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Technical Information Report
Talbot Substation Stormwater Support Puget Sound Energy
Renton, Washington April 17, 2017
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Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | i
Contents
1 Project Overview ................................................................................................................................. 1
1.1 Existing Conditions .................................................................................................................... 1
1.2 Proposed Conditions ................................................................................................................. 2
2 Conditions and Requirements Summary ............................................................................................ 2
3 Offsite Analysis .................................................................................................................................... 4
4 Flow Control and Water Quality Facility Analysis and Design ............................................................ 8
5 Conveyance System Analysis and Design ........................................................................................ 13
6 Special Reports and Studies ............................................................................................................. 13
7 Other Permits .................................................................................................................................... 13
8 CSWPPP Analysis and Design ......................................................................................................... 14
9 Bond Quantities, Facility Summaries, and Declaration of Covenant ................................................ 17
10 Operations and Maintenance Manual ............................................................................................... 17
11 References ........................................................................................................................................ 17
Tables
Table 1: Existing Condition Acreage and Peak Flow Values ........................................................................ 8
Table 2: Proposed Condition Acreage and Peak Flow Values ..................................................................... 9
Table 3: Existing and Proposed Land Use Summary ................................................................................. 10
Table 4: Pre-developed and Proposed Controlled Flow Comparison ........................................................ 12
Table 5: Additional Project Permit Requirements ....................................................................................... 14
Figures
Figure 1: TIR Worksheet
Figure 2: Site Location
Figure 3: Drainage Basins, Subbasins, and Site Characteristics
Figure 4: Soils
Figure 5: Flow Chart for Determining Type of Drainage Review Required
Figure 6: Offsite Analysis
Figure 7: Existing Hydrology
Figure 8: Proposed Hydrology
Figure 9: Flow Chart for Determining Individual Lot BMP Requirements of the SWDM
Figure 10: Pond Sketch
Technical Information Report
Talbot Substation Stormwater Support
ii | November 16, 2016
Appendices
Appendix A: Firmette
Appendix B: Drainage System Table
Appendix C: Site Photos
Appendix D: Reference 11-A Flow Control Areas
Appendix E: Stormwater Model Output
Appendix F: Construction Stormwater Pollution Prevention Plan
Appendix G: Facility Summaries and Declaration of Covenant
Appendix H: Operations and Maintenance Manual
Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | 1
1 Project Overview
Puget Sound Energy (PSE) is proposing a series of improvements at their Talbot
Substation located in Renton, Washington. A copy of the TIR Worksheet (Figure 1) is
located below. Figure 2 below shows the site location and adjacent critical areas.
Proposed improvements will occur on the eastern side of the substation (referred to as
the project area), and will include the installation of foundations, security perimeter fence,
landscape screening, paving of a small portion of the access road, installation of a new
stormwater drainage and flow control system, road maintenance, and on-site oil spill
control best management practices (BMPs). The extent of disturbance will be
approximately 5.89 acres. Approximately 4.17 acres will consist of gravel road and
surface improvements. Another 1.22 acres will be for the installation of new foundations
and Spill Prevention, Control, and Countermeasures (SPCC) structures. The remaining
0.5 acres will be for installation of a stormwater detention pond. The existing site
contains electrical structures, and yard rock covers the ground surface. The existing and
proposed conditions as well as the site constraints are described below.
1.1 Existing Conditions
1.1.1 Topography
The Talbot substation covers approximately 7.75 acres between Beacon Way South,
South Puget Drive, and Grant Ave South in Renton, W ashington, as shown in Figure 2.
The site is located near the top of a ridge and is primarily accessed from South Puget
Drive, which ties into a gravel driveway leading to the site. The topography inside the
substation slopes slightly away from the center to promote drainage away from electrical
equipment. The existing grade outside the substation fence generally slopes away from
the substation except on the eastern and northwestern sides where there is elevated
terrain.
1.1.2 Drainage
In general stormwater runoff flows outwards from the middle of the substation. Existing
drainage pipes on the northeast and southeast sides of the substation are tied to catch
basins within the fence line whose rims are slightly raised above the yard rock,
preventing them from capturing flow. The perimeter path on the northeastern side of the
substation is higher than the existing grade within the fence line, preventing flow from
draining off the site along this edge. An elevated field along the eastern edge of the site
prevents drainage away from the substation on this side. Runoff along the northeastern,
eastern, and southeastern sides of the substation therefore tends to pond within the
substation and infiltrate. Along the southern edge of the substation, runoff is able to flow
south across the southern perimeter path and into a depression located between the
substation and access road. This route presents the path of least resistance for
stormwater. The depression is drained by a culvert beneath the access road to a second
depression which drains eastwards, towards Grant Avenue South. Existing drainage
patterns are shown in Figure 3. Existing soil types can be found on Figure 4.
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual 1/9/2009
KING COUNTY, WASHINGTON
SURFACE WATER DESIGN MANUAL
REFERENCE 8-A
TECHNICAL INFORMATION
REPORT (TIR) WORKSHEET
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2009 Surface Water Design Manual 1/9/2009
1
Part 1 PROJECT OWNER AND
PROJECT ENGINEER Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Owner ________________________
Phone ______________________________
Address ____________________________
____________________________________
Project Engineer ______________________
Company ___________________________
Phone ______________________________
Project Name _________________________
DDES Permit # ________________________
Location Township ______________
Range ________________
Section ________________
Site Address __________________________
_____________________________________
Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS
Landuse Services
Subdivison / Short Subd. / UPD
Building Services
M/F / Commerical / SFR
Clearing and Grading
Right-of-Way Use
Other _______________________
DFW HPA
COE 404
DOE Dam Safety
FEMA Floodplain
COE Wetlands
Other ________
Shoreline
Management
Structural
Rockery/Vault/_____
ESA Section 7
Part 5 PLAN AND REPORT INFORMATION
Technical Information Report Site Improvement Plan (Engr. Plans)
Type of Drainage Review
(circle):
Date (include revision
dates):
Date of Final:
Full / Targeted /
Large Site
___________________
___________________
___________________
Type (circle one):
Date (include revision
dates):
Date of Final:
Full / Modified /
Small Site
__________________
__________________
__________________
Part 6 ADJUSTMENT APPROVALS
Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket
Description: (include conditions in TIR Section 2)
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
Date of Approval: ______________________
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2009 Surface Water Design Manual 1/9/2009
2
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes / No
Start Date: _______________________
Completion Date: _______________________
Describe: _________________________________
_________________________________________
_________________________________________
_________________________________________
_________________________________________
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Community Plan : _________________________________
Special District Overlays: __________________________________________________________
Drainage Basin: ___________________________________
Stormwater Requirements: ________________________________________________________
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
River/Stream _______________________
Lake _____________________________
Wetlands ___________________________
Closed Depression ___________________
Floodplain __________________________
Other ______________________________
___________________________________
Steep Slope ______________________
Erosion Hazard ___________________
Landslide Hazard __________________
Coal Mine Hazard __________________
Seismic Hazard ___________________
Habitat Protection __________________
_________________________________
Part 10 SOILS
Soil Type
_________________
_________________
_________________
_________________
Slopes
_________________
_________________
_________________
_________________
Erosion Potential
_________________
_________________
_________________
_________________
High Groundwater Table (within 5 feet)
Other ________________________
Sole Source Aquifer
Seeps/Springs
Additional Sheets Attached
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2009 Surface Water Design Manual 1/9/2009
3
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE
Core 2 – Offsite Analysis_________________
Sensitive/Critical Areas___________________
SEPA________________________________
Other_________________________________
_____________________________________
LIMITATION / SITE CONSTRAINT
_______________________________________
_______________________________________
_______________________________________
_______________________________________
_______________________________________
Additional Sheets Attached
Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area)
Threshold Discharge Area:
(name or description)
Core Requirements (all 8 apply)
Discharge at Natural Location Number of Natural Discharge Locations:
Offsite Analysis
Level: 1 / 2 / 3 dated:__________________
Flow Control
(incl. facility summary sheet)
Level: 1 / 2 / 3 or Exemption Number ____________
Small Site BMPs ___________________________________
Conveyance System
Spill containment located at: _________________________
Erosion and Sediment Control
ESC Site Supervisor:
Contact Phone:
After Hours Phone:
Maintenance and Operation
Responsibility: Private / Public
If Private, Maintenance Log Required: Yes / No
Financial Guarantees and
Liability
Provided: Yes / No
Water Quality
(include facility summary sheet)
Type: Basic / Sens. Lake / Enhanced Basicm / Bog
or Exemption No. ______________________
Landscape Management Plan: Yes / No
Special Requirements (as applicable)
Area Specific Drainage
Requirements
Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None
Name: ________________________
Floodplain/Floodway Delineation Type: Major / Minor / Exemption / None
100-year Base Flood Elevation (or range): ______________
Datum:
Flood Protection Facilities
Describe:
Source Control
(comm./industrial landuse)
Describe landuse:
Describe any structural controls:
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2009 Surface Water Design Manual 1/9/2009
4
Oil Control
High-use Site: Yes / No
Treatment BMP: ________________________________
Maintenance Agreement: Yes / No
with whom? ____________________________________
Other Drainage Structures
Describe:
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
Clearing Limits
Cover Measures
Perimeter Protection
Traffic Area Stabilization
Sediment Retention
Surface Water Collection
Dewatering Control
Dust Control
Flow Control
MINIMUM ESC REQUIREMENTS
AFTER CONSTRUCTION
Stabilize Exposed Surfaces
Remove and Restore Temporary ESC Facilities
Clean and Remove All Silt and Debris, Ensure
Operation of Permanent Facilities
Flag Limits of SAO and open space
preservation areas
Other ______________________
Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch)
Flow Control Type/Description Water Quality Type/Description
Detention
Infiltration
Regional Facility
Shared Facility
Flow Control
BMPs
Other
________________
________________
________________
________________
________________
________________
Biofiltration
Wetpool
Media Filtration
Oil Control
Spill Control
Flow Control BMPs
Other
________________
________________
________________
________________
________________
________________
________________
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2009 Surface Water Design Manual 1/9/2009
5
Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS
Drainage Easement
Covenant
Native Growth Protection Covenant
Tract
Other
Cast in Place Vault
Retaining Wall
Rockery > 4’ High
Structural on Steep Slope
Other
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this worksheet and the attached Technical Information Report. To the best of my
knowledge the information provided here is accurate.
Signed/Date
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Talbot Substation
Thunder Hills Creek
Ginger Creek
SE ROYAL HILLS DRSE 19TH STROLLING HILLS AVE SESE 18TH PL
SE 16TH PL
116TH AVE SES E 8 T H D R
JONES DR SEGRANT AVE SPUGET DR SESE 8TH PL
CEDAR RIDGE DR SE
PATH: G:\PROJEC TS\WAS HINGTON\PUGET_SOUND_EN ERGY_00 702 2\TAL BOT_STORMWATER_SUPPORT_2699 66\MAP_DOCS \DRAF T\T IR FIGURES\FIGURE_2 _SITE_LOCATION.MXD - USER: TAHOFFMA - DAT E: 11 /1 6/2 016
TALBOT STORMWATER SUPPORT
FIGURE 2
SITE LOCATION
STORMWATER TIR
0 500Feet
O
DATA SOURCE: City of Renton,King County (2016)
LEGEND
Project Are a
Roads
Streams
Coa lmineHazardArea
Wetlan ds
Landslide Hazard
Steep Slo pes
Project Location
SR-520
I-90
I-405
I-405
I-5
I-5
SR-167
Longe st Proposed Flow path toFlow Control Facility: 630 feet
Ex isting a nd ProposedDischarge Point
440
430
420
410
4304204604504 2 0410 410400420410410430
440
460450450
4
4
0
4 4 0
440440
420400
400460
4 4 0
430
4 2 0
410
Project Are aSubbasin:5.89 Acres
LocalizedDepression
LocalizedDepression
LocalizedDepression
PATH: G:\PROJEC TS\WAS HINGTON\PUGET_SOUND_EN ERGY_00 702 2\TAL BOT_STORMWATER_SUPPORT_2699 66\MAP_DOCS \DRAF T\T IR FIGURES\FIGURE_3 _DRAINAGE.MX D - USER: TAHOF FMA - DATE: 11/16 /20 16
TALBOT STORMWATER SUPPORT
FIGURE 3
DRAINAGE BASINS, SUBBASINS, AND SITE CH ARACTERISTICS
STORMWATER TIR
0 250Feet
O
DATA SOURCE: City of Renton,King County (2016)
LEGEND
Project Are a
Con to urs - 10 ft In te rval
Existin gFlow Pa th
Propo sedFlow Pa th
Existin gDrainageInfrastructur e
Propo sedDrainageInfrastructur e
Propo sedDetention Pond
Pond ed Wa terObserved Dur ingField Visit
ROLLINGHILLSAVE SE
LINCOLNCT SEBLAINE CT SEABERDEENCT SESE 16TH PL PUGET DR SEGRANT AVE SAgD
AmC
AgC
InC
BeD
PATH: G:\PROJECTS\WAS HINGTON\PUGET_SOUND_E NERGY_00 702 2\TALBOT_STORMWATER_SUPPORT_269 966\MAP_DOCS\DR AFT\TIR FIGURES\FIGURE_4 _SOILS.MXD - USER: TAHOFFMA - DAT E: 11 /1 6/2016
TALBOT STOMWATER SUPPORT
FIGURE 4
SOILS
STORMWATER TIR
0 190Feet
O
DATA SOURCE: USDA Web Soil Survey,King County
LEGEND
Project Area
Soil Group
Roads
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Talbot Substation Stormwater Support
2 | November 16, 2016
1.2 Proposed Conditions
Proposed conditions will include a re-graded gravel surface within the substation
(approximately 3.43 acres), additional SPCC structures and equipment foundations
(approximately 1.22 acres), re-grading of gravel and asphalt roads (approximately 0.74
acres), and the addition of a pond for flow control (approximately 0.5 acres). The
proposed conditions will increase impervious area at the site by approximately 15%. This
percentage is primarily due to the addition of the SPCC structures and equipment
foundations, as well as asphalt entries to the gravel access driveways. Yard rock
surfaces will only be replaced or re-graded, they will not be added.
The gravel surface inside the fence line of the substation will be re-graded to smooth any
slight depressions in the gravel, promote flow to catch basins, and subsequently limit
ponding around electrical equipment and structures. The proposed improvements will not
significantly modify the grade of the existing substation or access roads.
The impervious SPCC structures and equipment foundations will be added within the
substation fence. The asphalt surface will be added at the intersection of the gravel
access way and South Puget Drive.
Drainage improvements include a new stormwater conveyance network inside the
substation which will route flows to a 75,000 cubic foot stormwater detention pond
located along the southeastern edge of the substation. This pond will discharge to a
depression on the southern side of the existing access road, where flow will resume the
existing drainage path towards Grant Avenue South. Proposed drainage facilities can be
found on Figure 3.
Landscape screening will be installed along the southwest side of the substation property
border and the perimeter of the pond. Landscaping will replace non-native plant cover
such as blackberry shrubs and non-native grasses.
2 Conditions and Requirements Summary
The project is subject to the City of Renton Amendments to the 2009 King County
Surface Water Design Manual (KCSWDM), as well as the City of Renton Municipal
Code. According to Section 1.1.1 of the City of Renton Amendments to the KCSWDM
(COR SWDM), projects resulting in 2,000 square feet or more of new impervious
surface, replaced impervious surface, or new plus impervious surface, or 7,000 square
feet or more of land disturbing activity require a Drainage Review. Additionally, per
Section 1.1.2 of the COR SWDM projects which result in greater than 2,000 square feet
of new impervious surface and greater than 35,000 square feet of pervious surface are
required to perform a Full Drainage Review. Figure 5 contains the Flow Chart for
Determining Type of Drainage Review Required and shows that the project requires a
Full Drainage Review. Projects undergoing a Full Drainage Review must meet the Core
Requirements and Special Requirements contained in the COR SWDM. These
requirements are broken down and discussed in greater detail below.
Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | 3
2.1 Core Requirement #1: Discharge at the Natural
Location
Proposed projects must discharge runoff at the natural location and comply with the
discharge requirements of Core Requirement #1. The proposed stormwater detention
pond which collects runoff from the conveyance system within the substation discharges
to the natural discharge location, as shown on Figure 3. Per the discharge requirements
of Core Requirement # 1, if the proposed 100-year flow event peak discharge is greater
than 0.5 CFS a conveyance system must be provided to convey concentrated runoff to
an acceptable discharge point (COR SWDM, 2009). The 100-year peak flow event for
the proposed project is larger than 0.5 CFS, and will be routed through the proposed
conveyance system and stormwater detention pond to the natural discharge location.
The proposed stormwater detention pond will control stormwater flows generated by the
substation and discharge at a rate that meets the flow control regulatory requirements.
2.2 Core Requirement #2: Offsite Analysis
Core Requirement #2 is discussed in detail in Section 3 of this report.
2.3 Core Requirement #3: Flow Control
Core Requirement #3 is discussed in detail in Section 4 of this report.
2.4 Core Requirement #4: Conveyance System
Core Requirement #4 is discussed in detail in Section 5 of this report.
2.5 Core Requirement #5: Erosion and Sediment Control
Core Requirement #5 is discussed in detail in Section 8 of this report.
2.6 Core Requirement #6: Maintenance and Operations
Core Requirement #6 is discussed in detail in Section 10 of this report.
2.7 Core Requirement #7: Financial Guarantees and
Liability
Core Requirement # 7 is discussed in detail in Section 9 of this report.
2.8 Core Requirement #8: Water Quality
The project site qualifies for the Surface Area Exemption detailed in Section 1.2.8 of the
COR SWDM (City of Renton, 2009).
• Less than 5,000 square feet of new PGIS that is not fully dispersed will be added
and
Technical Information Report
Talbot Substation Stormwater Support
4 | November 16, 2016
• less than 5,000 square feet of new plus replaced PGIS that is not fully dispersed
will be created as part of a redevelopment project and
• less than 35,000 square feet of new PGPS that is not fully dispersed will be
added.
Because this project adds less than 5,000 square feet of PGIS and less than 35,000
square feet of new PGPS, water quality facilities are not required at the project site.
2.9 Special Requirement #1: Adopted Area Specific
Regulations
This requirement is not applicable as there are no adopted area specific regulations
within the project area.
2.10 Special Requirement #2: Flood Hazard Area
Delineation
This requirement is not applicable as the project area is not within or adjacent to a
mapped FEMA flood hazard area. The FIRMETTE (a web-based software program
designed to display mapped FEMA floodplains) for the project area can be found in
Appendix A.
2.11 Special Requirement #3: Flood Protection Facilities
This requirement is not applicable as the proposed project does not rely on an existing
flood protection facility or plan to modify or construct a new flood protection facility.
2.12 Special Requirement #4: Source Controls
This requirement is not applicable as the proposed project does not require a commercial
building or commercial site development permit.
2.13 Special Requirement #5: Oil Control
This requirement is not applicable as the proposed project does not have high use
characteristics. It should be noted that Spill Prevention, Containment, and Control
(SPCC) facilities will be installed around some electrical components which employ oil.
3 Offsite Analysis
A Level 1 Analysis was performed to identify any potential drainage, conveyance, or
environmental issues downstream of the site that could be affected by the project and
require an additional level of analysis. The Level 1 Analysis consists of a resource review
and a field inspection where offsite issues are identified. The resource review provides
information regarding large-scale existing issues in the project area prior to a site visit.
During the field inspection, evidence of on-site and off-site drainage issues or other
Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | 5
environmental problems are investigated and reported. The scale of the resource review
and the field inspection are defined by the downstream study area.
3.1 Task 1: Study Area
The study area and extent of the downstream analysis can be found on Figure 6. The
USGS StreamStats application in tandem with existing topographic and stormwater
conveyance data were used to define the downstream drainage path leaving the project
site. As mentioned in Section 1.1.2 above, stormwater runoff exits the project site via the
southern side of the substation, passing beneath the access road and eventually flowing
west towards Grant Avenue South.
The study area for Task 2 is required to extend 1 mile downstream of the project
discharge location per Section 1.2.2.1 of the COR SWDM. The study area is required to
extend upstream if backwater or upstream effects are anticipated, however the
substations location near the top of a ridge precludes any of these effects. The study
area for Tasks 3 through 5 must extend to a point where the proposed project area
extends less than 15% of the total tributary drainage area, but not less than one-quarter
mile downstream of the project area. StreamStats was used to delineate and calculate
the area of the watershed, and then determine at what distance the project area
composed less than 15% of the tributary drainage area. This distance was less than the
minimum distance, one quarter mile and therefore one quarter mile was used for the
extent the study area used in Tasks 3 through 5.
3.2 Task 2: Resource Review
The resource review was conducted according to Section 2.3.1.1 of the COR SWDM.
Information required to be reviewed includes FEMA Maps, presence of sensitive areas,
presence of wetlands, presence of nearby 303d listed waters, soil survey information,
adopted basin plans, and offsite analysis reports for other projects. The information
obtained during the review is detailed below.
Adopted basin plans were not available for the project area as of September 2016.
FEMA floodplain information was referenced from the online FEMA Flood Map Service
Center. The project site is not located within a flood hazard area. The FIRMETTE which
includes the project area is located in Appendix A.
King County iMap data indicates that the project area is located inside a Coal Mine
Hazard Area and adjacent to an Erosion Hazard Area. City of Renton GIS data was also
analyzed, and shows that environmentally sensitive or critical areas located near the
project area include erosion hazard areas and landslide areas (Figure 2). The closest
high-risk erosion hazard area is approximately 1,400 ft west/southwest of the site.
Moderate hazard landslide areas are present on the south, southwest, and west sides of
the project site. The closest high hazard landslide area is approximately 2,000 feet west
of the site. The project area will not discharge directly to any erosion or landslide hazard
areas.
King County iMap data indicates drainage complaints approximately three quarters of a
mile west of the project area, adjacent to I-405. The registered complaints were for
Technical Information Report
Talbot Substation Stormwater Support
6 | November 16, 2016
garbage dumping. The stormwater discharge from the proposed project area should not
have an effect.
Sensitive surface waters reviewed included wetlands and impaired waters. City of
Renton Wetland Inventory maps for the area do not show wetlands within one mile
downstream of the site. Additionally, following a review of the Department of Ecology’s
303d list of impaired waters, no impaired waters were found within one mile downstream
of the site.
Seven borings were performed as part of a geotechnical study at the project area. Five of
the borings were performed inside of the substation, and these discovered several feet of
fill soils overlaying seven to twenty-three feet of glacial till. In the area of the proposed
stormwater detention pond, two borings were performed which discovered several feet of
loose sand and organic topsoil overlaying glacial till. Advance outwash deposits were
found below the till soils in all boring samples. No groundwater was encountered at the
project site (GeoEngineers, 2016).
King County iMap does not identify any stormwater quality problems within the study
area.
No Basin Plans or Basin Reconnaissance Summary Reports were found for surface
waters downstream of the project site, and no nearby offsite analysis reports were
obtained as of September 2016 from the City of Renton Development Services Division.
Existing and potential problems identified above have been tabulated in the Drainage
System Table, located in Appendix B.
3.3 Task 3 through 5: Field Inspection & Results
The field inspection was conducted on January 18th, 2016 at the project area and the
study area within ¼ mile downstream of the site. The inspection focused on areas
identified in the resource review and in previous site visits, such as steep slopes and
erosion hazard areas. The purpose of the inspection was to note any erosion or
sedimentation, evidence of recurrent flooding, conveyance system issues, or other
drainage issues present, as well as observe existing site conditions and verify the
tributary drainage basin of the project site. Site photos taken during the visit are found in
Appendix C. It is important to note that the field inspection took place following 0.92
inches of rainfall in the two days prior to the visit, so wet weather conditions were
observed.
Land use immediately adjacent to the site is primarily undeveloped. Areas to the east
and west of the substation consist of tall grasses with interspersed shrubs, and the area
south of the site consists of moderate to dense trees and shrubs. Grasses surround the
north side of the site, with moderate to dense tree and shrub cover north of the grassy
areas. The closest developed area downstream of the site is a residential development
approximately 400 feet south of the site. A park lies between the residential development
and the substation, and consists of lawn grass and some taller grasses around the
border. South of the park is more undeveloped grassy and forested area, with a
maintained mountain bike trail in the forested area. A small stream or channel was
observed crossing the trail via a culvert. The stream appeared to end in the grass area to
Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | 7
the southwest where it converted to overland flow or infiltrated. No erosion or scour
problems were identified in this area.
To the east of the project area, the grade gradually slopes upward towards a ridge
between the substation and Beacon Way South (gravel road). South of the project area
and to the west of the gravel access road the topography is relatively flat. A slight
depression is present east of the access road which extends beyond the SE corner of
the substation. The west side of the substation is bounded by an approximately 10-ft
wide flat area and small ridge. West of the ridge, the grade becomes much steeper.
Runoff from the substation is constrained from reaching the steep slope by the ridge
feature. The ridge ends just before the southwest corner of the site, where a steep
access path leads southwest towards a transmission line tower. To the north of the
substation is relatively flat ground with areas of ponding. One depression is present near
the NE corner of the site. Two small ponded areas are present along the north edge of
the site. No outlets were observed from the ponded areas.
Topography downstream of the site consists of gradual slopes across a park and
moderate slopes to the west and southwest through forested and grassy areas. A gravel
access road intersects an undeveloped area between the park and the substation and
leads to a low area south of the road near the tower at the southwest corner of the
substation. The low area was identified as an additional area that would likely capture
runoff from the substation. The access road continues over a small ridge. Runoff that
escaped the low area would enter a forested section crisscrossed with mountain bike
paths. Many small depressions were observed along the mountain bike paths. Further
downstream is a grassy area west of the park. Moderate slopes continue across the
grassy area to Grant Avenue South, approximately ¼ mile downstream of the site.
Despite the steep slopes and paths on the west and south sides of the site, no rills or
signs of erosion or sedimentation were present during the field inspection of on-site and
off-site areas. Additionally, no evidence of recurrent flooding was present in the area.
Ponded areas were small, no overtopping of those areas was apparent, and water levels
were fairly low within the depressions despite the recent precipitation. These
observations suggest that the on-site and off-site areas do not suffer from erosion or
flooding drainage problems which could warrant additional flow control for the project.
Conveyance observed off-site in the downstream drainage path during the inspection
included two culverts. The outlet of a 4” PVC culvert was observed in a depression on
the south side of the site between the access road and substation. No water was flowing
in the culvert during the time of the inspection. The second culvert (4” PVC) was
observed with flow present underneath a section of the mountain bike trail southwest of
the site (Figure 6). About 200 feet downstream of the culvert, the flow converted into
overland flow through a grassy area. No flooding or erosion issues were observed
around the culvert.
Based on the observations made during the field inspection, no downstream drainage
problems - such as conveyance, flooding, or erosion issues - could be identified for the
project area or downstream drainage path within ¼ mile of the project area. Field
observations also verified the drainage basin delineation discussed in Section 1. The
lack of downstream drainage problems confirms that a Level 1 Analysis is sufficient for
the study area.
SECTION 1.1 DRAINAGE REVIEW
City of Renton 2009 Surface Water Design Manual Amendment
1-10
FIGURE 1.1.2.A FLOW CHART FOR DETERMINING TYPE OF DRAINAGE REVIEW REQUIRED
Is the project a single family residential project that results in ≥2,000 sf of
new and/or replaced impervious surface or ≥7,000 sf of land disturbing
activity, AND meets the following criteria?
• The project results in ≤5,000 sf of new impervious surface, and ≤35,000
sf of new pervious surface
Yes
SMALL PROJECT DRAINAGE
REVIEW
Section 1.1.2.1
Note: The project may also be
subject to Targeted Drainage
Review as determined below.
No
Does the new or redevelopment
project result in ≥2,000 sf of new
and/or replaced impervious surface or
≥35,000 sf of new pervious surface?
No
Does the project have the characteristics of one or more of the following
categories of projects (see more detailed threshold language on p. 1-13)?
1. Projects containing or adjacent to a flood, erosion, or steep slope
hazard area or documented drainage problem; projects within a
landslide hazard area or landslide hazard drainage area; or
projects that propose ≥7,000 sf (1 ac if project is in Small Project
Drainage Review) of land disturbing activity.
2. Projects proposing to construct or modify a drainage pipe/ditch that
is 12" or larger or receives runoff from a 12" or larger drainage
pipe/ditch.
Yes No Yes
Reassess whether
drainage review is
required per Section
1.1.1 (p. 1-8).
TARGETED DRAINAGE REVIEW
Section 1.1.2.2
Does the project result in ≥50 acres of new impervious
surface within a subbasin or multiple subbasins that are
hydraulically connected?
No
FULL DRAINAGE REVIEW
Section 1.1.2.3
Yes
LARGE PROJECT DRAINAGE
REVIEW
Section 1.1.2.4
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TALBOT STORMWATER SUPPORT
FIGURE 6
OFFSITE ANALYSIS
STORMWATER TIR
0 530Feet
O
LEGEND
Project Area
Task 2 Study Area
Task 3, 4, and 5 Study Are a
ParcelBoundary
Contours - 10 ft Interval
ApproximateDrainage Path
Wetland
Hazard Area
Steep Slope
Erosion
Landslide
Duwamish - Green River Watershed
Note: Task 2 Study Area Includes the Downsteram Flow Path 1 Mile Downstre am o f th e Project Are aTasks 3 through 5 Project Area Includes the Downstream Flow Path 1 /4 Mile Do wnstre am of the Proje ct Area
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Technical Information Report Talbot Substation Stormwater Support
8 | November 16, 2016
4 Flow Control and Water Quality Facility Analysis and Design
4.1 Existing Site Hydrology
The existing condition hydrologic analysis assumed that stormwater runoff within the project area was confined to one subbasin which drains to the depression located on the southwestern corner of the project area. Drainage characteristics of the site are discussed in greater detail in Section 1.1.2 of this report. Subbasin area and drainage characteristics can be seen on Figure 7. Existing land cover is primarily yard rock with electrical equipment foundations throughout the site. Existing hydrology was calculated based on a pre-developed forested condition as the project area is located within a designated Flow Control Area per Reference 11-A of the COR SWDM (Appendix D). Existing condition peak flow values were calculated using the KCRTS modeling software. Existing acreage input to the KCRTS model and model results can be found in Table 1, below.
Table 1: Existing Condition Acreage and Peak Flow Values Pre-Developed Till Forested Condition Area 5.89 Acres
Peak Flow Event Discharge (CFS)*
2- Year 0.16 5-Year 0.28 10-Year 0.29 25-Year 0.37 50-Year 0.44 100-Year 0.48 *Additional KCRTS flow output can be found in Appendix E.
4.2 Proposed Site Hydrology
Changes to the existing land cover include removal of existing electrical equipment and the addition of new concrete equipment foundations, placement of new yard rock within the facility, and addition of a new stormwater detention pond (Figure 8). The yard rock is considered a partially impervious surface while all other improvements are considered impervious surfaces. Per Table 3.2.2.E in the 2009 KCSWDM, yard rock (gravel) surfaces must be multiplied by an effective impervious fraction of 0.50 to determine the impervious percentage of yard rock (gravel) surfaces. The remaining fraction is considered pervious.
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380375370355
35034
53403
3
533
0325320315310305285280385
3
6
53
60300295
4204004
0
539
5390290
4
3
5
430
425
4 4 5
440430425
46
5460455450440435 415
4
1
0435430
420
4 1 5
4
1
5
410405400405400 4204 2 0440295 4
6
0
455
450
450
450440440
4 4 0
4
4
0
440
4 3 0 425415
4154054054 0 0
4
0
0
4 0 0395
280460ROLLINGHILLSAVE SE
LINCOLNCT SEBLAINE CT SEABERDEENCT SESE 16TH PL PUGET DR SEGRANT AVE SProject Area Subbasin:5.89 Acres
LocalizedDepression
LocalizedDepression
LocalizedDepression
8" CMP Culvert
8" CMP Culvert
12" CMP Culvert
4" Culvert
4" Culvert
PATH: G:\PROJECTS\WAS HINGTON\PUGET_SOUND_E NERGY_00 702 2\TALBOT_STORMWATER_SUPPORT_269 966\MAP_DOCS\DR AFT\TIR FIGURES\SITE_H YDROLOGY.MXD - USER : TAHOFFMA - DATE: 11/1 6/201 6
TALBOT STORMWATER SUPPORT
FIGURE 7
EXISTING SITE HYDROLOGY
STORMWATER TIR
0 200Feet
O
LEGEND
Project AreaSubbasin Boundary
Contours - 5 ft Interval
Ponded Water Observe dDuring Field Visit
DrainageInfrastructure
ApproximateDrainage Path
Drainage Path
Roads
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Technical Information Report Talbot Substation Stormwater Support
November 16, 2016 | 9
Proposed condition peak flow values were calculated using the KCRTS modeling software. Proposed acreage input to the KCRTS model and model results can be found in Table 2 below.
Table 2: Proposed Condition Acreage and Peak Flow Values Proposed Condition Impervious Area 3.83 Acres
Proposed Condition Till Grass Area 2.06 Acres
Total Area 5.89 Acres
Peak Flow Event Discharge (CFS)*
2- Year 1.11 5-Year 1.20 10-Year 1.34 25-Year 1.44 50-Year 1.98 100-Year 2.25 *Additional KCRTS flow output can be found in Appendix E.
4.3 Performance Standards
The project area is located within a designated Flow Control Area per Reference 11-A of the COR SWDM (Appendix D) and is subject to the Flow Control Duration Standard for forested conditions.
No drainage problems have been identified within the limits of the offsite analysis (discussed in detail in Section 3), so proposed conditions must match the flow durations for pre-developed, forested rates over the range of flows from 50% of the 2-year up to the full 50-year per Table 1.2.3.A of the COR SWDM (COR SWDM, 2009). Flow control facilities are required, as the project contains greater than 2,000 square feet of new plus replaced impervious surface. In Flow Control Duration Standard areas, these facilities must mitigate for target surfaces including:
New impervious surface that is not fully dispersed, New pervious surface that is not fully dispersed, Replaced impervious surface that is not fully dispersed on a parcel redevelopment project in which the total of new plus replaced impervious surface is 5,000 square feet or more.
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430420405
3903803753703503453403253153103053
0
0 4103953
8
5
3603
553
3
0320
2
9
529
03352854404354 2 5420
450
4 4 5
4 4 0
46
54604404352
8
02
754354 3 0
420
4 1 5
415
4
1
0
405400425400365 430
4554
6
0
4
5
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440
2954 5 0
450
4 5 0440440
4
4
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440440430
415
4 2 0415415405
4054004 0 0
4
0
0
4 0 0400395
460400
ROLLINGHILLSAVE SE
LINCOLNCT SEBLAINE CT SEABERDEENCT SESE 16TH PL PUGET DR SEGRANT AVE SProject Area Subbasin:5.89 Acres
75,000 CFDetention Pond
LocalizedDepression
LocalizedDepression
24" Culvert
4" Culvert
4" Culvert
PATH: G:\PROJECTS\WAS HINGTON\PUGET_SOUND_E NERGY_00 702 2\TALBOT_STORMWATER_SUPPORT_269 966\MAP_DOCS\DR AFT\TIR FIGURES\SITE_H YDROLOGY.MXD - USER : TAHOFFMA - DATE: 11/1 6/201 6
TALBOT STORMWATER SUPPORT
FIGURE 8
PROPOSED SITE HYDROLOGY
STORMWATER TIR
0 200Feet
O
LEGEND
Project AreaSubbasin Boundary
Contours - 5 ft Interval
DrainageInfrastructure
ApproximateDrainage Path
Drainage Path
Roads
ProposedDetention Pond
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Technical Information Report
Talbot Substation Stormwater Support
10 | November 16, 2016
Flow control facilities and design are discussed in detail in Section 4.4. The NPGIS and
pervious areas in Table 3 reflect the division of area covered by yard rock.
Table 3: Existing and Proposed Land Use Summary
Impervious
Pervious Total
NPGIS PGIS
Existing 3.33 0.00 2.56 5.89
Proposed 3.83 0.00 2.06 5.89
New 0.50 0.00 0.00 0.50
Replaced 3.33 0.00 2.06 5.39
Percent
Impervious
65%
Flow control BMPs must be provided to either supplement the flow mitigation provided by
flow control facilities or provide flow mitigation where flow control facilities are not
required (SWDM, 2009). These BMPs must be selected as directed in Section 5.2 of the
SWDM. The proposed project area must meet the large lot high impervious BMP
requirements listed in Section 5.2.1.2 of the SWDM as the project area is larger than
22,000 square feet and the impervious surface coverage is greater than 45% of the
project area. Figure 5.2.1.A Flow Chart for Determining Individual Lot BMP
Requirements of the SWDM is shown in Figure 9 below.
SECTION 5.2 FLOW CONTROL BMP REQUIREMENTS
1/9/2009 2009 Surface Water Design Manual
5-12
FIGURE 5.2.1.A FLOW CHART FOR DETERMING INDIVIDUAL LOT BMP REQUIREMENTS
Is the project on a site/lot
smaller than 22,000 square feet?Is it feasible and
applicable to
implement full
dispersion for the
roof area as per
Section C.2.1?
No further BMPs
required. Note:
Any proposed
connection of roof
downspouts to
local drainage
system must be
via perforated
pipe connection
per Section
C.2.11.
Is it feasible
and applicable
to implement
full infiltration
of the roof
runoff as per
Section C.2.2?
Apply one or more of the following to impervious area
>10% of site/lot for site/lot sizes <11,000 sf and > 20% of
site/lot for site/lot sizes between 11,000 and 22,000 sf (For
projects located in critical aquifer recharge areas these
impervious area amounts double):
1. Limited Infiltration (Section C.2.3)
2. Basic Dispersion (Section C.2.4)
3. Rain Garden (Section C.2.5)
4. Permeable Pavement (Section C.2.6)
5. Rainwater Harvesting (Section C.2.7)
6. Vegetated Roof (Section C.2.8)
7. Reduced Impervious Service Credit (Section C.2.9)
8. Native Growth Retention Credit (Section C.2.10)
No
Yes
Yes
Yes
No
Is the project on a site/lot 22,000 square feet
or larger with impervious surface
coverage of 45% or less?
Is it feasible and
applicable to implement
full dispersion on all
target impervious
surface as per
Section C.2.1?
No further BMPs
required. Note:
Any proposed
connection of roof
downspouts to local
drainage system
must be via
perforated pipe
connection per
Section C.2.11.
Is it feasible and applicable to
implement full infiltration of
the roof runoff as per
Section C.2.2 or Section 5.4?
One or more of the following BMPs must be implemented
for that portion of target impervious surface not addressed
with full dispersion or with full infiltration of roof runoff:
1. Full Infiltration (Section C.2.2 or Section 5.4)
2. Limited Infiltration (Section C.2.3)
3. Basic Dispersion (Section C.2.4)
4. Rain Garden (Section C.2.5)
5. Permeable Pavement (Section C.2.6)
6. Rainwater Harvesting (Section C.2.7)
7. Vegetated Roof (Section C.2.8)
8. Reduced Impervious Service Credit (Section C.2.9)
9. Native Growth Retention Credit (Section C.2.10)
Yes
Yes
Yes
No
Is there any remaining target
impervious surface not
addressed with full dispersion or
with full infiltration of roof runoff?
No
No
The project must be a site/lot 22,000 square feet
or larger with impervious surface
coverage of more than 45%?
Is it feasible and
applicable to implement
full dispersion on all
target impervious
surface as per
Section C.2.1?
No further BMPs
required. Note:
Any proposed
connection of roof
downspouts to
local drainage
system must be
via perforated
pipe connection
per Section
C.2.11.
Projects with impervious area greater than 45% and equal to or
less than 65% one or more of the following must be applied to an
impervious area greater than or equal to 20% of the site or 40% of
the target impervious surface whichever is less OR for projects
greater than 65% impervious one or more of the following must be
applied to an impervious area greater than or equal to 10% of site
or 20% of target impervious surface, whichever is less:
1. Full Infiltration (Section 5.4)
2. Limited Infiltration (Section C.2.3)
3. Basic Dispersion (Section C.2.4)
4. Rain Garden (Section C.2.5)
5. Permeable Pavement (Section C.2.6)
6. Rainwater Harvesting (Section C.2.7)
7. Vegetated Roof (Section C.2.8)
8. Reduced Impervious Service Credit (Section C.2.9)
9. Native Growth Retention Credit (Section C.2.10)
No
Yes
No
Yes
No
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Talbot Substation Stormwater Support
November 16, 2016 | 11
The following list discusses each flow control BMP and its feasibility at the project area.
• Full Infiltration
o The project area lies over fill materials which are not suited for infiltration
BMPs.
• Limited Infiltration
o The project area lies over fill materials which are not suited for infiltration
BMPs.
• Basic Dispersion
o Existing topography on the northern and eastern edges of the project
area forms high ground and prevents stormwater runoff from exiting the
site. These higher areas would also restrict the vegetated flow path of a
basic dispersion BMP to several feet, below the acceptable value. The
eastern side of the project area is within the substation and bordered by
yard rock not suitable for dispersion BMPs as there is no vegetated flow
path and discharging stormwater within a substation is not
recommended.
• Rain Garden
o There is no space available within the project area for a rain garden. The
projects natural discharge location is located on the southern edge of the
project area, and the proposed stormwater detention pond which has
been designed to mitigate for all target surfaces within the project area
lies in that location. Existing topography surrounding the northern and
eastern edges of the site prevents placement of a rain garden in these
locations, and a rain garden could not be placed on the western edge of
the project area within the substation fence.
• Permeable Pavement
o No major paving activities are being proposed at the project area.
• Rainwater Harvesting
o The control house is the only structure with a roof that lies inside the
project area. Storage of rainwater associated with a rainwater harvesting
facility within the fence line of the substation is not feasible. There is also
no use for harvested rainwater at the project site, no plants require
irrigation and there are no facilities which may use harvested water.
• Vegetated Roof
o Vegetated rooftops within substation facilities are not feasible as the
required maintenance would involve getting on top of or near the top of
the roof surface in close proximity to high voltage power facilities.
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Talbot Substation Stormwater Support
12 | November 16, 2016
• Reduced Impervious Surface Credit
o Impervious surfaces have been restricted to the maximum extent
feasible. Permeable yard rock is being used where vehicle access is not
required within the substation fence. Impervious surfaces within the
project area include the proposed stormwater detention pond, electrical
and SPCC facilities, and the access road required for vehicles.
• Native Growth Retention Credit
o There are no native growth areas located within the project area.
The proposed flow control facility will mitigate for all target surfaces at the project area.
Proposed conveyance systems must be designed to convey the 25-year peak flow event
with a minimum 6 inches of freeboard to the structure grate. Developed conditions must
be assumed for onsite tributary areas, while existing conditions shall be assumed for
offsite tributary areas. For events greater than the 25-year peak flow, structures may
overtop. However, the 100-year peak flow event may not create or exacerbate any
existing severe flooding or erosion problem per Core Requirement #2 of the COR
SWDM. All overflows for peak flow events up to and including the 100-year event must
discharge to their natural discharge location at the project area.
Stormwater water quality treatment facilities are not required at the project area as the
total area of pollution-generating surfaces is below the water quality requirement
thresholds. SPCC structures will be installed around electrical components requiring oil
in order to prevent stormwater contamination in the event an oil spill. These are the only
water quality facilities which will be present at the project site.
4.4 Flow Control System
An illustrative sketch of the proposed stormwater detention facility can be found below
(Figure 10). KCRTS output containing “Compare Flow Duration” files and other model
results can be found in Appendix E. While there are landslide hazard areas adjacent to
the project, the project is not located within those areas and therefore is not required to
use a safety factor when designing the stormwater detention facility (SWDM, 2009).
Table 4 below compares the pre-developed condition discharge to the proposed
condition site discharge from the flow control facility.
Table 4: Pre-developed and Proposed Controlled Flow Comparison
Peak Flow
Event
Discharge (CFS)
Existing Proposed from Flow
Control Facility
2- Year 0.16 0.09
5-Year 0.28 0.26
10-Year 0.29 0.28
25-Year 0.37 0.36
50-Year 0.44 0.82
100-Year 0.48 1.04
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Talbot Substation Stormwater Support
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4.5 Water Quality System
As mentioned above, stormwater water quality facilities are not required. SPCC facilities
will be placed where necessary.
5 Conveyance System Analysis and Design
During field observations, two four-inch outlet pipes and catch basins were observed at
the project area within the substation fence line at the northern and southern edges of
the substation. No further analysis was performed on the existing conveyance system.
The proposed stormwater conveyance system was designed to meet the conveyance
requirements discussed in Section 4.3 of this report and was analyzed using the Rational
Method and XP-SWMM. The Rational Method was used to assess the capacity of the
pipes within the conveyance system as required by the 2009 SWDM. XP-SWMM was
then used to demonstrate that the pipe system structures contain the hydraulic grade line
for the 25-year rainfall event as required by the 2009 SWDM.
The Rational Method conservatively calculates runoff flows based on basin area, rainfall
intensity, and a runoff coefficient specific to land cover. Runoff flows into each catch
basin were calculated for the 25-year event, and a water balance was performed to
estimate the flows which would need to be conveyed in each pipe. When the flows were
compared to the proposed conveyance system design pipe capacities, all proposed
pipes were sized appropriately to convey the 25-year event flows.
In XP-SWMM, conveyance system pipes were designed and modeled as 8-inch or 12
inch high density polyethylene (HDPE) pipe or perforated PVC pipe. Catch basins in the
conveyance system were either Type 1 or type 1L. The conveyance system was
designed to route runoff from the substation, SPCC curb areas, and control house roof
toward the south side of the substation, where a pipe outfalls to the proposed detention
pond. Slopes of all proposed pipes in the conveyance system were modeled as 0.5%.
Compliance with the requirements discussed in Section 4.3 was assessed by routing 25-
and 100-year rainfall events through the XP-SWMM model. During the 25-year event, all
structures appeared to maintain over 6 inches of freeboard in the model. Additionally, the
hydraulic grade line was contained within the conveyance pipes. The conveyance
system did not flood during the 100-year event. Model output can be found in Appendix
E.
6 Special Reports and Studies
No special reports or studies have been prepared for this project.
7 Other Permits
Table 5 below lists additional permits required for the project area and their effects on the
stormwater design.
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Talbot Substation Stormwater Support
14 | November 16, 2016
Table 5: Additional Project Permit Requirements
Permit Agency Effects on Stormwater Design
TBD TBD TBD
TBD TBD TBD
8 CSWPPP Analysis and Design
A CSWPPP has been developed for the project and is located in Appendix F.
8.1 ESC Plan Analysis and Design
The following ESC best management measures will be employed at the project area, as
shown on the TESC plans and discussed in the CSWPPP:
8.1.1 Clearing Limits
To protect adjacent properties and reduce the volume of soil exposed to construction,
construction limits will be clearly marked where necessary before construction begins.
The construction of the proposed stormwater detention pond and paving of a small
portion of the existing access road will be the only ground disturbing activity occurring
outside of the substation fence. Natural vegetation and topsoil at the project area shall be
retained to the maximum extent feasible. High visibility fence and silt fence BMPs will be
used around the perimeter of the project area so that disturbance is kept to a minimum
outside the work area.
8.1.2 Cover Measures
As the project is located west of the Cascade Mountain Crest, no soils shall remain
exposed and unworked for more than seven days during the dry season (May 1 to
September 30) and two days during the wet season (October 1 to April 30). Between
these times, exposed soils stored aboveground shall be protected with straw, wood fiber
mulch, compost, plastic sheeting, or equivalent. Regardless of time, all soils shall be
stabilized at the end of the shift before a holiday or weekend, and if needed, based on
weather forecasts. Any areas expected to remain unworked for greater than 30 days
must be seeded or sodded (King County, 1998). During the wet season, soil stockpiles
with slopes greater than or equal to 3H:1V, or with over ten feet of vertical relief must be
covered if they will remain unworked for over 12 hours. During the wet season sufficient
cover materials to stabilize all disturbed areas must be stockpiled on site, and the Wet
Season Provisions of Section D.5.S of the King County Erosion and Sediment Control
Standards must be followed (King County, 1998). Permanent stabilization will be
achieved by placement of yard rock within the substation, and seeding at the proposed
stormwater detention pond.
8.1.3 Perimeter Protection
Vegetation and slope characteristics vary within the project area. The eastern edge of
the project area is elevated and there is no risk contaminated stormwater will exit the
project site in that area. The proposed stormwater detention pond and its outlet structure
will be installed along the southern edge of the project area. Silt fence will be installed in
this area to ensure no contaminated stormwater exits the project area. Silt fencing will
Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | 15
extend along the existing access road to its intersection with Puget Drive Southeast to
prevent sediment generated from the proposed paving activities from exiting the project
site. Concrete will be poured on site for proposed electrical equipment foundations within
the substation. All concrete at the project area will be handled such that no cementitious
material will enter stormwater runoff. Handling procedures are detailed on the TESC
plans.
8.1.4 Traffic Area Stabilization
The project area will be accessed from the existing access road located on the southern
edge of the substation. This access road is a stabilized surface and does not require
additional stabilization. Proposed stormwater detention pond construction and access
road paving will occur from the existing access road.
8.1.5 Sediment Retention
The proposed stormwater detention pond will be retrofitted as a temporary sediment
storage facility for the duration of the project. All open grate catch basins and inlets
located at the project area will be protected with storm drain inlet protection in order to
prevent sediment contamination from entering the conveyance system. The sediment
pond must have adequate surface area as defined in Section D.4.5.2 of the King County
Erosion and Sediment Control Standards (King County, 1998).
Required Pond Surface Area at top of Riser - SA = 2 x Q2/0.00096
Proposed 2-year Peak Flow - Q2= 0.092
Required SA = 192 Square Feet
Provided Surface Area: ~ 16,000 Square Feet
8.1.6 Surface Water Collection
Outlet protection will be installed at the outlet of the proposed stormwater detention pond
before stormwater is routed through the facility.
8.1.7 Dewatering Control
Dewatering is not anticipated at the project site, as groundwater was not encountered
during field activities performed by GeoEngineers (GeoEngineers, 2016).
8.1.8 Dust Control
Wind transport of soils is not anticipated at the project site. Exposed soils will be
stabilized and will not remain exposed for long periods.
8.1.9 Flow Control
The project area triggers Core Requirement #3: Flow Control. The proposed stormwater
detention pond will be retrofitted to serve as a sediment pond during construction. During
this period, the hydraulic control structure and pond will continue to function as flow
control facility’s and restrict flow rates exiting the site to acceptable limits.
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Talbot Substation Stormwater Support
16 | November 16, 2016
8.2 CSWPPP Plan Design
The following ESC best management measures will be employed at the project area, as
shown on the TESC plans and discussed in the CSWPPP:
• High Visibility Plastic Fence
o High visibility plastic fence will be used around the perimeter of the
substation and access road to clearly mark the proposed limits of
construction. This will prevent unnecessary disturbance of existing
vegetation and soils.
• Silt Fence
o Silt fence will be placed along the southern border of the existing access
road to prevent sediment contaminated stormwater generated from the
construction of the proposed stormwater detention pond and paving of
the existing access road from exiting the project site. Silt fence will also
serve to delineate the construction limits on the southern boundary of the
project area
• Temporary Sediment Pond
o The proposed stormwater detention pond will be retrofitted as a
temporary sediment pond. It will serve to retain sediment generated
within the substation fence by placement of the proposed foundations,
yard rock, and electrical components. The sediment pond will prevent
sediment from exiting the project area. Sediment retention facilities are
required whenever the project area exceeds three acres. Flow control is
also required for the project, and the proposed stormwater detention
pond will continue to regulate outflows through its control structure while
it is being used as a temporary sediment retention facility.
• Catch Basin Insert
o Catch basin inserts will be placed on all catch basins within the
substation fence line. They will be used to prevent sediment generated
by work within the substation fence line from entering the proposed
stormwater conveyance system and being transported downstream.
• Outlet Protection
o Outlet protection will be used at the outlet of the proposed stormwater
detention pond. It will prevent scouring and erosion due to stormwater
discharges exiting the pond. This is a permanent BMP which will be
retained in place after construction is complete.
Updates to the SWPPP may be requested by King County at any time during project
construction if the County determines that pollutants generated on the construction site
have the potential to contaminate surface, storm, or ground water.
Technical Information Report
Talbot Substation Stormwater Support
November 16, 2016 | 17
9 Bond Quantities, Facility Summaries, and
Declaration of Covenant
9.1 Bond Quantities Worksheet
The Bond Quantities Worksheet is located in Appendix G.
9.2 Flow Control and Water Quality Facility Summary
Sheet and Sketch
The Flow Control and Water Quality Facility Summary Sheet and Sketch is located in
Appendix G.
9.3 Declaration of Covenant for Privately Maintained Flow
Control and WQ Facilities
Declaration of Covenant is not required for proposed privately maintained flow control
facilities.
9.4 Declaration of Covenant for Privately Maintained Flow
Control BMPs
There are no flow control BMPs present at the project area.
10 Operations and Maintenance Manual
A copy of the Operations and Maintenance Manual, along with the Maintenance
Requirements for Flow Control, Conveyance, and WQ Facilities is located in Appendix H.
11 References
City of Renton. (2010). City of Renton Amendments to the King County Surface Water Design
Manual. Renton: City of Renton.
King County. (2009). Surface Water Design Manual. Seattle: King County .
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Appendix A
FEMA Firmette
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Appendix B
Drainage System Table
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual 1/9/2009
KING COUNTY, WASHINGTON
SURFACE WATER DESIGN MANUAL
REFERENCE 8-B
OFFSITE ANALYSIS
DRAINAGE SYSTEM TABLE
1/9/2009 OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT #2 Basin: Subbasin Name: Subbasin Number: Symbol Drainage Component Type, Name, and Size Drainage Component Description Slope Distance from site discharge Existing Problems Potential Problems Observations of field inspector, resource reviewer, or resident see map Type: sheet flow, swale, stream, channel, pipe, pond; Size: diameter, surface area drainage basin, vegetation, cover, depth, type of sensitive area, volume % ¼ ml = 1,320 ft. constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion tributary area, likelihood of problem, overflow pathways, potential impacts
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Appendix C
Site Photographs
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Site Photos
January 18th, 2016
•Ponded water along eastern
edge of site.
•Ponded water along
northwestern edge of site.
•Elevated field located off of the
eastern edge of the substation,
looking south.
•Elevated area along northern
edge of substation, looking west.
•Culvert outletting from south
end of substation into
depression.
•Local depression along southern
edge of substation (site of
proposed stormwater detention
pond).
•Local depression located along
substation discharge path off the
southwest corner of the
substation.
•Typical mountain bike path
through downstream drainage
area.
•4” Culvert passing beneath
mountain bike path.
•Looking south towards Grant
Avenue South.
•Looking north towards
substation, along drainage path.
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Appendix D
Reference 11-A Flow Control
Areas
LakeDesire
ShadyLake (MudLake)
PantherLake LakeYoungs
LakeWashington
Bl a c kRi ver
Gr eenRiv
e
r
C
edarRi verUV900
UV167
UV515
UV169
UV900
UV169
UV167BN IncBN IncBBNNIInnccSSEE
RReennttoonn IIssss aa qquuaahh RR dd
RReennttoonn MMaappllee VVaalllleeyyRRdd
MMaapplleeVVaalllleeyyHHwwyy
110088tthhAAvveeSSEESSWW SSuunnsseettBBllvv
dd RRaaiinnii
eerrAAvveeNNNE 3rd S
t
NE 3rd S
t
SW 43rd StSW 43rd St SS EE CCaarrrrRR dd
NE 4th StNE 4th St
SSEE RReennttoonn MMaappllee VVaalllleeyy RRddLLooggaannAAvveeNN
SR 515SR 515PPaarrkkAAvveeNNOOaakkeessddaalleeAAvveeSSWWSSuunnsseettBBllvvddNN EE
DDuuvvaallllAAvveeNNEEI-405 FWYI-405 FWY II--440055FFWWYYSR 167SR 1671144
00tthh
WWaayy
SS
EENNEE 2277tthh SStt
115566tthhAAvveeSSEEUUnniioonnAAvveeNNEE111166tthhAAvveeSSEESW 7th StSW 7th St
N 8th StN 8th St
PP uuggeettDDrrSSEE
RR
ee
nnttoonnAAvvee SS
SSWW 2277tthh SStt BBeennssoonnRRddSSWWiilllliiaammssAAvveeSSMMoonnrrooeeAAvveeNNEESE 128th StSE 128th St
II
nntt
eerr
uurr
bbaannAA
vvee
SS HHooqquuiiaammAAvveeNNEE8844tthhAAvveeSSSSEEPPeett
rr
oovvii
tt
sskkyyRRddEEVVaalllleeyyHHwwyySE 192nd StSE 192nd St
SE 60th StSE 60th St
TTaallbboottRRddSSRRee
nn
tt
oo
nn
AAvveeSS116644tthhAAvveeSSEESE 208th StSE 208th St
SE 72nd StSE 72nd St
RR
aaiinniieerr
AA
vvee
SS 111166tthhAAvveeSSEES 128th StS 128th St
NNeewwccaassttllee WWaayy
SS 221122tthh SStt
SS 118800tthh SStt CCooaall
CCrreeeekkPPkkwwyySSEESW 41st StSW 41st St
114400tthhAAvveeSSEE112288tthhAAvveeSSEE6688tthhAAvveeSSSSEE 116688tthh SStt
NE 12th StNE 12th St
BBeeaaccoonn
AA
vv
ee
SS
FFoorreesstt DDrr SSEE
SSEE 116644tthh SStt 114488tthhAAvveeSSEESSEE MMaayy VVaalllleeyy RRdd
SS EE JJ oo nn ee ss RR dd
SS EE 22 00 44 tthh WW aayySW 34th StSW 34th St
SE 144th StSE 144th St
114488tthhAAvveeSSEE115544tthhPPllSSEELL
aa
kk
ee
WWaa
sshhii
nnggtt
oonnBBll
vvddNNEEddmmoonnddssAAvveeNNEEAAbbeerrddeeeennAAvveeNNEEEEMM eerrcceerrWWaayyWWeessttVVaalllleeyyHHwwyyEast Valley RdEast Valley Rd,§-405
,§-405
,§-405
µ0 1 2
Miles
Flow Control Application Map
Reference 11-A
Date: 01/09/2014
Flow Control Standards
Peak Rate Flow Control Standard (Existing Site Conditions)
Flow Control Duration Standard (Existing Site Conditions)
Flow Control Duration Standard (Forested Conditions)
Flood Problem Flow
Unincorporated King County Flow Control Standards
Renton City Limits
Potential Annexation Area
Project Location
Appendix E Stormwater Model Input & Output
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KCRTS Pre-developed and Developed Land Use Areas
Pre-developed and Developed Land Use Areas Model Input
Pre-developed Condition Land Use Areas Land Use Type Area (ac) Impervious 0.00 Till Forest 5.89
Developed Condition Land Use Areas Land Use Type Area (ac) Impervious 3.83 Till Grass 2.06 Total Area: 5.89
KCRTS
Pre-developed and Developed Duration Comparison
Predeveloped and Developed Duration Comparison
Duration Comparison Analysis
Base File: psetalbotpredev_020816.tsf
New File: pserdout_020816.tsf
Fraction of Time Check of Tolerance
Cutoff Base New % Change Prob Base New % Change
(CFS)
0.081 0.0095 0.0067 -29.5 0.0095 0.081 0.078 -4.6
0.104 0.0063 0.0056 -10.4 0.0063 0.104 0.087 -16.0
0.126 0.0050 0.0053 5.9 0.0050 0.126 0.132 4.4
0.148 0.0037 0.0038 3.1 0.0037 0.148 0.151 1.9
0.171 0.0029 0.0025 -11.9 0.0029 0.171 0.165 -3.4
0.193 0.0022 0.0018 -19.9 0.0022 0.193 0.178 -7.8
0.215 0.0015 0.0011 -23.9 0.0015 0.215 0.202 -6.0
0.237 0.0010 0.0007 -31.7 0.0010 0.237 0.221 -7.0
0.26 0.0006 0.0005 -15.8 0.0006 0.260 0.250 -3.8
0.282 0.0003 0.0004 4.8 0.0003 0.282 0.285 1.2
0.304 0.0002 0.0003 14.3 0.0002 0.304 0.316 3.9
0.326 0.0002 0.0002 20.0 0.0002 0.326 0.337 3.2
0.349 0.0001 0.0001 -28.6 0.0001 0.349 0.348 -0.2
0.371 0.0000 0.0000 -100.0 0.0000 0.371 0.363 -2.3
Maximum positive excursion = 0.008 cfs (6.7%) occurring at 0.120 cfs on the Base Data
(psetalbotpredev_020816.tsf) and at 0.128 cfs on the New Data (pserdout_020816.tsf).
Maximum negative excursion = 0.019 cfs (-19.0%) occurring at 0.099 cfs on the Base Data
(psetalbotpredev_020816.tsf) and at 0.080 cfs on the New Data (pserdout_020816.tsf).
KCRTS
Pond Design Results
Retention/Detention Facility
Type of Facility: Detention Pond
Side Slope: 2.00 H:1V
Pond Bottom Length: 241.81 ft
Pond Bottom Width: 27.00 ft
Pond Bottom Area: 6529. sq. ft
Top Area at 1 ft. FB: 16155. sq. ft
0.371 acres
Effective Storage Depth: 7.00 ft
Stage 0 Elevation: 425.50 ft
Storage Volume: 73876. cu. ft
1.696 ac-ft
Riser Head: 7.00 ft
Riser Diameter: 12.00 inches
Number of orifices: 3
Full Head Pipe
Orifice # Height Diameter Discharge Diameter
(ft) (in) (CFS) (in)
1 0.00 1.15 0.095
2 4.85 2.13 0.180 6.0
3 6.10 2.00 0.103 4.0
Top Notch Weir: None
Outflow Rating Curve: None
Stage Elevation Storage Discharge Percolation Surf
Area
(ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq.
ft)
0.00 425.50 0. 0.000 0.000 0.00
6529.
0.01 425.51 65. 0.001 0.004 0.00
6540.
0.02 425.52 131. 0.003 0.006 0.00
6551.
0.04 425.54 262. 0.006 0.007 0.00
6572.
0.05 425.55 328. 0.008 0.008 0.00
6583.
0.06 425.56 394. 0.009 0.009 0.00
6594.
0.07 425.57 460. 0.011 0.010 0.00
6604.
0.08 425.58 526. 0.012 0.010 0.00
6615.
0.10 425.60 658. 0.015 0.011 0.00
6637.
0.23 425.73 1530. 0.035 0.017 0.00
6777.
0.37 425.87 2490. 0.057 0.022 0.00
6929.
0.51 426.01 3470. 0.080 0.026 0.00
7082.
0.64 426.14 4400. 0.101 0.029 0.00
7224.
0.78 426.28 5422. 0.124 0.032 0.00
7377.
0.92 426.42 6466. 0.148 0.034 0.00
7532.
1.06 426.56 7531. 0.173 0.037 0.00
7687.
1.19 426.69 8540. 0.196 0.039 0.00
7831.
1.33 426.83 9647. 0.221 0.041 0.00
7987.
1.47 426.97 10776. 0.247 0.043 0.00
8144.
1.61 427.11 11928. 0.274 0.045 0.00
8302.
1.74 427.24 13016. 0.299 0.047 0.00
8448.
1.88 427.38 14210. 0.326 0.049 0.00
8607.
2.02 427.52 15426. 0.354 0.051 0.00
8766.
2.15 427.65 16576. 0.381 0.053 0.00
8915.
2.29 427.79 17835. 0.409 0.054 0.00
9075.
2.43 427.93 19117. 0.439 0.056 0.00
9236.
2.57 428.07 20421. 0.469 0.057 0.00
9398.
2.70 428.20 21653. 0.497 0.059 0.00
9549.
2.84 428.34 23001. 0.528 0.060 0.00
9712.
2.98 428.48 24372. 0.560 0.062 0.00
9875.
3.12 428.62 25766. 0.592 0.063 0.00
10040.
3.25 428.75 27081. 0.622 0.065 0.00
10193.
3.39 428.89 28520. 0.655 0.066 0.00
10358.
3.53 429.03 29981. 0.688 0.067 0.00
10524.
3.66 429.16 31359. 0.720 0.069 0.00
10679.
3.80 429.30 32866. 0.755 0.070 0.00
10846.
3.94 429.44 34396. 0.790 0.071 0.00
11014.
4.08 429.58 35950. 0.825 0.072 0.00
11182.
4.21 429.71 37414. 0.859 0.074 0.00
11339.
4.35 429.85 39013. 0.896 0.075 0.00
11509.
4.49 429.99 40637. 0.933 0.076 0.00
11679.
4.63 430.13 42284. 0.971 0.077 0.00
11850.
4.76 430.26 43835. 1.006 0.078 0.00
12010.
4.85 430.35 44920. 1.031 0.079 0.00
12120.
4.87 430.37 45163. 1.037 0.080 0.00
12145.
4.89 430.39 45406. 1.042 0.084 0.00
12170.
4.92 430.42 45772. 1.051 0.090 0.00
12207.
4.94 430.44 46016. 1.056 0.098 0.00
12231.
4.96 430.46 46261. 1.062 0.108 0.00
12256.
4.98 430.48 46507. 1.068 0.120 0.00
12281.
5.00 430.50 46752. 1.073 0.128 0.00
12305.
5.03 430.53 47122. 1.082 0.132 0.00
12342.
5.05 430.55 47369. 1.087 0.135 0.00
12367.
5.19 430.69 49113. 1.127 0.153 0.00
12541.
5.32 430.82 50754. 1.165 0.167 0.00
12702.
5.46 430.96 52544. 1.206 0.180 0.00
12877.
5.60 431.10 54359. 1.248 0.191 0.00
13052.
5.74 431.24 56199. 1.290 0.201 0.00
13228.
5.87 431.37 57929. 1.330 0.211 0.00
13392.
6.01 431.51 59816. 1.373 0.220 0.00
13569.
6.10 431.60 61043. 1.401 0.226 0.00
13683.
6.12 431.62 61317. 1.408 0.228 0.00
13709.
6.14 431.64 61591. 1.414 0.231 0.00
13734.
6.16 431.66 61866. 1.420 0.237 0.00
13760.
6.18 431.68 62141. 1.427 0.244 0.00
13785.
6.20 431.70 62417. 1.433 0.252 0.00
13811.
6.23 431.73 62832. 1.442 0.262 0.00
13849.
6.25 431.75 63109. 1.449 0.272 0.00
13874.
6.27 431.77 63387. 1.455 0.280 0.00
13900.
6.40 431.90 65205. 1.497 0.303 0.00
14066.
6.54 432.04 67187. 1.542 0.323 0.00
14246.
6.68 432.18 69194. 1.588 0.341 0.00
14426.
6.82 432.32 71226. 1.635 0.357 0.00
14606.
6.95 432.45 73136. 1.679 0.372 0.00
14775.
7.00 432.50 73876. 1.696 0.377 0.00
14840.
7.10 432.60 75367. 1.730 0.696 0.00
14970.
7.20 432.70 76870. 1.765 1.270 0.00
15100.
7.30 432.80 78387. 1.800 2.010 0.00
15231.
7.40 432.90 79916. 1.835 2.810 0.00
15362.
7.50 433.00 81459. 1.870 3.100 0.00
15493.
7.60 433.10 83015. 1.906 3.360 0.00
15625.
7.70 433.20 84584. 1.942 3.610 0.00
15757.
7.80 433.30 86167. 1.978 3.830 0.00
15889.
7.90 433.40 87762. 2.015 4.050 0.00
16022.
8.00 433.50 89371. 2.052 4.250 0.00
16155.
8.10 433.60 90993. 2.089 4.440 0.00
16288.
8.20 433.70 92629. 2.126 4.630 0.00
16422.
8.30 433.80 94278. 2.164 4.800 0.00
16556.
8.40 433.90 95940. 2.202 4.970 0.00
16690.
8.50 434.00 97616. 2.241 5.140 0.00
16825.
8.60 434.10 99305. 2.280 5.300 0.00
16960.
8.70 434.20 101008. 2.319 5.450 0.00
17095.
8.80 434.30 102724. 2.358 5.600 0.00
17230.
8.90 434.40 104454. 2.398 5.750 0.00
17366.
Hyd Inflow Outflow Peak Storage
Target Calc Stage Elev (Cu-Ft) (Ac-Ft)
1 2.25 0.47 1.05 7.16 432.66 76281. 1.751
2 1.11 ******* 0.36 6.80 432.30 71008. 1.630
3 1.12 ******* 0.26 6.23 431.73 62802. 1.442
4 1.18 ******* 0.17 5.37 430.87 51439. 1.181
5 1.34 ******* 0.28 6.27 431.77 63431. 1.456
6 0.70 ******* 0.09 4.92 430.42 45833. 1.052
7 0.91 ******* 0.08 4.57 430.07 41528. 0.953
8 0.99 ******* 0.07 3.37 428.87 28288. 0.649
----------------------------------
Route Time Series through Facility
Inflow Time Series File:psetalbotdev_020816.tsf
Outflow Time Series File:PSErdout_020816
Inflow/Outflow Analysis
Peak Inflow Discharge: 2.25 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: 1.04 CFS at 10:00 on Jan 9 in Year 8
Peak Reservoir Stage: 7.16 Ft
Peak Reservoir Elev: 432.66 Ft
Peak Reservoir Storage: 76281. Cu-Ft
: 1.751 Ac-Ft
KCRTS
Pre-developed and Developed Stormwater Pond Flow
Output
Predeveloped Peak Flows and Flow Frequency Analysis from KCRTS
Flow Frequency Analysis
Time Series File: psetalbotpredev_020816.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks- - Rank Return Prob
(CFS)
(CFS)
Period
0.372 2 2/9/2001 18:00 0.475 1 100 0.99
0.101 7 1/6/2002 3:00 0.372 2 25 0.96
0.276 4 2/28/2003 3:00 0.285 3 10 0.9
0.010 8 3/24/2004 20:00 0.276 4 5 0.8
0.164 6 1/5/2005 8:00 0.241 5 3 0.667
0.285 3 1/18/2006 21:00 0.164 6 2 0.5
0.241 5 11/24/2006 4:00 0.101 7 1.3 0.231
0.475 1 1/9/2008 9:00 0.010 8 1.1 0.091
Computed
Peaks
0.441
50 0.98
Developed Peak Flows and Flow Frequency Analysis before Stormwater
Detention Pond from KCRTS
Flow Frequency Analysis
Time Series File: psetalbotdev_020816.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks- - Rank Return Prob
(CFS)
(CFS)
Period
1.11 6 2/9/2001 2:00 2.25 1 100 0.99
0.912 8 1/5/2002 16:00 1.44 2 25 0.96
1.34 3 2/27/03 7:00 1.34 3 10 0.9
0.992 7 8/26/2004 2:00 1.20 4 5 0.8
1.20 4 10/28/2004 16:00 1.18 5 3 0.667
1.18 5 1/18/2006 16:00 1.11 6 2 0.5
1.44 2 10/26/2006 0:00 0.992 7 1.3 0.231
2.25 1 1/9/2008 6:00 0.912 8 1.1 0.091
Computed
Peaks
1.98
50 0.98
Proposed Peak Flows and Flow Frequency Analysis from Stormwater
Detention Pond from KCRTS
Flow Frequency Analysis
Time Series File:pserdout_020816.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks- - Rank Return Prob
(CFS)
(CFS) (ft)
Period
0.363 2 2/9/2001 21:00 1.04 7.16 1 100 0.99
0.077 7 1/7/2002 4:00 0.363 6.87 2 25 0.96
0.281 3 3/6/2003 22:00 0.281 6.27 3 10 0.9
0.066 8 8/26/2004 7:00 0.261 6.23 4 5 0.8
0.092 6 1/8/2005 5:00 0.172 5.37 5 3 0.667
0.172 5 1/19/2006 0:00 0.092 4.92 6 2 0.5
0.261 4 11/24/2006 8:00 0.077 4.57 7 1.3 0.231
1.04 1 1/9/2008 10:00 0.066 3.37 8 1.1 0.091
Computed
Peaks
0.818 7.12
50 0.98
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KCRTS
Pre-developed and Developed Flow Durations and Curve
Predeveloped Flow Durations from KCRTS
Flow Duration
Time Series File: psetalbotpredev_020816.tsf
Cutoff Count Frequency CDF
Exceedance
Probability
CFS % % %
0.082 60744 99.061 99.061 0.939 9.39E-03
0.092 112 0.183 99.243 0.757 7.57E-03
0.103 72 0.117 99.361 0.639 6.39E-03
0.113 41 0.067 99.428 0.572 5.72E-03
0.123 40 0.065 99.493 0.507 5.07E-03
0.134 35 0.057 99.550 0.450 4.50E-03
0.144 37 0.060 99.610 0.390 3.90E-03
0.154 27 0.044 99.654 0.346 3.46E-03
0.164 23 0.038 99.692 0.308 3.08E-03
0.175 22 0.036 99.728 0.272 2.72E-03
0.185 18 0.029 99.757 0.243 2.43E-03
0.195 17 0.028 99.785 0.215 2.15E-03
0.206 23 0.038 99.822 0.178 1.78E-03
0.216 19 0.031 99.853 0.147 1.47E-03
0.226 12 0.020 99.873 0.127 1.27E-03
0.236 15 0.024 99.897 0.103 1.03E-03
0.247 13 0.021 99.918 0.082 8.15E-04
0.257 9 0.015 99.933 0.067 6.69E-04
0.267 9 0.015 99.948 0.052 5.22E-04
0.278 9 0.015 99.962 0.038 3.75E-04
0.288 5 0.008 99.971 0.029 2.94E-04
0.298 2 0.003 99.974 0.026 2.61E-04
0.309 3 0.005 99.979 0.021 2.12E-04
0.319 2 0.003 99.982 0.018 1.79E-04
0.329 1 0.002 99.984 0.016 1.63E-04
0.340 1 0.002 99.985 0.015 1.47E-04
0.350 4 0.007 99.992 0.008 8.15E-05
0.360 3 0.005 99.997 0.003 3.26E-05
0.370 1 0.002 99.998 0.002 1.63E-05
0.381 1 0.002 100.000 0.000 0.00E+00
0.391 0 0.000 100.000 0.000 0.00E+00
0.401 0 0.000 100.000 0.000 0.00E+00
0.412 0 0.000 100.000 0.000 0.00E+00
0.422 0 0.000 100.000 0.000 0.00E+00
0.432 0 0.000 100.000 0.000 0.00E+00
0.443 0 0.000 100.000 0.000 0.00E+00
0.432 0 0.000 100.000 0.000 0.00E+00
0.443 0 0.000 100.000 0.000 0.00E+00
Developed Flow Durations from Stormwater Detention Pond from KCRTS
Flow Duration
Time Series File: psetalbotpredev_020816.tsf
Cutoff Count Frequency CDF
Exceedance
Probability
CFS % % %
0.005 30750 50.147 50.147 49.853 4.99E-01
0.015 6754 11.014 61.161 38.839 3.88E-01
0.026 5291 8.629 69.790 30.210 3.02E-01
0.036 5511 8.987 78.777 21.223 2.12E-01
0.046 4878 7.955 86.732 13.268 1.33E-01
0.056 3407 5.556 92.288 7.712 7.71E-02
0.066 2133 3.478 95.766 4.234 4.23E-02
0.077 1820 2.968 98.735 1.265 1.27E-02
0.087 390 0.636 99.371 0.629 6.29E-03
0.097 33 0.054 99.424 0.576 5.76E-03
0.107 11 0.018 99.442 0.558 5.58E-03
0.117 10 0.016 99.459 0.541 5.41E-03
0.128 10 0.016 99.475 0.525 5.25E-03
0.138 43 0.070 99.545 0.455 4.55E-03
0.148 43 0.070 99.615 0.385 3.85E-03
0.158 41 0.067 99.682 0.318 3.18E-03
0.168 31 0.051 99.733 0.267 2.67E-03
0.178 29 0.047 99.780 0.220 2.20E-03
0.189 20 0.033 99.812 0.188 1.88E-03
0.199 15 0.024 99.837 0.163 1.63E-03
0.209 21 0.034 99.871 0.129 1.29E-03
0.219 16 0.026 99.897 0.103 1.03E-03
0.229 15 0.024 99.922 0.078 7.83E-04
0.24 6 0.010 99.932 0.068 6.85E-04
0.25 4 0.007 99.938 0.062 6.20E-04
0.26 6 0.010 99.948 0.052 5.22E-04
0.27 4 0.007 99.954 0.046 4.57E-04
0.28 4 0.007 99.961 0.039 3.91E-04
0.291 6 0.010 99.971 0.029 2.94E-04
0.301 1 0.002 99.972 0.028 2.77E-04
0.311 2 0.003 99.976 0.024 2.45E-04
0.321 2 0.003 99.979 0.021 2.12E-04
0.331 3 0.005 99.984 0.016 1.63E-04
0.342 2 0.003 99.987 0.013 1.30E-04
0.352 3 0.005 99.992 0.008 8.15E-05
0.362 4 0.007 99.998 0.002 1.63E-05
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00.050.10.150.20.250.30.350.41.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Discharge (CFS)Probability ExceedenceFlow Duration Analysis from KCRTSDevelopedConditionsPredevelopedConditions
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Rational Method Documentation
Rational Method
Rational Method Pipe Capacity Analysis
Subbasin Name Area (ft2) Area (ac)Impervious Area (%)Runoff from Impervious Area (cfs)Runoff from Pervious Area (cfs)Total Runoff (cfs)Cumulative Flow in System (cfs)Downstream Pipe NamePipe Full Flow Capacity from XPSWMM (cfs)Compliant with Capacity Requirement?Runoff from Impervious Area (cfs)Runoff from Pervious Area (cfs)Total Runoff (cfs)Cumulative Flow in System (cfs)CB101783.80.0410.650.0200.0100.0300.030Link40.940Yes0.0230.0120.0340.034CB112272.80.0520.650.0250.0130.0380.068Link50.940Yes0.0290.0150.0440.078CB122504.30.0570.650.0280.0140.0420.110Link60.940Yes0.0320.0160.0480.126CB132324.60.0530.650.0260.0130.0390.149Link70.940Yes0.0300.0150.0450.170CB142243.20.0510.650.0250.0130.0380.186Link80.940Yes0.0290.0150.0430.213CB152279.50.0520.650.0250.0130.0380.284Link90.940Yes0.0290.0150.0440.326CB162101.10.0480.650.0230.0120.0350.319Link100.940Yes0.0270.0140.0400.366CB172260.60.0520.650.0250.0130.0380.357Link110.950Yes0.0290.0150.0430.409CB182388.40.0550.650.0260.0130.0400.397Link120.940Yes0.0300.0150.0460.455CB192369.60.0540.650.0260.0130.0400.437Link130.910Yes0.0300.0150.0450.501CB202541.30.0580.650.0280.0140.0420.479Link142.730Yes0.0320.0160.0490.549CB211809.50.0420.650.0200.0100.0300.509Link152.710Yes0.0230.0120.0350.584CB224239.40.0970.650.0470.0240.0710.071Link190.940Yes0.0540.0270.0810.081CB2372070.1650.650.0800.0410.1200.191Link200.940Yes0.0920.0470.1380.220CB245143.60.1180.650.0570.0290.0860.277Link211.100Yes0.0650.0330.0990.318CB253582.30.0820.650.0400.0200.0600.337Link220.950Yes0.0460.0230.0690.387CB265034.80.1160.650.0560.0280.0840.084Link160.940Yes0.0640.0330.0970.097CB277103.40.1630.650.0790.0400.1190.203Link170.940Yes0.0900.0460.1360.233CB284914.90.1130.650.0540.0280.0820.285Link182.730Yes0.0620.0320.0940.327CB292539.30.0580.650.0280.0140.0422.571Link542.730Yes0.0320.0160.0492.950CB304221.20.0970.650.0470.0240.0710.071Link230.940Yes0.0540.0270.0810.081CB317300.10.1680.650.0810.0410.1220.193Link240.940Yes0.0930.0470.1400.221CB325210.80.1200.650.0580.0290.0870.280Link250.940Yes0.0660.0340.1000.321CB333677.30.0840.650.0410.0210.0610.341Link260.940Yes0.0470.0240.0710.391CB345122.10.1180.650.0570.0290.0860.086Link270.940Yes0.0650.0330.0980.098CB357241.60.1660.650.0800.0410.1210.207Link280.940Yes0.0920.0470.1390.237CB365030.20.1150.650.0560.0280.0840.291Link292.730Yes0.0640.0330.0960.334CB372586.90.0590.650.0290.0150.0431.735Link302.730Yes0.0330.0170.0501.990CB385872.50.1350.650.0650.0330.0980.098Link310.940Yes0.0750.0380.1130.113CB394688.80.1080.650.0520.0260.0780.232Link320.940Yes0.0600.0300.0900.266CB403307.20.0760.650.0370.0190.0550.055Link440.940Yes0.0420.0210.0630.063CB415186.10.1190.650.0570.0290.0870.319Link330.940Yes0.0660.0340.0990.365CB423599.20.0830.650.0400.0200.0600.060Link430.940Yes0.0460.0230.0690.069CB434345.90.1000.650.0480.0240.0730.864Link342.110Yes0.0550.0280.0830.992CB4438950.0890.650.0430.0220.0650.971Link352.750Yes0.0500.0250.0751.114CB4537950.0870.650.0420.0210.0631.210Link372.730Yes0.0480.0250.0731.388CB4628290.0650.650.0310.0160.0470.075Link410.940Yes0.0360.0180.0540.086CB471648.90.03810.0280.0000.0280.028Link450.950Yes0.0320.0000.0320.032CB484692.40.1080.650.0520.0260.0781.336Link382.730Yes0.0600.0300.0901.533CB492852.10.0650.650.0320.0160.0480.048Link400.940Yes0.0360.0180.0550.055CB503854.10.0880.650.0430.0220.0641.401Link392.730Yes0.0490.0250.0741.607CB512488.90.0570.650.0280.0140.0420.042Link530.470Yes0.0320.0160.0480.048CB521505.10.0350.650.0170.0080.0250.025Link480.470Yes0.0190.0100.0290.029CB531460.60.0340.650.0160.0080.0240.050Link490.470Yes0.0190.0090.0280.05725-yr Capacity Analysis25-yr Flows (cfs)100-yr Flows (cfs)
CB542481.80.0570.650.0280.0140.0410.041Link520.470Yes0.0320.0160.0480.048CB551492.60.0340.650.0170.0080.0250.050Link510.470Yes0.0190.0100.0290.057CB561489.50.0340.650.0170.0080.0250.025Link500.520Yes0.0190.0100.0290.029CB573437.50.0790.650.0380.0190.0571.071Link362.730Yes0.0440.0220.0661.229CB582562.50.0590.650.0280.0140.0430.043Link420.940Yes0.0330.0170.0490.049GI-12475.20.0570.650.0270.0140.0410.133Link471.030Yes0.0310.0160.0470.152GI-22440.20.0560.650.0270.0140.0410.132Link461.030Yes0.0310.0160.0470.151
Rational Method Coefficient0.85for gravel pavement0.9for pavementRainfall Intensity (ft/s)0.00002for 25-yr0.00002for 100-yr
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XPSWMM Model Documentation
XPSWMM
XPSWMM Model Schematic
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XPSWMM
Catch Basin (Node) & Pipe (Link) Input Data
Link Input Data Summary
Link Name
Upstream
Node Name
Downstream
Node Name
Upstream Invert
Elevation (ft)
Downstream
Invert
Elevation (ft)
Diameter
(ft)
Length
(ft)
Conduit
Slope (%) Roughness
Link4 CB10 CB11 436.51 436.26 0.67 50 0.5 0.012
Link5 CB11 CB12 436.26 435.96 0.67 60 0.5 0.012
Link6 CB12 CB13 435.96 435.66 0.67 60 0.5 0.012
Link7 CB13 CB14 435.66 435.41 0.67 50 0.5 0.012
Link8 CB14 CB15 435.24 434.92 0.67 64 0.5 0.012
Link9 CB15 CB16 434.5 434.27 0.67 46 0.5 0.012
Link10 CB16 CB17 434.27 434.02 0.67 50 0.5 0.012
Link11 CB17 CB18 434.02 433.73 0.67 57 0.5 0.012
Link12 CB18 CB19 433.73 433.48 0.67 50 0.5 0.012
Link13 CB19 CB20 433.48 433.21 0.67 58 0.5 0.012
Link14 CB20 CB21 432.88 432.58 1 60 0.5 0.012
Link15 CB21 CB29 432.58 432.26 1 65 0.5 0.012
Link54 CB29 Pond 430.69 430.5 1 38 0.5 0.012
Link18 CB28 CB29 435.13 434.83 1 60 0.5 0.012
Link17 CB27 CB28 435.77 435.23 0.67 108 0.5 0.012
Link16 CB26 CB27 436.42 435.87 0.67 110 0.5 0.012
Link22 CB25 CB15 434.94 434.6 0.67 67 0.5 0.012
Link21 CB24 CB25 435.34 434.97 0.67 54 0.5 0.012
Link20 CB23 CB24 435.96 435.41 0.67 110 0.5 0.012
Link19 CB22 CB23 436.51 435.96 0.67 110 0.5 0.012
Link30 CB37 CB29 430.98 430.69 1 58 0.5 0.012
Link28 CB35 CB36 435.88 435.34 0.67 108 0.5 0.012
Link29 CB36 CB37 435.01 434.71 1 60 0.5 0.012
Link27 CB34 CB35 436.42 435.88 0.67 108 0.5 0.012
Link39 CB50 CB37 431.36 430.98 1 76 0.5 0.012
Link38 CB48 CB50 431.66 431.36 1 60 0.5 0.012
Link37 CB45 CB48 432.53 431.99 1 108 0.5 0.012
Link36 CB57 CB45 434.11 433.81 1 60 0.5 0.012
Link35 CB44 CB57 434.44 434.11 1 65 0.5 0.012
Link34 CB43 CB44 434.54 434.45 1 17 0.5 0.012
Link33 CB41 CB43 435.49 435.12 0.67 74 0.5 0.012
Link32 CB39 CB41 436.21 435.66 0.67 110 0.5 0.012
Link31 CB38 CB39 436.51 436.21 0.67 60 0.5 0.012
Link26 CB33 CB43 434.92 434.54 0.67 76 0.5 0.012
Link25 CB32 CB33 435.24 434.92 0.67 64 0.5 0.012
Link24 CB31 CB32 435.96 435.41 0.67 110 0.5 0.012
Link23 CB30 CB31 436.51 435.96 0.67 110 0.5 0.012
Link44 CB40 CB39 436.45 436.25 0.67 40 0.5 0.012
Link43 CB42 CB41 436.25 436.05 0.67 40 0.5 0.012
Link42 CB58 CB57 436 435.8 0.67 40 0.5 0.012
Link40 CB49 CB48 436 435.8 0.67 40 0.5 0.012
Link41 CB46 CB45 432.75 432.6 0.67 30 0.5 0.012
Link45 CB47 CB46 432.98 432.75 0.67 45 0.5 0.012
Link46 GI-2 CB43 435.21 434.79 0.67 83 0.5 0.011
Link47 GI-1 CB44 435.21 434.79 0.67 83 0.5 0.011
Link51 CB55 GI-1 435.93 435.71 0.5 43 0.5 0.011
Link50 CB56 CB55 436.45 435.93 0.5 83 0.5 0.011
Link52 CB54 GI-1 436.25 435.84 0.5 83 0.5 0.011
Link49 CB53 GI-2 435.93 435.71 0.5 43 0.5 0.011
Link48 CB52 CB53 436.45 436.03 0.5 83 0.5 0.011
Link53 CB51 GI-2 436.25 435.84 0.5 83 0.5 0.011
(Link 55) riserweir Pond OF NA NA NA NA NA NA
(Link 55) bottom orifice Pond OF NA NA 0.10 NA NA NA
(Link 55) side#1 Pond OF NA NA 0.18 NA NA NA
(Link 55) side#2 Pond OF NA NA 0.17 NA NA NA
Node Hydraulic Input Data
Node
Name
Ground Elevation
Spill Crest (ft)
Invert
Elevation
(ft)
CB10 437.92 436.51
CB11 437.92 436.26
CB12 437.92 435.96
CB13 437.92 435.66
CB14 437.92 435.24
CB15 437.92 434.5
CB16 437.92 434.27
CB17 437.92 434.02
CB18 437.92 433.73
CB19 437.92 433.48
CB20 437.92 432.88
CB21 437.92 432.58
CB29 437.92 430.69
CB28 437.75 435.13
CB27 437.75 435.77
CB26 437.75 436.42
CB25 437.75 434.94
CB24 437.75 435.24
CB23 437.75 435.96
CB22 437.75 436.51
CB37 437.92 430.98
CB35 437.75 435.88
CB36 437.75 435.01
CB34 437.75 436.42
CB50 437.92 431.36
CB48 437.75 431.66
CB45 437.75 432.53
CB57 437.75 434.11
CB44 437.75 434.44
CB43 437.75 434.54
CB41 437.75 435.49
CB39 437.75 436.21
CB38 437.75 436.51
CB33 437.75 434.92
CB32 437.75 435.24
CB31 437.75 435.96
CB30 437.75 436.51
CB40 437.54 436.45
CB42 437.5 436.25
CB58 437.5 436
CB49 437.75 436
CB46 437.75 432.75
CB47 437.75 432.98
GI-2 439.65 435.21
GI-1 439.65 435.21
CB55 438.25 435.93
CB56 438.25 436.45
CB54 438.25 436.25
CB53 438.25 435.93
CB52 438.25 436.45
CB51 438.25 436.25
Pond 437.5 425.5
OF 437.5 425
Node Runoff Input Data
Node
Name
Area
(ac)
Slope
(ft/ft)
Impervious
Percentage (%) Width (ft)
CB10 0.041 0.003 65 43
CB11 0.052 0.003 65 55
CB12 0.057 0.003 65 60
CB13 0.053 0.003 65 55
CB14 0.051 0.003 65 57
CB15 0.052 0.003 65 54
CB16 0.048 0.003 65 49
CB17 0.052 0.003 65 52
CB18 0.055 0.003 65 55
CB19 0.054 0.003 65 54
CB20 0.058 0.003 65 58
CB21 0.042 0.003 65 44
CB29 0.058 0.003 65 63
CB28 0.113 0.003 65 79
CB27 0.163 0.003 65 113
CB26 0.116 0.003 65 80
CB25 0.082 0.003 65 63
CB24 0.118 0.003 65 82
CB23 0.165 0.003 65 114
CB22 0.097 0.003 65 67
CB37 0.059 0.003 67 64
CB35 0.166 0.003 65 114
CB36 0.115 0.003 65 79
CB34 0.118 0.003 65 80
CB50 0.088 0.003 65 95
CB48 0.108 0.003 65 79
CB45 0.087 0.003 65 69
CB57 0.079 0.003 65 62.5
CB44 0.089 0.003 65 95
CB43 0.1 0.003 65 95
CB41 0.119 0.003 65 92
CB39 0.108 0.003 65 84
CB38 0.135 0.003 65 46
CB33 0.084 0.003 65 64
CB32 0.12 0.003 65 82
CB31 0.168 0.003 65 114
CB30 0.097 0.003 65 67
CB40 0.076 0.003 65 84
CB42 0.083 0.003 65 93
CB58 0.059 0.003 65 62.5
CB49 0.065 0.003 65 80
CB46 0.065 0.003 65 69
CB47 0.038 0.003 65 41
GI-2 0.056 0.003 65 50
GI-1 0.057 0.003 65 50
CB55 0.034 0.003 65 50
CB56 0.034 0.003 65 50
CB54 0.057 0.003 65 50
CB53 0.035 0.003 65 49
CB52 0.035 0.003 65 40
CB51 0.057 0.003 65 50
Pond NA NA NA NA
OF NA NA NA NA
XPSWMM
Catch Basin (Node) & Pipe (Link) Output Summary
Node Output Data Summary for 25-year Event
Node Name
Max Water
Elevation (ft)
Max Water Depth
(ft) Freeboard (ft)
Duration of
Surcharge
(min)
Duration of
Flooding (min)
CB10 436.590 0.080 1.33 0.0 0.0
CB11 436.379 0.119 1.54 0.0 0.0
CB12 436.110 0.150 1.81 0.0 0.0
CB13 435.837 0.177 2.08 0.0 0.0
CB14 435.438 0.198 2.48 0.0 0.0
CB15 434.864 0.364 3.06 0.0 0.0
CB16 434.648 0.378 3.27 0.0 0.0
CB17 434.411 0.391 3.51 0.0 0.0
CB18 434.141 0.411 3.78 0.0 0.0
CB19 433.911 0.431 4.01 0.0 0.0
CB20 433.230 0.350 4.69 0.0 0.0
CB21 432.938 0.358 4.98 0.0 0.0
CB29 431.476 0.786 6.44 0.0 0.0
CB28 435.343 0.213 2.41 0.0 0.0
CB27 435.978 0.208 1.77 0.0 0.0
CB26 436.554 0.134 1.20 0.0 0.0
CB25 435.210 0.270 2.54 0.0 0.0
CB24 435.563 0.323 2.19 0.0 0.0
CB23 436.162 0.202 1.59 0.0 0.0
CB22 436.631 0.121 1.12 0.0 0.0
CB37 431.639 0.659 6.28 0.0 0.0
CB35 436.090 0.210 1.66 0.0 0.0
CB36 435.225 0.215 2.53 0.0 0.0
CB34 436.554 0.134 1.20 0.0 0.0
CB50 431.908 0.548 6.01 0.0 0.0
CB48 432.178 0.518 5.57 0.0 0.0
CB45 433.015 0.485 4.73 0.0 0.0
CB57 434.566 0.456 3.18 0.0 0.0
CB44 434.875 0.435 2.87 0.0 0.0
CB43 434.982 0.442 2.77 0.0 0.0
CB41 435.780 0.290 1.97 0.0 0.0
CB39 436.433 0.223 1.32 0.0 0.0
CB38 436.652 0.142 1.10 0.0 0.0
CB33 435.203 0.283 2.55 0.0 0.0
CB32 435.485 0.245 2.26 0.0 0.0
CB31 436.163 0.203 1.59 0.0 0.0
CB30 436.631 0.121 1.12 0.0 0.0
CB40 436.558 0.108 0.98 0.0 0.0
CB42 436.364 0.114 1.14 0.0 0.0
CB58 436.097 0.097 1.40 0.0 0.0
CB49 436.102 0.102 1.65 0.0 0.0
CB46 433.017 0.267 4.73 0.0 0.0
CB47 433.057 0.077 4.69 0.0 0.0
GI-2 435.369 0.159 4.28 0.0 0.0
GI-1 435.368 0.158 4.28 0.0 0.0
CB55 436.037 0.107 2.21 0.0 0.0
CB56 436.522 0.072 1.73 0.0 0.0
CB54 436.349 0.099 1.90 0.0 0.0
CB53 436.038 0.108 2.21 0.0 0.0
CB52 436.528 0.078 1.72 0.0 0.0
CB51 436.349 0.099 1.90 0.0 0.0
OF 425.536 1.151 11.96 0.0 0.0
Node Output Data Summary for 100-year Event
Node Name
Max Water
Elevation (ft)
Max Water
Depth (ft)
Freeboard
(ft)
Duration of
Surcharge (min)
Duration of
Flooding (min)
CB10 436.596 0.086 1.32 0.0 0.0
CB11 436.389 0.129 1.53 0.0 0.0
CB12 436.123 0.163 1.80 0.0 0.0
CB13 435.852 0.192 2.07 0.0 0.0
CB14 435.455 0.215 2.46 0.0 0.0
CB15 434.904 0.404 3.02 0.0 0.0
CB16 434.691 0.421 3.23 0.0 0.0
CB17 434.457 0.437 3.46 0.0 0.0
CB18 434.190 0.460 3.73 0.0 0.0
CB19 433.960 0.480 3.96 0.0 0.0
CB20 433.262 0.382 4.66 0.0 0.0
CB21 432.971 0.391 4.95 0.0 0.0
CB29 431.570 0.880 6.35 0.0 0.0
CB28 435.361 0.231 2.39 0.0 0.0
CB27 435.996 0.226 1.75 0.0 0.0
CB26 436.565 0.145 1.18 0.0 0.0
CB25 435.234 0.294 2.52 0.0 0.0
CB24 435.583 0.343 2.17 0.0 0.0
CB23 436.179 0.219 1.57 0.0 0.0
CB22 436.641 0.131 1.11 0.0 0.0
CB37 431.737 0.757 6.18 0.0 0.0
CB35 436.109 0.229 1.64 0.0 0.0
CB36 435.243 0.233 2.51 0.0 0.0
CB34 436.565 0.145 1.19 0.0 0.0
CB50 431.982 0.622 5.94 0.0 0.0
CB48 432.237 0.577 5.51 0.0 0.0
CB45 433.065 0.535 4.69 0.0 0.0
CB57 434.610 0.500 3.14 0.0 0.0
CB44 434.918 0.478 2.83 0.0 0.0
CB43 435.023 0.483 2.73 0.0 0.0
CB41 435.808 0.318 1.94 0.0 0.0
CB39 436.453 0.243 1.30 0.0 0.0
CB38 436.664 0.154 1.09 0.0 0.0
CB33 435.234 0.314 2.52 0.0 0.0
CB32 435.509 0.269 2.24 0.0 0.0
CB31 436.180 0.220 1.57 0.0 0.0
CB30 436.641 0.131 1.11 0.0 0.0
CB40 436.567 0.117 0.97 0.0 0.0
CB42 436.373 0.123 1.13 0.0 0.0
CB58 436.105 0.105 1.40 0.0 0.0
CB49 436.110 0.110 1.64 0.0 0.0
CB46 433.066 0.316 4.68 0.0 0.0
CB47 433.081 0.101 4.67 0.0 0.0
GI-2 435.382 0.172 4.27 0.0 0.0
GI-1 435.382 0.172 4.27 0.0 0.0
CB55 436.045 0.115 2.20 0.0 0.0
CB56 436.528 0.078 1.72 0.0 0.0
CB54 436.357 0.107 1.89 0.0 0.0
CB53 436.047 0.117 2.20 0.0 0.0
CB52 436.534 0.084 1.72 0.0 0.0
CB51 436.357 0.107 1.89 0.0 0.0
Pond 429.500 5.105 8.00 0.0 0.0
OF 425.536 1.151 11.96 101.135
0.0
Link Output Data Summary for 25-year Event
Link Name
Upstream
Node Name
Downstream
Node Name
Design Full
Flow (cfs)
Max Depth
(ft)
Max d/D
(depth/diameter)
Max Flow
(cfs)
Max
Tailwater
(ft)
Max
Headwater
(ft)
Link4 CB10 CB11 0.94 0.119 0.177 0.028 436.379 436.590
Link5 CB11 CB12 0.94 0.150 0.225 0.064 436.110 436.379
Link6 CB12 CB13 0.94 0.177 0.264 0.104 435.837 436.110
Link7 CB13 CB14 0.94 0.177 0.264 0.140 435.581 435.837
Link8 CB14 CB15 0.94 0.198 0.296 0.176 435.112 435.438
Link9 CB15 CB16 0.94 0.378 0.564 0.531 434.648 434.864
Link10 CB16 CB17 0.94 0.391 0.584 0.564 434.411 434.648
Link11 CB17 CB18 0.95 0.411 0.613 0.600 434.141 434.411
Link12 CB18 CB19 0.94 0.431 0.644 0.637 433.911 434.141
Link13 CB19 CB20 0.91 0.431 0.644 0.675 433.596 433.911
Link14 CB20 CB21 2.73 0.358 0.358 0.715 432.938 433.230
Link15 CB21 CB29 2.71 0.358 0.358 0.743 432.618 432.938
Link54 CB29 Pond 2.73 0.786 0.786 2.842 431.223 431.476
Link18 CB28 CB29 2.73 0.213 0.213 0.271 435.042 435.343
Link17 CB27 CB28 0.94 0.208 0.311 0.193 435.431 435.978
Link16 CB26 CB27 0.94 0.134 0.201 0.080 435.998 436.554
Link22 CB25 CB15 0.95 0.270 0.403 0.319 434.864 435.210
Link21 CB24 CB25 1.10 0.240 0.358 0.263 435.210 435.563
Link20 CB23 CB24 0.94 0.202 0.301 0.181 435.605 436.162
Link19 CB22 CB23 0.94 0.202 0.301 0.067 436.162 436.631
Link30 CB37 CB29 2.73 0.786 0.786 1.788 431.476 431.639
Link28 CB35 CB36 0.94 0.210 0.314 0.196 435.543 436.090
Link29 CB36 CB37 2.73 0.215 0.215 0.276 434.924 435.225
Link27 CB34 CB35 0.94 0.210 0.314 0.082 436.090 436.554
Link39 CB50 CB37 2.73 0.659 0.659 1.472 431.639 431.908
Link38 CB48 CB50 2.73 0.548 0.548 1.411 431.908 432.178
Link37 CB45 CB48 2.73 0.485 0.485 1.292 432.470 433.015
Link36 CB57 CB45 2.73 0.456 0.456 1.161 434.264 434.566
Link35 CB44 CB57 2.75 0.456 0.456 1.066 434.566 434.875
Link34 CB43 CB44 2.11 0.442 0.442 0.879 434.875 434.982
Link33 CB41 CB43 0.94 0.291 0.434 0.359 435.398 435.780
Link32 CB39 CB41 0.94 0.223 0.333 0.220 435.875 436.433
Link31 CB38 CB39 0.94 0.223 0.333 0.093 436.433 436.652
Link26 CB33 CB43 0.94 0.442 0.659 0.324 434.981 435.203
Link25 CB32 CB33 0.94 0.283 0.422 0.266 435.203 435.485
Link24 CB31 CB32 0.94 0.203 0.303 0.183 435.606 436.163
Link23 CB30 CB31 0.94 0.203 0.303 0.067 436.163 436.631
Link44 CB40 CB39 0.94 0.183 0.273 0.053 436.433 436.558
Link43 CB42 CB41 0.94 0.114 0.170 0.057 436.158 436.364
Link42 CB58 CB57 0.94 0.097 0.145 0.041 435.890 436.097
Link40 CB49 CB48 0.94 0.102 0.152 0.045 435.895 436.102
Link41 CB46 CB45 0.94 0.415 0.620 0.071 433.015 433.017
Link45 CB47 CB46 0.95 0.267 0.398 0.026 433.017 433.057
Link46 GI-2 CB43 1.03 0.192 0.286 0.127 434.981 435.369
Link47 GI-1 CB44 1.03 0.158 0.236 0.126 434.948 435.368
Link51 CB55 GI-1 0.47 0.107 0.213 0.047 435.816 436.037
Link50 CB56 CB55 0.52 0.107 0.213 0.024 436.037 436.522
Link52 CB54 GI-1 0.47 0.099 0.198 0.039 435.937 436.349
Link49 CB53 GI-2 0.47 0.108 0.216 0.048 435.817 436.038
Link48 CB52 CB53 0.47 0.078 0.156 0.024 436.105 436.528
Link53 CB51 GI-2 0.47 0.099 0.198 0.039 435.937 436.349
Link56 Pond OF 0.00 -9.00E+99 0.000 0.000 0.000 0.000
Link56 Pond OF 8.95 5.103 4.434 16.008 425.536 429.135
Link56 Pond OF 41.69 0.253 0.119 0.068 429.322 429.478
Link56 Pond OF 35.63 -9.00E+99 0.000 0.000 0.000 0.000
Link Output Data Summary for 100-year Event
Link Name
Upstream
Node Name
Downstream
Node Name
Design Full
Flow (cfs)
Max
Depth (ft)
Max d/D
(depth/
diameter)
Max Flow
(cfs)
Max
Tailwater
(ft)
Max
Headwater
(ft)
Link4 CB10 CB11 0.94 0.129 0.192 0.033 436.389 436.596
Link5 CB11 CB12 0.94 0.163 0.243 0.076 436.123 436.389
Link6 CB12 CB13 0.94 0.192 0.286 0.122 435.852 436.123
Link7 CB13 CB14 0.94 0.192 0.286 0.165 435.596 435.852
Link8 CB14 CB15 0.94 0.215 0.321 0.206 435.128 435.455
Link9 CB15 CB16 0.94 0.421 0.628 0.623 434.691 434.904
Link10 CB16 CB17 0.94 0.437 0.652 0.662 434.457 434.691
Link11 CB17 CB18 0.95 0.460 0.687 0.704 434.190 434.457
Link12 CB18 CB19 0.94 0.480 0.717 0.749 433.960 434.190
Link13 CB19 CB20 0.91 0.480 0.717 0.792 433.630 433.960
Link14 CB20 CB21 2.73 0.391 0.391 0.840 432.971 433.262
Link15 CB21 CB29 2.71 0.391 0.391 0.873 432.650 432.971
Link54 CB29 Pond 2.73 0.880 0.880 3.339 431.281 431.570
Link18 CB28 CB29 2.73 0.231 0.231 0.318 435.060 435.361
Link17 CB27 CB28 0.94 0.226 0.338 0.226 435.449 435.996
Link16 CB26 CB27 0.94 0.145 0.217 0.094 436.009 436.565
Link22 CB25 CB15 0.95 0.304 0.454 0.375 434.904 435.234
Link21 CB24 CB25 1.10 0.264 0.394 0.309 435.234 435.583
Link20 CB23 CB24 0.94 0.219 0.327 0.213 435.622 436.179
Link19 CB22 CB23 0.94 0.219 0.327 0.079 436.179 436.641
Link30 CB37 CB29 2.73 0.880 0.880 2.101 431.570 431.737
Link28 CB35 CB36 0.94 0.229 0.341 0.231 435.561 436.109
Link29 CB36 CB37 2.73 0.233 0.233 0.324 434.942 435.243
Link27 CB34 CB35 0.94 0.229 0.341 0.096 436.109 436.565
Link39 CB50 CB37 2.73 0.757 0.757 1.729 431.737 431.982
Link38 CB48 CB50 2.73 0.622 0.622 1.658 431.982 432.237
Link37 CB45 CB48 2.73 0.535 0.535 1.518 432.512 433.065
Link36 CB57 CB45 2.73 0.500 0.500 1.364 434.304 434.610
Link35 CB44 CB57 2.75 0.500 0.500 1.252 434.610 434.918
Link34 CB43 CB44 2.11 0.483 0.483 1.033 434.918 435.023
Link33 CB41 CB43 0.94 0.318 0.475 0.422 435.422 435.808
Link32 CB39 CB41 0.94 0.243 0.362 0.258 435.894 436.453
Link31 CB38 CB39 0.94 0.243 0.362 0.109 436.453 436.664
Link26 CB33 CB43 0.94 0.483 0.722 0.381 435.023 435.234
Link25 CB32 CB33 0.94 0.314 0.469 0.313 435.234 435.509
Link24 CB31 CB32 0.94 0.220 0.329 0.215 435.623 436.180
Link23 CB30 CB31 0.94 0.220 0.329 0.079 436.180 436.641
Link44 CB40 CB39 0.94 0.203 0.303 0.062 436.453 436.567
Link43 CB42 CB41 0.94 0.123 0.184 0.067 436.167 436.373
Link42 CB58 CB57 0.94 0.105 0.156 0.048 435.898 436.105
Link40 CB49 CB48 0.94 0.110 0.164 0.053 435.903 436.110
Link41 CB46 CB45 0.94 0.465 0.694 0.084 433.060 433.062
Link45 CB47 CB46 0.95 0.316 0.472 0.031 433.066 433.081
Link46 GI-2 CB43 1.03 0.233 0.348 0.149 435.023 435.382
Link47 GI-1 CB44 1.03 0.172 0.256 0.148 434.961 435.382
Link51 CB55 GI-1 0.47 0.115 0.231 0.055 435.825 436.045
Link50 CB56 CB55 0.52 0.115 0.231 0.028 436.045 436.528
Link52 CB54 GI-1 0.47 0.107 0.214 0.046 435.945 436.357
Link49 CB53 GI-2 0.47 0.117 0.234 0.057 435.827 436.047
Link48 CB52 CB53 0.47 0.084 0.168 0.028 436.112 436.534
Link53 CB51 GI-2 0.47 0.107 0.214 0.046 435.945 436.357
Link55 Pond OF 0.00 -9.00E+99 0 0 0 0
Link55 Pond OF 8.95 5.103 4.434 16.008 425.536 429.135
Link55 Pond OF 41.69 0.253 0.119 0.068 429.322 429.478
Link55 Pond OF 35.63 -9.00E+99 0 0 0 0
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Appendix F
CSWPPP
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Appendix G
Facilities Summary and
Declaration of Covenant
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual 1/9/2009
KING COUNTY, WASHINGTON
SURFACE WATER DESIGN MANUAL
REFERENCE 8-D
FLOW CONTROL AND WATER
QUALITY FACILITY SUMMARY SHEET
AND SKETCH
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual 1/9/2009
1
STORMWATER FACILITY SUMMARY SHEET DDES Permit
Number__________________
(provide one Stormwater Facility Summary Sheet per Natural Discharge Location)
Overview:
Project Name
_______________________________________________________Date___________________
Downstream Drainage Basins
Major Basin Name _____________________________
Immediate Basin Name __________________________
Flow Control:
Flow Control Facility Name/Number ________________________________
Facility
Location________________________________________________________________________
___
If none,
Flow control provided in regional/shared facility (give
location)___________________________________
No flow control required_____________ Exemption number
_______________________________
General Facility Information:
Type/Number of detention facilities: Type/Number of infiltration facilities:
______ ponds ______ ponds
______ vaults ______ tanks
______ tanks ______ trenches
Control Structure Location
_____________________________________________________________________
Type of Control Structure ______________________________ Number of Orifices/Restrictions
_____________
Size of Orifice/Restriction: No. 1 ________________
No. 2 ________________
No. 3 ________________
No. 4 ________________
Flow Control Performance Standard _________________________________
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual 1/9/2009
2
Live Storage Volume __________________ Depth _______________ Volume Factor of Safety
________________
Number of Acres Served ____________________
Number of Lots ____________________
Dam Safety Regulations (Washington State Department of Ecology)
Reservoir Volume above natural grade ________________
Depth of Reservoir above natural grade _______________
Facility Summary Sheet Sketch
All detention, infiltration and water quality facilities must include a detailed sketch.
(11"x17" reduced size plan sheets may be used)
Propose dDischarge Point
No access topond from inside the substation
ProposedStormwaterDetention Pond
Control Structure Location
PondAccessRoad
PATH: G:\PROJEC TS\WAS HINGTON\PUGET_SOUND_EN ERGY_00 702 2\TAL BOT_STORMWATER_SUPPORT_2699 66\MAP_DOCS \DRAF T\T IR FIGURES\APPENDIX G FACILT Y SKE TCH.MX D - USER: TAHOF FMA - DATE: 11/16 /20 16
TALBOT STORMWATER SUPPORT
APPENDIX G
FLOW CONTROL FA CILITY SKETCH
STORMWATER TIR
0 150Feet
O
DATA SOURCE: City of Renton,King County (2016)
LEGEND
Project Are a
Con to urs - 10 ft In te rval
Propo sed C on tro lStructure
Propo sedFlow Pa th
Propo sedDrainageInfrastructur e
Propo sedDetention Pond
Propo sed Acce ssRoad
2009 Surface Water Design Manual Amendment City of Renton
CITY OF RENTON
AMENDMENTS TO THE KING COUNTY
SURFACE WATER DESIGN MANUAL
REFERENCE 8-H
BOND QUANTITIES WORKSHEET
Site Improvement Bond Quantity WorksheetOriginal bond computations prepared by:Name:Date:PE Registration Number:Tel. #:Firm Name:Address:Project No: Stabilization/Erosion Sediment Control (ESC) (A)Existing Right-of-Way Improvements (B)Future Public Road Improvements & Drainage Facilities (C)Private Improvements (D)Construction Bond* Amount (A+B+C+D) = TOTAL (T)Minimum bond* amount is $1000.Maintenance/Defect Bond* TotalNAME OF PERSON PREPARING BOND* REDUCTION:Date:* NOTE:The word "bond" as used in this document means any financial guarantee acceptable to the City of Renton.** NOTE: All prices include labor, equipment, materials, overhead and profit. Prices are from RS Means data adjusted for the Seattle areaor from local sources if not included in the RS Means database.REQUIRED BOND* AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY RDSD-$ -$ -$ (B+C) x 0.20 =-$ ROAD IMPROVEMENTS & DRAINAGE FACILITIES FINANCIAL GUARANTEE REQUIREMENTSPERFORMANCE BOND*,**AMOUNTPUBLIC ROAD & DRAINAGE MAINTENANCE/DEFECT BOND*,**-$ -$ Page 1 of 1REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
Site Improvement Bond Quantity WorksheetExisting Future Public PrivateRight-of-Way Road Improvements Improvements & Drainage FacilitiesQuant.Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete CostGENERAL ITEMSNo.Backfill & Compaction- embankment GI - 1 5.62$ CY0.00 0.00 0.00 0.00Backfill & Compaction- trench GI - 2 8.53$ CY0.00 0.00 0.00 0.00Clear/Remove Brush, by hand GI - 3 0.36$ SY 0.00 0.00 0.00 0.00Clearing/Grubbing/Tree Removal GI - 4 8,876.16$ Acre 0.00 0.00 0.00 0.00Excavation - bulk GI - 5 1.50$ CY0.00 0.00 0.00 0.00Excavation - Trench GI - 6 4.06$ CY0.00 0.00 0.00 0.00Fencing, cedar, 6' high GI - 7 18.55$ LF 0.00 0.00 0.00 0.00Fencing, chain link, vinyl coated, 6' high GI - 8 13.44$ LF 0.00 0.00 0.00 0.00Fencing, chain link, gate, vinyl coated, 20GI - 9 1,271.81$ Each 0.00 0.00 0.00 0.00Fencing, split rail, 3' high GI - 10 12.12$ LF 0.00 0.00 0.00 0.00Fill & compact - common barrow GI - 11 22.57$ CY0.00 0.00 0.00 0.00Fill & compact - gravel base GI - 12 25.48$ CY0.00 0.00 0.00 0.00Fill & compact - screened topsoil GI - 13 37.85$ CY0.00 0.00 0.00 0.00Gabion, 12" deep, stone filled mesh GI - 14 54.31$ SY 0.00 0.00 0.00 0.00Gabion, 18" deep, stone filled mesh GI - 15 74.85$ SY 0.00 0.00 0.00 0.00Gabion, 36" deep, stone filled mesh GI - 16 132.48$ SY 0.00 0.00 0.00 0.00Grading, fine, by hand GI - 17 2.02$ SY 0.00 0.00 0.00 0.00Grading, fine, with grader GI - 18 0.95$ SY 0.00 0.00 0.00 0.00Monuments, 3' long GI - 19 135.13$ Each 0.00 0.00 0.00 0.00Sensitive Areas Sign GI - 20 2.88$ Each 0.00 0.00 0.00 0.00Sodding, 1" deep, sloped ground GI - 21 7.46$ SY 0.00 0.00 0.00 0.00Surveying, line & grade GI - 22 788.26$ Day0.00 0.00 0.00 0.00Surveying, lot location/lines GI - 23 1,556.64$ Acre 0.00 0.00 0.00 0.00Traffic control crew ( 2 flaggers ) GI - 24 85.18$ HR0.00 0.00 0.00 0.00Trail, 4" chipped wood GI - 25 7.59$ SY 0.00 0.00 0.00 0.00Trail, 4" crushed cinder GI - 26 8.33$ SY 0.00 0.00 0.00 0.00Trail, 4" top course GI - 27 8.19$ SY 0.00 0.00 0.00 0.00Wall, retaining, concrete GI - 28 44.16$ SF 0.00 0.00 0.00 0.00Wall, rockery GI - 29 9.49$ SF 0.00 0.00 0.00 0.00Page 2 of 7 SUBTOTAL 0.00 0.00 0.00 0.00Quantity Completed (Bond Reduction)*REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
Site Improvement Bond Quantity WorksheetExisting Future Public PrivateBond Reduction*Right-of-wayRoad Improvements Improvements & Drainage FacilitiesQuant.Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete CostROAD IMPROVEMENTNo.AC Grinding, 4' wide machine < 1000sy RI - 1 23.00$ SY 0.00 0.00 0.00 0.00AC Grinding, 4' wide machine 1000-2000sRI - 2 5.75$ SY 0.00 0.00 0.00 0.00AC Grinding, 4' wide machine > 2000sy RI - 3 1.38$ SY 0.00 0.00 0.00 0.00AC Removal/Disposal/Repair RI - 4 41.14$ SY 0.00 0.00 0.00 0.00Barricade, type I RI - 5 30.03$ LF 0.00 0.00 0.00 0.00Barricade, type III ( Permanent ) RI - 6 45.05$ LF 0.00 0.00 0.00 0.00Curb & Gutter, rolled RI - 7 13.27$ LF 0.00 0.00 0.00 0.00Curb & Gutter, vertical RI - 8 9.69$ LF 0.00 0.00 0.00 0.00Curb and Gutter, demolition and disposal RI - 9 13.58$ LF 0.00 0.00 0.00 0.00Curb, extruded asphalt RI - 10 2.44$ LF 0.00 0.00 0.00 0.00Curb, extruded concrete RI - 11 2.56$ LF 0.00 0.00 0.00 0.00Sawcut, asphalt, 3" depth RI - 12 1.85$ LF 0.00 0.00 0.00 0.00Sawcut, concrete, per 1" depth RI - 13 1.69$ LF 0.00 0.00 0.00 0.00Sealant, asphalt RI - 14 0.99$ LF 0.00 0.00 0.00 0.00Shoulder, AC, ( see AC road unit price ) RI - 15 -$ SY 0.00 0.00 0.00 0.00Shoulder, gravel, 4" thick RI - 16 7.53$ SY 0.00 0.00 0.00 0.00Sidewalk, 4" thick RI - 17 30.52$ SY 0.00 0.00 0.00 0.00Sidewalk, 4" thick, demolition and disposaRI - 18 27.73$ SY 0.00 0.00 0.00 0.00Sidewalk, 5" thick RI - 19 34.94$ SY 0.00 0.00 0.00 0.00Sidewalk, 5" thick, demolition and disposaRI - 20 34.65$ SY 0.00 0.00 0.00 0.00Sign, handicap RI - 21 85.28$ Each 0.00 0.00 0.00 0.00Striping, per stall RI - 22 5.82$ Each 0.00 0.00 0.00 0.00Striping, thermoplastic, ( for crosswalk ) RI - 23 2.38$ SF 0.00 0.00 0.00 0.00Striping, 4" reflectorized line RI - 24 0.25$ LF 0.00 0.00 0.00 0.00Page 3 of 7 SUBTOTAL 0.00 0.00 0.00 0.00REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
Site Improvement Bond Quantity WorksheetExisting Future Public PrivateBond Reduction*Right-of-wayRoad Improvements Improvements & Drainage FacilitiesQuant.Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete CostROAD SURFACING (4" Rock = 2.5 base & 1.5" top course) For '93 KCRS ( 6.5" Rock= 5" base & 1.5" top course)For KCRS '93, (additional 2.5" base) add: RS - 1 3.60$ SY 0.00 0.00 0.00 0.00AC Overlay, 1.5" AC RS - 2 7.39$ SY 0.00 0.00 0.00 0.00AC Overlay, 2" AC RS - 3 8.75$ SY 0.00 0.00 0.00 0.00AC Road, 2", 4" rock, First 2500 SY RS - 4 17.24$ SY 0.00 0.00 0.00 0.00AC Road, 2", 4" rock, Qty. over 2500SY RS - 5 13.36$ SY 0.00 0.00 0.00 0.00AC Road, 3", 4" rock, First 2500 SY RS - 6 19.69$ SY 0.00 0.00 0.00 0.00AC Road, 3", 4" rock, Qty. over 2500 SY RS - 7 15.81$ SY 0.00 0.00 0.00 0.00AC Road, 5", First 2500 SY RS - 8 14.57$ SY 0.00 0.00 0.00 0.00AC Road, 5", Qty. Over 2500 SY RS - 9 13.94$ SY 0.00 0.00 0.00 0.00AC Road, 6", First 2500 SYRS - 1016.76$ SY 0.00 0.00 0.00 0.00AC Road, 6", Qty. Over 2500 SYRS - 1116.12$ SY 0.00 0.00 0.00 0.00Asphalt Treated Base, 4" thickRS - 129.21$ SY 0.00 0.00 0.00 0.00Gravel Road, 4" rock, First 2500 SYRS - 1311.41$ SY 0.00 0.00 0.00 0.00Gravel Road, 4" rock, Qty. over 2500 SYRS - 147.53$ SY 0.00 0.00 0.00 0.00PCC Road, 5", no base, over 2500 SYRS - 1521.51$ SY 0.00 0.00 0.00 0.00PCC Road, 6", no base, over 2500 SYRS - 1621.87$ SY 0.00 0.00 0.00 0.00Thickened EdgeRS - 176.89$ LF 0.00 0.00 0.00 0.00Page 4 of 7 SUBTOTAL 0.00 0.00 0.00 0.00REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
Site Improvement Bond Quantity WorksheetExisting Future Public PrivateBond Reduction*Right-of-wayRoad Improvements Improvements & Drainage FacilitiesQuant.Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete CostDRAINAGE (CPP = Corrugated Plastic Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.Access Road, R/D D - 1 16.74$ SY 0.00 0.00 0.00 0.00Bollards - fixed D - 2 240.74$ Each 0.00 0.00 0.00 0.00Bollards - removable D - 3 452.34$ Each 0.00 0.00 0.00 0.00* (CBs include frame and lid)CB Type I D - 4 1,257.64$ Each 0.00 0.00 0.00 0.00CB Type IL D - 5 1,433.59$ Each 0.00 0.00 0.00 0.00CB Type II, 48" diameter D - 6 2,033.57$ Each 0.00 0.00 0.00 0.00 for additional depth over 4' D - 7 436.52$ FT 0.00 0.00 0.00 0.00CB Type II, 54" diameter D - 8 2,192.54$ Each 0.00 0.00 0.00 0.00 for additional depth over 4' D - 9 486.53$ FT 0.00 0.00 0.00 0.00CB Type II, 60" diameter D - 10 2,351.52$ Each 0.00 0.00 0.00 0.00 for additional depth over 4' D - 11 536.54$ FT 0.00 0.00 0.00 0.00CB Type II, 72" diameter D - 12 3,212.64$ Each 0.00 0.00 0.00 0.00 for additional depth over 4' D - 13 692.21$ FT 0.00 0.00 0.00 0.00Through-curb Inlet Framework (Add) D - 14 366.09$ Each 0.00 0.00 0.00 0.00Cleanout, PVC, 4" D - 15 130.55$ Each 0.00 0.00 0.00 0.00Cleanout, PVC, 6" D - 16 174.90$ Each 0.00 0.00 0.00 0.00Cleanout, PVC, 8" D - 17 224.19$ Each 0.00 0.00 0.00 0.00Culvert, PVC, 4" D - 18 8.64$ LF 0.00 0.00 0.00 0.00Culvert, PVC, 6" D - 19 12.60$ LF 0.00 0.00 0.00 0.00Culvert, PVC, 8" D - 20 13.33$ LF 0.00 0.00 0.00 0.00Culvert, PVC, 12" D - 21 21.77$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 8" D - 22 17.25$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 12" D - 23 26.45$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 15" D - 24 32.73$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 18" D - 25 37.74$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 24" D - 26 53.33$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 30" D - 27 71.45$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 36" D - 28 112.11$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 48" D - 29 140.83$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 60" D - 30 235.45$ LF 0.00 0.00 0.00 0.00Culvert, CMP, 72" D - 31 302.58$ LF 0.00 0.00 0.00 0.00Page 5 of 7 SUBTOTAL 0.00 0.00 0.00 0.00REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
Site Improvement Bond Quantity WorksheetExisting Future Public PrivateBond Reduction*Right-of-wayRoad Improvements ImprovementsDRAINAGE CONTINUED & Drainage FacilitiesQuant.No. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete CostCulvert, Concrete, 8" D - 32 21.02$ LF 0 0 0 0Culvert, Concrete, 12" D - 33 30.05$ LF 0 0 0 0Culvert, Concrete, 15" D - 34 37.34$ LF 0 0 0 0Culvert, Concrete, 18" D - 35 44.51$ LF 0 0 0 0Culvert, Concrete, 24" D - 36 61.07$ LF 0 0 0 0Culvert, Concrete, 30" D - 37 104.18$ LF 0 0 0 0Culvert, Concrete, 36" D - 38 137.63$ LF 0 0 0 0Culvert, Concrete, 42" D - 39 158.42$ LF 0 0 0 0Culvert, Concrete, 48" D - 40 175.94$ LF 0 0 0 0Culvert, CPP, 6" D - 41 10.70$ LF 0 0 0 0Culvert, CPP, 8" D - 42 16.10$ LF 0 0 0 0Culvert, CPP, 12" D - 43 20.70$ LF 0 0 0 0Culvert, CPP, 15" D - 44 23.00$ LF 0 0 0 0Culvert, CPP, 18" D - 45 27.60$ LF 0 0 0 0Culvert, CPP, 24" D - 46 36.80$ LF 0 0 0 0Culvert, CPP, 30" D - 47 48.30$ LF 0 0 0 0Culvert, CPP, 36" D - 48 55.20$ LF 0 0 0 0Ditching D - 49 8.08$ CY00 0 0Flow Dispersal Trench (1,436 base+) D - 50 25.99$ LFFrench Drain (3' depth) D - 51 22.60$ LF 0 0 0 0Geotextile, laid in trench, polypropylene D - 52 2.40$ SY 0 0 0 0Infiltration pond testing D - 53 74.75$ HR00 0 0Mid-tank Access Riser, 48" dia, 6' deep D - 54 1,605.40$ Each 0 0 0 0Pond Overflow SpillwayD - 55 14.01$ SY 0 0 0 0Restrictor/Oil Separator, 12" D - 56 1,045.19$ Each 0 0 0 0Restrictor/Oil Separator, 15" D - 57 1,095.56$ Each 0 0 0 0Restrictor/Oil Separator, 18" D - 58 1,146.16$ Each 0 0 0 0Riprap, placed D - 59 39.08$ CY00 0 0Tank End Reducer (36" diameter) D - 60 1,000.50$ Each 0 0 0 0Trash Rack, 12" D - 61 211.97$ Each 0 0 0 0Trash Rack, 15" D - 62 237.27$ Each 0 0 0 0Trash Rack, 18" D - 63 268.89$ Each 0 0 0 0Trash Rack, 21" D - 64 306.84$ Each 0 0 0 0Page 6 of 7 SUBTOTAL00 0 0REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
Site Improvement Bond Quantity WorksheetExisting Future Public PrivateBond Reduction*Right-of-wayRoad Improvements Improvements & Drainage FacilitiesQuant.Unit Price Unit Quant. Price Quant. Cost Quant. Cost Complete CostPARKING LOT SURFACINGNo.2" AC, 2" top course rock & 4" borrow PL - 1 15.84$ SY 0 0 0 02" AC, 1.5" top course & 2.5" base coursPL - 2 17.24$ SY 0 0 0 04" select borrow PL - 3 4.55$ SY 0 0 0 01.5" top course rock & 2.5" base course PL - 4 11.41$ SY 0 0 0 0WRITE-IN-ITEMS(Such as detention/water quality vaults.)No.WI - 1 Each 0 0.00 0.00 0.00WI - 2 SY 0 0.00 0.00 0.00WI - 3 CY0 0.00 0.00 0.00WI - 4 LF 0 0.00 0.00 0.00WI - 5 FT 0 0.00 0.00 0.00WI - 6 0 0.00 0.00 0.00WI - 7 0 0.00 0.00 0.00WI - 8 0 0.00 0.00 0.00WI - 9 0 0.00 0.00 0.00WI - 100 0.00 0.00 0.00SUBTOTAL 0.00 0.00 0.00 0.00SUBTOTAL (SUM ALL PAGES):0.00 0.00 0.00 0.0030% CONTINGENCY & MOBILIZATION:0.00 0.00 0.00 0.00 GRANDTOTAL: 0.00 0.00 0.00 0.00COLUMN: B C D EPage 7 of 7REF 8-H BOND QUANTITY WORKSHEET.xlsUnit prices updated: 2/12/02Version: 4/22/02Report Date: 1/19/2010
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Appendix H
Operations and Maintenance
Manual
The following manual includes a brief description of each facility and component requiring
periodic maintenance at the project area. It also details the recommended frequency of
maintenance activities and refers to the Maintenance Requirements for Flow Control,
Conveyance, and WQ Facilities.
Facility Description Recommended Frequency of
Maintenance
Detention
Pond
The proposed stormwater
detention pond is located along
the southeastern corner of the
substation. It is used to control
flow rates exiting the proposed
facility and prevent
downstream erosion.
Perform maintenance tasks listed in
No. 1 – Detention Ponds of the
Maintenance Requirements for Flow
Control, Conveyance, and WQ
Facilities after significant storm events.
Control
Structure
Control structures are placed
within or adjacent to
stormwater detention ponds
and are the facilities which
restrict runoff from exiting the
stormwater detention pond.
Perform maintenance tasks listed in
No. 4 – Control Structure / Flow
Restrictor of the Maintenance
Requirements for Flow Control,
Conveyance, and WQ Facilities after
significant storm events.
Conveyance
Pipes
Conveyance pipes are placed
within the substation and are
used to convey water to the
proposed stormwater detention
pond.
Perform maintenance tasks listed in
No. 6 – Conveyance Pipes and Ditches
of the Maintenance Requirements for
Flow Control, Conveyance, and WQ
Facilities after significant storm events.
Debris
Barriers
A debris barrier is placed within
the stormwater detention pond
at the inlet to the control
structure. This prevents trash
and other foreign objects from
entering the structure and
damaging or blocking it.
Perform maintenance tasks listed in
No. 7 – Debris Barries of the
Maintenance Requirements for Flow
Control, Conveyance, and WQ
Facilities after significant storm events.
Fencing Fencing is placed around the
perimeter of the stormwater
detention pond and substation
to prevent unauthorized
individuals from entering the
facilities.
Perform maintenance tasks listed in
No. 9 – Fencing of the Maintenance
Requirements for Flow Control,
Conveyance, and WQ Facilities during
all site visits.
Access
Roads
An access road along the
southern side of the substation
is used to gain vehicle access
to the site.
Perform maintenance tasks listed in
No. 12 – Access Roads of the
Maintenance Requirements for Flow
Control, Conveyance, and WQ
Facilities after significant storm events.
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
1/9/2009
KING COUNTY, WASHINGTON
SURFACE WATER DESIGN MANUAL
APPENDIX A
MAINTENANCE REQUIREMENTS FOR
FLOW CONTROL, CONVEYANCE AND
WQ FACILITIES
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-1
APPENDIX A
MAINTENANCE REQUIREMENTS FOR FLOW
CONTROL, CONVEYANCE, AND WQ FACILITIES
This appendix contains the maintenance requirements for the following typical stormwater control
facilities and components:
No. 1 – Detention Ponds (p. A-2)
No. 2 – Infiltration Facilities (p. A-3)
No. 3 – Detention Tanks and Vaults (p. A-5)
No. 4 – Control Structure/Flow Restrictor (p. A-7)
No. 5 – Catch Basins and Manholes (p. A-9)
No. 6 – Conveyance Pipes and Ditches (p. A-11)
No. 7 – Debris Barriers (e.g., Trash Racks) (p. A-12)
No. 8 – Energy Dissipaters (p. A- 13)
No. 9 – Fencing (p. A-14)
No. 10 – Gates/Bollards/Access Barriers (p. A-15)
No. 11 – Grounds (Landscaping) (p. A-16)
No. 12 – Access Roads (p. A-17)
No. 13 – Basic Biofiltration Swale (grass) (p. A-18)
No. 14 – Wet Biofiltration Swale (p. A-19)
No. 15 – Filter Strip (p. A-20)
No. 16 – Wetpond (p. A-21)
No. 17 – Wetvault (p. A-23)
No. 18 – Stormwater Wetland (p. A-24)
No. 19 – Sand Filter Pond (p. A-26)
No. 20 – Sand Filter Vault (p. A-28)
No. 21 – Stormfilter (Cartridge Type) (p. A-30)
No. 22 – Baffle Oil/Water Separator (p. A-32)
No. 23 – Coalescing Plate Oil/Water Separator (p. A-33)
No. 24 – Catch Basin Insert (p. A-35)
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-2
NO. 1 – DETENTION PONDS
Maintenance
Component
Defect or Problem Conditions When Maintenance Is Needed Results Expected When
Maintenance Is Performed
Trash and debris Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Rodent holes Any evidence of rodent holes if facility is acting
as a dam or berm, or any evidence of water
piping through dam or berm via rodent holes.
Rodents removed or destroyed and
dam or berm repaired.
Tree growth Tree growth threatens integrity of slopes, does
not allow maintenance access, or interferes with
maintenance activity. If trees are not a threat or
not interfering with access or maintenance, they
do not need to be removed.
Trees do not hinder facility
performance or maintenance
activities.
Erosion Eroded damage over 2 inches deep where cause
of damage is still present or where there is
potential for continued erosion. Any erosion
observed on a compacted slope.
Slopes stabilized using appropriate
erosion control measures. If erosion
is occurring on compacted slope, a
licensed civil engineer should be
consulted to resolve source of
erosion.
Top or Side Slopes
of Dam, Berm or
Embankment
Settlement Any part of a dam, berm or embankment that has
settled 4 inches lower than the design elevation.
Top or side slope restored to design
dimensions. If settlement is
significant, a licensed civil engineer
should be consulted to determine
the cause of the settlement.
Sediment
accumulation
Accumulated sediment that exceeds 10% of the
designed pond depth.
Sediment cleaned out to designed
pond shape and depth; pond
reseeded if necessary to control
erosion.
Storage Area
Liner damaged
(If Applicable)
Liner is visible or pond does not hold water as
designed.
Liner repaired or replaced.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe.
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Tree growth Tree growth impedes flow or threatens stability of
spillway.
Trees removed. Emergency
Overflow/Spillway
Rock missing Only one layer of rock exists above native soil in
area five square feet or larger or any exposure of
native soil on the spillway.
Spillway restored to design
standards.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-3
NO. 2 – INFILTRATION FACILITIES
Maintenance
Component
Defect or Problem Conditions When Maintenance Is Needed Results Expected When
Maintenance Is Performed
Trash and debris Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Rodent holes Any evidence of rodent holes if facility is acting
as a dam or berm, or any evidence of water
piping through dam or berm via rodent holes.
Rodents removed or destroyed and
dam or berm repaired.
Tree growth Tree growth threatens integrity of dams, berms or
slopes, does not allow maintenance access, or
interferes with maintenance activity. If trees are
not a threat to dam, berm, or embankment
integrity or not interfering with access or
maintenance, they do not need to be removed.
Trees do not hinder facility
performance or maintenance
activities.
Erosion Eroded damage over 2 inches deep where cause
of damage is still present or where there is
potential for continued erosion. Any erosion
observed on a compacted slope.
Slopes stabilized using appropriate
erosion control measures. If erosion
is occurring on compacted slope, a
licensed civil engineer should be
consulted to resolve source of
erosion.
Infiltration Pond, Top
or Side Slopes of
Dam, Berm or
Embankment
Settlement Any part of a dam, berm or embankment that has
settled 4 inches lower than the design elevation.
Top or side slope restored to design
dimensions. If settlement is
significant, a licensed civil engineer
should be consulted to determine
the cause of the settlement.
Infiltration Pond,
Tank, Vault, Trench,
or Small Basin
Storage Area
Sediment
accumulation
If two inches or more sediment is present or a
percolation test indicates facility is working at or
less than 90% of design.
Facility infiltrates as designed.
Plugged air vent Any blockage of the vent. Tank or vault freely vents.
Tank bent out of
shape
Any part of tank/pipe is bent out of shape more
than 10% of its design shape.
Tank repaired or replaced to design.
Infiltration Tank
Structure
Gaps between
sections, damaged
joints or cracks or
tears in wall
A gap wider than ½-inch at the joint of any tank
sections or any evidence of soil particles entering
the tank at a joint or through a wall.
No water or soil entering tank
through joints or walls.
Infiltration Vault
Structure
Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks or qualified
inspection personnel determines that the vault is
not structurally sound.
Vault is sealed and structurally
sound.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-4
NO. 2 – INFILTRATION FACILITIES
Maintenance
Component
Defect or Problem Conditions When Maintenance Is Needed Results Expected When
Maintenance Is Performed
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipes
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and covers access
opening completely.
Large access
doors/plate
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
Infiltration Pond,
Tank, Vault, Trench,
or Small Basin Filter
Bags
Plugged Filter bag more than 1/2 full. Replace filter bag or redesign
system.
Infiltration Pond,
Tank, Vault, Trench,
or Small Basin Pre-
settling Ponds and
Vaults
Sediment
accumulation
6" or more of sediment has accumulated. Pre-settling occurs as designed
Infiltration Pond,
Rock Filter
Plugged High water level on upstream side of filter
remains for extended period of time or little or no
water flows through filter during heavy rain
storms.
Rock filter replaced evaluate need
for filter and remove if not
necessary.
Rock missing Only one layer of rock exists above native soil in
area five square feet or larger, or any exposure of
native soil at the top of out flow path of spillway.
Rip-rap on inside slopes need not be replaced.
Spillway restored to design
standards.
Infiltration Pond
Emergency Overflow
Spillway
Tree growth Tree growth impedes flow or threatens stability of
spillway.
Trees removed.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-5
NO. 3 – DETENTION TANKS AND VAULTS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Trash and debris Any trash and debris accumulated in vault or tank
(includes floatables and non-floatables).
No trash or debris in vault. Tank or Vault
Storage Area
Sediment
accumulation
Accumulated sediment depth exceeds 10% of the
diameter of the storage area for ½ length of
storage vault or any point depth exceeds 15% of
diameter. Example: 72-inch storage tank would
require cleaning when sediment reaches depth of
7 inches for more than ½ length of tank.
All sediment removed from storage
area.
Plugged air vent Any blockage of the vent. Tank or vault freely vents.
Tank bent out of
shape
Any part of tank/pipe is bent out of shape more
than 10% of its design shape.
Tank repaired or replaced to design.
Tank Structure
Gaps between
sections, damaged
joints or cracks or
tears in wall
A gap wider than ½-inch at the joint of any tank
sections or any evidence of soil particles entering
the tank at a joint or through a wall.
No water or soil entering tank
through joints or walls.
Vault Structure Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks or qualified
inspection personnel determines that the vault is
not structurally sound.
Vault is sealed and structurally
sound.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipes
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-6
NO. 3 – DETENTION TANKS AND VAULTS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and covers access
opening completely.
Large access
doors/plate
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-7
NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash or debris of more than ½ cubic foot which
is located immediately in front of the structure
opening or is blocking capacity of the structure by
more than 10%.
No Trash or debris blocking or
potentially blocking entrance to
structure.
Trash or debris in the structure that exceeds 1/3
the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
No trash or debris in the structure.
Trash and debris
Deposits of garbage exceeding 1 cubic foot in
volume.
No condition present which would
attract or support the breeding of
insects or rodents.
Sediment Sediment exceeds 60% of the depth from the
bottom of the structure to the invert of the lowest
pipe into or out of the structure or the bottom of
the FROP-T section or is within 6 inches of the
invert of the lowest pipe into or out of the
structure or the bottom of the FROP-T section.
Sump of structure contains no
sediment.
Corner of frame extends more than ¾ inch past
curb face into the street (If applicable).
Frame is even with curb.
Top slab has holes larger than 2 square inches or
cracks wider than ¼ inch.
Top slab is free of holes and cracks.
Damage to frame
and/or top slab
Frame not sitting flush on top slab, i.e.,
separation of more than ¾ inch of the frame from
the top slab.
Frame is sitting flush on top slab.
Cracks wider than ½ inch and longer than 3 feet,
any evidence of soil particles entering structure
through cracks, or maintenance person judges
that structure is unsound.
Structure is sealed and structurally
sound.
Cracks in walls or
bottom
Cracks wider than ½ inch and longer than 1 foot
at the joint of any inlet/outlet pipe or any evidence
of soil particles entering structure through cracks.
No cracks more than 1/4 inch wide at
the joint of inlet/outlet pipe.
Settlement/
misalignment
Structure has settled more than 1 inch or has
rotated more than 2 inches out of alignment.
Basin replaced or repaired to design
standards.
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the structure at the joint of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of inlet/outlet pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Structure
Ladder rungs missing
or unsafe
Ladder is unsafe due to missing rungs,
misalignment, rust, cracks, or sharp edges.
Ladder meets design standards and
allows maintenance person safe
access.
T section is not securely attached to structure
wall and outlet pipe structure should support at
least 1,000 lbs of up or down pressure.
T section securely attached to wall
and outlet pipe.
Structure is not in upright position (allow up to
10% from plumb).
Structure in correct position.
Connections to outlet pipe are not watertight or
show signs of deteriorated grout.
Connections to outlet pipe are water
tight; structure repaired or replaced
and works as designed.
FROP-T Section Damage
Any holes—other than designed holes—in the
structure.
Structure has no holes other than
designed holes.
Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-8
NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Cleanout gate is not watertight. Gate is watertight and works as
designed.
Gate cannot be moved up and down by one
maintenance person.
Gate moves up and down easily and
is watertight.
Chain/rod leading to gate is missing or damaged. Chain is in place and works as
designed.
Damaged or missing Control device is not working properly due to
missing, out of place, or bent orifice plate.
Plate is in place and works as
designed.
Orifice Plate
Obstructions Any trash, debris, sediment, or vegetation
blocking the plate.
Plate is free of all obstructions and
works as designed.
Obstructions Any trash or debris blocking (or having the
potential of blocking) the overflow pipe.
Pipe is free of all obstructions and
works as designed.
Overflow Pipe
Deformed or damaged
lip
Lip of overflow pipe is bent or deformed. Overflow pipe does not allow
overflow at an elevation lower than
design
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design
standards.
Trash and debris Trash and debris that is blocking more than 20%
of grate surface.
Grate free of trash and debris.
footnote to guidelines for disposal
Metal Grates
(If Applicable)
Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design
standards.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open structure requires urgent
maintenance.
Cover/lid protects opening to
structure.
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Manhole Cover/Lid
Cover/lid difficult to
Remove
One maintenance person cannot remove
cover/lid after applying 80 lbs. of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-9
NO. 5 – CATCH BASINS AND MANHOLES
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Sediment Sediment exceeds 60% of the depth from the
bottom of the catch basin to the invert of the
lowest pipe into or out of the catch basin or is
within 6 inches of the invert of the lowest pipe
into or out of the catch basin.
Sump of catch basin contains no
sediment.
Trash or debris of more than ½ cubic foot which
is located immediately in front of the catch basin
opening or is blocking capacity of the catch basin
by more than 10%.
No Trash or debris blocking or
potentially blocking entrance to
catch basin.
Trash or debris in the catch basin that exceeds
1/3 the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
No trash or debris in the catch basin.
Dead animals or vegetation that could generate
odors that could cause complaints or dangerous
gases (e.g., methane).
No dead animals or vegetation
present within catch basin.
Trash and debris
Deposits of garbage exceeding 1 cubic foot in
volume.
No condition present which would
attract or support the breeding of
insects or rodents.
Corner of frame extends more than ¾ inch past
curb face into the street (If applicable).
Frame is even with curb.
Top slab has holes larger than 2 square inches or
cracks wider than ¼ inch.
Top slab is free of holes and cracks.
Damage to frame
and/or top slab
Frame not sitting flush on top slab, i.e.,
separation of more than ¾ inch of the frame from
the top slab.
Frame is sitting flush on top slab.
Cracks wider than ½ inch and longer than 3 feet,
any evidence of soil particles entering catch
basin through cracks, or maintenance person
judges that catch basin is unsound.
Catch basin is sealed and
structurally sound.
Cracks in walls or
bottom
Cracks wider than ½ inch and longer than 1 foot
at the joint of any inlet/outlet pipe or any evidence
of soil particles entering catch basin through
cracks.
No cracks more than 1/4 inch wide at
the joint of inlet/outlet pipe.
Settlement/
misalignment
Catch basin has settled more than 1 inch or has
rotated more than 2 inches out of alignment.
Basin replaced or repaired to design
standards.
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the catch basin at the joint of the inlet/outlet
pipes.
No cracks more than ¼-inch wide at
the joint of inlet/outlet pipes.
Structure
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-10
NO. 5 – CATCH BASINS AND MANHOLES
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design
standards.
Trash and debris Trash and debris that is blocking more than 20%
of grate surface.
Grate free of trash and debris.
footnote to guidelines for disposal
Metal Grates
(Catch Basins)
Damaged or missing Grate missing or broken member(s) of the grate.
Any open structure requires urgent
maintenance.
Grate is in place and meets design
standards.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open structure requires urgent
maintenance.
Cover/lid protects opening to
structure.
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Manhole Cover/Lid
Cover/lid difficult to
Remove
One maintenance person cannot remove
cover/lid after applying 80 lbs. of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-11
NO. 6 – CONVEYANCE PIPES AND DITCHES
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Sediment & debris
accumulation
Accumulated sediment or debris that exceeds
20% of the diameter of the pipe.
Water flows freely through pipes.
Vegetation/roots Vegetation/roots that reduce free movement of
water through pipes.
Water flows freely through pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to protective
coating or corrosion
Protective coating is damaged; rust or corrosion
is weakening the structural integrity of any part of
pipe.
Pipe repaired or replaced.
Pipes
Damaged Any dent that decreases the cross section area of
pipe by more than 20% or is determined to have
weakened structural integrity of the pipe.
Pipe repaired or replaced.
Trash and debris Trash and debris exceeds 1 cubic foot per 1,000
square feet of ditch and slopes.
Trash and debris cleared from
ditches.
Sediment
accumulation
Accumulated sediment that exceeds 20% of the
design depth.
Ditch cleaned/flushed of all sediment
and debris so that it matches design.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vegetation Vegetation that reduces free movement of water
through ditches.
Water flows freely through ditches.
Erosion damage to
slopes
Any erosion observed on a ditch slope. Slopes are not eroding.
Ditches
Rock lining out of
place or missing (If
Applicable)
One layer or less of rock exists above native soil
area 5 square feet or more, any exposed native
soil.
Replace rocks to design standards.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-12
NO. 7 – DEBRIS BARRIERS (E.G., TRASH RACKS)
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed.
Trash and debris Trash or debris plugging more than 20% of the
area of the barrier.
Barrier clear to receive capacity flow. Site
Sediment
accumulation
Sediment accumulation of greater than 20% of
the area of the barrier
Barrier clear to receive capacity flow.
Structure Cracked broken or
loose
Structure which bars attached to is damaged -
pipe is loose or cracked or concrete structure is
cracked, broken of loose.
Structure barrier attached to is
sound.
Bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inche spacing.
Bars are bent out of shape more than 3 inches. Bars in place with no bends more
than ¾ inch.
Bars are missing or entire barrier missing. Bars in place according to design.
Bars
Damaged or missing
bars
Bars are loose and rust is causing 50%
deterioration to any part of barrier.
Repair or replace barrier to design
standards.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-13
NO. 8 – ENERGY DISSIPATERS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed.
Trash and debris Trash and/or debris accumulation. Dissipater clear of trash and/or
debris.
Site
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Rock Pad Missing or moved
Rock
Only one layer of rock exists above native soil in
area five square feet or larger or any exposure of
native soil.
Rock pad prevents erosion.
Pipe plugged with
sediment
Accumulated sediment that exceeds 20% of the
design depth.
Pipe cleaned/flushed so that it
matches design.
Not discharging water
properly
Visual evidence of water discharging at
concentrated points along trench (normal
condition is a “sheet flow” of water along trench).
Water discharges from feature by
sheet flow.
Perforations plugged. Over 1/4 of perforations in pipe are plugged with
debris or sediment.
Perforations freely discharge flow.
Water flows out top of
“distributor” catch
basin.
Water flows out of distributor catch basin during
any storm less than the design storm.
No flow discharges from distributor
catch basin.
Dispersion Trench
Receiving area over-
saturated
Water in receiving area is causing or has
potential of causing landslide problems.
No danger of landslides.
Damaged mesh Mesh of gabion broken, twisted or deformed so
structure is weakened or rock may fall out.
Mesh is intact, no rock missing.
Corrosion Gabion mesh shows corrosion through more than
¼ of its gage.
All gabion mesh capable of
containing rock and retaining
designed form.
Collapsed or
deformed baskets
Gabion basket shape deformed due to any
cause.
All gabion baskets intact, structure
stands as designed.
Gabions
Missing rock Any rock missing that could cause gabion to
loose structural integrity.
No rock missing.
Worn or damaged
post, baffles or side of
chamber
Structure dissipating flow deteriorates to ½ or
original size or any concentrated worn spot
exceeding one square foot which would make
structure unsound.
Structure is in no danger of failing.
Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch or any evidence of soil
entering the structure through cracks, or
maintenance inspection personnel determines
that the structure is not structurally sound.
Manhole/chamber is sealed and
structurally sound.
Manhole/Chamber
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the structure at the joint of the inlet/outlet pipes.
No soil or water enters and no water
discharges at the joint of inlet/outlet
pipes.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-14
NO. 9 – FENCING
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Site Erosion or holes
under fence
Erosion or holes more than 4 inches high and 12-
18 inches wide permitting access through an
opening under a fence.
No access under the fence.
Missing or damaged
parts
Missing or broken boards, post out of plumb by
more than 6 inches or cross members broken
No gaps on fence due to missing or
broken boards, post plumb to within
1½ inches, cross members sound.
Weakened by rotting
or insects
Any part showing structural deterioration due to
rotting or insect damage
All parts of fence are structurally
sound.
Wood Posts, Boards
and Cross Members
Damaged or failed
post foundation
Concrete or metal attachments deteriorated or
unable to support posts.
Post foundation capable of
supporting posts even in strong
wind.
Post out of plumb more than 6 inches. Post plumb to within 1½ inches.
Top rails bent more than 6 inches. Top rail free of bends greater than
1 inch.
Any part of fence (including post, top rails, and
fabric) more than 1 foot out of design alignment.
Fence is aligned and meets design
standards.
Damaged parts
Missing or loose tension wire. Tension wire in place and holding
fabric.
Deteriorated paint or
protective coating
Part or parts that have a rusting or scaling
condition that has affected structural adequacy.
Structurally adequate posts or parts
with a uniform protective coating.
Metal Posts, Rails
and Fabric
Openings in fabric Openings in fabric are such that an 8-inch
diameter ball could fit through.
Fabric mesh openings within 50% of
grid size.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-15
NO. 10 – GATES/BOLLARDS/ACCESS BARRIERS
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Missing gate. Gates in place.
Broken or missing hinges such that gate cannot
be easily opened and closed by a maintenance
person.
Hinges intact and lubed. Gate is
working freely.
Gate is out of plumb more than 6 inches and
more than 1 foot out of design alignment.
Gate is aligned and vertical.
Damaged or missing
members
Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in
place.
Locking mechanism
does not lock gate
Locking device missing, no-functioning or does
not link to all parts.
Locking mechanism prevents
opening of gate.
Chain Link Fencing
Gate
Openings in fabric Openings in fabric are such that an 8-inch
diameter ball could fit through.
Fabric mesh openings within 50% of
grid size.
Damaged or missing
cross bar
Cross bar does not swing open or closed, is
missing or is bent to where it does not prevent
vehicle access.
Cross bar swings fully open and
closed and prevents vehicle access.
Locking mechanism
does not lock gate
Locking device missing, no-functioning or does
not link to all parts.
Locking mechanism prevents
opening of gate.
Bar Gate
Support post
damaged
Support post does not hold cross bar up. Cross bar held up preventing vehicle
access into facility.
Damaged or missing Bollard broken, missing, does not fit into support
hole or hinge broken or missing.
No access for motorized vehicles to
get into facility.
Bollards
Does not lock Locking assembly or lock missing or cannot be
attached to lock bollard in place.
No access for motorized vehicles to
get into facility.
Dislodged Boulders not located to prevent motorized vehicle
access.
No access for motorized vehicles to
get into facility.
Boulders
Circumvented Motorized vehicles going around or between
boulders.
No access for motorized vehicles to
get into facility.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-16
NO. 11 – GROUNDS (LANDSCAPING)
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash or litter Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Hazard Any tree or limb of a tree identified as having a
potential to fall and cause property damage or
threaten human life. A hazard tree identified by
a qualified arborist must be removed as soon
as possible.
No hazard trees in facility.
Limbs or parts of trees or shrubs that are split or
broken which affect more than 25% of the total
foliage of the tree or shrub.
Trees and shrubs with less than 5%
of total foliage with split or broken
limbs.
Trees or shrubs that have been blown down or
knocked over.
No blown down vegetation or
knocked over vegetation. Trees or
shrubs free of injury.
Trees and Shrubs
Damaged
Trees or shrubs which are not adequately
supported or are leaning over, causing exposure
of the roots.
Tree or shrub in place and
adequately supported; dead or
diseased trees removed.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-17
NO. 12 – ACCESS ROADS
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris exceeds 1 cubic foot per 1,000
square feet (i.e., trash and debris would fill up
one standards size garbage can).
Roadway drivable by maintenance
vehicles.
Trash and debris
Debris which could damage vehicle tires or
prohibit use of road.
Roadway drivable by maintenance
vehicles.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Any obstruction which reduces clearance above
road surface to less than 14 feet.
Roadway overhead clear to 14 feet
high.
Site
Blocked roadway
Any obstruction restricting the access to a 10- to
12 foot width for a distance of more than 12 feet
or any point restricting access to less than a 10
foot width.
At least 12-foot of width on access
road.
Erosion, settlement,
potholes, soft spots,
ruts
Any surface defect which hinders or prevents
maintenance access.
Road drivable by maintenance
vehicles.
Road Surface
Vegetation on road
surface
Trees or other vegetation prevent access to
facility by maintenance vehicles.
Maintenance vehicles can access
facility.
Erosion Erosion within 1 foot of the roadway more than 8
inches wide and 6 inches deep.
Shoulder free of erosion and
matching the surrounding road.
Shoulders and
Ditches
Weeds and brush Weeds and brush exceed 18 inches in height or
hinder maintenance access.
Weeds and brush cut to 2 inches in
height or cleared in such a way as to
allow maintenance access.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Modular Grid
Pavement
Damaged or missing Access surface compacted because of broken on
missing modular block.
Access road surface restored so
road infiltrates.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-18
NO. 13 – BASIC BIOFILTRATION SWALE (GRASS)
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Any trash and/or debris accumulated on the
bioswale site.
No trash or debris on the bioswale
site.
Site
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Sediment depth exceeds 2 inches in 10% of the
swale treatment area.
No sediment deposits in grass
treatment area of the bioswale.
Sediment inhibits grass growth over 10% of
swale length.
Grass growth not inhibited by
sediment.
Sediment
accumulation
Sediment inhibits even spreading of flow. Flow spreads evenly through swale
Erosion/scouring Eroded or scoured swale bottom due to
channelization or high flows.
No eroded or scoured areas in
bioswale. Cause of erosion or scour
addressed.
Poor vegetation
coverage
Grass is sparse or bare or eroded patches occur
in more than 10% of the swale bottom.
Swale has no bare spots and grass
is thick and healthy.
Grass too tall Grass excessively tall (greater than 10 inches),
grass is thin or nuisance weeds and other
vegetation has taken over.
Grass is between 3 and 4 inches tall,
thick and healthy. No clippings left
in swale. No nuisance vegetation
present.
Excessive shade
Grass growth is poor because sunlight does not
reach swale.
Health grass growth or swale
converted to a wet bioswale.
Constant baseflow Continuous flow through the swale, even when it
has been dry for weeks or an eroded, muddy
channel has formed in the swale bottom.
Baseflow removed from swale by a
low-flow pea-gravel drain or
bypassed around the swale.
Standing water Water pools in the swale between storms or does
not drain freely.
Swale freely drains and there is no
standing water in swale between
storms.
Swale Section
Channelization Flow concentrates and erodes channel through
swale.
No flow channels in swale.
Flow Spreader Concentrated flow Flow from spreader not uniformly distributed
across entire swale width.
Flows are spread evenly over entire
swale width.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-19
NO. 14 – WET BIOFILTRATION SWALE
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance Is Performed
Trash and debris Any trash and/or debris accumulated at the site. No trash or debris at the site. Site
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Sediment
accumulation
Sediment depth exceeds 2 inches in 10% of the
swale treatment area.
No sediment deposits in treatment
area.
Erosion/scouring Eroded or scoured swale bottom due to
channelization or high flows.
No eroded or scoured areas in
bioswale. Cause of erosion or scour
addressed.
Water depth Water not retained to a depth of about 4 inches
during the wet season.
Water depth of 4 inches through out
swale for most of wet season.
Vegetation ineffective Vegetation sparse, does not provide adequate
filtration or crowded out by very dense clumps of
cattail or nuisance vegetation.
Wetland vegetation fully covers
bottom of swale and no cattails or
nuisance vegetation present.
Swale Section
Insufficient water Wetland vegetation dies due to lack of water. Wetland vegetation remains healthy
(may require converting to grass
lined bioswale
Flow Spreader Concentrated flow Flow from spreader not uniformly distributed
across entire swale width.
Flows are spread evenly over entire
swale width.
Sediment
accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-20
NO. 15 – FILTER STRIP
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance Is Performed
Trash and debris Any trash and debris accumulated on the filter
strip site.
Filter strip site free of any trash or
debris
Site
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Sediment
accumulation
Sediment accumulation on grass exceeds 2
inches depth.
No sediment deposits in treatment
area.
Erosion/scouring Eroded or scoured swale bottom due to
channelization or high flows.
No eroded or scoured areas in
bioswale. Cause of erosion or scour
addressed.
Grass too tall Grass excessively tall (greater than 10 inches),
grass is thin or nuisance weeds and other
vegetation has taken over.
Grass is between 3 and 4 inches tall,
thick and healthy. No clippings left
in swale. No nuisance vegetation
present.
Grass Strip
Vegetation ineffective Grass has died out, become excessively tall
(greater than 10 inches) or nuisance vegetation is
taking over.
Grass is healthy, less than 9 inches
high and no nuisance vegetation
present.
Flow Spreader Concentrated flow Flow from spreader not uniformly distributed
across entire swale width.
Flows are spread evenly over entire
swale width.
Sediment
accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-21
NO. 16 – WETPOND
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed
Results Expected When
Maintenance Is Performed
Trash and debris Any trash and debris accumulated on the
wetpond site.
Wetpond site free of any trash or
debris.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Rodent holes Any evidence of rodent holes if facility is acting
as a dam or berm, or any evidence of water
piping through dam or berm via rodent holes.
Rodents removed or destroyed and
dam or berm repaired.
Tree growth Tree growth threatens integrity of dams, berms or
slopes, does not allow maintenance access, or
interferes with maintenance activity. If trees are
not a threat to dam, berm or embankment
integrity, are not interfering with access or
maintenance or leaves do not cause a plugging
problem they do not need to be removed.
Trees do not hinder facility
performance or maintenance
activities.
Side Slopes of Dam,
Berm, internal berm
or Embankment
Erosion Eroded damage over 2 inches deep where cause
of damage is still present or where there is
potential for continued erosion. Any erosion
observed on a compacted slope.
Slopes stabilized using appropriate
erosion control measures. If erosion
is occurring on compacted slope, a
licensed civil engineer should be
consulted to resolve source of
erosion.
Settlement Any part of a dam, berm or embankment that has
settled 4 inches lower than the design elevation.
Top or side slope restored to design
dimensions. If settlement is
significant, a licensed civil engineer
should be consulted to determine
the cause of the settlement.
Top or Side Slopes
of Dam, Berm,
internal berm or
Embankment
Irregular surface on
internal berm
Top of berm not uniform and level. Top of berm graded to design
elevation.
Sediment
accumulation (except
first wetpool cell)
Accumulated sediment that exceeds 10% of the
designed pond depth.
Sediment cleaned out to designed
pond shape and depth.
Sediment
accumulation (first
wetpool cell)
Sediment accumulations in pond bottom that
exceeds the depth of sediment storage (1 foot)
plus 6 inches.
Sediment storage contains no
sediment.
Liner damaged (If
Applicable)
Liner is visible or pond does not hold water as
designed.
Liner repaired or replaced.
Water level (first
wetpool cell)
First cell empty, doesn't hold water. Water retained in first cell for most of
the year.
Pond Areas
Algae mats (first
wetpool cell)
Algae mats develop over more than 10% of the
water surface should be removed.
Algae mats removed (usually in the
late summer before Fall rains,
especially in Sensitive Lake
Protection Areas.)
Inoperable valve Valve will not open and close. Valve opens and closes normally. Gravity Drain
Valve won’t seal Valve does not seal completely. Valve completely seals closed.
Emergency Overflow
Spillway
Tree growth Tree growth impedes flow or threatens stability of
spillway.
Trees removed.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-22
NO. 16 – WETPOND
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed
Results Expected When
Maintenance Is Performed
Rock missing Only one layer of rock exists above native soil in
area five square feet or larger, or any exposure of
native soil at the top of out flow path of spillway.
Rip-rap on inside slopes need not be replaced.
Spillway restored to design
standards.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-23
NO. 17 – WETVAULT
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from
facility site.
Trash and debris Any trash and debris accumulated in vault
(includes floatables and non-floatables).
No trash or debris in vault.
Sediment
accumulation
Sediment accumulation in vault bottom exceeds
the depth of the sediment zone plus 6 inches.
No sediment in vault.
Treatment Area
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks, vault does
not retain water or qualified inspection personnel
determines that the vault is not structurally
sound.
Vault is sealed and structurally
sound.
Baffles damaged Baffles corroding, cracking, warping and/or
showing signs of failure or baffle cannot be
removed.
Repair or replace baffles or walls to
specifications.
Vault Structure
Ventilation Ventilation area blocked or plugged. No reduction of ventilation area
exists.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Inoperable valve Valve will not open and close. Valve opens and closes normally. Gravity Drain
Valve won’t seal Valve does not seal completely. Valve completely seals closed.
Access cover/lid
damaged or difficult to
open
Access cover/lid cannot be easily opened by one
person. Corrosion/deformation of cover/lid.
Access cover/lid can be opened by
one person.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access doors/plate
has gaps, doesn't
cover completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and covers access
opening completely.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-24
NO. 18 – STORMWATER WETLAND
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed
Results Expected When
Maintenance Is Performed
Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from
facility site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Rodent holes Any evidence of rodent holes if facility is acting
as a dam or berm, or any evidence of water
piping through dam or berm via rodent holes.
Rodents removed or destroyed and
dam or berm repaired.
Tree growth Tree growth threatens integrity of dams, berms or
slopes, does not allow maintenance access, or
interferes with maintenance activity. If trees are
not a threat to dam, berm, or embankment
integrity or not interfering with access or
maintenance, they do not need to be removed.
Trees do not hinder facility
performance or maintenance
activities.
Side Slopes of Dam,
Berm, internal berm
or Embankment
Erosion Eroded damage over 2 inches deep where cause
of damage is still present or where there is
potential for continued erosion. Any erosion
observed on a compacted slope.
Slopes stabilized using appropriate
erosion control measures. If erosion
is occurring on compacted slope, a
licensed civil engineer should be
consulted to resolve source of
erosion.
Settlement Any part of a dam, berm or embankment that has
settled 4 inches lower than the design elevation.
Top or side slope restored to design
dimensions. If settlement is
significant, a licensed civil engineer
should be consulted to determine
the cause of the settlement.
Top or Side Slopes
of Dam, Berm,
internal berm or
Embankment
Irregular surface on
internal berm
Top of berm not uniform and level. Top of berm graded flat to design
elevation.
Sediment
accumulation (first
cell/forebay)
Sediment accumulations in pond bottom that
exceeds the depth of sediment storage (1 foot)
plus 6 inches.
Sediment storage contains no
sediment.
Sediment
accumulation (wetland
cell)
Accumulated sediment that exceeds 10% of the
designed pond depth.
Sediment cleaned out to designed
pond shape and depth.
Liner damaged (If
Applicable)
Liner is visible or pond does not hold water as
designed.
Liner repaired or replaced.
Water level (first
cell/forebay)
Cell does not hold 3 feet of water year round. 3 feet of water retained year round.
Water level (wetland
cell)
Cell does not retain water for at least 10 months
of the year or wetland plants are not surviving.
Water retained at least 10 months of
the year or wetland plants are
surviving.
Algae mats (first
cell/forebay)
Algae mats develop over more than 10% of the
water surface should be removed.
Algae mats removed (usually in the
late summer before Fall rains,
especially in Sensitive Lake
Protection Areas.)
Pond Areas
Vegetation Vegetation dead, dying, or overgrown (cattails) or
not meeting original planting specifications.
Plants in wetland cell surviving and
not interfering with wetland function.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-25
NO. 18 – STORMWATER WETLAND
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed
Results Expected When
Maintenance Is Performed
Inoperable valve Valve will not open and close. Valve opens and closes normally. Gravity Drain
Valve won’t seal Valve does not seal completely. Valve completely seals closed.
Tree growth Tree growth impedes flow or threatens stability of
spillway.
Trees removed. Emergency Overflow
Spillway
Rock missing Only one layer of rock exists above native soil in
area five square feet or larger, or any exposure of
native soil at the top of out flow path of spillway.
Rip-rap on inside slopes need not be replaced.
Spillway restored to design
standards.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-26
NO. 19 – SAND FILTER POND
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance Is Performed
Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from
facility site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover
(not in the treatment
area)
Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Sediment
accumulation
Sediment accumulations in pond bottom that
exceeds the depth of sediment storage (1 foot)
plus 6 inches.
Sediment storage contains no
sediment.
Liner damaged (If
Applicable)
Liner is visible or pond does not hold water as
designed.
Liner repaired or replaced.
Water level Cell empty, doesn't hold water. Water retained in first cell for most of
the year.
Pre-Treatment (if
applicable)
Algae mats Algae mats develop over more than 10% of the
water surface should be removed.
Algae mats removed (usually in the
late summer before Fall rains,
especially in Sensitive Lake
Protection Areas.)
Sediment
accumulation
Sediment or crust depth exceeds ½-inch over 10
% of surface area of sand filter.
No sediment or crust deposit on
sand filter that would impede
permeability of the filter section.
Pond Area
Grass (if applicable) Grass becomes excessively tall (greater than 6
inches) or when nuisance weeds and other
vegetation start to take over or thatch build up
occurs.
Mow vegetation and/or remove
nuisance vegetation.
Rodent holes Any evidence of rodent holes if facility is acting
as a dam or berm, or any evidence of water
piping through dam or berm via rodent holes.
Rodents removed or destroyed and
dam or berm repaired.
Tree growth Tree growth threatens integrity of dams, berms or
slopes, does not allow maintenance access, or
interferes with maintenance activity. If trees are
not a threat to dam, berm, or embankment
integrity or not interfering with access or
maintenance, they do not need to be removed.
Trees do not hinder facility
performance or maintenance
activities.
Side Slopes of Pond
Erosion Eroded damage over 2 inches deep where cause
of damage is still present or where there is
potential for continued erosion. Any erosion
observed on a compacted slope.
Slopes stabilized using appropriate
erosion control measures. If erosion
is occurring on compacted slope, a
licensed civil engineer should be
consulted to resolve source of
erosion.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-27
NO. 19 – SAND FILTER POND
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance Is Performed
Plugging Drawdown of water through the sand filter media,
takes longer than 24 hours, and/or flow through
the overflow pipes occurs frequently. A sieve
analysis of >4% -100 or >2% -200 requires
replacing sand filter media.
Sand filter media surface is aerated
and drawdown rate is normal.
Prolonged flows Sand is saturated for prolonged periods of time
(several weeks) and does not dry out between
storms due to continuous base flow or prolonged
flows from detention facilities.
Excess flows bypassed or confined
to small portion of filter media
surface.
Short circuiting Flows become concentrated over one section of
the sand filter rather than dispersed or drawdown
rate of pool exceeds 12 inches per hour.
Flow and percolation of water
through the sand filter is uniform and
dispersed across the entire filter
area and drawdown rate is normal.
Sand Filter Media
Media thickness Sand thickness is less than 6 inches. Rebuild sand thickness to a
minimum of 6 inches and preferably
to 18 inches.
Underdrains and
Clean-Outs
Sediment/debris Underdrains or clean-outs partially plugged or
filled with sediment and/or debris. Junction
box/cleanout wyes not watertight.
Underdrains and clean-outs free of
sediment and debris and are
watertight.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Rock Pad Missing or out of
place
Only one layer of rock exists above native soil in
area five square feet or larger, or any exposure of
native soil.
Rock pad restored to design
standards.
Flow spreader Concentrated flow Flow from spreader not uniformly distributed
across sand filter.
Flows spread evenly over sand filter.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-28
NO. 20 – SAND FILTER VAULT
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from
facility site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Pre-Treatment
Chamber
Sediment
accumulation
Sediment accumulation exceeds the depth of the
sediment zone plus 6 inches.
Sediment storage contains no
sediment.
Sediment
accumulation
Sediment depth exceeds ½-inch on sand filter
media.
Sand filter freely drains at normal
rate.
Trash and debris Trash and debris accumulated in vault (floatables
and non-floatables).
No trash or debris in vault.
Plugging Drawdown of water through the sand filter media,
takes longer than 24 hours, and/or flow through
the overflow pipes occurs frequently. A sieve
analysis of >4% -100 or >2% -200 requires
replacing sand filter media.
Sand filter media drawdown rate is
normal.
Sand Filter Media
Short circuiting Seepage or flow occurs along the vault walls and
corners. Sand eroding near inflow area.
Cleanout wyes are not watertight.
Sand filter media section re-laid and
compacted along perimeter of vault
to form a semi-seal. Erosion
protection added to dissipate force
of incoming flow and curtail erosion.
Damaged to walls,
frame, bottom and/or
top slab.
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks or qualified
inspection personnel determines that the vault is
not structurally sound.
Vault replaced or repaired to provide
complete sealing of the structure.
Vault Structure
Ventilation Ventilation area blocked or plugged. No reduction of ventilation area
exists.
Underdrains and
Cleanouts
Sediment/debris Underdrains or clean-outs partially plugged, filled
with sediment and/or debris or not watertight.
Underdrains and clean-outs free of
sediment and debris and sealed.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-29
NO. 20 – SAND FILTER VAULT
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove One maintenance person cannot remove
cover/lid after applying 80 lbs of lift. Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Damaged or difficult
to open Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely Large access doors not flat and/or access
opening not completely covered.
Doors close flat and covers access
opening completely.
Large access
doors/plate
Lifting Rings missing,
rusted Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-30
NO. 21 – STORMFILTER (CARTRIDGE TYPE)
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Any trash or debris which impairs the function of
the facility.
Trash and debris removed from
facility.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oils, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Site
Life cycle System has not been inspected for three years. Facility is re-inspected and any
needed maintenance performed.
Sediment on vault
floor
Greater than 2 inches of sediment. Vault is free of sediment.
Sediment on top of
cartridges
Greater than ½ inch of sediment. Vault is free of sediment.
Vault Treatment
Area
Multiple scum lines
above top of
cartridges
Thick or multiple scum lines above top of
cartridges. Probably due to plugged canisters or
underdrain manifold.
Cause of plugging corrected,
canisters replaced if necessary.
Damage to wall,
Frame, Bottom, and/or
Top Slab
Cracks wider than ½-inch and any evidence of
soil particles entering the structure through the
cracks, or qualified inspection personnel
determines the vault is not structurally sound.
Vault replaced or repaired to design
specifications.
Vault Structure
Baffles damaged Baffles corroding, cracking warping, and/or
showing signs of failure as determined by
maintenance/inspection person.
Repair or replace baffles to
specification.
Standing water in
vault
9 inches or greater of static water in the vault for
more than 24 hours following a rain event and/or
overflow occurs frequently. Probably due to
plugged filter media, underdrain or outlet pipe.
No standing water in vault 24 hours
after a rain event.
Filter Media
Short circuiting Flows do not properly enter filter cartridges. Flows go through filter media.
Underdrains and
Clean-Outs
Sediment/debris Underdrains or clean-outs partially plugged or
filled with sediment and/or debris.
Underdrains and clean-outs free of
sediment and debris.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Large access
doors/plate
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-31
NO. 21 – STORMFILTER (CARTRIDGE TYPE)
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and cover access
opening completely.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-32
NO. 22 – BAFFLE OIL/WATER SEPARATOR
Maintenance
Component
Defect Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Any trash or debris which impairs the function of
the facility.
Trash and debris removed from
facility.
Site
Contaminants and
pollution
Floating oil in excess of 1 inch in first chamber,
any oil in other chambers or other contaminants
of any type in any chamber.
No contaminants present other than
a surface oil film.
Sediment
accumulation
Sediment accumulates exceeds 6 inches in the
vault.
No sediment in the vault.
Discharge water not
clear
Inspection of discharge water shows obvious
signs of poor water quality- effluent discharge
from vault shows thick visible sheen.
Effluent discharge is clear.
Trash or debris
accumulation
Any trash and debris accumulation in vault
(floatables and non-floatables).
Vault is clear of trash and debris.
Vault Treatment
Area
Oil accumulation Oil accumulations that exceed 1 inch, at the
surface of the water in the oil/water separator
chamber.
No visible oil depth on water.
Damage to Wall,
Frame, Bottom, and/or
Top Slab
Cracks wider than ½-inch or evidence of soil
particles entering the structure through the
cracks, or maintenance/inspection personnel
determines that the vault is not structurally
sound.
Vault replaced or repaired to design
specifications.
Vault Structure
Baffles damaged Baffles corroding, cracking, warping and/or
showing signs of failure as determined by
maintenance inspection personnel.
Repair or replace baffles to
specifications.
Inoperable valve Valve will not open and close. Valve opens and closes normally. Gravity Drain
Valve won’t seal Valve does not seal completely. Valve completely seals closed.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does
not work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and cover access
opening completely.
Large access
doors/plate
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or cover/lid.
Lifting rings sufficient to lift or
remove cover/lid.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-33
NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR
Maintenance
Component
Defect Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Trash and debris Any trash or debris which impairs the function of
the facility.
Trash and debris removed from
facility.
Site
Contaminants and
pollution
Floating oil in excess of 1 inch in first chamber,
any oil in other chambers or other contaminants
of any type in any chamber.
No contaminants present other than
a surface oil film.
Sediment
accumulation in the
forebay
Sediment accumulation of 6 inches or greater in
the forebay.
No sediment in the forebay.
Discharge water not
clear
Inspection of discharge water shows obvious
signs of poor water quality - effluent discharge
from vault shows thick visible sheen.
Repair function of plates so effluent
is clear.
Trash or debris
accumulation
Trash and debris accumulation in vault
(floatables and non-floatables).
Trash and debris removed from
vault.
Vault Treatment
Area
Oil accumulation Oil accumulation that exceeds 1 inch at the water
surface in the in the coalescing plate chamber.
No visible oil depth on water and
coalescing plates clear of oil.
Damaged Plate media broken, deformed, cracked and/or
showing signs of failure.
Replace that portion of media pack
or entire plate pack depending on
severity of failure.
Coalescing Plates
Sediment
accumulation
Any sediment accumulation which interferes with
the operation of the coalescing plates.
No sediment accumulation
interfering with the coalescing
plates.
Damage to Wall,
Frame, Bottom, and/or
Top Slab
Cracks wider than ½-inch and any evidence of
soil particles entering the structure through the
cracks, or maintenance inspection personnel
determines that the vault is not structurally
sound.
Vault replaced or repaired to design
specifications.
Vault Structure
Baffles damaged Baffles corroding, cracking, warping and/or
showing signs of failure as determined by
maintenance/inspection person.
Repair or replace baffles to
specifications.
Ventilation Pipes Plugged Any obstruction to the ventilation pipes. Ventilation pipes are clear.
Shutoff Valve Damaged or
inoperable
Shutoff valve cannot be opened or closed. Shutoff valve operates normally.
Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Inlet/Outlet Pipe
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access Manhole
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
1/9/2009 2009 Surface Water Design Manual – Appendix A
A-34
NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR
Maintenance
Component
Defect Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and cover access
opening completely.
Large access
doors/plate
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
2009 Surface Water Design Manual – Appendix A 1/9/2009
A-35
NO. 24 – CATCH BASIN INSERT
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Visible Oil Visible oil sheen passing through media Media inset replaced.
Insert does not fit
catch basin properly
Flow gets into catch basin without going through
media.
All flow goes through media.
Filter media plugged Filter media plugged. Flow through filter media is normal.
Oil absorbent media
saturated
Media oil saturated. Oil absorbent media replaced.
Water saturated Catch basin insert is saturated with water, which
no longer has the capacity to absorb.
Insert replaced.
Service life exceeded Regular interval replacement due to typical
average life of media insert product, typically one
month.
Media replaced at manufacturer’s
recommended interval.
Media Insert
Seasonal
maintenance
When storms occur and during the wet season. Remove, clean and replace or install
new insert after major storms,
monthly during the wet season or at
manufacturer’s recommended
interval.