new impervious surfaces of the
sidewalk and the plater strip could not be routed to the detention facility and therefore were
modeled as bypass areas.
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ALTERNATE FOR FRONTAGE SURFACE WATER MANAGEMENT
At the time of Utility Construction Permit Application, the Water Department may elect to
incorporate additional low-impact development techniques for the proposed frontage
improvements. The curb and gutter may incorporate curb cuts allowing stormwater to flow
off the roadway and into the adjacent planter strip. The planter strip will act as a swale allowing
water to filter and partially infiltrate into the planter. Any excess stormwater that cannot
infiltrate will flow over the proposed sidewalk, which can be sloped toward the site to allow
for full dispersion on-site. This would mimic the existing conditions wherein the existing road
runoff that sheet flows onto the site tends to disperse into the existing grass surfaces without
any defined channelized flow. Appendix G contains the frontage improvement details. The
asphalt pavement along the frontage is existing, and no new or replaced impervious surfaces
are proposed for the driving lanes; therefore, the asphalt is not subject to detention or water
quality treatment requirements as it already exists. However, some level of treatment and
dispersion could be achieved by allowing the road runoff to disperse and infiltrate through the
planter strip. The proposed sidewalk for the frontage improvements is a new impervious
surface. Basic dispersion could be considered as a flow control BMP, thus the dispersed
impervious area (sidewalk) could be modeled as 50-percent impervious and 50-percent grass
in the KCRTS modeling software, as per KCSWD Table 1.2.3.C. Due to the planter strip being
the same cover as existing conditions, there will be no change in peak flow from this area and
it was modeled as such. Appendix H contains the KCRTS Calculations.
Flow Control BMPs are proposed in the form of infiltrating road base for the target
impervious surface (described above).
WATER QUALITY SYSTEM (PART E)
A formal water quality control facility is not proposed for this project.
SECTION 5 – CONVEYANCE SYSTEM ANALYSIS AND DESIGN
An on-site piped conveyance system exists on the project site, and additional piped
conveyance systems are proposed as a part of this project. The preliminary conveyance design
has been provided for this permit submittal package.
For the Johns Creek TDA, an on-site conveyance system will be developed to route runoff
from existing and proposed surfaces to the proposed detention vault. The detention vault will
contain a pump with a VFD to pump water up to NE 12th Street where a gravity-conveyance
system will be constructed and routed to the west to connect to the existing gravity storm-
conveyance system in NE 12th Street.
For the Honey Creek TDA, the runoff from the unaffected portion of the site will be routed
to a proposed piped conveyance system which will replace the existing on-site system. The
flow will then outfall to the existing system to the northeast of the project site.
The proposed conveyance systems are to be designed in accordance with RKCSWDM Section
1.2.4.1. For the final design the proposed pipes will be sized to convey and contain the 25-
year peak flow at a minimum, and any overtopping of the system up to the 100-year event will
be routed as appropriate to the detention facility and discharge at the natural location (Honey
Creek) or the pumped system (Johns Creek). The tributary area is less than 10 acres; therefore,
in accordance with RKCSWDM Table 3.2, the Rational Method will be used to size and
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confirm conveyance components in conjunction with backwater analyses. The sizing,
confirmation and final design of conveyance components and layout will be provided for the
Utility Construction Permit application submittal.
The existing on-site conveyance system will be analyzed in accordance with RKCSWDM
Section 1.2.4.2. There will be a change in flow characteristics since some of the proposed pipes
will connect to the existing conveyance system. This requires the existing conveyance systems
to have sufficient capacity to convey and contain the 10-year peak flow at a minimum, and be
designed so that the 100-year event will not create or aggravate a severe flooding problem or
severe erosion problem for either TDA. In accordance with RKCSWDM Section 4.2.1.2, the
existing pipes need to be analyzed via a backwater analysis to confirm conveyance capacity.
At the time that the Utility Construction Permit Application is prepared, Appendix I will
contain the analyses of the existing and proposed conveyance systems.
SECTION 6 – SPECIAL REPORTS AND STUDIES
A Geotechnical Report has been prepared for the project site and is included in Appendix B.
Other special reports or studies have not been prepared for this project.
SECTION 7 – OTHER PERMITS
In addition to this Full Drainage Review, RH2 anticipates that the following City Permits will
be required:
State Environmental Protection Act (SEPA) compliance;
Fill and Grade Permit;
Conditional Use Permit;
Critical Areas Review; and
Utility Construction Permit.
An Ecology Construction Stormwater General Permit will be required since the proposed
project will disturb more than 1 acre of land. This will require the City Water Department to
prepare a Construction Surface Water Pollution Prevention Plan (SWPPP, known as a
CSWPPP in the RKCSWDM), submit a Notice of Intent (NOI) and publish associated public
notices. These documents will be prepared at a future date.
The project will also require review and approval from the Washington State Department of
Health for potable water facilities.
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SECTION 8 – CSWPPP ANALYSIS AND DESIGN
The CSWPPP will be updated prior to submitting documents for construction and permitting
approval.
ESC PLAN ANALYSIS AND DESIGN (PART A)
ESC MEASURES
Clearing Limits
Half of the existing site is already cleared and developed, the other half will require clearing
and grubbing to construct the proposed improvements. The proposed work will generally
require construction of cast in place concrete structures, mechanical piping, asphalt paving,
and landscaping that extend throughout the project site. As such, the clearing limits will
generally be dictated as the property boundaries. The project plans show these as the clearing
limits.
It seems that physical delineation of the perimeter of the property with high visibility fencing
or stake and wire fencing would yield little benefit to the contractor, especially since the
existing site perimeter is generally already fenced in. Trees within the construction area that
are to be preserved have been delineated on the plans, and trees to be removed are clearly
marked on the plans as well. Notes are provided on the plans to indicate that prior to beginning
land disturbing activities, including clearing and grading, trees to be preserved and trees to be
removed will be clearly marked.
Notes are provided on the plans to preserve native vegetation to the maximum extent possible,
particularly on slopes.
Applicable BMPs:
Preserving Natural Vegetation
Cover Measures
Exposed and unworked soils will be temporarily or permanently stabilized through the use of
hydroseeding, mulching, nets/blankets, plastic covering, crushed rock surfacing, cold-mix
asphalt, permanent asphalt or concrete paving. The areas to be permanently stabilized are
shown on the plans and generally consist of asphalt pavement, concrete pavement and grass
sod. (Note: City of Renton requires restoration using grass sod due to issues with lawn
establishment via seeding.)
Cut and fill slopes and trench restoration in lawn areas will most commonly be protected using
mulching and sodding.
From October 1 through April 30, no soils shall remain exposed and unworked for more than
two days. This two-day requirement may be applied at other times of the year if storm events
warrant more conservative measures. From May 1 to September 30, no soils shall remain
exposed and unworked for more than seven days. These stabilization requirements apply to
all soils on site, whether at final grade or not. Exposed soil must be covered immediately at
the threat of rain. These time limits may be adjusted by the local permitting authority if it can
be shown that the average time between storm events justifies a different standard.
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Applicable BMPs:
Mulching
Nets and Blankets
Plastic Covering
Sodding
Perimeter Protection
To the extent possible, the duff layer, native top soil and natural vegetation shall be retained
in an undisturbed state. This will provide good perimeter protection in itself. Since the project
site will remain entirely inhabited by the residents of 435 Pressure Zone Project, the contractor
must use a phased construction approach and limit disturbed areas to one parking lot at a time,
or one area of walkways to be replaced. Because the proposed construction will be phased in
a manner that will not substantially disturb and leave large areas of exposed soil subject to
rainfall and runoff, it is not anticipated that substantial perimeter protections will be necessary
and/or beneficial. Any runoff from the site will be routed through a catch basin that will be
equipped with inlet protection to filter sediment, see the Sediment Retention Section in this
TIR below.
Traffic Area Stabilization
Construction vehicle access will be limited to the existing driveway for the site off SE 204th
Street, although it is anticipated that some construction vehicles may occasionally exit the site
via the existing driveway at Benson Highway. The access points and construction vehicle
parking are already stabilized with asphalt pavement. It is not anticipated that substantial
vehicle travel will occur between paved areas and areas where the existing pavement is
removed, hence limiting sediment tracking.
Any sediment transported off the project site onto existing roads will require daily clean-up
utilizing shoveling and/or pickup sweeping, and the refuse shall be transported to a controlled
sediment disposal area. It is not anticipated that a wheel wash will be required.
Dust will primarily be controlled using limited clearing techniques of phased construction,
stabilizing surfaces with crushed surfacing and watering. It is not anticipated that dust
palliatives will be required at the project site.
Sediment Retention
The project does not propose a sediment pond or trap since it is not anticipated that substantial
areas of exposed soils will exist during construction, and a location for siting such a facility is
not readily feasible on the already developed site. To the extent possible, the duff layer, native
top soil and natural vegetation shall be retained in an undisturbed state.
Storm drain inlets operable during construction will be protected so that stormwater runoff
does not enter the conveyance system without first being filtered or treated to remove
sediment. Prefabricated, below-grate inlet protection devices will be installed following
construction of the proposed catch basins to trap sediment at the catch basins. Inlets will be
inspected regularly to ensure their functionality.
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Applicable BMPS:
Preserving Natural Vegetation
Storm Drain Inlet Protection
Surface Water Collection
The proposed project will generally use the existing on-site system of catch basins and pipes
to collect and convey water. It is not anticipated that the proposed project will construct a
temporary sediment trap or pond. Water entering the on-site collection system will be filtered
using storm drain inlet protection.
Dewatering Control
It is not anticipated the proposed project will require dewatering.
Dust Control
Dust will be controlled through the use of phased construction to limit disturb areas, watering
and/or vacuum street sweepers.
Flow Control
The project does not propose flow control facilities.
ESC PERFORMANCE AND COMPLIANCE PROVISIONS
The changing conditions typical of construction sites call for frequent field adjustments of
existing ESC measures or additional ESC measures in order to meet required performance. In
some cases, strict adherence to specified measures may not be necessary or practicable based
on site conditions or project type. In other cases, immediate action may be needed to avoid
severe impacts. Therefore, careful attention must be paid to ESC performance and compliance
in accordance with the following provisions.
ESC Supervisor
City of Renton has negotiated with the general contracting firm, W.G. Clark. W.G. Clark
possesses multiple staff members qualified to perform the role of ESC Supervisor and they
propose to use Trevor Johnson, Superintendent for the ESC Supervisor on the 435 Pressure
Zone Project.
Monitoring of Discharges
The ESC supervisor from W.G. Clark will have a turbidity meter on-site and shall use it to
monitor surface and stormwater discharges from the project site whenever runoff occurs from
on-site activities and during storm events. The project site is subject to a NPDES general
permit for construction issued by the Washington State Department of Ecology, and the
project will comply with the monitoring requirements of that permit.
ESC Performance
ESC measures shall be applied/installed and maintained to prevent, to the maximum extent
practicable, the transport of sediment from the project site to downstream drainage systems
or surface waters or into on-site wetlands, streams, or lakes or onto adjacent properties. This
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performance is intended to be achieved through proper selection, installation and operation
of the above ESC measures as detailed on the plan sheets. However, the ESC supervisor or
King County may determine at any time during construction that the approved measures are
not sufficient and that additional action is required based on any of the following criteria.
1) If a turbidity test of surface and stormwater discharge leaving the project site is greater
than the benchmark value of 25 NTU (nephelometric turbidity units) set by the
Washington State Department of Ecology, but less than 250 NTU, the ESC Supervisor
shall:
a) Review the ESC plan for compliance and make appropriate revisions within 7 days of
the discharge that exceeded the benchmark of 25 NTU;
b) Fully implement and maintain appropriate ESC measures as soon as possible but no
later than 10 days after the discharge that exceeded the benchmark; and
c) Document ESC implementation and maintenance in the site log book.
2) If a turbidity test of surface or stormwater entering on-site wetlands, streams or lakes
indicates a turbidity level greater than 5 NTU above background when the background
turbidity is 50 NTU or less, or 10 percent above background when the background
turbidity is greater than 50 NTU, then corrective actions and/or additional measures
beyond those specified in Section 1.2.5.1 shall be implemented as deemed necessary by
the King County inspector or on-site ESC supervisor.
3) If discharge turbidity is 250 NTU or greater, the ESC Supervisor shall:
a) Notify King County by telephone;
b) Review the ESC plan for compliance and make appropriate revisions within 7 days of
the discharge that exceeded the benchmark of 25 NTU;
c) Fully implement and maintain appropriate ESC measures as soon as possible but no
later than 10 days after the discharge that exceeded the benchmark;
d) Document ESC implementation and maintenance in the site log book; and
e) Continue to sample discharges until turbidity is 25 NTU or lower, or the turbidity is
no more than 10 percent over background turbidity.
4) If King County determines that the condition of the construction site poses a hazard to
an adjacent property or may adversely impact drainage facilities or water resources, then
additional measures beyond those specified in Section 1.2.5.1 may be required by King
County.
STORMWATER POLLUTION PREVENTION AND SPILL (SWPPS) PLAN (PART B)
This SWPPS Plan shall be kept on site at all times and consists of three elements: the SWPPS
Site Plan in the plan set; the Pollution Prevention Report; and the Spill Prevention and Cleanup
Report. The contractor shall provide a copy of this SWPPS Plan to all subcontractors and
have the subcontractors return a signed form that states the subcontractors have read and
agree to the SWPPS Plan.
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POLLUTION PREVENTION REPORT
All pollutants, including waste materials, that occur during construction will be handled and
disposed of in a manner that does not cause environmental contamination. Material Safety
Data Sheets (MSDS) shall be kept on the project site and reviewed prior to use of any
associated liquids or materials.
Storage and Handling of Liquids
Source: The following liquids will likely be handled or stored onsite: petroleum products, fuel,
solvents, detergents, paint, pesticides, concrete admixtures and form oils. These liquids shall
be stored in the original containers shipped by the manufacturer and applied in a manner
consistent with the manufacturers’ recommendations so as to not create pollution. It is
anticipated that product size will be 5 gallons or less each. Secondary containment shall be
provided for all liquids stored on the site.
Monitoring: Places for storing liquids shall be inspected at least weekly to confirm containers
are not leaking and that secondary containment is intact. Handling of the liquids shall be
monitored by reviewing the labels on the original containers to ensure handling is consistent
with the manufacturers’ recommendations.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
Storage and Stockpiling of Construction Materials and Wastes
Source: Construction materials and wastes that may be generated or stockpiled onsite are
anticipated to be asphalt, concrete, crushed rock and soil. The locations where these materials
and wastes will be generated and stockpiled are generally in the parking areas of the project
site.
For any materials stockpiled, plastic covering shall be installed per the detail and notes on the
plan sheets to keep rainwater from contacting construction materials and wastes that can
contribute pollutants to storm, surface and ground water.
If wastes are kept in containers, they shall have secure lids that keep rainwater out of the
containers.
Monitoring: Construction wastes that are stockpiled onsite shall be visually inspected to ensure
that proper plastic covering is provided to keep rainwater from contacting the materials. If
waste containers are provided, they shall be inspected to ensure the lids are closed and secure
after depositing material.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
Fueling
Source: It is anticipated that fueling operations will occur via mobile truck mounted fueling
tanks. Fueling operations shall be located to ensure leaks or spills will not discharge, flow or
be washed into the storm drainage system, surface water or groundwater. Drip pans and/or
absorbent pads shall be used capture drips or spills during fueling operations. If fueling occurs
during evening hours, the contractor shall provide a mobile lighting unit.
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Monitoring: Fueling operations and areas around them shall be visually inspected before,
during and after fueling to evaluate and ensure a spill does not exist or occur.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
Maintenance, Repairs, and Storage of Vehicles and Equipment
Source: Maintenance and repair areas shall generally be located within the existing parking
areas of the site. Use of drip pans or plastic beneath vehicles is required. The contractor shall
implement spill prevention techniques during all maintenance activities. Collection and storage
shall be done using containers approved for such use. Disposal of vehicle fluids shall be in
conformance with all applicable laws and regulations. All spills shall be reported to the
Washington Emergency Management Division at 1-800-258-5990, National Response Center
at 1-800-424-8802 and Department of Ecology at 1-425-649-7000.
No vehicle washing may occur on the project site. If an area is designated for vehicle
maintenance, signs must be posted that state no vehicle washing may occur in the area.
Monitoring: Areas for maintenance, repair and storage of vehicles shall be visually inspected
to ensure that a leak or spill does not exist or occur. Vehicles shall be inspected at least weekly
for signs of any leaks of fluids.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
Concrete Saw Cutting, Slurry, and Washwater Disposal
Source: The project will require the installation of concrete walkways; therefore, the contractor
will be required to wash concrete chutes within an area that does not have conveyance to the
surface water. The contractor shall provide necessary sumps within the project site. Hand tools
including, but not limited to, screeds, shovels, rakes, floats and trowels shall be rinsed at the
same sump location(s).
Sawcutting of pavement requires vacuuming of the slurry and cuttings following the operation.
The slurry and cuttings will be disposed of in a manner that does not violate groundwater and
surface water quality standards. The slurry will not be allowed to remain on the pavement
overnight.
Monitoring: The responsible person for this spill control item shall inspect wash areas during
all wash outs to ensure no conveyance to surface water occurs. Sawcutting of pavement shall
be visually inspected during the cutting process to ensure that slurry and cuttings are
immediately removed and properly disposed of.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
Handling of pH Elevated Water
Source: It is not anticipated that the proposed concrete walkways will cause collected water to
have an elevated pH. In the event that water does collect and generate an elevated pH, this
water cannot be discharged to storm or surface water until neutralized. The contractor shall
provide methods for neutralizing the pH and/or disposing of it without violating groundwater
and surface water quality standards
Monitoring: The responsible person shall review areas before concrete pours to identify
locations where the potential exists to create a pooling of pH elevated water. After concrete
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pours, any areas identified shall be monitored by the responsible individual. Testing shall occur
if elevated pH water is suspected.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
Application of Chemicals, including Pesticides and Fertilizers
Source: It is anticipated that fertilizer may be used on the project to establish lawn (sod) for
landscaped areas that are disturbed. It is anticipated that weed killer may be used prior to
establishing paved areas, which are delineated on the plans as asphalt paving with subgrade.
Chemicals shall be stored in the contractor’s trailer or tools storage box and secondary
containment for the chemicals shall be provided.
Application of agricultural chemicals, including fertilizers and herbicides, shall be conducted
in a manner and at application rates that will not result in loss of chemical to stormwater
runoff. Manufacturers’ recommendations for application rates and procedures shall be
followed.
Monitoring: Individuals applying chemicals shall review the labeling on the original containers
for appropriate application rates and conform to those rates. The responsible individual shall
monitor application process to ensure it occurs consistent with the manufacturers’
recommendations.
Personnel Responsible: Trevor Johnson, Superintendent, (206) 624-5244 or (206) 708-9801
The contractor shall maintain spill response materials at the job trailer and/or tools storage
box.
Sample worksheets are provided in Appendix J for record keeping and reporting.
The following activities are anticipated for the project site and the associated BMPs from the
King County Stormwater Pollution Prevention Manual and Stormwater Management Manual for Western
Washington are included in Appendix K.
Activity Sheet A-4: Storage of Soil, Sand, and Other Erodible Materials
Activity Sheet A-17: Fueling Operations
Activity Sheet A-18: Engine Repair and Maintenance
Activity Sheet A-20: Concrete and Asphalt at Temporary Sites
Activity Sheet A-26: Landscaping Activities
BMP C151: Concrete Handling
BMP C152: Sawcutting and Surfacing Pollution Prevention
SPILL PREVENTION AND CLEANUP REPORT
MSDS shall be kept on the project site and reviewed prior to use of any associated liquids or
materials.
Sources of a spill are generally consistent with the activities described above in the Pollution
Prevention Report and include the following.
Storage and Handling of Liquids
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Storage and Stockpiling of Construction Materials and Wastes
Fueling
Maintenance, Repairs, and Storage of Vehicles and Equipment
Concrete Saw Cutting, Slurry and Washwater Disposal
Handling of pH Elevated Water
Application of Chemicals, including Pesticides and Fertilizers
Spill prevention BMPs are the same as implementing the strategies listed above in the Pollution
Prevention Report. Additional BMPs include the following good housekeeping practices.
An effort will be made to store only enough product required to do the job.
All materials stored onsite will be stored in a neat, orderly manner in their appropriate
containers and, if possible, under a roof or other enclosure.
Products will be kept in their original containers with the original manufacturer's label.
Substances will not be mixed with one another unless recommended by the
manufacturer.
Whenever possible, all of a product will be used up before disposing of the container.
Manufacturers' recommendations for proper use and disposal will be followed.
The site superintendent will inspect daily to ensure proper use and disposal of
materials.
The person responsible for spill prevention and cleanup is Trevor Johnson, Superintendent,
(206) 624-5244 or (206) 708-9801.
Procedures for monitoring spill prevention shall be via informing construction crews to
inform the spill prevention lead (responsible person) of any spills and to monitor activities as
described in the Spill Prevention Report as detailed above.
The following procedures are provided as a guideline for responding to a spill, and the
contractor will need to develop procedures specific to the construction operations as
appropriate.
1. Immediately alert area occupants and supervisor, and evacuate the area, if necessary.
2. If there is a fire or medical attention is needed, contact Emergency Services at 911.
3. Attend to any people who may be contaminated. Contaminated clothing should be
removed immediately and, if appropriate, the skin flushed with water. Clothing should
be laundered before reuse. Seek first aid for chemical exposures as appropriate.
4. If a volatile, flammable material is spilled, immediately warn everyone, control sources
of ignition and ventilate the area.
5. Don personal protective equipment as appropriate to the hazards. Refer to the MSDS
or other references for information.
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6. Consider the need for respiratory protection. The use of a respirator or self-contained
breathing apparatus requires specialized training and medical surveillance. Never enter
a contaminated atmosphere without protection or use a respirator without training. If
respiratory protection is needed and no trained personnel are available, call Emergency
Services at 911. If respiratory protection is used, be sure there is another person
outside the spill area in communication, in case of an emergency. If no one is available,
contact Emergency Services.
7. If the spill is large, there has been a release to the environment or there is no one
knowledgeable about spill clean-up available, contact Emergency Services at 911.
8. Protect drains or other means for environmental release. Spill socks and absorbents
may be placed around drains, as needed.
9. If appropriate, contain and clean-up the spill accordingly. Spill control materials may
be distributed over the entire spill area, working from the outside, circling to the inside.
This reduces the chance of splash or spread of the spilled chemical.
10. When spilled materials have been absorbed, use tools to brush and scoop the materials
to remove them to an appropriate container. Polyethylene bags may be used for small
spills. Five gallon pails or 20 gallon drums with polyethylene liners may be appropriate
for larger quantities.
11. Complete a hazardous waste sticker, identifying the material as Spill Debris involving
XYZ Chemical, and affix onto the container. Spill control materials will probably need
to be disposed of as hazardous waste. Contact the Washington State Department of
Ecology for advice on storage and packaging for disposal.
12. If appropriate, decontaminate the surfaces where the spill occurred using a mild
detergent and water.
The contractor shall maintain spill response materials at the job trailer and/or tools storage
box.
Sample worksheets are provided in Appendix J for recordkeeping and reporting.
The following activities are anticipated for the project site and the associated BMPs from the
King County Stormwater Pollution Prevention Manual and Stormwater Management Manual for Western
Washington are included in Appendix K.
Activity Sheet A-4: Storage of Soil, Sand, and Other Erodible Materials
Activity Sheet A-17: Fueling Operations
Activity Sheet A-18: Engine Repair and Maintenance
Activity Sheet A-20: Concrete and Asphalt at Temporary Sites
Activity Sheet A-26: Landscaping Activities
BMP C151: Concrete Handling
BMP C152: Sawcutting and Surfacing Pollution Prevention
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SECTION 9 – BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF
COVENANT
In accordance with RKCSWDM Section 1.2.7 – Core Requirement No. 7 – Financial
Guarantees and Liability, all persons constructing any surface water facilities are required to
post with the City of Renton a bond, assignment of funds or certified check. For this project
the City of Renton’s Water Department requests that this requirement be waived, consistent
with RCW 35.21.470, which states:
“A city or town may not require any state agency or unit of local government to secure
the performance of a permit requirement with a surety bond or other financial security
device, including cash or assigned account, as a condition of issuing a permit to that
unit of local government for a building construction project.
As used in this section, "building construction project" includes, in addition to its usual
meaning, associated landscaping, street alteration, pedestrian or vehicular access
alteration, or other amenities or alterations necessarily associated with the project.”
The Declaration of Covenant is not anticipated to be required since the facilities are to be
owned by the City of Renton.
SECTION 10 – OPERATIONS AND MAINTENANCE MANUAL
The operations and maintenance manual can be found in Appendix L. The elements covered
are as follows.
1. Control Structure/Flow Restrictor (Spill Control Manhole)
2. Catch Basins and Manholes
3. Conveyance Pipes and Ditches
4. Debris Barriers
This concludes the Technical Information Report.