HomeMy WebLinkAboutWWP2703473_2Stormwater Pollution Prevention Plan
Stormwater Pollution Prevention Plan
For
Stonegate Lift Station Conveyance Improvements
Prepared For
Northwest Regional Office
3190 - 160th Avenue SE
Bellevue, WA 98008-5452
425-649-7000
A
Owner Developer Operator/Contractor
City of Renton N/A Shoreline Construction Co.
1055 South Grady Way N/A 8315 216th ST SE
Renton, WA 98057 N/A Woodinville, WA 98072
Project Site Location
Field Ave NE and NE Sunset Blvd, Renton, WA 98059
Certified Erosion and Sediment Control Lead
Jay Brown
206-571-3573
SWPPP Prepared By
Roth Hill, LLC.
11130 NE 33rd Place, Suite 200
Bellevue, WA, 98004
425-869-9448
Paul Weller, EIT AICP, Designer/Planner
SWPPP Preparation Date
April 28, 2010
Approximate Project Construction Dates
May 10, 2010
November 05, 2010
i
Stormwater Pollution Prevention Plan
Storm water Pollution Prevention Plan
For
Stonegate Lift Station Conveyance Improvements
Prepared For
Northwest Regional Office
3190 - 160th Avenue SE
Bellevue, WA 98008-5452
425-649-7000
Owner Developer Operator/Contractor
City of Renton N/A Shoreline Construction Co.
1055 South Grady Way N/A 8315 216th ST SE
Renton, WA 98057 N/A Woodinville, WA 98072
Project Site Location
Field Ave NE and NE Sunset Blvd, Renton, WA 98059
Certified Erosion and Sediment Control Lead
Jay Brown
206-571-3573
SWPPP Prepared By
Roth Hill, LLC.
11130 NE 33rd Place, Suite 200
Bellevue, WA, 98004
425-869-9448
Paul Weller, EIT AICP, Designer/Planner
SWPPP Preparation Date
April 28, 2010
Approximate Project Construction Dates
May 10, 2010
November 05, 2010
Stormwater Pollution Prevention Plan
Contents
1.0 Introduction...................................................................:........................................................... I
2.0 Site Description........................................................................................................................5
2.1
Existing Conditions...........................................................................................................5
2.2
Proposed Construction
Activities......................................................................................6
3.0 Construction Stormwater BMPs
...............................................................................................9
3.1
The 12 BMP Elements
.......................................................................................................9
3.1.1 Element #1 —
Mark Clearing Limits...................................................................9
3.1.2 Element #2 —
Establish Construction Access.....................................................9
3.1.3 Element #3 —
Control Flow Rates.......................................................................9
3.1.4 Element #4 —
Install Sediment Controls.............................................................9
3.1.5 Element #5 —
Stabilize Soils.............................................................................10
3.1.6 Element #6 —
Protect Slopes.............................................................................11
3.1.7 Element #7 —
Protect Drain Inlets.....................................................................11
3.1.8 Element #8 —
Stabilize Channels and Outlets...................................................11
3.1.9 Element #9 —
Control Pollutants.......................................................................12
3.1.10 Element #10
— Control Dewatering.................................................................13
3.1.11 Element #11
—Maintain BMPs.......................................................................14
3.1.12 Element #12
— Manage the Project..................................................................14
3.2
Site Specific BMPs..........................................................................................................17
3.3
Additional Advanced BMPs............................................................................................17
4.0 Construction Phasing and BMP Implementation.....................................................................19
5.0 Pollution Prevention Team......................................................................................................21
5.1 Roles and Responsibilities...............................................................................................21
5.2 Team Members................................................................................................................21
6.0 Site Inspections and Monitoring.............................................................................................23
6.1 Site Inspection.................................................................................................................23
6.1.1 Site Inspection Frequency................................................................................23
6.1.2 Site Inspection Documentation.........................................................................24
6.2 Stormwater Quality Monitoring......................................................................................24
6.2.1 Turbidity Sampling...........................................................................................24
6.2.1 Turbidity Sampling...........................................................................................25
6.2.2 pH Sampling.....................................................................................................26
7.0 Reporting and Recordkeeping................................................................................................27
7.1 Recordkeeping.................................................................................................................27
7.1.1 Site Log Book...................................................................................................27
7.1.2 Records Retention.............................................................................................27
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Stormwater Pollution Prevention Plan
7.1.3
Access to Plans and Records............................................................................27
7.1.4
Updating the SWPPP........................................................................................27
7.1.5
Treatment Records............................................................................................28
7.2 Reporting
.........................................................................................................................28
7.2.1
Discharge Monitoring Reports.........................................................................28
7.2.2
Notification of Noncompliance........................................................................28
AppendixA
— Site Plans.........................................................................................................29
Appendix B
— Construction BMPs.........................................................................................31
Appendix C
— Alternative BMPs............................................................................................33
Appendix D
— General Permit................................................................................................35
Appendix E
— Site Inspection Forms (and Site Log)..............................................................37
Appendix A Site plans
■ Vicinity map
■ Drainage Basin Maps
■ TESC Drawings and Details
Appendix B Construction BMPs
Appendix C Alternative Construction BMP list
Appendix D General Permit
Appendix E Site Log and Inspection Forms
Stormwater Pollution Prevention Plan
IV
Stormwater Pollution Prevention Plan
1.0 Introduction
This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the
NPDES stormwater permit requirements for the Stonegate Lift Station Conveyance
Improvements in Renton, Washington. The project is located at the intersection of Field Ave.
NE and NE Sunset Blvd. The project will include the construction of the following:
• 4,760 linear feet of 8 "diameter PVC force main to connect the proposed Stonegate Lift
Station with the existing gravity system at the intersection of Field Ave. NE and NE
Sunset Blvd.
• 590 linear feet of 15"diameter PVC gravity sewer pipe and 1201inear feet of 12"
diameter PVC gravity sewer pipe to replace undersized existing sewer pipes along Field
Ave. NE and NE Sunset Blvd.
• 2401inear feet of 10" diameter HDPE sewer pipe utilizing horizontal directional drilling
between the Summerwind Lift Station and the cul-de-sac at NE 24`" Ct.
• Side sewer reconnections, bore and jack under an existing storm culvert, full grind and
asphalt overlay of all roadways, sidewalk, and curb/gutter.
Associated Construction activities will include pavement grinding, pavement cutting, asphalt
concrete pavement removal, cement concrete pavement removal, excavation, dewatering,
removal and disposal of waste material, bedding, and pipe zone fill material, placement of
subsequent backfill materials, compaction, grading, and surface restoration.
The purpose of this SWPPP is to describe the proposed construction activities and all
temporary and permanent erosion and sediment control (TESC) measures, pollution
prevention measures, inspection/monitoring activities, and recordkeeping that will be
implemented during the proposed construction project. The objectives of the SWPPP are
to:
1. Implement Best Management Practices (BMPs) to prevent erosion
and sedimentation, and to identify, reduce, eliminate or prevent
stormwater contamination and water pollution from construction
activity.
2. Prevent violations of surface water quality, ground iNater quality, or
sediment management standards.
3. Prevent, during the construction phase, adverse water quality impacts
including impacts on beneficial uses of the receiving water by
controlling peak flow rates and volumes of stormwater runoff at the
Permittee's outfalls and downstream of the outfalls.
Stormwater Pollution Prevention Plan
This SWPPP was prepared using the Ecology SWPPP Template downloaded from the
Ecology website on July 2, 2005. This SWPPP was prepared based on the requirements set
forth in the Construction Stormwater General Permit, Stormwater Management Manual for
Western Washington (SWMMWW 2005). The report is divided into seven main sections with
several appendices that include stormwater related reference materials. The topics presented in
the each of the main sections are:
■ Section I — INTRODUCTION. This section provides a summary
description of the project, and the organization of the SWPPP document.
■ Section 2 — SITE DESCRIPTION. This section provides a detailed
description of the existing site conditions, proposed construction activities,
and calculated stormwater flow rates for existing conditions and post —
construction conditions.
■ Section 3 — CONSTRUCTION BMPs. This section provides a detailed
description of the BMPs to be implemented based on the 12 required
elements of the SWPPP (SWMMEW 2004).
■ Section 4 — CONSTRUCTION PHASING AND BMP
IMPLEMENTATION. This section provides a description of the timing
of the BMP implementation in relation to the project schedule.
■ Section 5 — POLLUTION PREVENTION TEAM. This section identifies
the appropriate contact names (emergency and non -emergency),
monitoring personnel, and the onsite temporary erosion and sedimentation
control inspector
■ Section 6 — INSPECTION AND MONITORING. This section provides a
description of the inspection and monitoring requirements such as the
parameters of concern to be monitored, sample locations, sample
frequencies, and sampling methods for all stormwater discharge locations
from the site.
Section 7 — RECORDKEEPING. This section describes the requirements
for documentation of the BMP implementation, site inspections,
monitoring results, and changes to the implementation of certain BMPs
due to site factors experienced during construction.
Supporting documentation and standard forms are provided in the following Appendices:
Appendix A — Site plans
Appendix B — Construction BMPs
Appendix C — Alternative Construction BMP list
Appendix D — General Permit
Stormwater Pollution Prevention Plan
Appendix E — Site Log and Inspection Forms
Stormwater Pollution Prevention Plan
2.0 Site Description
2.1 Existing Conditions
The existing site is approximately 4.9 acres of paved roadway and is located in the NE quarter of
Section 3, T23N, R5E, WM. The north end of the site is south of an adjacent 100-foot wetland
buffer along May Creek and is located within the existing Summerwind and Stonegate
residential developments. From south to north, the project begins at the intersection of NE
Sunset Blvd and Field Ave NE and proceeds north along Field Ave NE and ends at the
intersection of NE 26`h St and 1481h Ave SE. The project passes through an emergency roadway
that connects NE 201h ST with NE 22°d Ct. See the vicinity map in Appendix A.
The site generally slopes toward the north. The stormwater is collected through catch basins
within the roadway and discharged into the existing regional stormwater system, retained in
either a pond, a vault, or discharged into a ditch before reaching May Creek. Generally, the site
is hydraulically separated from surrounding areas by rolled curb and gutter throughout the
project.
The site consists of five drainage basins which are are illustrated on the basin maps in Appendix
A.
• Drainage Basin one is located generally within the roadway of 146`h Ave SE and NE 26`h
St. The stormwater is collected through catch basins and directed to a detention pond
north of NE 26`' St where it is then discharged into an unnamed creek which then
discharges into May Creek.
• Drainage Basin two is located just south of the emergency roadway connecting NE 201"
St and NE 22nd Ct along the north side of NE 201h St. The stormwater is collected
through catch basins and directed to a detention pond on NE 23`d St along the roadway
Ilwaco Ave NE. The stormwater is then discharged back into the basin number one,
where it eventually ends at May Creek.
• Drainage Basin three collects the stormwater along the south side of NE 20`' St and
directs the water through a vault located at the east end of NE 20`h St. The stormwater is
then discharged to an upstream location of the unnamed creek where it is eventually
meets with May Creek.
• Drainage Basin four collects the stormwater within Field Ave NE. The stormwater is
collected through catch basins and directed to a pond located east of Field Ave and North
of Sunset Blvd. The stormwater is infiltrated. An emergency overflow directs the flow
into a ditch on the south side of Sunset Blvd.
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Stormwater Pollution Prevention Plan
Drainage Basin five collects the stonnwater along Sunset Blvd NE. The stormwater is
collected through catch basins and directed to the ditch on the south side of Sunset Blvd
NE.
USDA NRCS Soils Mapping for King County indicates that the site is largely underlain by
Ragnar-Indianola, a Hydrologic Group -A and B soil, suitable for infiltration.
2.2 Proposed Construction Activities
The purpose of this project is to combine the sewer flows of two lift stations into a single force
main system. The existing Summerwind lift station, located off of NE 23`d St, will be converted
into a manhole and a new gravity sewer will be installed between the existing Stonegate sewer
manhole located in NE 24th Court and the new converted wet well. The combined Stonegate
and Summerwind flows will then be conveyed by the existing Stonegate gravity system to the lift
station located at the northwest quadrant of the intersection of 148th Avenue SE and NE 26th
Street, Renton, Washington (next to the existing Stonegate lift station).
The proposed construction project includes:
• 4,760 linear feet of 8 ".diameter PVC force main to connect the proposed Stonegate Lift
Station with the existing gravity system at the intersection of Field Ave. NE and NE
Sunset Blvd.
• 590 linear feet of 15 "diameter PVC gravity sewer pipe and 120 linear feet of 12 "
diameter PVC gravity sewer pipe to replace undersized existing sewer pipes along Field
Ave. NE and NE Sunset Blvd.
• 240 linear feet of 10"diameter HDPE sewer pipe utilizing horizontal directional drilling
between the Summerwind Lift Station and the cul-de-sac at NE 24th Ct.
• Side sewer reconnections, bore and jack under an existing storm culvert, full grind and
asphalt overlay of all roadways, sidewalk, and curb/gutter.
Construction activities will include TESC installation, pavement grinding, pavement cutting,
asphalt concrete pavement removal, cement concrete pavement removal, excavation, dewatering,
removal and disposal of waste material, bedding, and pipe zone fill material, placement of
subsequent backfill materials, compaction, grading, asphalt paving, concrete work and surface
restoration.
The proposed project is completely within the roadway and no pervious surfaces will be
disturbed for this project. The existing drainage system will be maintained during construction
Stormwater Pollution Prevention Plan
by providing catch basin protection for the existing catch basins, filter fabric fence, inlet/outlet
protection, check dams, and any other method deemed necessary as described in the following
section 3.
Stormwater Pollution Prevention Plan
3.0 Construction Stormwater BMPs
3.1 The 12 BMP Elements
3.1.1 Element #1— Mark Clearing Limits
To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of
construction will be clearly marked before land -disturbing activities begin. Trees that are to be
preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the
field and on the plans. In general, natural vegetation and native topsoil shall be retained in an
undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing
limits that will be applied for this project include:
High Visibility Plastic or Metal Fence (BMP C103)
3.1.2 Element #2 — Establish Construction Access
All construction activities for this project will occur on paved right of way and therefore, no
BMPs are implemented for construction access.
3.1.3 Element #3 — Control Flow Rates
The project will have no new impervious surfaces. No BMPs to be implemented to control the
flow rates.
3.1.4 Element #4 — Install Sediment Controls
All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal
BMP before leaving the construction site or prior to being discharged to an infiltration facility.
The specific BMPs to be used for controlling sediment on this project include:
• Silt Fence (BMP C233)
• Sediment Trap (BMP C240)
• Storm Drain Inlet Protection (BMP C220)
In addition, sediment will be removed from paved areas in and adjacent to construction work
areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on
vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in
runoff.
Stormwater Pollution Prevention Plan
Whenever possible, sediment laden water shall be discharged into onsite, relatively level,
vegetated areas (BMP C240 paragraph 5, page 4-102).
In some cases, sediment discharge in concentrated runoff can be controlled using permanent
stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the
effectiveness of some permanent stormwater BMPs, such as those used for infiltration or
biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention
ponds) can be used during the construction phase. When permanent stormwater BMPs will be
used to control sediment discharge during construction, the structure will be protected from
excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated
sediment shall be removed after construction is complete and the permanent stormwater BMP
will be restabilized with vegetation per applicable design requirements once the remainder of the
site has been stabilized.
The following BMPs will be implemented as end -of -pipe sediment controls as required to meet
permitted turbidity limits in the site discharge(s). Prior to the implementation of these
technologies, sediment sources and erosion control and soil stabilization BMP efforts will be
maximized to reduce the need for end -of -pipe sedimentation controls.
Construction Stormwater Filtration (BMP C251)
Construction Stormwater Chemical Treatment (BMP C 250)
(implemented only with prior written approval from Ecology).
3.1.5 Element #5 — Stabilize Soils
Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent
erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be
used on this project include:
• Plastic Covering (BMP C123)
• Dust Control (BMP C140)
The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain
exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and
2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils
shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather
forecasts.
In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be
temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion,
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Stormwater Pollution Prevention Plan
protected with sediment trapping measures, and where possible, be located away from storin
drain inlets, waterways, and drainage channels.
3.1.6 Element #6 — Protect Slopes
No slopes are to be cut or filled for this project. The following specific BMPs will be used to
protect slopes for this project:
No BMPs to be implemented
3.1.7 Element #7 — Protect Drain Inlets
All storm drain inlets and culverts made operable during construction shall be protected to
prevent unfiltered or untreated water from entering the drainage conveyance system. However,
the first priority is to keep all access roads clean of sediment and keep street wash water separate
from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP
C220) will be implemented for all drainage inlets and culverts that could potentially be impacted
by sediment -laden runoff on and near the project site. The following inlet protection measures
will be applied on this project:
Drop Inlet Protection
• Catch Basin Filters
• Alternative BMP not included in the SWMMWW (2005) or SWMMEW
(2004)
Culvert Inlet Protection
• Culvert Inlet Sediment Trap
• Alternative BMP not included in the SWMMWW (2005) or SWMMEW (2004)
3.1.8 Element #8 — Stabilize Channels and Outlets
Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural
drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for
channel and outlet stabilization that shall be used on this project include:
• Check Dams
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Stormwater Pollution Prevention Plan
The project site is located west of the Cascade Mountain Crest. As such, all temporary on -site
conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the
expected peak 10 minute velocity of flow from a Type 1 A, 10-year, 24-hour recurrence interval
storm for the developed condition. Alternatively, the 10-year, 1-hour peak flow rate indicated by
an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used.
Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent
streambanks, slopes, and downstream reaches shall be provided at the outlets of all conveyance
systems.
3.1.9 Element #9 — Control Pollutants
All pollutants, including waste materials and demolition debris, that occur onsite shall be
handled and disposed of in a manner that does not cause contamination of stormwater. Good
housekeeping and preventative measures will be taken to ensure that the site will be kept clean,
well organized, and free of debris. If required, BMPs to be implemented to control specific
sources of pollutants are discussed below.
Vehicles, construction equipment, and/or petroleum product storage/dispensing:
■ All vehicles, equipment, and petroleum product storage/dispensing areas
will be inspected regularly to detect any leaks or spills, and to identify
maintenance needs to prevent leaks or spills.
■ On -site fueling tanks and petroleum product storage containers shall
include secondary containment.
■ Spill prevention measures, such as drip pans, will be used when
conducting maintenance and repair of vehicles or equipment.
■ In order to perform emergency repairs on site, temporary plastic will be
placed beneath and, if raining, over the vehicle.
■ Contaminated surfaces shall be cleaned immediately following any
discharge or spill incident.
Excavation and tunneling spoils dewatering waste:
Demotion:
Dewatering BMPs and BMPs specific to the excavation and tunneling
(including handling of contaminated soils) are discussed under Element
10.
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Stormwater Pollution Prevention Plan
■ Dust released from demolished sidewalks, buildings, or structures will be
controlled using Dust Control Measures (BMP C 140).
■ Storm drain inlets vulnerable to stormwater discharge carrying dust, soil,
or debris will be protecte using Storm Drain Inlet Protection (BMP C220
as described above for Element 7).
■ Process water and slurry resulting from sawcutting and surfacing
operations will be prevented from entering the waters of the State by
implementing Sawcutting and Surfacing Pollution Prevention measures
(BMP C152).
Excavation and tunneling spoils dewatering waste:
■ Dewatering BMPs and BMPs specific to the excavation and tunneling
(including handling of contaminated soils) are discussed under Element
10.
Concrete and grout:
Other:
■ Process water and slurry resulting from concrete work will be prevented
from entering the waters of the State by implementing Concrete Handling
measures (BMP C151).
Other BMPs will be administered as necessary to address any additional
pollutant sources on site.
The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under
the Federal regulations of the Clean Water Act (CWA).
3.1.10 Element #10 — Control Dewatering
All dewatering water from open cut excavation, tunneling, foundation work, trench, or
underground vaults shall be discharged into a controlled conveyance system prior to discharge to
a sediment trap or sediment pond, or other excepted and approved method. Channels will be
stabilized, per Element #8. Clean, non -turbid dewatering water will not be routed through
stormwater sediment ponds, and will be discharged to systems tributary to the receiving waters
of the State in a manner that does not cause erosion, flooding, or a violation of State water
quality standards in the receiving water. Highly turbid dewatering water from soils known or
suspected to be contaminated, or from use of construction equipment, will require additional
monitoring and treatment as required for the specific pollutants based on the receiving waters
into which the discharge is occurring. Such monitoring is the responsibility of the contractor.
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Stormwater Pollution Prevention Plan
However, the dewatering of soils known to be free of contamination will trigger BMPs to trap
sediment and reduce turbidity. At a minimum, geotextile fabric socks/bags/cells will be used to
filter this material. Other BMPs to be used for sediment trapping and turbidity reduction include
the following:
■ Concrete Handling (BMP C 151)
■ Temporary Sediment Pond (BMP C241)
■ Construction Stormwater Chemical Treatment (BMP C250)
■ Construction Stormwater Filtration (BMP C 251)
■ Infiltration
■ Use of a sedimentation bag, with outfall to a ditch or swale for small
volumes of localized dewatering.
■ Portable Water Storage Tanks (e.g. Baker Tanks)
3.1.11 Element #11— Maintain BMPs
All temporary and permanent erosion and sediment control BMPs shall be maintained and
repaired as needed to assure continued performance of their intended function. Maintenance and
repair shall be conducted in accordance with each particular BMPs specifications (attached).
Visual monitoring of the BMPs will be conducted at least once every calendar week and within
24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes
inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every
month.
All temporary erosion and sediment control BMPs shall be removed within 30 days after the
final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped
sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs
or vegetation shall be permanently stabilized.
3.1.12 Element #12 — Manage the Project
Erosion and sediment control BMPs for this project have been designed based on the following
principles:
Design the project to fit the existing topography, soils, and drainage
patterns.
Emphasize erosion control rather than sediment control.
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Stormwater Pollution Prevention Plan
■ Minimize the extent and duration of the area exposed.
■ Keep runoff velocities low.
■ Retain sediment on site.
■ Thoroughly monitor site and maintain all ESC measures.
■ Schedule major earthwork during the dry season.
As this project site is located west of the Cascade Mountain Crest, the project will be managed
according to the following key project components:
Phasing of Construction
The construction project is being phased to the extent practicable in order
to prevent soil erosion, and, to the maximum extent possible, the transport
of sediment from the site during construction.
Revegetation of exposed areas and maintenance of that vegetation shall be
an integral part of the clearing activities during each phase of construction,
per the Scheduling BMP (C 162).
Seasonal Work Limitations
From October 1 through April 30, clearing, grading, and other soil
disturbing activities shall only be permitted if shown to the satisfaction of
the local permitting authority that silt -laden runoff will be prevented from
leaving the site through a combination of the following:
❑ Site conditions including existing vegetative coverage, slope, soil
type, and proximity to receiving waters; and
❑ Limitations on activities and the extent of disturbed areas; and
❑ Proposed erosion and sediment control measures.
Based on the information provided and/or local weather conditions, the
local permitting authority may expand or restrict the seasonal limitation on
site disturbance.
The following activities are exempt from the seasonal clearing and grading
limitations:
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Stonnwater Pollution Prevention Plan
❑ Routine maintenance and necessary repair of erosion and sediment
control BMPs;
❑ Routine maintenance of public facilities or existing utility
structures that do not expose the soil or result in the removal of the
vegetative cover to soil; and
❑ Activities where there is 100 percent infiltration of surface water
runoff within the site in approved and installed erosion and
sediment control facilities.
Coordination with Utilities and Other Jurisdictions
Care has been taken to coordinate with utilities, other construction
projects, and the local jurisdiction in preparing this SWPPP and
scheduling the construction work.
Inspection and Monitoring
All BMPs shall be inspected, maintained, and repaired as needed to assure
continued performance of their intended function. Site inspections shall
be conducted by a person who is knowledgeable in the principles and
practices of erosion and sediment control. This person has the necessary
skills to:
❑ Assess the site conditions and construction activities that could
impact the quality of stormwater, and
❑ Assess the effectiveness of erosion and sediment control measures
used to control the quality of stormwater discharges.
A Certified Erosion and Sediment Control Lead shall be on -site or on -call
at all times.
Whenever inspection and/or monitoring reveals that the BMPs identified
in this SWPPP are inadequate, due to the actual discharge of or potential
to discharge a significant amount of any pollutant, appropriate BMPs or
design changes shall be implemented as soon as possible.
Maintaining an Updated Construction SWPPP
This SWPPP shall be retained on -site or within reasonable access to the
site.
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Stornwater Pollution Prevention Plan
The SWPPP shall be modified whenever there is a change in the design,
construction, operation, or maintenance at the construction site that has, or
could have, a significant effect on the discharge of pollutants to waters of
the state.
■ The SWPPP shall be modified if, during inspections or investigations
conducted by the owner/operator, or the applicable local or state
regulatory authority, it is determined that the SWPPP is ineffective in
eliminating or significantly minimizing pollutants in stormwater
discharges from the site. The SWPPP shall be modified as necessary to
include additional or modified BMPs designed to correct problems
identified. Revisions to the SWPPP shall be completed within seven (7)
days following the inspection.
3.2 Site Specific BNZPs
Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site
specific plan sheets will be updated annually.
3.3 Additional Advanced BMPs
Written pre -approval through Department of Ecology is required for the use of construction
stormwater chemical treatment.
Construction Stormwater Chemical Treatment (BMP C250)
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Stonnwater Pollution Prevention Plan
4.0 Construction Phasing and BMP
Implementation
The BMP implementation schedule will be driven by the construction schedule. The following
provides a sequential list of the proposed construction schedule milestones and the corresponding
BMP implementation schedule. The list contains key milestones such as wet season
construction.
The BMP implementation schedule listed below is keyed to proposed phases of the construction
project, and reflects differences in BMP installations and inspections that relate to wet season
construction. The project site is located west of the Cascade Mountain Crest. As such, the dry
season is considered to be from May I to September 30 and the wet season is considered to be
from October I to April 30.
■ Estimated Construction start date: 05/11/2010
■ Estimated Construction finish date: 11/05/2010
■ Pre -Construction Meeting: 05/05/2010
■ Mobilize equipment on -site: 05/10/2010
■ Install ESC measures: 05/10/2010
■ Begin Excavation for pipe trench: 06/14/2010
■ Begin Road Restoration: 09/06/2010
■ Wet Season Starts: 10/01/2010
■ Site Inspections and monitoring conducted weekly and for applicable rain
events as detailed in Section 6 of this SWPPP: 10/01/2010
■ Implement Element #12 BMPs and manage site to minimize soil
disturbance during the wet season: 10/01/2010
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Stormwater Pollution Prevention Plan
5.0 Pollution Prevention Team
5.1 Roles and Responsibilities
The pollution prevention team consists of personnel responsible for implementation of the
SWPPP, including the following:
Certified Erosion and Sediment Control Lead (CESCL) — primary
contractor contact, responsible for site inspections (BMPs, visual
monitoring, sampling, etc.); to be called upon in case of failure of any
ESC measures.
Resident Engineer — For projects with engineered structures only
(sediment ponds/traps, sand filters, etc.): site representative for the owner
that is the project's supervising engineer responsible for inspections and
issuing instructions and drawings to the contractor's site supervisor or
representative
■ Emergency Ecology Contact — individual to be contacted at Ecology in
case of emergency.
■ Emergency Owner Contact — individual that is the site owner or
representative of the site owner to be contacted in the case of an
emergency.
■ Non -Emergency Ecology Contact — individual that is the site owner or
representative of the site owner than can be contacted if required.
■ Monitoring Personnel — personnel responsible for conducting water
quality monitoring; for most sites this person is also the Certified Erosion
and Sediment Control Lead.
5.2 Team Members
Names and contact information for those identified as members of the pollution prevention team
are provided in the following table.
Title
Name(s)
Phone Number
Certified Erosion and Sediment Control Lead (CESCL)
Jay Brown
206-571-3573
Resident Engineer
Ron McPhee
425-430-7432
21
Stormwater Pollution Prevention Plan
Emergency Ecology Contact
Kevin Fitzgerald
425-649-7033
Emergency Owner Contact
John Hobson
425-430-7279
Non -Emergency Ecology Contact
Jay Brown - Forcman (Shoreline
Construction Co.)
206-571=3573
Monitoring Personnel
Alec Andry - Superintendent (Shoreline
Construction Co.)
206-571-3572
T?
Stormwater Pollution Prevention Plan
6.0 Site Inspections and Monitoring
Monitoring includes visual inspection, monitoring for water quality parameters of concern, and
documentation of the inspection and monitoring findings in a site log book. A site log book will
be maintained for all on -site construction activities and will include:
A record of the implementation of the SWPPP and other permit
requirements;
■ Site inspections; and,
Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site log book. This SWPPP may function as the
site log book if desired, or the forms may be separated and included in a separate site log book.
However, if separated, the site log book but must be maintained on -site or within reasonable
access to the site and be made available upon request to Ecology or the local jurisdiction.
6.1 Site Inspection
All BMPs will be inspected, maintained, and repaired as needed to assure continued performance
of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead
(CESCL) per BMP C160. The naive and contact information for the CESCL is provided in
Section 5 of this SWPPP.
Site inspection will occur in all areas disturbed by construction activities and at all stormwater
discharge points. Stormwater will be examined for the presence of suspended sediment,
turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the
effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the
BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be
documented in the site log book or forms provided in this document. All new BMPs or design
changes will be documented in the SWPPP as soon as possible.
6.1.1 Site Inspection Frequency
Site inspections will be conducted at least once a week and within 24 hours following any
discharge from the site. For sites with temporary stabilization measures, the site inspection
frequency can be reduced to once every month.
23
Stormwater Pollution Prevention Plan
6.1.2 Site Inspection Documentation
The site inspector will record each site inspection using the site log inspection forms provided in
Appendix E. The site inspection log forms may be separated from this SWPPP document, but
will be maintained on -site or within reasonable access to the site and be made available upon
request to Ecology or the local jurisdiction.
6.2 Stormwater Quality Monitoring
6.2.1 Turbidity Sampling
Monitoring requirements for the proposed project will include either turbidity or water
transparency sampling to monitor site discharges for water quality compliance with the 2005
Construction Stormwater General Permit (Appendix D). Sampling will be conducted at all
discharge points at least once per calendar week.
Turbidity or transparency monitoring will follow the analytical methodologies described in
Section S4 of the 2005 Construction Stormwater General Permit (Appendix D). The key
benchmark values that require action are 25 NTU for turbidity (equivalent to 32 cm
transparency) and 250 NTU for turbidity (equivalent to 6 cm transparency). If the 25 NTU
benchmark for turbidity (equivalent to 32 cm transparency) is exceeded, the following steps will
be conducted:
1. Ensure all BMPs specified in this SWPPP are installed and functioning as
intended.
2. Assess whether additional BMPs should be implemented, and document
revisions to the SWPPP as necessary.
3. Sample discharge location daily until the analysis results are less than 25
NTU (turbidity) or greater than 32 cm (transparency).
If the turbidity is greater than 25 NTU (or transparency is less than 32 cm) but less than 250
NTU (transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be
implemented within 24 hours of the third consecutive sample that exceeded the benchmark
value. Additional treatment BMPs to be considered will include, but are not limited to, off -site
treatment, infiltration, filtration and chemical treatment.
If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any time,
the following steps will be conducted:
1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of
this SWPPP for contact information).
24
Stormwater Pollution Prevention Plan
2. Continue daily sampling until the turbidity is less than 25 NTU (or
transparency is greater than 32 cm).
Initiate additional treatment BMPs such as off -site treatment, infiltration,
filtration and chemical treatment within 24 hours of the first 250 NTU
exceedance.
4. Implement additional treatment BMPs as soon as possible, but within 7
days of the first 250 NTU exceedance.
Describe inspection results and remedial actions taken in the site log book
and in monthly discharge monitoring reports as described in Section 7.0 of
this SWPPP.
6.2.1 Turbidity Sampling
Monitoring requirements for the proposed project will include either turbidity or water
transparency sampling to monitor site discharges for water quality compliance with the 2005
Construction Stormwater General Permit (Appendix D). Sampling will be conducted at all
discharge points at least once per calendar week.
Turbidity or transparency monitoring will follow the analytical methodologies described in
Section S4 of the 2005 Construction Stormwater General Permit (Appendix D). The key
benchmark values that require action are 25 NTU for turbidity (equivalent to 32 cm
transparency) and 250 NTU for turbidity (equivalent to 6 cm transparency). If the 25 NTU
benchmark for turbidity (equivalent to 32 cm transparency) is exceeded, the following steps will
be conducted:
Ensure all BMPs specified in this SWPPP are installed and functioning as
intended.
2. Assess whether additional BMPs should be implemented, and document
revisions to the SWPPP as necessary.
3. Sample discharge location daily until the analysis results are less than 25
NTU (turbidity) or greater than 32 cm (transparency).
If the turbidity is greater than 25 NTU (or transparency is less than 32 cm) but less than 250
NTU (transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be
implemented within 24 hours of the third consecutive sample that exceeded the benchmark
value. Additional treatment BMPs to be considered will include, but are not limited to, off -site
treatment, infiltration, filtration and chemical treatment.
25
Stormwater Pollution Prevention Plan
If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any time,
the following steps will be conducted:
1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this
SWPPP for contact information).
2. Continue daily sampling until the turbidity is less than 25 NTU (or
transparency is greater than 32 cm).
3. Initiate additional treatment BMPs such as off -site treatment, infiltration,
filtration and chemical treatment within 24 hours of the first 250 NTU
exceedance.
4. Implement additional treatment BMPs as soon as possible, but within 7 days
of the first 250 NTU exceedance.
5. Describe inspection results and remedial actions taken in the site log book and
in monthly discharge monitoring reports as described in Section 7.0 of this
SWPPP.
6.2.2 pH Sampling
Sampling and monitoring for pH will occur during the first day of activity that includes more
than 40 yards of poured or recycled concrete, or after the application of "Engineered Soils" such
as, Portland cement treated base, cement kiln, or fly ash. For concrete work, pH monitoring will
start the first day concrete is poured and continued until fully cured (3 weeks from last pour) and
discharges are documented to be below pH 8.5. Samples will be collected weekly at points of
discharge to surface water. Samples will be analyzed for pH using a calibrated pH meter and
recorded in the site log book.
The key benchmark pH value for stormwater is a maximum of 8.5. If a pH greater than 8.5 is
measured at points of discharge to surface water, the following steps will be conducted:
1. Prevent (detain) all discharges from leaving the site and entering surface
waters or storm drains if the pH is greater than 8.5
2. Adjust or neutralize the high pH water if necessary using appropriate
technology such as CO2 sparging (liquid or dry ice).
3. Contact Ecology if chemical treatment other than CO2 sparging is planned.
26
Stormwater Pollution Prevention Plan
7.0 Reporting and Recordkeeping
7.1 Recordkeeping
7.1.1 Site Log Book
A site log book will be maintained for all on -site construction activities and will include:
■ A record of the implementation of the SWPPP and other permit
requirements;
1 ■ Site inspections; and,
■ Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site log book.
7.1.2 Records Retention
Records of all monitoring information (site log book, inspection reports/checklists, etc.), this
Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit
requirements will be retained during the life of the construction project and for a minimum of
three years following the termination of permit coverage in accordance with permit condition
S5.C.
7.1.3 Access to Plans and Records
The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained
on site or within reasonable access to the site and will be made immediately available upon
request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology
within 14 days of receipt of a written request for the SWPPP from Ecology. Any other
information requested by Ecology will be submitted within a reasonable time. A copy of the
SWPPP or access to the SWPPP will be provided to the public when requested in writing in
accordance with permit condition S5.G.
7.1.4 Updating the SWPPP
In accordance with Conditions S3, S4.13, and S9.13.3 of the General Permit, this SWPPP will be
modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in
stormwater discharges from the site or there has been a change in design, construction, operation,
or maintenance at the site that has a significant effect on the discharge, or potential for discharge,
27
Stormwater Pollution Prevention Plan
of pollutants to the waters of the State. The SWPPP will be modified within seven days of
determination based on inspection(s) that additional or modified BMPs are necessary to correct
problems identified, and an updated timeline for BMP implementation will be prepared.
7.1.5 Treatment Records
Alec Andry - (Superintendent Shoreline Construction Co.) will be performing regular monitoring
of all discharges. These records will be summarized monthly for submittal with the Discharge
Monitoring Report to DOE.
7.2 Reporting
7.2.1 Discharge Monitoring Reports
[Prior to October 2008] If cumulative soil disturbance is smaller than 5 acres: Discharge
Monitoring Report (DMR) forms will not be submitted to Ecology because water quality
sampling is not being conducted at the site.
If cumulative soil disturbance is 5 acres or larger: Discharge Monitoring Reports (DMRs) will be
submitted to Ecology monthly. If there was no discharge during a given monitoring period, the
Permittee shall submit the form as required, with the words "No discharge" entered in the place
of monitoring results. The DMR due date is 15 days following the end of each month.
7.2.2 Notification of Noncompliance
If any of the terms and conditions of the permit are not met, and it causes a threat to human
health or the environment, the following steps will be taken in accordance with permit section
S5.F:
1. Ecology will be immediately notified of the failure to comply.
2. Immediate action will be taken to control the noncompliance issue and to
correct the problem. If applicable, sampling and analysis of any
noncompliance will be repeated immediately and the results submitted to
Ecology within five (5) days of becoming aware of the violation.
3. A detailed written report describing the noncompliance will be submitted
to Ecology within five (5) days, unless requested earlier by Ecology.
In accordance with permit condition S2.A, a complete application form will be submitted to
Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General
Permit.
28
Stormwater Pollution Prevention Plan
Appendix A — Site Plans
• Vicinity Map
0 Drainage Basin Maps
• TESC Drawings and Details
29
Stormwater Pollution Prevention Plan
30
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FILTER FABRIC (NIRAFI IDOX OR EOUIV. 2'. 2'. 14 W.
80' WIDE BOLLS) USE STAPLES OR WIRE WIRE FABRIC
RING TO ATTACH FABRIC TO WIRE (TYP) OR EQUAL (TYP)
Q Q
it
II ^ I
li `BURY BOTTOM OF FABRIC II H
Li MATERIAL IN 4'. 4' TRENCH U MINt�
(� 6MAX
PROVIDE ]/•• - I I/2' DIA.
2'. 4' WQOU PQST4. STANDMO OR BETTER WASEO GRAVEL BACKFILL WITH
GRADE OR EQUAL B 6' O.C. NATIVE SOIL
ALTERNATE: STEEL FENCE POSTS
POST S�ACINC MAY BE INCREASED
" O a F WIRE BAC"IM Its USED SIDE VIEW
FILTER FABRIC FENCE NOTES:
I. THE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH GF THE SHRIEK TO
AVOID USE OF JOINTS WHEN .DINTS ARE NECESSARY. FILTER CLOTH SMALL BE SPLICED TOGETHER ONLY
AT A SUPPORT POST. WITH A MINI" a -INCH OVERLAP MID BOTH ENDS SECURELY FASTENED TO THE POST,
2 THE FILTER FABRIC FENCE SHALL BC INSTALLED TO FOLLOW THE CONTOURS (WHERE FEASIBLE). THE FENCE
PO POSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND MOAN SECURELY INTO THE GROU(MINI"
OF 30 INCHES).
3 A TRENEH SHALL BE EXCAVATED. IWFIILY 4 INCHES WIDE AND 4 INCHES DEER. UPSLOPE AM AGJACENT TO
THE WOOD, POST To ALLOY THE FILTER FABRIC TO BE BIA IED
4 WHEN STANDARD STRENGTH FILTER FABRIC IS USED. A WIRE MESH SUPPORT FENCE SHALL BE FASTENED
SECURELY TO THE UPSLOPE SIDE Or THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST I INCH LONG.
TIE WIRES OR HOG RINGS THE WIRE SHALL EXTEND INTO THE TRENCH A MINI" Or 4 INCHES AND SHALL
MT EXTEND MORE THAN 36 INCHES ABOVE THE ORIGINAL GROUND SURFACE.
3 THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE. AND 20 INCHES OF
THE FABRIC SHALL BC EXTENDED INTO THE FRENCH THE FABRIC SHALL MT EXTEND MORE THAN 30 INCHES
ABOVE THE ORIGINAL GROUND SURFACE FILTER FABRIC SHALL HOT BE STAPLED TO EXISTING TREES
6 WHEN EXTRA -STRENGTH FILTER FABRIC AND CLOSER POST SPACING ME USED. THE WIRE MESH SUPPORT
FENCE MAY BE ELIMINATED. IN SUCH A CASE. THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO
THE POSTS WITH ALL OTHER PROVISIONS OF STANDARD NOTE S APPLYING.
THE TRENCH SHALL BE BACNFILLED WITH 3/4-INCH. MINIMUM DIAMETER WASNEO GRAVEL.
tl FILTCP FABRIC FENCES SHALL BE REIGNED WHEN THEY HAVE SERVED THEIR USEFUL PURPOSE. BUT NOT
BEFORE THE UPSLOPE MEA HAS BEEN PERMANENTLY STABILIZED.
9 FILTCR FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AD AT LEAST DAILY
DUPING PROLONGED MINFALL. MY REQUIRED REPAIRS SHALL BE MADE IMCI(p IATELV
FILTER FABRIC FENCE DETAIL
NTS
DROP INLET WITH GRATE RUNOFF WATER
WITF1 SEDIMENT
FILTER FABRIC UNDER FILTER FABRIC UNDER
GRATING GRATING
PROVIDE AT ALL CATCH BASINS DRAINING AREA AFFECTED BY WORK.
CB PROTECTION DETAIL
N T',
TOP OF FLON LINE
DITCH
SILT FENCE
I I
I I
CULVERT---4
1
1 I
NOTES,
PLACE SILT FENCE OR FILTER BAGS IN
DITCH FLOW LINE TO PREVENT SEDIMENT
AND DEBRIS FROM ENTERING THE CON-
VEYANCE SYSTEM.
INLET/OUTLET PROTECTION
NT,
R(YrFIHILL
Roth Hil, LLC Te1425.869.9W www.rothhill.com
11130 NE 33rd Place, Suite 200 Bellevue, WA 98004
SAND BAGS MUST COMPLETELY CO*M
THE BOTTOM AND SIDES OF _NE DITCH
6'MI�
CROSS SECTION 1
SAW
L- DISTANCE SUCH MAT POINTS A k B ARE OF
EQUAL ELEVATION.
CHECK DAM DETAIL
NTS
TEMPORARY EROSIONISEDIMENTATION CONTROL NOTES:
1, APPROVAL OF THIS TEMPORARY EROSION/SEDIMENTATION CONTROL (TESL)
PLAN DOES NOT CONSTITUTE AN APPROVAL OF PERMANENT ROAD OR
DRAINAGE DESIGN (E.G. SIZE AND LOCATION OF ROADS, PIPES, RESTRICTORS,
CHANNELS. RETENTION FACILITIES. UTILITIES, ETC.)
2. CONTRACTOR REQUIRED TO SUBMIT TESC AND DEWATERING PLAN TO OWNER
AND ENGINEER FOR REVIEW PRIOR TO CONSTRUCTION.
3. CONTRACTOR AND AN ON -SITE REPRESENTATIVE OF OWNER WILL REVIEW THE
INSTALLATICN, MAINTENANCE AND PERFORMANCE OF THE TESC MEASURES
SHOWN ON THE APPROVED PLANS. THE TESC OBSERVER OR PERMITTING
AGENCY MAY RECOMMEND ADDITIONAL MEASURES OR CHANGES TO THE TESL
PLAN THAT ARE WARRANTED DURING CONSTRUCTION. THE CONTRACTOR AND
OBSERVER WILL EXAMINE ALL TESC MEASURES PERIODICALLY DURING THE
CONSTRUCTION PERIOD, AND AFTER STORMS HAVING 0.5 INCHES OR MORE OF
RAINFALL IN A 24-HOUR PERIOD. THE OBSERVER AND THE PERMITTING
AGENCYHAVE THE AUTHORITY TO REQUIRE CORRECTIVE ACTION IN ORDER TO
ACHIEVE EROSION CONTROL OBJECTIVES.
4. THE IMPLEMENTATION OF THESE TESC PLANS AND THE CONSTRUCTION,
MAINTENANCE, REPLACEMENT, AND UPGRADING OF THESE TESC FACILITIES 15
THE RESPONSIBILITY OF THE CONTRACTOR UNTIL ALL CONSTRUCTION IS
APPROVED. TESC MEASURES SHALL REMAIN FUNCTIONING AND IN PLACE UNTIL
THE SITE HAS BEEN STABILIZED AND THE PERMITTING AGENCY, OWNER OR
ENGINEER HAS APPROVED THE REMOVAL OF THE TESC MEASURES.
5. AS CONSTRUCTION PROGRESSES AND UNEXPECTED SEASONAL CONDITIONS
DICTATE, ADDITIONAL TESC MEASURES MAY BECOME NECESSARY TO PROTECT
ADJACENT PROPERTIES AND TO ENSURE WATER QUALITY FOR SITE RUNOFF. IT
SHALL BE THE CONTRACTOR'S RESPONSIBILITY TO ADDRESS DEFICIENT TESC
CONDITIONS. AND TO PROVIDE ADDITIONAL FACILITIES, OVER AND ABOVE THE
MINIMUM REQUIREMENTS OUTLINED ON THE APPROVED PLANS AS NEEDED.
6. THE TESC FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED IN
CONJUNCTION WITH ALL CLEARING AND GRADING ACTIVITIES. AND IN SUCH A
MANNER AS TO INSURE THAT SEDIMENT LADEN WATER DOES NOT ENTER THE
DRAINAGE SYSTEM OR VIOLATE APPLICABLE WATER QUALITY STANDARDS.
7. THE TESC FACILITIES SHOWN ON THIS PLAN ARE THE MINIMUM REQUIREMENTS
FOR ANTICIPATED SITE CONDITIONS. DURING THE CONSTRUCTION PERIOD, THESE
TESC FACILITIES SHALL BE UPGRADED (E.G. ADDITIONAL SUMPS, RELOCATION OF
DITCHES AND SILT FENCES, ETC.) AS NEEDED FOR STORM EVENTS.
B. THE TESC FACILITIES SHALL BE INSPECTED DAILY BY THE CONTRACTOR AND
MAINTAINED AS NECESSARY TO ENSURE THEIR CONTINUED FUNCTIONING.
9. ANY AREA NEEDING TE5C MEASURE, NOT REQUIRING IMMEDIATE ATTENTION,
SHALL BE STABILIZED WITHIN FIFTEEN (15) DAYS.
10. AT NO TIME SHALL MORE THAN ONE FOOT OF SEDIMENT BE ALLOWED TO
ACCUMULATE WITHIN A CATCH BASIN. ALL CATCH BASINS AND CONVEYANCE
LINES SHALL BE CLEANED PRIOR TO PAVING. THE CLEANING OPERATION SHALL
NOT FLUSH SEDIMENT LADEN WATER INTO THE DOWNSTREAM SYSTEM.
mHL �L FeIcAS NOTED wlnw�'iwe Wo Iw�X IwI
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N0. REVISION BY DATE APPIR
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CITY OF STONEGATE LIFT STATION CONVEYANCE
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Plonning/BwldiNq/Public works Dept. MISC. DETAILS
26
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PLANE EX. PAVEMENT & MATCH EX.—•�—.
PAVEMENT GRADE PER BUTT JOINT
DETAIL SHT. 26
REPLACE EX. CURB, GUTTER &�
SIDEWALK PER CITY OF RENTON
STD, PLANS 101, 102 & 103
INSTALL WHEELCHAIR RAMP w/—
DETECTABLE WARNING PATTERN
PER OTY OF RENTON STD.
PLAN 106.1
CONTRACTOR SHALL MAKE REPAIRS —
TO EX, IRRIGATION SYSTEM AS REO'D.
148TH AVE SE / NILE AVE NEWM
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INSTALL INLET/OUTLET PROTECTION
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(TYP) SEE DETAIL SHT. 28
PHILL 20 D SCALE 20 40
Roth Hill, LLC Tel 425.869.9448 www.rothhill.com ( FEET )
11130 NE 331d Place, Suite 200 Bellevue, WA 98004 1 INCH - 20 FT
FOR CONTINUATION SEE SHT. 23
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IEe329.88 IE-326.18
16"CMP 12"CMP
PLANE EX. PAVEMENT & MATCH EX.
6\ PAVEMENT GRADE PER BUTT JOINT
DETAIL SHT. 26
DOUBLE YELLOI
I 1
1
PLANE EXISTING PAVEMENT
PLACE NEW 4" THICK CONCRETE SIDEWALK
PLACE NEW 2" THICK ASPHALT OVERLAY
NOTES:
1. CONTRACTOR IS RESPONSIBLE FOR
ADJUSTING ALL MANHOLE LIDS, CATCH BASIN
FRAMES AND GRATES, AND UTILITY VALVE
BOXES TO FINISH GRADE.
2. CONTRACTOR IS RESPONSBLE FOR REPLACING
ALL EXISTING PAVEMENT MARKINGS & TRAFFIC
BUTTONS IN NEW ASPHALT OVERLAY AREAS.
e� OQ WA
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NO. REVISION BY DATE APPR �� � '�" ^m°°R' 148TH AVE SE / NILE AVE NE 25
Stormwater Pollution Prevention Plan
Appendix B — Construction BMPs
High Visibility Plastic or Metal Fence (BMP C103)
Plastic Covering (BMP C123)
Dust Control (BMP C 140)
Concrete Handling (BMP C151)
Sawcutting and Surface Pollution Prevention (BMP C152)
Scheduling (BMP C 162)
Check Dams (BMP C207)
Storm Drain Inlet Protection (BMP C220)
Silt Fence (BMP C233)
Sediment Trap (BMP C240)
Construction Stormwater Chemical Treatment (BMP C250)
Construction Stormwater Filtration (BMP C251)
31
Stormwater Pollution Prevention Plan
32
BMP C103: High Visibility Plastic or Metal Fence
Ptu pose Fencing is intended to: (1) restrict clearing to approved limits; (2) prevent
disturbance of sensitive areas, their buffers, and other areas required to be
left undisturbed; (3) limit construction traffic to designated construction
entrances or roads; and, (4) protect areas where marking with survey tape
may not provide adequate protection.
Conditions of Use To establish clearing limits, plastic or metal fence may be used:
• At the boundary of sensitive areas, their buffers, and other areas
required to be left uncleared.
• As necessary to control vehicle access to and on the site.
Design and High visibility plastic fence shall be composed of a high -density
Installation polyethylene material and shall be at least four feet in height. Posts
Specifications for the fencing shall be steel or wood and placed every 6 feet on
center (maximum) or as needed to ensure rigidity. The fencing shall
be fastened to the post every six inches with a polyethylene tie. On
long continuous lengths of fencing, a tension wire or rope shall be
used as a top stringer to prevent sagging between posts. The fence
color shall be high visibility orange. The fence tensile strength shall
be 360 lbs./ft. using the ASTM D4595 testing method.
• Metal fences shall be designed and installed according to the
manufacturer's specifications.
• Metal fences shall be at least 3 feet high and must be highly visible.
• Fences shall not be wired or stapled to trees.
Maintenance If the fence has been damaged or visibility reduced, it shall be
Standards repaired or replaced immediately and visibility restored.
4-6 Volume 11 — Construction Stormwater Pollution Prevention February 2005
BMP C123: Plastic Covering
Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
Conditions of Plastic covering may be used on disturbed areas that require cover
Use measures for less than 30 days, except as stated below.
• Plastic is particularly useful for protecting cut and fill slopes and
stockpiles. Note: The relatively rapid breakdown of most polyethylene
sheeting makes it unsuitable for long-term (greater than six months)
applications.
• Clear plastic sheeting can be used over newly -seeded areas to create a
greenhouse effect and encourage grass growth if the hydroseed was
installed too late in the season to establish 75 percent grass cover, or if
the wet season started earlier than normal. Clear plastic should not be
used for this purpose during the summer months because the resulting
high temperatures can kill the grass.
• Due to rapid runoff caused by plastic sheeting, this method shall not be
used upslope of areas that might be adversely impacted by
concentrated runoff. Such areas include steep and/or unstable slopes.
• While plastic is inexpensive to purchase, the added cost of installation,
maintenance, removal, and disposal make this an expensive material,
up to $1.50-2.00 per square yard.
• Whenever plastic is used to protect slopes, water collection measures
must be installed at the base of the slope. These measures include
plastic -covered berms, channels, and pipes used to covey clean
rainwater away from bare soil and disturbed areas. At no time is clean
runoff from a plastic covered slope to be mixed with dirty runoff from
a project.
Other uses for plastic include:
1. Temporary ditch liner;
2. Pond liner in temporary sediment pond;
3. Liner for bermed temporary fuel storage area if plastic is not
reactive to the type of fuel being stored;
4. Emergency slope protection during heavy rains; and,
5. Temporary drainpipe ("elephant trunk') used to direct water.
4-26 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Design and Plastic slope cover must be installed as follows:
Installation 1. Run plastic up and down slope, not across slope;
Specifications
2. Plastic may be installed perpendicular to a slope if the slope length
is less than 10 feet;
3. Minimum of 8-inch overlap at seams;
Maintenance
Standards
4. On long or wide slopes, or slopes subject to wind, all seams should
be taped;
5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench
at the top of the slope and backfill with soil to keep water from
flowing underneath;
6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and pound a wooden stake through each to hold them in
place;
7. Inspect plastic for rips, tears, and open seams regularly and repair
immediately. This prevents high velocity runoff from contacting
bare soil which causes extreme erosion;
8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
• Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
• If erosion at the toe of a slope is likely, a gravel berm, riprap, or other
suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
• Torn sheets must be replaced and open seams repaired.
• If the plastic begins to deteriorate due to ultraviolet radiation, it must
be completely removed and replaced.
When the plastic is no longer needed, it shall be completely removed.
• Dispose of old tires appropriately.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-27
BMP C140: Dust Control
Purpose Dust control prevents wind transport of dust from disturbed soil surfaces
onto roadways, drainage ways, and surface waters.
Conditions of Use In areas (including roadways) subject to surface and air movement of
dust where on -site and off -site impacts to roadways, drainage ways, or
surface waters are likely.
Design and . Vegetate or mulch areas that will not receive vehicle traffic. In areas
Installation where planting, mulching, or paving is impractical, apply gravel or
Specifications landscaping rock.
• Limit dust generation by clearing only those areas where immediate
activity will take place, leaving the remaining area(s) in the original
condition, if stable. Maintain the original ground cover as long as
practical.
• Construct natural or artificial windbreaks or windscreens. These may
be designed as enclosures for small dust sources.
• Sprinkle the site with water until surface is wet. Repeat as needed. To
prevent carryout of mud onto street, refer to Stabilized Construction
Entrance (BMP C105).
• Irrigation water can be used for dust control. Irrigation systems should
be installed as a first step on sites where dust control is a concern.
• Spray exposed soil areas with a dust palliative, following the
manufacturer's instructions and cautions regarding handling and
application. Used oil is prohibited from use as a dust suppressant.
Local governments may approve other dust palliatives such as calcium
chloride or PAM.
• PAM (BMP C 126) added to water at a rate of 0.5 lbs. per 1,000
gallons of water per acre and applied from a water truck is more
effective than water alone. This is due to the increased infiltration of
water into the soil and reduced evaporation. In addition, small soil
particles are bonded together and are not as easily transported by wind.
Adding PAM may actually reduce the quantity of water needed for
dust control, especially in eastern Washington. Since the wholesale
cost of PAM is about $ 4.00 per pound, this is an extremely cost-
effective dust control method.
Techniques that can be used for unpaved roads and lots include:
• Lower speed limits. High vehicle speed increases the amount of dust
stirred up from unpaved roads and lots.
• Upgrade the road surface strength by improving particle size, shape,
and mineral types that make up the surface and base materials.
4-40 Volume 11 — Construction Stormwater Pollution Prevention February 2005
• Add surface gravel to reduce the source of dust emission. Limit the
amount of fine particles (those smaller than .075 mm) to 10 to 20
percent.
• Use geotextile fabrics to increase the strength of new roads or roads
undergoing reconstruction.
• Encourage the use of alternate, paved routes, if available.
• Restrict use by tracked vehicles and heavy trucks to prevent damage to
road surface and base.
• Apply chemical dust suppressants using the admix method, blending
the product with the top few inches of surface material. Suppressants
may also be applied as surface treatments.
• Pave unpaved permanent roads and other trafficked areas.
• Use vacuum street sweepers.
• Remove mud and other dirt promptly so it does not dry and then turn
into dust.
• Limit dust -causing work on windy days.
• Contact your local Air Pollution Control Authority for guidance and
training on other dust control measures. Compliance with the local Air
Pollution Control Authority constitutes compliance with this BMP.
Maintenance Respray area as necessary to keep dust to a minimum.
Standards
February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-41
BMP C151: Concrete Handling
Purpose Concrete work can generate process water and slurry that contain fine
particles and high pH, both of which can violate water quality standards in
the receiving water. This BMP is intended to minimize and eliminate
concrete process water and slurry from entering waters of the state.
Conditions of Use Any time concrete is used, these management practices shall be utilized.
Concrete construction projects include, but are not limited to, the
following:
• Curbs
Sidewalks
Roads
Bridges
Foundations
• Floors
Runways
Design and • Concrete truck chutes, pumps, and internals shall be washed out only
Installation into formed areas awaiting installation of concrete or asphalt.
Specifications • Unused concrete remaining in the truck and pump shall be returned to
the originating batch plant for recycling.
• Hand tools including, but not limited to, screeds, shovels, rakes, floats,
and trowels shall be washed off only into formed areas awaiting
installation of concrete or asphalt.
• Equipment that cannot be easily moved, such as concrete pavers, shall
only be washed in areas that do not directly drain to natural or
constructed stormwater conveyances.
• Washdown from areas such as concrete aggregate driveways shall not
drain directly to natural or constructed stormwater conveyances.
• When no formed areas are available, washwater and leftover product
shall be contained in a lined container. Contained concrete shall be
disposed of in a manner that does not violate groundwater or surface
water quality standards.
Maintenance Containers shall be checked for holes in the liner daily during concrete
Standards pours and repaired the same day.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-43
BMP C152: Sawcutting and Surfacing Pollution Prevention
Pnipose Sawcutting and surfacing operations generate slurry and process water
that contains fine particles and high pH (concrete cutting), both of which
can violate the water quality standards in the receiving water. This BMP
is intended to minimize and eliminate process water and slurry from
entering waters of the State.
Conditions of Use Anytime sawcutting or surfacing operations take place, these
management practices shall be utilized. Sawcutting and surfacing
operations include, but are not limited to, the following:
• Sawing
• Coring
• Grinding
• Roughening
• Hydro -demolition
• Bridge and road surfacing
Design and • Slurry and cuttings shall be vacuumed during cutting and surfacing
Installation operations.
Specifications • Slurry and cuttings shall not remain on permanent concrete or asphalt
pavement overnight.
• Slurry and cuttings shall not drain to any natural or constructed
drainage conveyance.
• Collected slurry and cuttings shall be disposed of in a manner that does
not violate groundwater or surface water quality standards.
• Process water that is generated during hydro -demolition, surface
roughening or similar operations shall not drain to any natural or
constructed drainage conveyance and shall be disposed of in a manner
that does not violate groundwater or surface water quality standards.
• Cleaning waste material and demolition debris shall be handled and
disposed of in a manner that does not cause contamination of water. If
the area is swept with a pick-up sweeper, the material must be hauled
out of the area to an appropriate disposal site.
Maintenance Continually monitor operations to determine whether slurry, cuttings, or
Standards process water could enter waters of the state. If inspections show that a
violation of water quality standards could occur, stop operations and
immediately implement preventive measures such as berms, barriers,
secondary containment, and vacuum trucks.
4-44 Volume 11 — Construction Stormwater Pollution Prevention February 2005
BMP C162: Scheduling
Purpose Sequencing a construction project reduces the amount and duration of soil
exposed to erosion by wind, rain, runoff, and vehicle tracking.
Conditions of Use The construction sequence schedule is an orderly listing of all major land -
disturbing activities together with the necessary erosion and sedimentation
control measures planned for the project. This type of schedule guides the
contractor on work to be done before other work is started so that serious
erosion and sedimentation problems can be avoided.
Following a specified work schedule that coordinates the timing of land -
disturbing activities and the installation of control measures is perhaps the
most cost-effective way of controlling erosion during construction. The
removal of surface ground cover leaves a site vulnerable to accelerated
erosion. Construction procedures that limit land clearing, provide timely
installation of erosion and sedimentation controls, and restore protective
cover quickly can significantly reduce the erosion potential of a site.
Design • Avoid rainy periods.
Considerations . Schedule projects to disturb only small portions of the site at any one
time. Complete grading as soon as possible. Immediately stabilize the
disturbed portion before grading the next portion. Practice staged
seeding in order to revegetate cut and fill slopes as the work
progresses.
4-54 Volume 11 — Construction Stormwater Pollution Prevention February 2005
BMP C207: Check Dams
Purpose
Construction of small dams across a swale or ditch reduces the velocity of
concentrated flow and dissipates energy at the check dam.
Conditions of Use
Where temporary channels or permanent channels are not yet vegetated,
channel lining is infeasible, and velocity checks are required.
• Check dams may not be placed in streams unless approved by the State
Department of Fish and Wildlife. Check dams may not be placed in
wetlands without approval from a permitting agency.
• Check dams shall not be placed below the expected backwater from
any salmonid bearing water between October 1 and May 31 to ensure
that there is no loss of high flow refuge habitat for overwintering
juvenile salmonids and emergent salmonid fry.
Design and
Whatever material is used, the dam should form a triangle when viewed
Installation
from the side. This prevents undercutting as water flows over the face of
Specifications
the dam rather than falling directly onto the ditch bottom.
Check dams in association with sumps work more effectively at slowing
flow and retaining sediment than just a check dam alone. A deep sump
should be provided immediately upstream of the check dam.
• In some cases, if carefully located and designed, check dams can
remain as permanent installations with very minor regrading. They
may be left as either spillways, in which case accumulated sediment
would be graded and seeded, or as check dams to prevent further
sediment from leaving the site.
• Check dams can be constructed of either rock or pea -gravel filled bags.
Numerous new products are also available for this purpose. They tend
to be re -usable, quick and easy to install, effective, and cost efficient.
• Check dams should be placed perpendicular to the flow of water.
• The maximum spacing between the dams shall be such that the toe of
the upstream dam is at the same elevation as the top of the downstream
dam.
• Keep the maximum height at 2 feet at the center of the dam.
• Keep the center of the check dam at least 12 inches lower than the
outer edges at natural ground elevation.
• Keep the side slopes of the check dam at 2:1 or flatter.
• Key the stone into the ditch banks and extend it beyond the abutments
a minimum of 18 inches to avoid washouts from overflow around the
dam.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-75
• Use filter fabric foundation under a rock or sand bag check dam. If a
blanket ditch liner is used, this is not necessary. A piece of organic or
synthetic blanket cut to fit will also work for this purpose.
• Rock check dams shall be constructed of appropriately sized rock.
The rock must be placed by hand or by mechanical means (no
dumping of rock to form dam) to achieve complete coverage of the
ditch or swale and to ensure that the center of the dam is lower than
the edges. The rock used must be large enough to stay in place given
the expected design flow through the channel.
• In the case of grass -lined ditches and swales, all check dams and
accumulated sediment shall be removed when the grass has matured
sufficiently to protect the ditch or Swale - unless the slope of the swale
is greater than 4 percent. The area beneath the check dams shall be
seeded and mulched immediately after dam removal.
• Ensure that channel appurtenances, such as culvert entrances below
check dams, are not subject to damage or blockage from displaced
stones. Figure 4.13 depicts a typical rock check dam.
Maintenance Check dams shall be monitored for performance and sediment
Standards accumulation during and after each runoff producing rainfall. Sediment
shall be removed when it reaches one half the sump depth.
• Anticipate submergence and deposition above the check dam and
erosion from high flows around the edges of the dam.
• If significant erosion occurs between dams, install a protective riprap
liner in that portion of the channel.
4-76 Volume 11— Construction Stormwater Pollution Prevention February 2005
View Looking Upstream
NOTE:
Key stone into channel banks and
extend it beyond the abutments a
minimum of 18" (0.5m) to prevent
flow around dam.
Section A - A
PI 01A/
18" (0.5m) —
A00
M)l
)
24" (0.6m)
A
Spacing Between Check Dams
'L' = the distance such that points 'A' and
'B' are of equal elevation.
POINT 'A'
Figure 4.13 — Check Dams
POINT ' B'
NOT TO SCALE
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-77
BMP C220: Storm Drain Inlet Protection
Purpose To prevent coarse sediment from entering drainage systems prior to
permanent stabilization of the disturbed area.
Conditions of Use Where storm drain inlets are to be made operational before permanent
stabilization of the disturbed drainage area. Protection should be provided
for all storm drain inlets downslope and within 500 feet of a disturbed or
construction area, unless the runoff that enters the catch basin will be
conveyed to a sediment pond or trap. Inlet protection may be used
anywhere to protect the drainage system. It is likely that the drainage
system will still require cleaning.
Table 4.9 lists several options for inlet protection. All of the methods for
storm drain inlet protection are prone to plugging and require a high
frequency of maintenance. Drainage areas should be limited to 1 acre or
less. Emergency overflows may be required where stormwater ponding
would cause a hazard. If an emergency overflow is provided, additional
end -of -pipe treatment may be required.
Table 4.9
Storm
Drain Inlet Protetion
Applicable for
Type of Inlet
Emergency
Paved/ Earthen
Protection
Overflow
Surfaces
Conditions of Use
Drop Inlet Protection
Excavated drop inlet
Yes,
Earthen
Applicable for heavy flows. Easy
protection
temporary
to maintain. Large area
flooding will
Requirement: 30' X 30'/acre
occur
Block and gravel drop
Yes
Paved or Earthen
Applicable for heavy concentrated
inlet protection
flows. Will not pond.
Gravel and wire drop
No
Applicable for heavy concentrated
inlet protection
flows. Will pond. Can withstand
traffic.
Catch basin filters
Yes
Paved or Earthen
Frequent maintenance required.
Curb Inlet Protection
Curb inlet protection
Small capacity
Paved
Used for sturdy, more compact
with a wooden weir
overflow
installation.
Block and gravel curb
Yes
Paved
Sturdy, but limited filtration.
inlet protection
Culvert Inlet Protection
Culvert inlet sediment
18 month expected life.
trap
4-82 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Design and Excavated Drop Inlet Protection - An excavated impoundment around the
Installation storm drain. Sediment settles out of the stormwater prior to entering the
Specifications storm drain.
• Depth 1-2 ft as measured from the crest of the inlet structure.
• Side Slopes of excavation no steeper than 2:1.
• Minimum volume of excavation 35 cubic yards.
• Shape basin to fit site with longest dimension oriented toward the
longest inflow area.
• Install provisions for draining to prevent standing water problems.
• Clear the area of all debris.
• Grade the approach to the inlet uniformly.
• Drill weep holes into the side of the inlet.
• Protect weep holes with screen wire and washed aggregate.
• Seal weep holes when removing structure and stabilizing area.
• It may be necessary to build a temporary dike to the down slope side
of the structure to prevent bypass flow.
Block and Gravel Filter - A barrier formed around the storm drain inlet
with standard concrete blocks and gravel. See Figure 4.14.
• Height 1 to 2 feet above inlet.
• Recess the first row 2 inches into the ground for stability.
Support subsequent courses by placing a 2x4 through the block
opening.
Do not use mortar.
Lay some blocks in the bottom row on their side for dewatering the
pool.
Place hardware cloth or comparable wire mesh with'/2-inch openings
over all block openings.
Place gravel just below the top of blocks on slopes of 2:1 or flatter.
An alternative design is a gravel donut.
Inlet slope of 3:1.
Outlet slope of 2:1.
• 1-foot wide level stone area between the structure and the inlet.
• Inlet slope stones 3 inches in diameter or larger.
• Outlet slope use gravel'/2- to 3/-inch at a minimum thickness of' 1-foot.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-83
Plan View A
Drain
Grate °o0.
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Filter Fabric
Gravel Backfill — Overflow
Ponding Height
Water
Water 1 F IF11
U. v,o a,
/\ /\\/\\/\�
Drop Inlet
Notes:
1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%)
2. Excavate a basin of sufficient size adjacent to the drop inlet.
3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent
runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure.
Figure 4.14 — Block and Gravel Filter
Gravel and Wire Mesh Filter - A gravel barrier placed over the top of the
inlet. This structure does not provide an overflow.
• Hardware cloth or comparable wire mesh with'h-inch openings.
• Coarse aggregate.
• Height 1-foot or more, 18 inches wider than inlet on all sides.
• Place wire mesh over the drop inlet so that the wire extends a
minimum of 1-foot beyond each side of the inlet structure.
• If more than one strip of mesh is necessary, overlap the strips.
• Place coarse aggregate over the wire mesh.
• The depth of the gravel should be at least 12 inches over the entire
inlet opening and extend at least 18 inches on all sides.
4-84 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Catchbasin Filters - Inserts should be designed by the manufacturer for
use at construction sites. The limited sediment storage capacity increases
the amount of inspection and maintenance required, which may be daily
for heavy sediment loads. The maintenance requirements can be reduced
by combining a catchbasin filter with another type of inlet protection.
This type of inlet protection provides flow bypass without overflow and
therefore may be a better method for inlets located along active rights -of -
way.
5 cubic feet of storage.
Dewatering provisions.
High -flow bypass that will not clog under normal use at a construction
site.
The catchbasin filter is inserted in the catchbasin just below the
grating.
Curb Inlet Protection with Wooden Weir — Barrier formed around a curb
inlet with a wooden frame and gravel.
• Wire mesh with'`/z-inch openings.
• Extra strength filter cloth.
• Construct a frame.
• Attach the wire and filter fabric to the frame.
• Pile coarse washed aggregate against wire/fabric.
• Place weight on frame anchors.
Block and Gravel Curb Inlet Protection — Barrier formed around an inlet
with concrete blocks and gravel. See Figure 4.14.
• Wire mesh with `/2-inch openings.
• Place two concrete blocks on their sides abutting the curb at either side
of the inlet opening. These are spacer blocks.
• Place a 2x4 stud through the outer holes of each spacer block to align
the front blocks.
• Place blocks on their sides across the front of the inlet and abutting the
spacer blocks.
• Place wire mesh over the outside vertical face.
• Pile coarse aggregate against the wire to the top of the barrier.
Curb and Gutter Sediment Barrier — Sandbag or rock berm (riprap and
aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure
4.16.
• Construct a horseshoe shaped berm, faced with coarse aggregate if
using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet.
• Construct a horseshoe shaped sedimentation trap on the outside of the
berm sized to sediment trap standards for protecting a culvert inlet.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-85
Maintenance Catch basin filters should be inspected frequently, especially after
Standards storm events. If the insert becomes clogged, it should be cleaned or
replaced.
• For systems using stone filters: If the stone filter becomes clogged
with sediment, the stones must be pulled away from the inlet and
cleaned or replaced. Since cleaning of gravel at a construction site
may be difficult, an alternative approach would be to use the clogged
stone as fill and put fresh stone around the inlet.
• Do not wash sediment into storm drains while cleaning. Spread all
excavated material evenly over the surrounding land area or stockpile
and stabilize as appropriate.
4-86 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Plan View
SeCi��v�� #-"% — /--% (20mm)
%I'Drain Gravel
(20mm)
Ponding Height
Concrete Block
r
rfl
Wire Screen or %V>/���/��
Filter Fabric �i�/
Catch Basin
4 Wood Stud
(100x50 Timber Stud)
NOTES:
1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment,
where water can pond and allow sediment to separate from runoff.
2. Barrier shall allow for overflow from severe storm event.
3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed
from the traveled way immediately.
Figure 4.15 — Block and Gravel Curb Inlet Protection
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-87
Plan View
Back of Sidewalk
('Dinh Rosin
NOTES:
1. Place curb type sediment barriers on gently sloping street segments, where water can pond and alloxv
sediment to separate from runoff.
2. Sandbags of either burlap or woven 'geotextile' fabric, are filled with gravel, layered and packed tightly.
3. Leave a one sandbag gap in the top row to provide a spillway for overflow.
4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from
the traveled way immediately.
Figure 4.16 — Curb and Gutter Barrier
4-88 Volume 11 — Construction Stormwater Pollution Prevention February 2005
BMP C233: Silt Fence
Purpose
Conditions of Use
Design and
Installation
Specifications
Use of a silt fence reduces the transport of coarse sediment from a
construction site by providing a temporary physical barrier to sediment
and reducing the runoff velocities of overland flow. See Figure 4.19 for
details on silt fence construction.
Silt fence may be used downslope of all disturbed areas.
Silt fence is not intended to treat concentrated flows, nor is it intended
to treat substantial amounts of overland flow. Any concentrated flows
must be conveyed through the drainage system to a sediment pond.
The only circumstance in which overland flow can be treated solely by
a silt fence, rather than by a sediment pond, is when the area draining
to the fence is one acre or less and flow rates are less than 0.5 cfs.
• Silt fences should not be constructed in streams or used in V-shaped
ditches. They are not an adequate method of silt control for anything
deeper than sheet or overland flow.
Joints in filter fabric shall be spliced at
posts. Use staples, wire rings or 2"x2" by 14 Ga. wire or
equivalent to attach fabric to posts equivalent, if standard _
strength fabric used
Filter fabric
II I E
N
II _
_T Lw - 6' max — Minimum 4"x4" trench
Backfill trench with native soil 107- t N
Post spacing may be increased or 3/4"-1.5" washed gravel
to 8' if wire backing is used
2"x2" wood posts, steel fence
posts, or equivalent
Figure 4.19 — Silt Fence
• Drainage area of 1 acre or less or in combination with sediment basin
in a larger site.
• Maximum slope steepness (normal (perpendicular) to fence line) 1:1.
• Maximum sheet or overland flow path length to the fence of 100 feet.
No flows greater than 0.5 cfs.
• The geotextile used shall meet the following standards. All geotextile
properties listed below are minimum average roll values (i.e., the test
result for any sampled roll in a lot shall meet or exceed the values
shown in Table 4.10):
4-94
Volume 11 — Construction Stormwater Pollution Prevention February 2005
Table 4.10
Geotextile Standards
Polymeric Mesh AOS
0.60 mm maximum for slit film wovens (#30 sieve). 0.30
(ASTM D4751)
mm maximum for all other geotextile types (#50 sieve).
0.15 mm minimum for all fabric types (#100 sieve).
Water Permittivity
0.02 sec-1 minimum
(ASTM D4491)
Grab Tensile Strength
180 lbs. Minimum for extra strength fabric.
(ASTM D4632)
1001bs minimum for standard strength fabric.
Grab Tensile Strength
30% maximum
(ASTM D4632)
Ultraviolet Resistance
70% minimum
(ASTM D4355)
• Standard strength fabrics shall be supported with wire mesh, chicken
wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the
strength of the fabric. Silt fence materials are available that have
synthetic mesh backing attached.
• Filter fabric material shall contain ultraviolet ray inhibitors and
stabilizers to provide a minimum of six months of expected usable
construction life at a temperature range of 0°F. to 120°F.
100 percent biodegradable silt fence is available that is strong, long
lasting, and can be left in place after the project is completed, if
permitted by local regulations.
Standard Notes for construction plans and specifications follow. Refer
to Figure 4.19 for standard silt fence details.
The contractor shall install and maintain temporary silt fences at the
locations shown in the Plans. The silt fences shall be constructed in
the areas of clearing, grading, or drainage prior to starting those
activities. A silt fence shall not be considered temporary if the silt
fence must function beyond the life of the contract. The silt fence
shall prevent soil carried by runoff water from going beneath, through,
or over the top of the silt fence, but shall allow the water to pass
through the fence.
The minimum height of the top of silt fence shall be 2 feet and the
maximum height shall be 21/2feet above the original ground surface.
The geotextile shall be sewn together at the point of manufacture, or at
an approved location as determined by the Engineer, to form geotextile
lengths as required. All sewn seams shall be located at a support post.
Alternatively, two sections of silt fence can be overlapped, provided
the Contractor can demonstrate, to the satisfaction of the Engineer, that
the overlap is long enough and that the adjacent fence sections are
close enough together to prevent silt laden water from escaping
through the fence at the overlap.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-95
The geotextile shall be attached on the up -slope side of the posts and
support system with staples, wire, or in accordance with the
manufacturer's recommendations. The geotextile shall be attached to
the posts in a manner that reduces the potential for geotextile tearing at
the staples, wire, or other connection device. Silt fence back-up
support for the geotextile in the form of a wire or plastic mesh is
dependent on the properties of the geotextile selected for use. If wire
or plastic back-up mesh is used, the mesh shall be fastened securely to
the up -slope of the posts with the geotextile being up -slope of the
mesh back-up support.
The geotextile at the bottom of the fence shall be buried in a trench to
a minimum depth of 4 inches below the ground surface. The trench
shall be backfilled and the soil tamped in place over the buried portion
of the geotextile, such that no flow can pass beneath the fence and
scouring can not occur. When wire or polymeric back-up support
mesh is used, the wire or polymeric mesh shall extend into the trench a
minimum of 3 inches.
The fence posts shall be placed or driven a minimum of 18 inches. A
minimum depth of 12 inches is allowed if topsoil or other soft
subgrade soil is not present and a minimum depth of 18 inches cannot
be reached. Fence post depths shall be increased by 6 inches if the
fence is located on slopes of 3:1 or steeper and the slope is
perpendicular to the fence. If required post depths cannot be obtained,
the posts shall be adequately secured by bracing or guying to prevent
overturning of the fence due to sediment loading.
Silt fences shall be located on contour as much as possible, except at
the ends of the fence, where the fence shall be turned uphill such that
the silt fence captures the runoff water and prevents water from
flowing around the end of the fence.
If the fence must cross contours, with the exception of the ends of the
fence, gravel check dams placed perpendicular to the back of the fence
shall be used to minimize concentrated flow and erosion along the
back of the fence. The gravel check dams shall be approximately 1-
foot deep at the back of the fence. It shall be continued perpendicular
to the fence at the same elevation until the top of the check dam
intercepts the ground surface behind the fence. The gravel check dams
shall consist of crushed surfacing base course, gravel backfill for
walls, or shoulder ballast. The gravel check dams shall be located
every 10 feet along the fence where the fence must cross contours.
The slope of the fence line where contours must be crossed shall not
be steeper than 3:1.
Wood, steel or equivalent posts shall be used. Wood posts shall have
minimum dimensions of 2 inches by 2 inches by 3 feet minimum
length, and shall be free of defects such as knots, splits, or gouges.
4-96 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Steel posts shall consist of either size No. 6 rebar or larger, ASTM A
120 steel pipe with a minimum diameter of 1-inch, U, T, L, or C shape
steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts
having equivalent strength and bending resistance to the post sizes
listed. The spacing of the support posts shall be a maximum of 6 feet.
Fence back-up support, if used, shall consist of steel wire with a
maximum mesh spacing of 2 inches, or a prefabricated polymeric
mesh. The strength of the wire or polymeric mesh shall be equivalent
to or greater than 180 lbs. grab tensile strength. The polymeric mesh
must be as resistant to ultraviolet radiation as the geotextile it supports.
• Silt fence installation using the slicing method specification details
follow. Refer to Figure 4.20 for slicing method details.
The base of both end posts must be at least 2 to 4 inches above the top
of the silt fence fabric on the middle posts for ditch checks to drain
properly. Use a hand level or string level, if necessary, to mark base
points before installation.
Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet
apart in standard applications.
Install posts 24 inches deep on the downstream side of the silt fence,
and as close as possible to the fabric, enabling posts to support the
fabric from upstream water pressure.
Install posts with the nipples facing away from the silt fence fabric.
Attach the fabric to each post with three ties, all spaced within the top
8 inches of the fabric. Attach each tie diagonally 45 degrees through
the fabric, with each puncture at least 1 inch vertically apart. In
addition, each tie should be positioned to hang on a post nipple when
tightening to prevent sagging.
Wrap approximately 6 inches of fabric around the end posts and secure
with 3 ties.
No more than 24 inches of a 36-inch fabric is allowed above ground
level.
The rope lock system must be used in all ditch check applications.
The installation should be checked and corrected for any deviation
before compaction. Use a flat -bladed shovel to tuck fabric deeper into
the ground if necessary.
Compaction is vitally important for effective results. Compact the soil
immediately next to the silt fence fabric with the front wheel of the
tractor, skid steer, or roller exerting at least 60 pounds per square inch.
Compact the upstream side first and then each side twice for a total of
four trips.
February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-97
• Any damage shall be repaired immediately.
Maintenance If concentrated flows are evident uphill of the fence, they must be
Standards intercepted and conveyed to a sediment pond.
• It is important to check the uphill side of the fence for signs of the
fence clogging and acting as a barrier to flow and then causing
channelization of flows parallel to the fence. If this occurs, replace the
fence or remove the trapped sediment.
• Sediment deposits shall either be removed when the deposit reaches
approximately one-third the height of the silt fence, or a second silt
fence shall be installed.
• If the filter fabric (geotextile) has deteriorated due to ultraviolet
it shall be
Pondiny height
POST SPACING:
__ 24-
r tnnx on pen runs
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tMre over each .iM of
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fabric.
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e Position each tia chaga
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vertically
• Mang each " m
a post rtippie and 6phten
.ecvdy.
No more than 24" of a 36e fabric
use cabie ties (5ob4
or sat wire.
is allowed above ground.
Rol of sit fence
♦— Oppration
fba
inialed
after
Fahic
compaction
O above
9a�
Sit Fence
,•A,�,�;�p
1
200-300mm
yr,
•%i ry
Horcantal chisel powrt Slicing blade
(76 nwr wdtti) (18 mm w ktth)
Completed
kiwaMtlort
Vibratory plow is not acceptable because of horizontal compaction
Figure 4.20 — Silt Fence Installation by Slicing Method
4-98 Volume ll — Construction Stormwater Pollution Prevention February 2005
BMP C240: Sediment Trap
Purpose A sediment trap is a small temporary ponding area with a gravel outlet
used to collect and store sediment from sites cleared and/or graded during
construction. Sediment traps, along with other perimeter controls, shall be
installed before any land disturbance takes place in the drainage area.
Conditions of Use Prior to leaving a construction site, stormwater runoff must pass through a
sediment pond or trap or other appropriate sediment removal best
management practice. Non -engineered sediment traps may be used on -site
prior to an engineered sediment trap or sediment pond to provide
additional sediment removal capacity.
It is intended for use on sites where the tributary drainage area is less than
3 acres, with no unusual drainage features, and a projected build -out time
of six months or less. The sediment trap is a temporary measure (with a
design life of approximately 6 months) and shall be maintained until the
site area is permanently protected against erosion by vegetation and/or
structures.
Sediment traps and ponds are only effective in removing sediment down
to about the medium silt size fraction. Runoff with sediment of finer
grades (fine silt and clay) will pass through untreated, emphasizing the
need to control erosion to the maximum extent first.
Whenever possible, sediment -laden water shall be discharged into onsite,
relatively level, vegetated areas (see BMP C234 — Vegetated Strip). This
is the only way to effectively remove fine particles from runoff unless
chemical treatment or filtration is used. This can be particularly useful
after initial treatment in a sediment trap or pond. The areas of release
must be evaluated on a site -by -site basis in order to determine appropriate
locations for and methods of releasing runoff. Vegetated wetlands shall
not be used for this purpose. Frequently, it may be possible to pump water
from the collection point at the downhill end of the site to an upslope
vegetated area. Pumping shall only augment the treatment system, not
replace it, because of the possibility of pump failure or runoff volume in
excess of pump capacity.
All projects that are constructing permanent facilities for runoff quantity
control should use the rough -graded or final -graded permanent facilities
for traps and ponds. This includes combined facilities and infiltration
facilities. When permanent facilities are used as temporary sedimentation
facilities, the surface area requirement of a sediment trap or pond must be
met. If the surface area requirements are larger than the surface area of
the permanent facility, then the trap or pond shall be enlarged to comply
with the surface area requirement. The permanent pond shall also be
divided into two cells as required for sediment ponds.
4-102 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Either a permanent control structure or the temporary control structure
(described in BMP C241, Temporary Sediment Pond) can be used. If a
permanent control structure is used, it may be advisable to partially restrict
the lower orifice with gravel to increase residence time while still allowing
dewatering of the pond. A shut-off valve may be added to the control
structure to allow complete retention of stormwater in emergency
situations. In this case, an emergency overflow weir must be added.
A skimmer may be used for the sediment trap outlet if approved by the
Local Permitting Authority.
Design and • See Figures 4.22 and 4.23 for details.
Installation . If permanent runoff control facilities are part of the project, they
Specifications
should be used for sediment retention.
• To determine the sediment trap geometry, first calculate the design
surface area (SA) of the trap, measured at the invert of the weir. Use
the following equation:
SA = FS(Q2/Vs)
where
Q2 = Design inflow based on the peak discharge from the
developed 2-year runoff event from the contributing
drainage area as computed in the hydrologic analysis. The
10-year peak flow shall be used if the project size, expected
timing and duration of construction, or downstream
conditions warrant a higher level of protection. If no
hydrologic analysis is required, the Rational Method may
be used.
Vs = The settling velocity of the soil particle of interest. The
0.02 mm (medium silt) particle with an assumed density of
2.65 g/cm3 has been selected as the particle of interest and
has a settling velocity (Vs) of 0.00096 ft/sec.
FS = A safety factor of 2 to account for non -ideal settling.
Therefore, the equation for computing surface area becomes:
SA = 2 x Q210.00096 or
2080 square feet per cfs of inflow
Note: Even if permanent facilities are used, they must still have a
surface area that is at least as large as that derived from the above
formula. If they do not, the pond must be enlarged.
• To aid in determining sediment depth, all sediment traps shall have a
staff gauge with a prominent mark 1-foot above the bottom of the trap.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-103
• Sediment traps may not be feasible on utility projects due to the
limited work space or the short-term nature of the work. Portable
tanks may be used in place of sediment traps for utility projects.
Maintenance • Sediment shall be removed from the trap when it reaches 1-foot in
Standards depth.
• Any damage to the pond embankments or slopes shall be repaired.
Surface area determined 4' Min.
at top of weir t
a
_ 1' Min. Overflow
T 1' Min.
3.5'-5' ': 1' Min.
� :. �.•. ;.::� �.:'.; •.::•�:'`:.
1.5' Min. \ -
Flat Bottom
73/s" - 1.5" \ 2"-4" RockipRap
Washed gravel
Note: Trap may be formed by berm or by Geotextile %
partial or complete excavation
Discharge to stabilized
conveyance, outlet, or
level spreader
Figure 4.22 Cross Section of Sediment Trap
6' Min.
=1 1=1 11=1 11=1 11=1 1=1 I 1' Min. depth overflow spillway
Native soil or11=I I' Min. 1' depth
compacted backfill —III 2" 4"' rock
Geotextile -III—III—III—III=III=III—III=1 I=III Min. 1' depth 3/4"-1.5"
-1 I I-1 I I-111-111=1 11=11 I—III-1 I I-1 washed gravel
Figure 4.23 Sediment Trap Outlet
4-104 Volume 11— Construction Stormwater Pollution Prevention February 2005
BMP C250: Construction Stormwater Chemical Treatment
Purpose Turbidity is difficult to control once fine particles are suspended in
stormwater runoff from a construction site. Sedimentation ponds are
effective at removing larger particulate matter by gravity settling, but are
ineffective at removing smaller particulates such as clay and fine silt.
Sediment ponds are typically designed to remove sediment no smaller than
medium silt (0.02 mm). Chemical treatment may be used to reduce the
turbidity of stormwater runoff.
Conditions of Use Chemical treatment can reliably provide exceptional reductions of
turbidity and associated pollutants. Very high turbidities can be reduced
to levels comparable to what is found in streams during dry weather.
Traditional BMPs used to control soil erosion and sediment loss from sites
under development may not be adequate to ensure compliance with the
water quality standard for turbidity in the receiving water. Chemical
treatment may be required to protect streams from the impact of turbid
stormwater discharges, especially when construction is to proceed through
the wet season.
Formal written approval from Ecology and the Local Permitting
Authority is required for the use of chemical treatment regardless of
site size. The intention to use Chemical Treatment shall be indicated
on the Notice of Intent for coverage under the General Construction
Permit. Chemical treatment systems should be designed as part of the
Construction SWPPP, not after the fact. Chemical treatment may be
used to correct problem sites in limited circumstances with formal
written approval from Ecology and the Local Permitting Authority.
The SEPA review authority must be notified at the application phase of
the project review (or the time that the SEPA determination on the project
is performed) that chemical treatment is proposed. If it is added after this
stage, an addendum will be necessary and may result in project approval
delay.
Design and See Appendix II-B for background information on chemical treatment.
Installation
Specifications Criteria for Chemical Treatment Product Use: Chemically treated
stormwater discharged from construction sites must be nontoxic to aquatic
organisms. The following protocol shall be used to evaluate chemicals
proposed for stormwater treatment at construction sites. Authorization to
use a chemical in the field based on this protocol does not relieve the
applicant from responsibility for meeting all discharge and receiving
water criteria applicable to a site.
Treatment chemicals must be approved by EPA for potable water use.
Petroleum -based polymers are prohibited.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-111
Prior to authorization for field use, jar tests shall be conducted to
demonstrate that turbidity reduction necessary to meet the receiving
water criteria can be achieved. Test conditions, including but not
limited to raw water quality and jar test procedures, should be
indicative of field conditions. Although these small-scale tests cannot
be expected to reproduce performance under field conditions, they are
indicative of treatment capability.
• Prior to authorization for field use, the chemically treated stormwater
shall be tested for aquatic toxicity. Applicable procedures defined in
Chapter 173-205 WAC, Whole Effluent Toxicity Testing and Limits,
shall be used. Testing shall use stormwater from the construction site
at which the treatment chemical is proposed for use or a water solution
using soil from the proposed site.
• The proposed maximum dosage shall be at least a factor of five lower
than the no observed effects concentration (NOEC).
• The approval of a proposed treatment chemical shall be conditional,
subject to full-scale bioassay monitoring of treated stormwater at the
construction site where the proposed treatment chemical is to be used.
• Treatment chemicals that have already passed the above testing
protocol do not need to be reevaluated. Contact the Department of
Ecology Regional Office for a list of treatment chemicals that have
been evaluated and are currently approved for use.
Treatment System Design Considerations: The design and operation of
a chemical treatment system should take into consideration the factors that
determine optimum, cost-effective performance. It may not be possible to
fully incorporate all of the -classic concepts into the design because of
practical limitations at construction sites. Nonetheless, it is important to
recognize the following:
• The right chemical must be used at the right dosage. A dosage that is
either too low or too high will not produce the lowest turbidity. There
is an optimum dosage rate. This is a situation where the adage "adding
more is always better" is not the case.
• The coagulant must be mixed rapidly into the water to insure proper
dispersion.
• A flocculation step is important to increase the rate of settling, to
produce the lowest turbidity, and to keep the dosage rate as low as
possible.
• Too little energy input into the water during the flocculation phase
results in flocs that are too small and/or insufficiently dense. Too
much energy can rapidly destroy floc as it is formed.
4-112 Volume 11— Construction Stormwater Pollution Prevention February 2005
• Since the volume of the basin is a determinant in the amount of energy
per unit volume, the size of the energy input system can be too small
relative to the volume of the basin.
• Care must be taken in the design of the withdrawal system to minimize
outflow velocities and to prevent floc discharge. The discharge should
be directed through a physical filter such as a vegetated swale that
would catch any unintended floc discharge.
Treatment System Design: Chemical treatment systems shall be
designed as batch treatment systems using either ponds or portable trailer -
mounted tanks. Flow -through continuous treatment systems are not
allowed at this time.
A chemical treatment system consists of the stormwater collection system
(either temporary diversion or the permanent site drainage system), a
storage pond, pumps, a chemical feed system, treatment cells, and
interconnecting piping.
The treatment system shall use a minimum of two lined treatment cells.
Multiple treatment cells allow for clarification of treated water while other
cells are being filled or emptied. Treatment cells may be ponds or tanks.
Ponds with constructed earthen embankments greater than six feet high
require special engineering analyses. Portable tanks may also be suitable
for some sites.
The following equipment should be located in an operations shed:
• the chemical injector;
• secondary containment for acid, caustic, buffering compound, and
treatment chemical,
• emergency shower and eyewash, and
• monitoring equipment which consists of a pH meter and a
turbidimeter.
Sizing Criteria: The combination of the storage pond or other holding
area and treatment capacity should be large enough to treat stormwater
during multiple day storm events. It is recommended that at a minimum
the storage pond or other holding area should be sized to hold 1.5 times
the runoff volume of the 10-year, 24-hour storm event. Bypass should be
provided around the chemical treatment system to accommodate extreme
storm events. Runoff volume shall be calculated using the methods
presented in Volume 3, Chapter 2. If no hydrologic analysis is required
for the site, the Rational Method may be used.
Primary settling should be encouraged in the storage pond. A forebay
with access for maintenance may be beneficial.
There are two opposing considerations in sizing the treatment cells. A
larger cell is able to treat a larger volume of water each time a batch is
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-113
processed. However, the larger the cell the longer the time required to
empty the cell. A larger cell may also be less effective at flocculation and
therefore require a longer settling time. The simplest approach to sizing
the treatment cell is to multiply the allowable discharge flow rate times the
desired drawdown time. A 4-hour drawdown time allows one batch per
cell per 8-hour work period, given I hour of flocculation followed by two
hours of settling.
The permissible discharge rate governed by potential downstream effect
can be used to calculate the recommended size of the treatment cells. The
following discharge flow rate limits shall apply:
• If the discharge is directly or indirectly to a stream, the discharge flow
rate shall not exceed 50 percent of the peak flow rate of the 2-year, 24-
hour event for all storm events up to the 10-year, 24-hour event.
• If discharge is occurring during a storm event equal to or greater than
the 10-year, 24-hour event, the allowable discharge rate is the peak
flow rate of the 10-year, 24-hour event.
• Discharge to a stream should not increase the stream flow rate by more
than 10 percent.
• If the discharge is directly to a lake, a major receiving water listed in
Appendix C of Volume I, or to an infiltration system, there is no
discharge flow limit.
• If the discharge is to a municipal storm drainage system, the allowable
discharge rate may be limited by the capacity of the public system. It
may be necessary to clean the municipal storm drainage system prior
to the start of the discharge to prevent scouring solids from the
drainage system.
• Runoff rates shall be calculated using the methods presented in
Volume 3, Chapter 2 for the predeveloped condition. If no hydrologic
analysis is required for the site, the Rational Method may be used.
Maintenance Monitoring: The following monitoring shall be conducted. Test results
Standards shall be recorded on a daily log kept on site:
Operational Monitoring
• pH, conductivity (as a surrogate for alkalinity), turbidity and
temperature of the untreated stormwater
• Total volume treated and discharged
• Discharge time and flow rate
• Type and amount of chemical used for pH adjustment
• Amount of polymer used for treatment
• Settling time
4-114 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Compliance Monitoring
• pH and turbidity of the treated stormwater
• pH and turbidity of the receiving water
Biomonitoring
Treated stormwater shall be tested for acute (lethal) toxicity. Bioassays
shall be conducted by a laboratory accredited by Ecology, unless
otherwise approved by Ecology. The performance standard for acute
toxicity is no statistically significant difference in survival between the
control and 100 percent chemically treated stormwater.
Acute toxicity tests shall be conducted with the following species and
protocols:
• Fathead minnow, Pimephales promelas (96 hour static -renewal test,
method: EPA/600/4-90/027F). Rainbow trout, Oncorhynchus mykiss
(96 hour static -renewal test, method: EPA/600/4-90/027F) may be
used as a substitute for fathead minnow.
• Daphnid, Ceriodaphnia dubia, Daphnia pulex, or Daphnia magna (48
hour static test, method: EPA/600/4-90/027F).
All toxicity tests shall meet quality assurance criteria and test conditions in
the most recent versions of the EPA test method and Ecology Publication
# WQ-R-95-80, Laboratory Guidance and Whole Effluent Toxicity Test
Review Criteria.
Bioassays shall be performed on the first five batches and on every tenth
batch thereafter, or as otherwise approved by Ecology. Failure to meet the
performance standard shall be immediately reported to Ecology.
Discharge Compliance: Prior to discharge, each batch of treated
stormwater must be sampled and tested for compliance with pH and
turbidity limits. These limits may be established by the water quality
standards or a site -specific discharge permit. Sampling and testing for
other pollutants may also be necessary at some sites. Turbidity must be
within 5 NTUs of the background turbidity. Background is measured in
the receiving water, upstream from the treatment process discharge point.
pH must be within the range of 6.5 to 8.5 standard units and not cause a
change in the pH of the receiving water of more than 0.2 standard units. It
is often possible to discharge treated stormwater that has a lower turbidity
than the receiving water and that matches the pH.
Treated stormwater samples and measurements shall be taken from the
discharge pipe or another location representative of the nature of the
treated stormwater discharge. Samples used for determining compliance
with the water quality standards in the receiving water shall not be taken
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-115
from the treatment pond prior to decanting. Compliance with the water
quality standards is determined in the receiving water.
Operator Training: Each contractor who intends to use chemical
treatment shall be trained by an experienced contractor on an active site
for at least 40 hours.
Standard BMPs: Surface stabilization BMPs should be implemented on
site to prevent significant erosion. All sites shall use a truck wheel wash
to prevent tracking of sediment off site.
Sediment Removal And Disposal:
Sediment shall be removed from the storage or treatment cells as
necessary. Typically, sediment removal is required at least once
during a wet season and at the decommissioning of the cells.
Sediment remaining in the cells between batches may enhance the
settling process and reduce the required chemical dosage.
• Sediment may be incorporated into the site away from drainages.
4-116 Volume II — Construction Stormwater Pollution Prevention February 2005
BMP C251: Construction Stormwater Filtration
P111Pose Filtration removes sediment from runoff originating from disturbed areas
of the site.
Conditions of Use Traditional BMPs used to control soil erosion and sediment loss from sites
under development may not be adequate to ensure compliance with the
water quality standard for turbidity in the receiving water. Filtration may
be used in conjunction with gravity settling to remove sediment as small
as fine silt (0.5 µm). The reduction in turbidity will be dependent on the
particle size distribution of the sediment in the stormwater. In some
circumstances, sedimentation and filtration may achieve compliance with
the water quality standard for turbidity.
Design and
Installation
Specifications
Unlike chemical treatment, the use of construction stormwater filtration
does not require approval from Ecology.
Filtration may also be used in conjunction with polymer treatment in a
portable system to assure capture of the flocculated solids.
Background Information
Filtration with sand media has been used for over a century to treat water
and wastewater. The use of sand filtration for treatment of stormwater
has developed recently, generally to treat runoff from streets, parking lots,
and residential areas. The application of filtration to construction
stormwater treatment is currently under development.
Two types of filtration systems may be applied to construction stormwater
treatment: rapid and slow. Rapid sand filters are the typical system used
for water and wastewater treatment. They can achieve relatively high
hydraulic flow rates, on the order of 2 to 20 gpm/sf, because they have
automatic backwash systems to remove accumulated solids. In contrast,
slow sand filters have very low hydraulic rates, on the order of 0.02
gpm/sf, because they do not have backwash systems. To date, slow sand
filtration has generally been used to treat stormwater. Slow sand filtration
is mechanically simple in comparison to rapid sand filtration but requires a
much larger filter area.
Filtration Equipment. Sand media filters are available with automatic
backwashing features that can filter to 50 µm particle size. Screen or bag
filters can filter down to 5 µm. Fiber wound filters can remove particles
down to 0.5 µm. Filters should be sequenced from the largest to the
smallest pore opening. Sediment removal efficiency will be related to
particle size distribution in the stormwater.
Treatment Process Description. Stormwater is collected at interception
point(s) on the site and is diverted to a sediment pond or tank for removal
of large sediment and storage of the stormwater before it is treated by the
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-117
filtration system. The stormwater is pumped from the trap, pond, or tank
through the filtration system in a rapid sand filtration system. Slow sand
filtration systems are designed as flow through systems using gravity.
If large volumes of concrete are being poured, pH adjustment may be
necessary.
Maintenance Rapid sand filters typically have automatic backwash systems that are
Standards triggered by a pre-set pressure drop across the filter. If the backwash
water volume is not large or substantially more turbid than the stormwater
stored in the holding pond or tank, backwash return to the pond or tank
may be appropriate. However, land application or another means of
treatment and disposal may be necessary.
• Screen, bag, and fiber filters must be cleaned and/or replaced when
they become clogged.
• Sediment shall be removed from the storage and/or treatment ponds as
necessary. Typically, sediment removal is required once or twice
during a wet season and at the decommissioning of the ponds.
4-118 Volume 11— Construction Stormwater Pollution Prevention February 2005
Stormwater Pollution Prevention Plan
Appendix C — Alternative BMPs
The following includes a list of possible alternative BMPs for each of the 12 elements not
described in the main SWPPP text. This list can be referenced in the event a BMP for a specific
element is not functioning as designed and an alternative BMP needs to be implemented.
• Construction Stormwater Chemical Treatment (BMP C250)
33
Stormwater Pollution Prevention Plan
34
BMP C250: Construction Stormwater Chemical Treatment
Purpose Turbidity is difficult to control once fine particles are suspended in
stormwater runoff from a construction site. Sedimentation ponds are
effective at removing larger particulate matter by gravity settling, but are
ineffective at removing smaller particulates such as clay and fine silt.
Sediment ponds are typically designed to remove sediment no smaller than
medium silt (0.02 mm). Chemical treatment may be used to reduce the
turbidity of stormwater runoff.
Conditions of Use Chemical treatment can reliably provide exceptional reductions of
turbidity and associated pollutants. Very high turbidities can be reduced
to levels comparable to what is found in streams during dry weather.
Traditional BMPs used to control soil erosion and sediment loss from sites
under development may not be adequate to ensure compliance with the
water quality standard for turbidity in the receiving water. Chemical
treatment may be required to protect streams from the impact of turbid
stormwater discharges, especially when construction is to proceed through
the wet season.
Formal written approval from Ecology and the Local Permitting
Authority is required for the use of chemical treatment regardless of
site size. The intention to use Chemical Treatment shall be indicated
on the Notice of Intent for coverage under the General Construction
Permit. Chemical treatment systems should be designed as part of the
Construction SWPPP, not after the fact. Chemical treatment may be
used to correct problem sites in limited circumstances with formal
written approval from Ecology and the Local Permitting Authority.
The SEPA review authority must be notified at the application phase of
the project review (or the time that the SEPA determination on the project
is performed) that chemical treatment is proposed. If it is added after this
stage, an addendum will be necessary and may result in project approval
delay.
Design and See Appendix II-B for background information on chemical treatment.
Installation
Specifications Criteria for Chemical Treatment Product Use: Chemically treated
stormwater discharged from construction sites must be nontoxic to aquatic
organisms. The following protocol shall be used to evaluate chemicals
proposed for stormwater treatment at construction sites. Authorization to
use a chemical in the field based on this protocol does not relieve the
applicant from responsibility for meeting all discharge and receiving
water criteria applicable to a site.
Treatment chemicals must be approved by EPA for potable water use.
Petroleum -based polymers are prohibited.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-111
Prior to authorization for field use, jar tests shall be conducted to
demonstrate that turbidity reduction necessary to meet the receiving
water criteria can be achieved. Test conditions, including but not
limited to raw water quality and jar test procedures, should be
indicative of field conditions. Although these small-scale tests cannot
be expected to reproduce performance under field conditions, they are
indicative of treatment capability.
Prior to authorization for field use, the chemically treated stormwater
shall be tested for aquatic toxicity. Applicable procedures defined in
Chapter 173-205 WAC, Whole Effluent Toxicity Testing and Limits,
shall be used. Testing shall use stormwater from the construction site
at which the treatment chemical is proposed for use or a water solution
using soil from the proposed site.
• The proposed maximum dosage shall be at least a factor of five lower
than the no observed effects concentration (NOEC).
• The approval of a proposed treatment chemical shall be conditional,
subject to full-scale bioassay monitoring of treated stormwater at the
construction site where the proposed treatment chemical is to be used.
• Treatment chemicals that have already passed the above testing
protocol do not need to be reevaluated. Contact the Department of
Ecology Regional Office for a list of treatment chemicals that have
been evaluated and are currently approved for use.
Treatment System Design Considerations: The design and operation of
a chemical treatment system should take into consideration the factors that
determine optimum, cost-effective performance. It may not be possible to
fully incorporate all of the~classic concepts into the design because of
practical limitations at construction sites. Nonetheless, it is important to
recognize the following:
• The right chemical must be used at the right dosage. A dosage that is
either too low or too high will not produce the lowest turbidity. There
is an optimum dosage rate. This is a situation where the adage "adding
more is always better" is not the case.
• The coagulant must be mixed rapidly into the water to insure proper
dispersion.
• A flocculation step is important to increase the rate of settling, to
produce the lowest turbidity, and to keep the dosage rate as low as
possible.
• Too little energy input into the water during the flocculation phase
results in flocs that are too small and/or insufficiently dense. Too
much energy can rapidly destroy floc as it is formed.
4-112 Volume 11 — Construction Stormwater Pollution Prevention February 2005
• Since the volume of the basin is a determinant in the amount of energy
per unit volume, the size of the energy input system can be too small
relative to the volume of the basin.
• Care must be taken in the design of the withdrawal system to minimize
outflow velocities and to prevent floc discharge. The discharge should
be directed through a physical filter such as a vegetated swale that
would catch any unintended floc discharge.
Treatment System Design: Chemical treatment systems shall be
designed as batch treatment systems using either ponds or portable trailer -
mounted tanks. Flow -through continuous treatment systems are not
allowed at this time.
A chemical treatment system consists of the stormwater collection system
(either temporary diversion or the permanent site drainage system), a
storage pond, pumps, a chemical feed system, treatment cells, and
interconnecting piping.
The treatment system shall use a minimum of two lined treatment cells.
Multiple treatment cells allow for clarification of treated water while other
cells are being filled or emptied. Treatment cells may be ponds or tanks.
Ponds with constructed earthen embankments greater than six feet high
require special engineering analyses. Portable tanks may also be suitable
for some sites.
The following equipment should be located in an operations shed:
• the chemical injector;
• secondary containment for acid, caustic, buffering compound, and
treatment chemical;
• emergency shower and eyewash, and
• monitoring equipment which consists of a pH meter and a
turbidimeter.
Sizing Criteria: The combination of the storage pond or other holding
area and treatment capacity should be large enough to treat stormwater
during multiple day storm events. It is recommended that at a minimum
the storage pond or other holding area should be sized to hold 1.5 times
the runoff volume of the 10-year, 24-hour storm event. Bypass should be
provided around the chemical treatment system to accommodate extreme
storm events. Runoff volume shall be calculated using the methods
presented in Volume 3, Chapter 2. If no hydrologic analysis is required
for the site, the Rational Method may be used.
Primary settling should be encouraged in the storage pond. A forebay
with access for maintenance may be beneficial.
There are two opposing considerations in sizing the treatment cells. A
larger cell is able to treat a larger volume of water each time a batch is
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-113
processed. However, the larger the cell the longer the time required to
empty the cell. A larger cell may also be less effective at flocculation and
therefore require a longer settling time. The simplest approach to sizing
the treatment cell is to multiply the allowable discharge flow rate times the
desired drawdown time. A 4-hour drawdown time allows one batch per
cell per 8-hour work period, given 1 hour of flocculation followed by two
hours of settling.
The permissible discharge rate governed by potential downstream effect
can be used to calculate the recommended size of the treatment cells. The
following discharge flow rate limits shall apply:
• If the discharge is directly or indirectly to a stream, the discharge flow
rate shall not exceed 50 percent of the peak flow rate of the 2-year, 24-
hour event for all storm events up to the 10-year, 24-hour event.
• If discharge is occurring during a storm event equal to or greater than
the 10-year, 24-hour event, the allowable discharge rate is the peak
flow rate of the 10-year, 24-hour event.
• Discharge to a stream should not increase the stream flow rate by more
than 10 percent.
• If the discharge is directly to a lake, a major receiving water listed in
Appendix C of Volume I, or to an infiltration system, there is no
discharge flow limit.
• If the discharge is to a municipal storm drainage system, the allowable
discharge rate may be limited by the capacity of the public system. It
may be necessary to clean the municipal storm drainage system prior
to the start of the discharge to prevent scouring solids from the
drainage system.
• Runoff rates shall be calculated using the methods presented in
Volume 3, Chapter 2 for the predeveloped condition. If no hydrologic
analysis is required for the site, the Rational Method may be used.
Maintenance Monitoring: The following monitoring shall be conducted. Test results
Standards shall be recorded on a daily log kept on site:
Operational Monitoring
• pH, conductivity (as a surrogate for alkalinity), turbidity and
temperature of the untreated stormwater
• Total volume treated and discharged
• Discharge time and flow rate
• Type and amount of chemical used for pH adjustment
• Amount of polymer used for treatment
• Settling time
4-114 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Compliance Monitoring
• pH and turbidity of the treated stormwater
• pH and turbidity of the receiving water
Biomonitorina
Treated stormwater shall be tested for acute (lethal) toxicity. Bioassays
shall be conducted by a laboratory accredited by Ecology, unless
otherwise approved by Ecology. The performance standard for acute
toxicity is no statistically significant difference in survival between the
control and 100 percent chemically treated stormwater.
Acute toxicity tests shall be conducted with the following species and
protocols:
Fathead minnow, Pimephales promelas (96 hour static -renewal test,
method: EPA/600/4-90/027F). Rainbow trout, Oncorhynchus mykiss
(96 hour static -renewal test, method: EPA/600/4-90/027F) may be
used as a substitute for fathead minnow.
• Daphnid, Ceriodaphnia dubia, Daphnia pulex, or Daphnia magna (48
hour static test, method: EPA/600/4-90/027F).
All toxicity tests shall meet quality assurance criteria and test conditions in
the most recent versions of the EPA test method and Ecology Publication
# WQ-R-95-80, Laboratory Guidance and Whole Effluent Toxicity Test
Review Criteria.
Bioassays shall be performed on the first five batches and on every tenth
batch thereafter, or as otherwise approved by Ecology. Failure to meet the
performance standard shall be immediately reported to Ecology.
Discharge Compliance: Prior to discharge, each batch of treated
stormwater must be sampled and tested for compliance with pH and
turbidity limits. These limits may be established by the water quality
standards or a site -specific discharge permit. Sampling and testing for
other pollutants may also be necessary at some sites. Turbidity must be
within 5 NTUs of the background turbidity. Background is measured in
the receiving water, upstream from the treatment process discharge point.
pH must be within the range of 6.5 to 8.5 standard units and not cause a
change in the pH of the receiving water of more than 0.2 standard units. It
is often possible to discharge treated stormwater that has a lower turbidity
than the receiving water and that matches the pH.
Treated stormwater samples and measurements shall be taken from the
discharge pipe or another location representative of the nature of the
treated stormwater discharge. Samples used for determining compliance
with the water quality standards in the receiving water shall not be taken
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-115
from the treatment pond prior to decanting. Compliance with the water
quality standards is determined in the receiving water.
Operator Training: Each contractor who intends to use chemical
treatment shall be trained by an experienced contractor on an active site
for at least 40 hours.
Standard BMPs: Surface stabilization BMPs should be implemented on
site to prevent significant erosion. All sites shall use a truck wheel wash
to prevent tracking of sediment off site.
Sediment Removal And Disposal:
• Sediment shall be removed from the storage or treatment cells as
necessary. Typically, sediment removal is required at least once
during a wet season and at the decommissioning of the cells.
Sediment remaining in the cells between batches may enhance the
settling process and reduce the required chemical dosage.
• Sediment may be incorporated into the site away from drainages.
4-116 Volume 11 — Construction Stormwater Pollution Prevention February 2005
Appendix II-B
Background Information on Chemical Treatment
Coagulation and flocculation have been used for over a century to treat water. It is used less
frequently for the treatment of wastewater. The use of coagulation and flocculation for treating
stormwater is a very recent application. Experience with the treatment of water and wastewater
has resulted in a basic understanding of the process, in particular factors that affect performance.
This experience can provide insights as to how to most effectively design and operate similar
systems in the treatment of stormwater.
Fine particles suspended in water give it a milky appearance, measured as turbidity. Their small
size, often much less than 1 µm in diameter, give them a very large surface area relative to their
volume. These fine particles typically carry a negative surface charge. Largely because of these
two factors, small size and negative charge, these particles tend to stay in suspension for
extended periods of time. Thus, removal is not practical by gravity settling. These are called
stable suspensions. Polymers, as well as inorganic chemicals such as alum, speed the process of
clarification. The added chemical destabilizes the suspension and causes the smaller particles to
agglomerate. The process consists of three steps: coagulation, flocculation, and settling or
clarification. Each step is explained below as well as the factors that affect the efficiency of the
process.
Coagulation: Coagulation is the first step. It is the process by which negative charges on the
fine particles that prevent their agglomeration are disrupted. Chemical addition is one method of
destabilizing the suspension, and polymers are one class of chemicals that are generally
effective. Chemicals that are used for this purpose are called coagulants. Coagulation is
complete when the suspension is destabilized by the neutralization of the negative charges.
Coagulants perform best when they are thoroughly and evenly dispersed under relatively intense
mixing. This rapid mixing involves adding the coagulant in a manner that promotes rapid
dispersion, followed by a short time period for destabilization of the particle suspension. The
particles are still very small and are not readily separated by clarification until flocculation
occurs.
Flocculation: Flocculation is the process by which fine particles that have been destabilized bind
together to form larger particles that settle rapidly. Flocculation begins naturally following
coagulation, but is enhanced by gentle mixing of the destabilized suspension. Gentle mixing
helps to bring particles in contact with one another such that they bind and continually grow to
form "flocs." As the size of the flocs increases they become heavier and tend to settle more
rapidly.
Clarification: The final step is the settling of the particles. Particle density, size and shape are
important during settling. Dense, compact flocs settle more readily than less dense, fluffy flocs.
Because of this, flocculation to form dense, compact flocs is particularly important during water
treatment. Water temperature is important during settling. Both the density and viscosity of
water are affected by temperature; these in turn affect settling. Cold temperatures increase
viscosity and density, thus slowing down the rate at which the particles settle.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 8-1
The conditions under which clarification is achieved can affect performance. Currents can affect
settling. Currents can be produced by wind, by differences between the temperature of the
incoming water and the water in the clarifier, and by flow conditions near the inlets and outlets.
Quiescent water such as that which occurs during batch clarification provides a good
environment for effective performance as many of these factors become less important in
comparison to typical sedimentation basins. One source of currents that is likely important in
batch systems is movement of the water leaving the clarifier unit. Given that flocs are relatively
small and light the exit velocity of the water must be as low as possible. Sediment on the bottom
of the basin can be resuspended and removed by fairly modest velocities.
Coagulants: Polymers are large organic molecules that are made up of subunits linked together
in a chain -like structure. Attached to these chain -like structures are other groups that carry
positive or negative charges, or have no charge. Polymers that carry groups with positive
charges are called cationic, those with negative charges are called anionic, and those with no
charge (neutral) are called nonionic.
Cationic polymers can be used as coagulants to destabilize negatively charged turbidity particles
present in natural waters, wastewater and stormwater. Aluminum sulfate (alum) can also be used
as this chemical becomes positively charged when dispersed in water. In practice, the only way
to determine whether a polymer is effective for a specific application is to perform preliminary
or on -site testing.
Polymers are available as powders, concentrated liquids, and emulsions (which appear as milky
liquids). The latter are petroleum based, which are not allowed for construction stormwater
treatment. Polymer effectiveness can degrade with time and also from other influences. Thus,
manufacturers' recommendations for storage should be followed. Manufacturer's
recommendations usually do not provide assurance of water quality protection or safety to
aquatic organisms. Consideration of water quality protection is necessary in the selection and
use of all polymers.
Application Considerations: Application of coagulants at the appropriate concentration or
dosage rate for optimum turbidity removal is important for management of chemical cost, for
effective performance, and to avoid aquatic toxicity. The optimum dose in a given application
depends on several site -specific features. Turbidity of untreated water can be important with
turbidities greater than 5,000 NTU. The surface charge of particles to be removed is also
important. Environmental factors that can influence dosage rate are water temperature, pH, and
the presence of constituents that consume or otherwise affect polymer effectiveness. Laboratory
experiments indicate that mixing previously settled sediment (floc sludge) with the untreated
stormwater significantly improves clarification, therefore reducing the effective dosage rate.
Preparation of working solutions and thorough dispersal of polymers in water to be treated is
also important to establish the appropriate dosage rate.
For a given water sample, there is generally an optimum dosage rate that yields the lowest
residual turbidity after settling. When dosage rates below this optimum value (underdosing) are
applied, there is an insufficient quantity of coagulant to react with, and therefore destabilize, all
of the turbidity present. The result is residual turbidity (after flocculation and settling) that is
higher than with the optimum dose. Overdosing, application of dosage rates greater than the
8-2 Volume 11 — Construction Stormwater Pollution Prevention February 2005
optimum value, can also negatively impact performance. Again, the result is higher residual
turbidity than that with the optimum dose.
Mixinp, in Coagulation/Flocculation: The G-value, or just "G", is often used as a measure of the
mixing intensity applied during coagulation and flocculation. The symbol G stands for "velocity
gradient", which is related in part to the degree of turbulence generated during mixing. High G-
values mean high turbulence, and vice versa. High G-values provide the best conditions for
coagulant addition. With high G's, turbulence is high and coagulants are rapidly dispersed to
their appropriate concentrations for effective destabilization of particle suspensions.
Low G-values provide the best conditions for flocculation. Here, the goal is to promote
formation of dense, compact flocs that will settle readily. Low G's provide low turbulence to
promote particle collisions so that flocs can form. Low G's generate sufficient turbulence such
that collisions are effective in floc formation, but do not break up flocs that have already formed.
Design engineers wishing to review more detailed presentations on this subject are referred to the
following textbooks.
• Fair, G., J. Geyer and D. Okun, Water and Wastewater Engineering, Wiley and Sons, NY,
1968.
• American Water Works Association, Water Quality and Treatment, McGraw-Hill, NY, 1990.
• Weber, W.J., Physiochemical Processes for Water Quality Control, Wiley and Sons, NY,
1972.
Polymer Batch Treatment Process Description: Stormwater is collected at interception point(s)
on the site and is diverted by gravity or by pumping to a storage pond or other holding area. The
stormwater is stored until treatment occurs. It is important that the holding pond be large enough
to provide adequate storage.
The first step in the treatment sequence is to check the pH of the stormwater in the storage pond.
The pH is adjusted by the application of acid or base until the stormwater in the storage pond is
within the desired pH range. When used, acid is added immediately downstream of the transfer
pump. Typically sodium bicarbonate (baking soda) is used as a base, although other bases may
be used. When needed, base is added directly to the storage pond. The stormwater is
recirculated with the treatment pump to provide mixing in the storage pond. Initial pH
adjustments should be based on daily bench tests. Further pH adjustments can be made at any
point in the process.
Once the stormwater is within the desired pH range, the stormwater is pumped from the storage
pond to a treatment cell as polymer is added. The polymer is added upstream of the pump to
facilitate rapid mixing.
After polymer addition, the water is kept in a lined treatment cell for clarification of the
sediment -floc. In a batch mode process, clarification typically takes from 30 minutes to several
hours. Prior to discharge samples are withdrawn for analysis of pH and turbidity. If both are
acceptable, the treated water is discharged.
February 2005 Volume 11— Construction Stormwater Pollution Prevention 8-3
Several configurations have been developed to withdraw treated water from the treatment cell.
The original configuration is a device that withdraws the treated water from just beneath the
water surface using a float with adjustable struts that prevent the float from settling on the cell
bottom. This reduces the possibility of picking up sediment -floc from the bottom of the pond.
The struts are usually set at a minimum clearance of about 12 inches; that is, the float will come
within 12 inches of the bottom of the cell. Other systems have used vertical guides or cables
which constrain the float, allowing it to drift up and down with the water level. More recent
designs have an H-shaped array of pipes, set on the horizontal.
This scheme provides for withdrawal from four points rather than one. This configuration
reduces the likelihood of sucking settled solids from the bottom. It also reduces the tendency for
a vortex to form. Inlet diffusers, a long floating or fixed pipe with many small holes in it, are also
an option.
Safety is a primary concern. Design should consider the hazards associated with operations,
such as sampling. Facilities should be designed to reduce slip hazards and drowning. Tanks and
ponds should have life rings, ladders, or steps extending from the bottom to the top.
Adjustment of the pH and AlkalinitT. The pH must be in the proper range for the polymers to be
effective, which is 6.5 to 8.5 for Calgon CatFloc 2953, the most commonly used polymer. As
polymers tend to lower the pH, it is important that the stormwater have sufficient buffering
capacity. Buffering capacity is a function of alkalinity. Without sufficient alkalinity, the
application of the polymer may lower the pH to below 6.5. A pH below 6.5 not only reduces the
effectiveness of the polymer, it may create a toxic condition for aquatic organisms. Stormwater
may not be discharged without readjustment of the pH to above 6.5. The target pH should be
within 0.2 standard units of the receiving water pH.
Experience gained at several projects in the City of Redmond has shown that the alkalinity needs
to be at least 50 mg/L to prevent a drop in pH to below 6.5 when the polymer is added. Baking
soda has been used to raise both the alkalinity and the pH. Although lime is less expensive than
baking soda, if overdosed lime can raise the pH above 8.5 requiring downward adjustment for
the polymer to be effective. Baking soda has the advantage of not raising the pH above 8.3
regardless of the amount that is added. Experience indicates that the amount of baking soda
sufficient to raise the alkalinity to above 50 mg/L produces a pH near neutral or 7.
Alkalinity cannot be easily measured in the field. Therefore, conductivity, which can be
measured directly with a hand-held probe, has been used to ascertain the buffering condition. It
has been found through local experience that when the conductivity is above about 100 µS/cm
the alkalinity is above 50 mg/L. This relationship may not be constant and therefore care must
be taken to define the relationship for each site.
Experience has shown that the placement of concrete has a significant effect on the pH of
construction stormwater. If the area of fresh exposed concrete surface is significant, the pH of
the untreated stormwater may be considerably above 8.5. Concrete equipment washwater shall
be controlled to prevent contact with stormwater. Acid may be added to lower the pH to the
background level pH of the receiving water. The amount of acid needed to adjust the pH to the
desired level is not constant but depends upon the polymer dosage, and the pH, turbidity, and
B-4 Volume 11— Construction Stormwater Pollution Prevention February 2005
alkalinity of the untreated stormwater. The acid commonly used is sulfuric although muriatic
and ascorbic acids have been used. Pelletized dry ice has also been used and reduces the safety
concerns associated with handling acid.
February 2005 Volume 11 — Construction Stormwater Pollution Prevention 8-5
Stormwater Pollution Prevention Plan
Appendix D — General Permit
35
Stormwater Pollution Prevention Plan
36
STONEGATE LIFT STATION
WAR011834 King Co
Issuance Date: November 16, 2005
Effective Date: December 16, 2005
Expiration Date: December 16, 2010
CONSTRUCTION STORMWATER GENERAL PERMIT
National Pollutant Discharge Elimination System (NPDES) and State Waste
Discharge General Permit for Stormwater Discharges Associated With
Construction Activity
State of Washington
Department of Ecology
Olympia, Washington 98504-7600
In compliance with the provisions of
The State of Washington Water Pollution Control Law
Chapter 90.48 Revised Code of Washington
and
The Federal Water Pollution Control Act
(The Clean Water Act)
Title 33 United States Code, Section 1251 et seq.
Until this permit expires, is modified or revoked, Permittees that have properly obtained
coverage under this general permit are authorized to discharge in accordance with the special and
general conditions which follow.
David C. Peeler
Water Quality Program
Washington State Department of Ecology
Page 2 of 46
TABLE OF CONTENTS
SUMMARY OF PERMIT REPORT SUBMITTALS.....................................................................3
SUMMARY OF REQUIRED ON SITE DOCUMENTATION.....................................................3
SPECIAL CONDITIONS
S1. PERMIT COVERAGE.....................................:..................................................................4
S3. COMPLIANCE WITH STANDARDS........:......................................................................9
S4. MONITORING REQUIREMENTS..................................................................................10
S5. REPORTING AND RECORDKEEPING REQUIREMENTS.........................................15
S6. PERMIT FEES...................................................................................................................18
ST SOLID AND LIQUID WASTE DISPOSAL ........................... ....18
.....................................
S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES................................................18
S9. STORMWATER POLLUTION PREVENTION PLAN...................................................21
S 10. NOTICE OF TERMINATION..........................................................................................29
GENERALCONDITIONS...........................................................................................................30
G1.
DISCHARGE VIOLATIONS...........................................................................................30
G2.
SIGNATORY REQUIREMENTS.....................................................................................30
G3.
RIGHT OF INSPECTION AND ENTRY.........................................................................31
G4.
GENERAL PERMIT MODIFICATION AND REVOCATION
......................................31
G5.
REVOCATION OF COVERAGE UNDER THE PERMIT.............................................31
G6.
REPORTING A CAUSE FOR MODIFICATION............................................................32
G7.
COMPLIANCE WITH OTHER LAWS AND STATUTES.............................................32
G8.
DUTY TO REAPPLY.......................................................................................................32
G9.
TRANSFER OF GENERAL PERMIT COVERAGE.......................................................32
G10.
REMOVED SUBSTANCES.............................................................................................33
Gl 1.
DUTY TO PROVIDE INFORMATION...........................................................................33
G12.
OTHER REQUIREMENTS OF 40 CFR...........................................................................33
G13.
ADDITIONAL MONITORING........................................................................................33
G14.
PENALTIES FOR VIOLATING PERMIT CONDITIONS.............................................33
G15.
UPSET...............................................................................................................................34
G16.
PROPERTY RIGHTS........................................................................................................34
G17.
DUTY TO COMPLY........................................................................................................34
G18.
TOXIC POLLUTANTS.....................................................................................................34
G19.
PENALTIES FOR TAMPERING.....................................................................................35
G20.
REPORTING PLANNED CHANGES..............................................................................35
G21.
REPORTING OTHER INFORMATION..........................................................................35
Page 3 of 46
G22. REPORTING ANTICIPATED NON-COMPLIANCE.....................................................35
G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT .......... 36
G24. APPEALS.....................................................................:....................................................36
G25. SEVERABILITY...............................................................................................................36
G26. BYPASS PROHIBITED....................................................................................................36
APPENDIX A — DEFINITIONS...................................................................................................39
APPENDIX B — ACRONYMS.....................................................................................................46
SUMMARY OF PERMIT REPORT SUBMITTALS
Refer to the Special and General Conditions for additional submittal requirements.
Permit Submittal Frequency First Submittal Date
Section
S5.A High Turbidity/Transparency Phone As Necessary Within 24 hours
Reporting
S5.B Discharge Monitoring Report Monthly Within 15 days after the
applicable monitoring
period
S51 Noncompliance Notification As necessary Immediately
S51
Noncompliance Notification — Written
As necessary
Within 5 Days of non -
Report
compliance
G2.
Notice of Change in Authorization
As necessary
G6.
Permit Application for Substantive
As necessary
Changes to the Discharge
G8.
Application for Permit Renewal
1/permit cycle
No later than 180 days
before expiration
G9.
Notice of Permit Transfer
As necessary
G20.
Notice of Planned Changes
As necessary
G22.
Reporting Anticipated Non-compliance
As necessary
SUMMARY OF REQUIRED ON
SITE DOCUMENTATION
Permit Conditions
Document Title
Conditions S2, S5
Permit Coverage Letter
Conditions S2, S5
Construction Stormwater General Permit
Conditions S4, S5
Site Log Book
Conditions S9, S5
Stormwater Pollution Prevention Plan SWPPP
Page 4 of 46
SPECIAL CONDITIONS
S1. PERMIT COVERAGE
A. Permit Area
This general permit covers all areas of Washington State, except for federal and tribal
lands specified in S 1.D.3.
B. OQperators Required to Seek Coverage Under this General Permit:
1. Operators of the following construction activities are required to seek coverage under
this permit:
a. Clearing, grading and/or excavation which results in the disturbance of one or
more acres, and discharges stormwater to surface waters of the state; and clearing,
grading and/or excavation on sites smaller than one acre which are part of a larger
common plan of development or sale, if the common plan of development or sale
will ultimately disturb one acre or more, and discharges stormwater to surface
waters of the state.
i. This includes forest practices that are part of a construction activity that will
result in the disturbance of one or more acres, and discharges to surface waters
of the state (i.e., forest practices which are preparing a site for construction
activities); and
b. Any size construction activity discharging stormwater to waters of the state which
the Department of Ecology (Ecology): .
i. Determines to be a significant contributor ofpollutants to waters of the state of
Washington, or
ii. Reasonably expects to cause a violation of any water quality standard.
2. Operators of the following activities are not required to seek coverage under this
permit, unless specifically required under Condition S 1.13. Lb. (Significant
Contributor):
a. Construction activities which discharge all stormwater and non-stormwater to
ground water, and have no point source discharge to surface water or a storm
sewer system that drains to surface waters of the state;
b. Construction activities covered under an Erosivity Waiver (Condition S2.C);
c. Routine maintenance that is performed to maintain the original line and grade,
hydraulic capacity, or original purpose of a facility.
Page 5 of 46
C. Authorized Discharges:
1. Stormwater Associated with Construction Activity. Subject to compliance with the
terms and conditions of this permit, Permittees are authorized to discharge
stormwater associated with construction activity to surface waters of the state or to a
storm sewer system that drains to surface waters of the state.
2. Stormwater Associated with Construction Support Activity. This permit also
authorizes stormwater discharges from support activities related to the permitted
construction site (e.g., off -site equipment staging yards, material storage areas,
borrow areas, etc.) provided:
a. The support activity is directly related to the permitted construction site that is
required to have an NPDES permit; and
b. The support activity is not a commercial operation serving multiple unrelated
construction projects, and does not operate beyond the completion of the
construction activity; and
c. Appropriate controls and measures are identified in the Stormwater Pollution
Prevention Plan (SWPPP)for the discharges from the support activity areas.
3. Non-Stormwater Discharges. Tile categories and sources of non-stormwater
discharges identified below are conditionally authorized, provided the discharge is
consistent with the terms and conditions of this permit:
a. Discharges from fire fighting activities;
b. Fire hydrant system flushing;
c. Potable water including uncontaminated water line flushing (de -chlorinated);
d. Pipeline hydrostatic test water;
e. Uncontaminated air conditioning or compressor condensate;
f. Uncontaminated ground water or spring water;
g. Uncontaminated excavation de -watering (in accordance with S9.D.10)
h. Uncontaminated discharges from foundation or footing drains;
i. Water used to control dust;
j. Routine external building wash down that does not use detergents; and
k. Landscape irrigation.
Page 6 of 46
All authorized non-stormwater discharges, except for discharges from fire fighting
activities, shall be adequately addressed in the SWPPP and comply with Special
Condition S3.
D. Limitations on Coveraize
The Director may require any discharger to apply for and obtain coverage under an
individual permit or another more specific general permit. Such alternative coverage
will be required when Ecology determines that this general permit does not provide
adequate assurance that water quality will be protected; or there is a reasonable potential
for the project to cause or contribute to a violation of water quality standards.
The following stormwater discharges are not covered by this permit:
1. Post -construction stormwater discharges that originate from the site after construction
activities have been completed and the site has undergone final stabilization.
2. Nonpoint source silvicultural activities such as nursery operations, site preparation,
reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and
fire control, harvesting operations, surface drainage, or road construction and
maintenance from which there is natural runoff as excluded in 40 CFR Subpart
122.27.
3. Stormwater from any federal project or project on federal land or land within an
Indian Reservation except for the Puyallup Reservation. Within the Puyallup
Reservation, any project that discharges to surface water on land held in trust by the
federal government may be covered by this permit.
4. Stormwater from any site covered under an existing NPDES individual permit in
which stormwater management and/or treatment requirements are included for all
stormwater discharges associated with construction activity.
5. Where an applicable Total Maximum Daily Load (TMDL) specifically precludes or
prohibits discharges from construction activity, the operator is not eligible for
coverage under this permit.
S2. APPLICATION REQUIREMENTS
A. Permit Application Forms
1. Notice of Intent Form/Timeline
a. Operators of new or previously unpermitted construction activities shall submit a
complete and accurate permit application form [Notice of Intent (NOI)] to
Ecology. Applicants are encouraged to use Ecology's internet-based electronic
NOI to apply for permit coverage.
b. The NOI shall be submitted on or before the date of the first public notice (see
Condition S2.B below) and at least 60 days prior to the discharge of stormwater
Page 7 of 46
from construction activities. The 30-day public comment period required by WAC
173-226-130(5) begins on the publication date of the second public notice. Unless
Ecology responds to the complete application in writing, based on public
comments, or any other relevant factors, coverage under the general permit will
automatically commence on the thirty-first day following receipt by Ecology of a
completed NOI, or the issuance date of this permit, whichever is later; unless a
later date is specified by Ecology in writing.
c. Applicants that discharge to a storm sewer system operated by Seattle, King
County, Snohomish County, Tacoma, Pierce County, or Clark County shall also
submit a copy of the NOI to the appropriate jurisdiction.
2. Transfer of Coverage Form
Current coverage under this permit may be transferred to one or more new operators,
including operators of sites within a Common Plan of Development, by submitting
a Transfer of Coverage Form in accordance with Condition G9. Transfers do not
require public notice.
B. Public Notice
For new or previously unpermitted sites, the applicant shall publish a public notice at
least one time each week for two consecutive weeks, with a 7-day time span between
dates, in a newspaper that has general circulation in the county m which the construction
is to take place. The notice shall contain the following:
1. A statement that "The applicant is seeking coverage under the Washington State
Department of Ecology's Construction Stormwater NPDES and State Waste Discharge
General Permit";
2. The name, address and location of the construction site;
3. The name and address of the applicant;
4. The type of construction activity that will result in a discharge, (e.g., residential
construction, commercial construction, etc.) and the number of acres to be disturbed;
5. The name of the receiving water(s) (i.e., the surface water(s) that the site will discharge
to), or if the discharge is through a storm sewer system, the name of the operator of the
storm sewer; and
6. The statement: "Any person desiring to present their views to the Department of
Ecology regarding this application, or interested in the Department's action on this
application may notify the Department of Ecology in writing within 30 days of the last
date of publication of this notice. Comments can be submitted to: Department of
Ecology, P.O. Box 47696, Olympia, WA 98504-7696, Attn: Water Quality Program,
Construction Stormwater".
Page 8 of 46
C. Erosivity Waiver
Operators may qualify for a waiver from the permit if the following conditions are met:
The site will result in the disturbance of less than 5 acres; and the site is not a portion
of a common plan of development or sale that will disturb 5 acres or greater.
2. Calculation of Erosivity "R" Factor and Regional Timeframe:
a. The project's rainfall erosivity factor ("R" Factor) must be less than 5 during the
period of construction activity, as calculated using the Texas A&M University
online rainfall erosivity calculator at: htty://ei.tamu.edu/. The period of
construction activity begins at initial earth disturbance and ends with final
stabilization; and, in addition:
b. The entire period of construction activity must fall within the following
timeframes:
i. For sites west of the Cascades Crest: June 15 — September 15; or
ii. For sites east of the Cascades Crest, excluding the Central Basin: June 15 —
October 15; or
iii. For sites east of the Cascades Crest, within the Central Basin*: no additional
timeframe restrictions apply.
*Note: The Central Basin is defined as the portions of Eastern Washington
with mean annual precipitation of less than 12 inches.
3. Operators must submit a complete Erosivity Waiver Certification Form at least one
week prior to commencing land disturbing activities. Certification must include:
a. A statement that the operator will comply with applicable local stormwater
requirements; and
b. A statement that the operator will implement appropriate erosion and sediment
control BAVs to prevent violations of water quality standards.
4. This waiver is not available for facilities declared a significant contributor of
pollutants as defined in Condition S I.B. Lb.
5. This waiver does not apply to construction activity which includes non-stormwater
discharges listed in S1.C.3.
6. If construction activity extends beyond the certified waiver period for any reason, the
operator shall either:
Page 9 of 46
a. Recalculate the rainfall erosivity "R" factor using the original start date and a new
projected ending date and, if the "R" factor is still under 5 and the entire project
falls within the applicable regional timeframe in S2.C.2.b, complete and submit
an amended waiver certification form before the original waiver expires; or
b. Submit a complete permit application to Ecology in accordance with Condition
S2.A and B before the end of the certified waiver period.
S3. COMPLIANCE WITH STANDARDS
A. Discharges shall not cause or contribute to a violation of surface water quality standards
(Chapter 173-201A WAC), ground water quality standards (Chapter 173-200 WAC),
sediment management standards (Chapter 173-204 WAC), and human health -based
criteria in the National Toxics Rule (40 CFR Part 131.36). Discharges that are not in
compliance with these standards are not authorized.
B. Prior to the discharge of stormwater and non-stormwater to waters of the state, the
Permittee shall apply all known, available, and reasonable methods of prevention,
control, and treatment (AKAR7). This includes the preparation and implementation of an
adequate Stormwater Pollution Prevention Plan (SWPPP), with all appropriate best
management practices (BMPs) installed and maintained in accordance with the SWPPP
and the terms and conditions of this permit.
C. Compliance with water quality standards shall be presumed, unless discharge monitoring
data or other site specific information demonstrates that a discharge causes or contributes
to a violation of water quality standards, when the Permittee is:
1. In full compliance with all permit conditions, including planning, sampling,
monitoring, reporting, and recordkeeping conditions; and
2. Fully implementing stormwater BMPs contained in stormwater management manuals
published or approved by Ecology, or BMPs that are demonstrably equivalent to
BMPs contained in stormwater technical manuals published or approved by Ecology,
including the proper selection, implementation, and maintenance of all applicable and
appropriate BMPs for on -site pollution control. -
D. For sites that discharge to both surface water and ground water, all ground water
discharges are also subject to the terms and conditions of this permit. Permittees who
discharge to ground water through an injection well shall comply with any applicable
- requirements of the Underground Injection Control (UIC) regulations, Chapter 173-218
WAC.
Page 10 of 46
S4. MONITORING REQUIREMENTS
The primary monitoring requirements are summarized in Table 3 (below):
Table 3. Summary of Monitoring Requirements'
Size of Soil Disturbance
Weekly
Weekly
Weekly
Weekly
Site
Sampling w/
Sampling w/
pH
Inspections
Turbidity Meter
Transparency
sampling3
Tube
Sites which disturb less than 1
Required
Not Required
Not Required
Not
acre
Required
Sites which disturb 1 acre or
Required
Sampling Required — either
Required
more, but less than 5 acres
method
Sites which disturb 5 acres or
Required
Required
Not Required5
Required
more
A. Site Log Book
The Permittee shall maintain a site log book that contains a record of the
implementation of the SWPPP and other permit requirements including the installation
and maintenance of BMPs, site inspections, and stormwater monitoring.
B. Site Inspections
1. Site inspections shall include all areas disturbed by construction activities, all BMPs,
and all stormwater discharge points. Stormwater shall be visually examined for the
' Additional monitoring requirements may apply for: 1) discharges to 303(d) listed waterbodies and waterbodies
with applicable TMDLs for turbidity, fine sediment, high pH, or phosphorus - see Condition S8; and 2) sites
required to perform additional monitoring by Ecology order — see Condition G13.
2 Soil disturbance is calculated by adding together all areas affected by construction activity. Construction Activity
means clearing, grading, excavation, and any other activity which disturbs the surface of the land, including
ingress/egress from the site.
3 Beginning October 1, 2006, if construction activity involves significant concrete work or the use of engineered
soils, and stormwater from the affected area drains to a stormwater collection system or other surface water, the
Permittee shall conduct pH sampling in accordance with Condition S4.D.
4 Beginning October 1, 2008, sites with one or more acres, but less than 5 acres of soil disturbance, shall conduct
turbidity or transparency sampling in accordance with Condition S4.C.
5 Beginning October 1, 2006, sites greater than or equal to 5 acres of soil disturbance shall conduct turbidity
sampling using a turbidity meter in accordance with Condition S4.C.
Page 11 of 46
presence of suspended sediment, turbidity, discoloration, and oil sheen. Inspectors
shall evaluate the effectiveness of BMPs and determine if it is necessary to install,
maintain, or repair BMPs to improve the quality of stormwater discharges.
Based on the results of the inspection, the Permittee shall correct the problems
identified as follows:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the inspection; and
b. Fully implement and maintain appropriate source control and/or treatment BAfPs
as soon as possible, but no later than 10 days of the inspection; and
c. Document BMP implementation and maintenance in the site log book.
2. The site inspections shall be conducted at least once every calendar week and within
24 hours of any discharge from the site. The inspection frequency for temporarily
stabilized, inactive sites may be reduced to once every calendar month.
3. Site inspections shall be conducted by a person who is knowledgeable in the
principles and practices of erosion and sediment control. The inspector shall have the
skills to:
a. Assess the site conditions and construction activities that could impact the quality
of stormwater, and
b. Assess the effectiveness of erosion and sediment control measures used to control
the quality of stormwater discharges.
4. Beginning October 1, 2006, construction sites one acre or larger that discharge
stormwater to surface waters of the state, shall have site inspections conducted by a
Certified Erosion and Sediment Control Lead (CESCL). The CESCL shall be
identified in the SWPPP and shall be present on -site or on -call at all times.
Certification shall be obtained through an approved erosion and sediment control
training program that meets the minimum training standards established by Ecology
(see BMP C160 in the Manual).
5. The inspector shall summarize the results of each inspection in an inspection report or
checklist and be entered into, or attached to, the site log book. At a minimum, each
inspection report or checklist shall include:
a. Inspection date and time.
b. Weather information; general conditions during inspection and approximate
amount of precipitation since the last inspection, and within the last 24 hours.
c. A summary or list of all BMPs which have been implemented, including
observations of all erosion/sediment control structures or practices.
d. The following shall be noted:
i. locations of BMPs inspected,
Page 12 of 46
ii. locations of BMPs that need maintenance,
iii. the reason maintenance is needed,
iv. locations of BMPs that failed to operate as designed or intended, and
v. locations where additional or different BMPs are needed, and the reason(s) why.
e. A description of stormwater discharged from the site. The inspector shall note the
presence of suspended sediment, turbid water, discoloration, and/or oil sheen, as
applicable.
f. Any water quality monitoring performed during inspection.
g. General comments and notes, including a brief description of any BMP repairs,
maintenance or installations made as a result of the inspection.
h. A statement that, in the judgment of the person conducting the site inspection, the
site is either in compliance or out of compliance with the terms and conditions of
the SWPPP and the permit. If the site inspection indicates that the site is out of
compliance, the inspection report shall include a summary of the remedial actions
required to bring the site back into compliance, as well as a schedule of
implementation.
i. Name, title, and signature of the person conducting site inspection; and the
following statement: "I certify that this report is true, accurate, and complete, to
the best of my knowledge and belief'.
C. Turbidity/Transparency Sampling Requirements
1. Sampling Methods/Effective Dates
a. Beginning October 1, 2006, if construction activity will involve the disturbance
of 5 acres or more, the Permittee shall conduct turbidity sampling per Condition
S4.C.
b. Beginning October 1, 2008, if construction activity will involve greater than or
equal to 1 acre, but less than 5 acres of soil disturbance, the Permittee shall
conduct transparency sampling or turbidity sampling per Condition S4.C.
2. Sampling Frequency
a. Sampling shall be conducted at least once every calendar week, when there is a
discharge of stormwater (or authorized non-stormwater) from the site. Samples
shall be representative of the flow and characteristics of the discharge.
b. When there is no discharge during a calendar week, sampling is not required.
c. Sampling is not required outside of normal working hours or during unsafe
conditions. If a Permittee is unable to sample during a monitoring period, the
Discharge Monitoring Report (DMR) shall include a brief explanation.
Page 13 of 46
Sampling Locations
a. Sampling is required at all discharge points where stormwater (or authorized non-
stormwater) is discharged off -site.
b. All sampling point(s) shall be identified on the SWPPP site map and be clearly
. marked in the field with a flag, tape, stake or other visible marker.
4. Sampling and Analysis Methods
a. Turbidity analysis shall be performed with a calibrated turbidity meter
(turbidimeter), either on -site or at an accredited lab. The results shall be recorded
in the site log book in Nephelometric Turbidity Units (NTU).
b. Transparency analysis shall be performed on -site with a 1 3/4 inch diameter, 60
centimeter (cm) long Transparency Tube. The results shall be recorded in the site
log book in centimeters (cm). Transparency Tubes are available from:
http://watennonitoringeguip.com/i)alzes/stream.html
Parameter
Units
Analytical
Method
Sampling
Frequency
Benchmark
Value
Turbidity
NTU
SM2130 or
Weekly, if
25 NTU
EPA180.1
discharging
Transparency
cm
Manufacturer
Weekly, if
31 cm
instructions, or
discharging
Ecology
Guidance
5. Turbidity/Transparency Benchmark Values
The benchmark value for turbidity is 25 NTU (Nephelometric Turbidity Units); and
the benchmark value for transparency is 31 cm.
a. Turbidity 26 — 249 NTU or Transparency 30 — 7 cm:
If discharge turbidity is greater than 25 NTU, but less than 250 NTU; or if
discharge transparency is less than 31 cm, but greater than 6 cm, the CESCL
shall:
i. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the benchmark; and
ii. Fully implement and maintain appropriate source control and/or treatment
BMPs as soon as possible, but within 10 days of the discharge that
exceeded the benchmark; and
iii. Document BMP implementation and maintenance in the site log book.
b. Turbidity 250 NTU or gueater, or Transparency 6 cm or less:
Page 14 of 46
If discharge turbidity is greater than or equal to 250 NTU; or if discharge
transparency is less than or equal to 6 cm, the CESCL shall:
i. Notify Ecology by phone in accordance with Condition S5.A.; and
ii. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the benchmark; and
iii. Fully implement and maintain appropriate source control and/or treatment
BMPs as soon as possible, but within 10 days of the discharge that
exceeded the benchmark;
iv. Document BUT implementation and maintenance in the site log book; and
v. Continue to sample discharges daily until:
1. turbidity is 25 NTU (or lower); or
2. transparency is 31 cm (or greater); or
3. the CESCL has demonstrated compliance with the water quality
standard for turbidity:
a. no more than 5 NTU over background turbidity, if background is
less than 50 NTU, or
b. no more than 10% over background turbidity, if background is 50
NTU or greater; or
4. the discharge stops or is eliminated.
D. pH Monitoring: Sites with Significant Concrete Work or Engineered Soils
Beginning October 1, 2006, if construction activity will result in the disturbance of 1
acre or more, and involves significant concrete work or the use of engineered soils, and
stormwater from the affected area drains to surface waters of the state or to a storm
sewer system that drains to surface waters of the state, the Permittee shall conduct pH
monitoring as set forth below:
1. For sites with significant concrete work, the pH monitoring period shall commence
when the concrete is first exposed to precipitation and continue weekly until
stormwater pH is 8.5 or less.
a. "Significant concrete work" means greater than 1000 cubic yards poured concrete
or recycled concrete.
2. For sites with engineered soils, the pH monitoring period shall commence when the
soil amendments are first exposed to precipitation and shall continue until the area of
engineered soils is fully stabilized.
Page 15 of 46
a. "Engineered soils" means soil amendments including, but not limited, to Portland
cement treated base (CTB), cement kiln dust (CKD), or fly ash.
3. During the pH monitoring period, the Permittee shall obtain a representative sample
of stormwater and conduct pH analysis at least once per week.
4. The Permittee shall monitor pH in the sediment trap/pond(s) or other locations that
receive stormwater runoff from the area of significant concrete work or engineered
soils prior to discharge to surface waters.
5. The benchmark value for pH is 8.5 standard units. Any time sampling indicates that
pH is 8.5 or greater, the Permittee shall:
a. Prevent the high pH water (8.5 or above) from entering storm sewer systems or
surface waters; and
b. If necessary, adjust or neutralize the high pH water using an appropriate treatment
BMP such as CO2 sparging or dry ice. The Permittee shall obtain written
approval from Ecology prior to using any form of chemical treatment other than
CO2 sparging or dry ice.
6. The Permittee shall perform pH analysis on -site with a calibrated pH meter, pH test
kit, or wide range pH indicator paper. The Permittee shall record pH monitoring
results in the site log book.
S5. REPORTING AND RECORDKEEPING REQUIREMENTS
A. High Turbidity Phone Reporting
Any time sampling performed in accordance with Special Condition S4.0 indicates
turbidity is 250 NTU or greater (or transparency is 6 cm or less) the Permittee shall notify
the appropriate Ecology regional office by phone within 24 hours of analysis.
B. Discharge Monitoring Reports
1. Permittees required to conduct water quality sampling in accordance with Special
Conditions SAC (Turbidity/Transparency), S4.D (pH) and/or S8 [303(d)/TMDL
sampling] shall submit the results to Ecology monthly on Discharge Monitoring
Report (DMR) forms provided by Ecology.
Permittees are authorized and encouraged to submit electronic DMRs using the "E-
DMR Form" on Ecology's Construction Stormwater web site:
http://www.ecy.wa.gov/programs/wq/stonnwater/construction/.
2. The Permittee shall submit DMR forms electronically or by mail to be received by
Ecology within 15 days following the end of each month. If there was no discharge
during a given monitoring period, the Permittee shall submit the form as required
with the words "no discharge" entered in place of the monitoring results. If the
Permittee is unable to submit discharge monitoring reports electronically, the
Permittee may mail reports to the address listed below:
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Department of Ecology
Water Quality Program - Construction Stormwater
PO Box 47696
Olympia, Washington 98504-7696
C. Records Retention
The Permittee shall retain records of all monitoring information (site log book, sampling
results, inspection reports/checklists, etc.), Stormwater Pollution Prevention Plan, and
any other documentation of compliance with permit requirements during the life of the
construction project and for a minimum of three years following the termination of
permit coverage. Such information shall include all calibration and maintenance records,
and records of all data used to complete the application for this permit. This period of
retention shall be extended during the course of any unresolved litigation regarding the
discharge of pollutants by the Permittee or when requested by Ecology.
D. Recording of Results
For each measurement or sample taken, the Permittee shall record the following
information:
1. Date, place, method, and time of sampling or measurement;
2. The individual who performed the sampling or measurement;
3. The dates the analyses were performed;
4. The individual who performed the analyses;
5. The analytical techniques or methods used; and
6. The results of all analyses.
E. Additional Monitoring by the Permittee
If the Permittee monitors any pollutant more frequently than required by this permit using
test procedures specified by Condition S4 of this permit, the results of this monitoring
shall be included in the calculation and reporting of the data submitted in the Permittee's
DMR.
F. Noncompliance Notification
In the event the Permittee is unable to comply with any of the terms and conditions of
this permit which may cause a threat to human health or the environment, the Permittee
shall:
1. Immediately notify Ecology of the failure to comply.
2. Immediately take action to prevent the discharge/pollution, or otherwise stop or
correct the noncompliance, and, if applicable, repeat sampling and analysis of any
noncompliance immediately and submit the results to Ecology within five (5) days
after becoming aware of the violation.
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3. Submit a detailed written report to Ecology within five (5) days, unless requested
earlier by Ecology. The report shall contain a description of the noncompliance,
including exact dates and times, and if the noncompliance has not been corrected, the
anticipated time it is expected to continue; and the steps taken or planned to reduce,
eliminate, and prevent reoccurrence of the noncompliance.
Compliance with these requirements does not relieve the Permittee from
responsibility to maintain continuous compliance with the terms and conditions of
this permit or the resulting liability for failure to comply.
G. Access to Plans and Records
1. The Permittee shall retain the following permit documentation (plans and records) on -
site, or within reasonable access to the site, for use by the operator; or on -site review
by Ecology or the local jurisdiction:
a. General Permit;
b. Permit Coverage Letter;
c. Stormwater Pollution Prevention Plan (SWPPP); and
d. Site Log Book
2. The Permittee(s) shall address written requests for plans and records listed above
(Condition S5.G.1) as follows:
a. A copy of plans and records shall be provided to Ecology within 14 days of
receipt of a written request from Ecology.
b. A copy of plans and records shall be provided to the public when requested in
writing. Upon receiving a written request from the public for the Permittee's
plans and records, the Permittee shall either:
i. Provide a copy of the plans and records to the requestor within .14 days of a
receipt of the written request; or
ii. Notify the requestor within 10 days of receipt of the written request of the
location and times within normal business hours when the plans and records
may be viewed, and provide access to the plans and records within 14 days of
receipt of the written request; or
iii. Within 14 days of receipt of the written request, the Permittee may submit a
copy of the plans and records to Ecology for viewing and/or copying by the
requestor at an Ecology office, or a mutually agreed upon location. If plans
and records are viewed and/or copied at a location other than at an Ecology
office, the Permittee will provide reasonable access to copying services for
which a reasonable fee may be charged. The Permittee shall notify the
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requestor within 10 days of receipt of the request where the plans and records
may be viewed and/or copied.
S6. PERMIT FEES
The Permittee shall pay permit fees assessed by Ecology. Fees for stormwater discharges
covered under this permit shall be established by Chapter 173-224 WAC. Permit fees will
continue to be assessed until the permit is terminated in accordance with Special Condition
S 10 or revoked in accordance with General Condition G5.
S7. SOLID AND LIQUID WASTE DISPOSAL
Solid and liquid wastes generated by construction activity such as demolition debris,
construction materials, contaminated materials, and waste materials from maintenance
activities, including liquids and solids from cleaning catch basins and other stormwater
facilities, shall be handled and disposed of in accordance with:
1. Special Condition S3, Compliance with Standards, and
2. WAC 173-216-110, and other applicable regulations.
S8. DISCHARGES TO 303(D) OR TMDL WATERBODIES
A. Sampling and Numeric Effluent Limitations For Discharges to 303(d)-listed Waterbodies
1.Permittees that discharge to water bodies listed as impaired by the State of
Washington under Section 303(d) of the Clean Water Act for turbidity, fine
sediment, high pH, or phosphorus, shall conduct water quality sampling according
to the requirements of this section.
2. All references and requirements associated with Section 303(d) of the Clean Water
Act mean the most current listing by Ecology of impaired waters that exists on
November 16, 2005, or the date when the operator's complete permit application is
received by Ecology, whichever is later.
B. Discharges to 303(d)-Listed Waterbodies (Turbidity, Fine Sediment, or Phosphorus)
1. Permittees which discharge to waterbodies on the 303(d) list for turbidity, fine
sediment, or phosphorus shall conduct turbidity sampling at the following locations
to evaluate compliance with the water quality standard for turbidity:
a. Background turbidity shall be measured in the 303(d)-listed receiving water
immediately upstream (upgradient) or outside the area of influence of the
discharge; and
b. Discharge turbidity shall be measured at the point of discharge into the 303(d)
listed receiving waterbody, inside the area of influence of the discharge; or
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Alternatively, discharge turbidity may be measured at the point where the
discharge leaves the construction site, rather than in the receiving waterbody.
2. Based on sampling, if the discharge turbidity exceeds the water quality standard for
turbidity (more than 5 NTU over background turbidity when the background
turbidity is 50 NTU or less, or more than a 10% increase in turbidity when the
background turbidity is more than 50 NTU), all future discharges shall comply with
a numeric effluent limit which is equal to the water quality standard for turbidity:
3. If a future discharge exceeds the water quality standard for turbidity, the Permittee
shall:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the standard;
b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible, but within 10 days of the discharge that exceeded the
standard;
c. Document BMP implementation and maintenance in the site log book;
d. Notify the appropriate Ecology Regional Office by phone within 24 hours of
analysis;
e. Continue to sample daily until discharge turbidity meets the water quality
standard for turbidity.
C. Discharges to waterbodies on the 303(d) list for High pH
Permittees which discharge to waterbodies on the 303(d) list for high pH shall
conduct sampling at one of the following locations to evaluate compliance with the
water quality standard for pH (in the range of 6.5 — 8.5):
a. pH shall be measured at the point of discharge into the 303(d) listed waterbody,
inside the area of influence of the discharge; or
b. Alternatively; pH may be measured at the point where the discharge leaves the
construction site, rather than in the receiving water.
2. Based on the sampling set forth above, if the pH exceeds the water quality standard
for pH (in the range of 6.5 — 8.5), all future discharges shall comply with a numeric
effluent limit which is equal to the water quality standard for pH.
3. If a future discharge exceeds the water quality standard for pH, the Permittee shall:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the water quality standard;
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b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible, but within 10 days of the discharge that exceeded the
standards;
c. Document BUT implementation and maintenance in the site log book;
d. Notify the appropriate Ecology Regional Office by phone within 24 hours of
analysis; and
e. Continue to sample daily until discharge meets the water quality standard for pH
(in the range of 6.5 — 8.5) or the discharge stops or is eliminated.
Parameter identified
in 303(d) listing
Parameter/Units
Analytical
Method
Sampling
Frequency
Water Quality
Standard
Turbidity
Turbidity/NTU
SM2130 or
Weekly, if
If background is 50
Fine Sediment
EPA180.1
discharging
NTU or less: 5 NTU
Phosphorus
over background; or
If background is
more than 50 NTU:
10% over
background
High pH
pH/Standard
pH meter
Weekly, if
In the range of
Units
discharging
6.5 — 8.5
D. Sampling and Limitations For Sites Discharging to Applicable TMDLs
1. Discharges to a waterbodies subject to an applicable Total Maximum Daily Load
(TMDL) for turbidity, fine sediment, high pH, or phosphorus, shall be consistent with
the assumptions and requirements of the TMDL.
a. Where an applicable TAML sets specific waste load allocations or requirements
for discharges covered by this permit, discharges shall be consistent with any
specific waste load allocations or requirements established by the applicable
TMDL.
ii. The Permittee shall sample discharges weekly, or as otherwise specified by the
TMDL, to evaluate compliance with the specific waste load allocations or
requirements.
iii. Analytical methods used to meet the monitoring requirements shall conform to
the latest revision of the Guidelines Establishing Test Procedures for the
Analysis of Pollutants contained in 40 CFR Part 136. Turbidity and pH methods
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need not be accredited or registered unless conducted at a laboratory which must
otherwise be accredited or registered.
b. Where an applicable TMDL has established a general waste load allocation for
construction stormwater discharges, but no specific requirements have been
identified, compliance with Conditions S4 (Monitoring) and S9 (SWPPPs) will be
assumed to be consistent with the approved TMDL.
c. Where an applicable TMDL has not specified a waste load allocation for
construction stormwater discharges, but has not excluded these discharges,
compliance with Conditions S4 (Monitoring) and S9 (SWPPPs) will be assumed
to be consistent with the approved TMDL.
d. Where an applicable TMDL specifically precludes or prohibits discharges from
construction activity, the operator is not eligible for coverage under this permit.
2. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or
phosphorus, which has been completed and approved by EPA prior to November 16,
2005, or prior to the date the operator's complete permit application is received by
Ecology, whichever is later. TMDLs completed after the operator's complete permit
application is received by Ecology become applicable to the Permittee only if they are
imposed through an administrative order by Ecology, or through a modification of
permit coverage.
S9. STORMWATER POLLUTION PREVENTION PLAN
An adequate Stormwater Pollution Prevention Plan (SWPPP) for construction activity shall
be prepared and implemented in accordance with the requirements of this permit beginning
with initial soil disturbance and until final stabilization.
A. The SWPPP shall meet the following objectives:
1. To implement Best Management Practices (BMPs) to prevent erosion and
sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination'
and water pollution from construction activity.
2. To prevent violations of surface water quality, ground water quality, or sediment
management standards.
3. To control peak volumetric flow rates and velocities of stormwater discharges.
B. General Requirements
The SWPPP shall include a narrative and drawings. All BMPs shall be clearly
referenced in the narrative and marked on the drawings.
The SWPPP narrative shall include documentation to explain and justify the pollution
prevention decisions made for the project. Documentation shall include:
a. Information about existing site conditions (topography, drainage, soils,
vegetation, etc.);
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b. Potential erosion problem areas;
c. The 12 elements of a SWPPP in S9.D.1-12, including BMPs used to address each
element;
d. Construction phasing/sequence and general BMP implementation schedule;
e. The actions to be taken if BMP performance goals are not achieved; and
f. Engineering calculations for ponds and any other designed structures.
2. The Permittee shall modify the SWPPP if, during inspections or investigations
conducted by the owner/operator, or the applicable local or state regulatory authority,
it is determined that the SWPPP is, or would be, ineffective in eliminating or
significantly minimizing pollutants in stormwater discharges from the site. The
Permittee shall take the following actions:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the inspection or investigation;
b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible, but no later than 10 days from the inspection or investigation;
and
c. Document BMP implementation and maintenance in the site log book.
3. The Permittee shall modify the SWPPP whenever there is a change in design,
construction, operation, or maintenance at the construction site that has, or could
have, a significant effect on the discharge of pollutants to waters of the state.
C. Stormwater Best Management Practices (L3MPs)
BMPs shall be consistent with:
1. Stormwater Management Manual for Western Washington (most recent edition), for
sites west of the crest of the Cascade Mountains;
2. Stormwater Management Manual for Eastern Washington (most recent edition), for
sites east of the crest of the Cascade Mountains; or
3. Other stormwater management guidance documents or manuals which provide an
equivalent level of pollution prevention and are approved by Ecology; or
4. Documentation in the SWPPP that the BMPs selected provides an equivalent level of
pollution prevention, compared to the applicable Stormwater Management Manuals,
including:
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a. The technical basis for the selection of all stormwater BMPs (scientific, technical
studies, and/or modeling) which support the performance claims for the BMPs
being selected; and
b. An assessment of how the selected BMP will satisfy AKART requirements and
the applicable federal technology -based treatment requirements under 40 CFR
part 125.3.
D. SWPPP — Narrative Contents and Requirements
The Permittee shall include each of the 12 elements below in S9.D.1-12 in the narrative
of the SWPPP and ensure that they are implemented unless site conditions render the
element unnecessary and the exemption from that element is clearly justified in the
SWPPP.
1. Preserve Vegetation/Mark Clearing Limits
a. Prior to beginning land disturbing activities, including clearing and grading,
clearly mark all clearing limits, sensitive areas and their buffers, and trees that are
to be preserved within the construction area.
b. The duff layer, native top soil, and natural vegetation shall be retained in an
undisturbed state to the maximum degree practicable.
2. Establish Construction Access
a. Construction vehicle access and exit shall be limited to one route, if possible.
b. Access points shall be stabilized with a pad of quarry spalls, crushed rock, or other
equivalent BAP, to minimize the tracking of sediment onto public roads.
c. Wheel wash or tire baths shall be located on site, if the stabilized construction
entrance is not effective in preventing sediment from being tracked onto public
roads.
d. If sediment is tracked off site, public roads shall be cleaned thoroughly at the end of
each day, or more frequently during wet weather. Sediment shall be removed from
roads by shoveling or pickup sweeping and shall be transported to a controlled
sediment disposal area.
e. Street washing is allowed only after sediment is removed in accordance with
S9.D.2.d. Street wash wastewater shall be controlled by pumping back on site or
otherwise be prevented from discharging into systems tributary to waters of the
state.
3. Control Flow Rates
a. Properties and waterways downstream from development sites shall be protected
from erosion due to increases in the velocity and peak volumetric flow rate of
stormwater runoff from the project site, as required by local plan approval
authority.
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b. Where necessary to comply with S9.D.3.a., stormwater retention or detention
facilities shall be constructed as one of the first steps in grading. Detention
facilities shall be functional prior to construction of site improvements (e.g.,
impervious surfaces).
c. If permanent infiltration ponds are used for flow control during construction, these
facilities shall be protected from siltation during the construction phase.
4. Install Sediment Controls
a. Stormwater runoff from disturbed areas shall pass through a sediment pond or other
appropriate sediment removal BMP, prior to leaving a construction site or prior to
discharge to an infiltration facility. Runoff from fully stabilized areas may be
discharged without a sediment removal BMP, but shall meet the flow control
performance standard of S9.D.3.a.
b. Sediment control BMPs (sediment ponds, traps, filters, etc.) shall be constructed as
one of the first steps in grading. These BMPs shall be functional before other land
disturbing activities take place.
c. BMPs intended to trap sediment on site shall be located in a manner to avoid
interference with the movement of juvenile salmonids attempting to enter off -
channel areas or drainages.
5. Stabilize Soils
a. Exposed and unworked soils shall be stabilized by application of effective BMPs
that prevent erosion. Applicable BMPs include, but are not limited to: temporary
and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics
and matting, soil application of polyacrylamide (PAM), the early application of
gravel base on areas to be paved, and dust control.
b. Depending on the geographic location of the project, no soils shall remain exposed
and unworked for more than the time periods set forth below to prevent erosion:
West of the Cascade Mountains Crest
During the dry season (May 1 - Sept. 30): 7 days
During the wet season (October 1 - April 30): 2 days
East of the Cascade Mountains Crest, except for Central Basin*
During the dry season (July 1 - September 30): 10 days
During the wet season (October 1 - June 30): 5 days
The Central Basin*, East of the Cascade Mountains Crest
During the dry Season (July 1 - September 30): 30 days
During the wet season (October 1 - June 30): 15 days
*Note: The Central Basin is defined as the portions of Eastern Washington
with mean annual precipitation of less than 12 inches.
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The time period may be adjusted by a local jurisdiction, if the jurisdiction
can show that local precipitation data justify a different standard.
c. Soils shall be stabilized at the end of the shift before a holiday or weekend if needed
based on the weather forecast.
d. Soil stockpiles shall be stabilized from erosion, protected with sediment trapping
measures, and where possible, be located away from storm drain inlets, waterways,
and drainage channels.
6. Protect Slopes
a. Design and construct cut and fill slopes in a manner that will minimize erosion.
Applicable practices include, but are not limited to, reducing continuous length of
slope with terracing and diversions, reducing slope steepness, and roughening slope
surfaces (e.g., track walking).
b. Off -site stormwater (run-on) or groundwater shall be diverted away from slopes and
disturbed areas with interceptor dikes, pipes, and/or swales. Off -site stormwater
should be managed separately from stormwater generated on the site.
c. At the top of slopes, collect drainage in pipe slope drains or protected channels to
prevent erosion.
i. West of the Cascade Mountains Crest: Temporary pipe slope drains shall
handle the peak 10-minute velocity of flow from a Type IA, 10-year, 24-hour
frequency storm for the developed condition. Alternatively, the 10-year, 1-
hour flow rate predicted by an approved continuous runoff model, increased
by a factor of 1.6, may be used. The hydrologic analysis shall use the existing
land cover condition for predicting flow rates from tributary areas outside the
project limits. For tributary areas on the project site, the analysis shall use the
temporary or permanent project land cover condition, whichever will produce
the highest flow rates. If using the WWHM to predict flows, bare soil areas
should be modeled as "landscaped area."
ii. East of the Cascade Mountains Crest: Temporary pipe slope drains shall
handle the expected peak flow velocity from a 6-month, 3-hour storm for the
developed condition, referred to as the short duration storm.
d. Excavated material shall be placed on the uphill side of trenches, consistent with
safety and space considerations.
e. Check dams shall be placed at regular intervals within constructed channels that
are cut down a slope.
7. Protect Drain Inlets
a. All storm drain inlets made operable during construction shall be protected so that
stormwater runoff does not enter the conveyance system without first being filtered
or treated to remove sediment.
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b. Inlet protection devices shall be cleaned or removed and replaced when sediment
has filled one-third of the available storage (unless a different standard is specified
by the product manufacturer).
8. Stabilize Channels and Outlets
a. All temporary on -site conveyance channels shall be designed, constructed, and
stabilized to prevent erosion from the following expected peak flows:
i. West of the Cascade Mountains Crest: Channels shall handle the peak 10
minute velocity of flow from a Type 1A, 10-year, 24-hour frequency storm for
the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated
by an approved continuous runoff model, increased by a factor of 1.6, may be
used. The hydrologic analysis shall use the existing land cover condition for
predicting flow rates from tributary areas outside the project limits. For
tributary areas on the project site, the analysis shall use the temporary or
permanent project land cover condition, whichever will produce the highest
flow rates. If using the WWHM to predict flows, bare soil areas should be
modeled as "landscaped area."
ii. East of the Cascade Mountains Crest: Channels shall handle the expected peak
flow velocity from a 6-month, 3-hour storm for the developed condition,
referred to as the short duration storm.
b. Stabilization, including armoring material, adequate to prevent erosion of outlets,
adjacent stream banks, slopes, and downstream reaches shall be provided at the
outlets of all conveyance systems.
9. Control Pollutants
a. All pollutants, including waste materials and demolition debris, that occur onsite
shall be handled and disposed of in a manner that does not cause contamination of
stormwater.
b. Cover, containment, and protection from vandalism shall be provided for all
chemicals, liquid products, petroleum products, and other materials that have the
potential to pose a threat to human health or the environment. On -site fueling tanks
shall include secondary containment.
c. Maintenance, fueling, and repair of heavy equipment and vehicles shall be
conducted using spill prevention and control measures. Contaminated surfaces shall
be cleaned immediately following any spill incident.
d. Wheel wash or tire bath wastewater shall be discharged to a separate on -site
treatment system or to the sanitary sewer with local sewer district approval.
e. Application of fertilizers and pesticides, shall be conducted in a manner and at
application rates that will not result in loss of chemical to stormwater runoff.
Manufacturers' label requirements for application rates and procedures shall be
followed.
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f. BMPs shall be used to prevent or treat contamination of stormwater runoff by pH
modifying sources. These sources include, but are not limited to: bulk cement,
cement kiln dust, fly ash, new concrete washing and curing waters, waste streams
generated from concrete grinding and sawing, exposed aggregate processes,
dewatering concrete vaults, concrete pumping and mixer washout waters.
Permittees shall adjust the pH of stormwater if necessary to prevent violations of
water quality standards.
g. Permittees shall obtain written approval from Ecology prior to using chemical
treatment, other than CO2 or dry ice to adjust pH.
10. Control De -Watering
a. Foundation, vault, and trench de -watering water, which have similar characteristics
to stormwater runoff at the site, shall be discharged into a controlled conveyance
system prior to discharge to a sediment trap or sediment pond.
b. Clean, non -turbid de -watering water, such as well -point ground water, can be
discharged to systems tributary to, or directly into surface waters of the state, as
specified in S9.D.8, provided the de -watering flow does not cause erosion or
flooding of receiving waters. Clean de -watering water should not be routed through
stormwater sediment ponds.
c. Other de -watering disposal options may include:
i. infiltration
ii. transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in
a manner that does not pollute state waters,
iii. Ecology -approved on -site chemical treatment or other suitable treatment
technologies,
iv. sanitary sewer discharge with local sewer district approval, if there is no other
option, or
v. use of a sedimentation bag with outfall to a ditch or swale for small volumes of
localized de -watering.
d. Highly turbid or contaminated dewatering water shall be handled separately from
stormwater.
11. Maintain BMPs
a. All temporary and permanent erosion and sediment control BMPs shall be
maintained and repaired as needed to assure continued performance of their
intended function in accordance with BMP specifications.
b. All temporary erosion and sediment control BMPs shall be removed within 30 days
after final site stabilization is achieved or after the temporary BMPs are no longer
needed.
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12. Manage the Project
a. Development projects shall be phased to the maximum degree practicable and shall
take into account seasonal work limitations.
b. Inspection and Monitoring
All BMPs shall be inspected, maintained, and repaired as needed to assure
continued performance of their intended function. Site inspections and monitoring
shall be conducted in accordance with S4.
c. Maintaining an Updated Construction SWPPP
The SWPPP shall be maintained, updated, and implemented in accordance with
Conditions S3, S4 and S9.
E. SWPPP — Man Contents and Requirements
The SWPPP shall also include a vicinity map or general location map (e.g. USGS
Quadrangle map, a portion of a county or city map, or other appropriate map) with
enough detail to identify the location of the construction site and receiving waters within
one mile of the site.
The SWPPP shall also include a legible site map (or maps) showing the entire
construction site. The following features shall be. identified, unless not applicable due to
site conditions:
1. The direction of north, property lines, and existing structures and roads;
2. Cut and fill slopes indicating the top and bottom of slope catch lines;
3. Approximate slopes, contours, and direction of stormwater flow before and after
major grading activities;
4. Areas of soil disturbance and areas that will not be disturbed;
5. Locations of structural and nonstructural controls (BMPs) identified in the SWPPP
6. Locations of off -site material, stockpiles, waste storage, borrow areas, and
vehicle/equipment storage areas;
7. Locations of all surface water bodies, including wetlands;
8. Locations where stormwater or non-stormwater discharges off -site and/or to a surface
water body, including wetlands;
9. Location of water quality sampling station(s), if sampling is required by state or local
permitting authority; and
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10. Areas where final stabilization has been accomplished and no further construction -
phase permit requirements apply.
S10. NOTICE OF TERMINATION
A. The site is eligible for termination when either of the following conditions have been met:
1. The site has undergone final stabilization, all temporary BMPs have been removed,
and all stormwater discharges associated with construction activity have been
eliminated; or
2. All portions of the site which have not undergone final stabilization per S 1 O.A.1 have
been sold and/or transferred (per Condition G9), and the Permittee no longer has
operational control of the construction activity.
B. When the site is eligible for termination, the Permittee shall submit a complete and
accurate Notice of Termination (NOT) form, signed in accordance with General
Condition G2, to:
Department of Ecology
Water Quality Program - Construction Stormwater
PO Box 47696
Olympia, Washington 98504-7696
C. The termination is effective on the date the NOT form was received by Ecology, unless
the Permittee is notified by Ecology within 30 days that termination request is denied
because the eligibility requirements in Condition S 10.A have not been met.
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GENERAL CONDITIONS
G1. DISCHARGE VIOLATIONS
All discharges and activities authorized by this general permit shall be consistent with the
terms and conditions of this general permit. Any discharge of any pollutant more frequent
than or at a level in excess of that identified and authorized by the general permit shall
constitute a violation of the terms and conditions of this permit.
G2. SIGNATORY REQUIREMENTS
A. All permit applications shall bear a certification of correctness to be signed:
1. In the case of corporations, by a responsible corporate officer of at least the level of
vice president of a corporation;
2. In the case of a partnership, by a general partner of a partnership;
3. In the case of sole proprietorship, by the proprietor; or
4. In the case of a municipal, state, or other public facility, by either a principal
executive officer or ranking elected official.
B. All reports required by this permit and other information requested by Ecology shall be
signed by a person described above or by a duly authorized representative of that person.
A person is a duly authorized representative only if.
1. The authorization is made in writing by a person described above and submitted to
the Ecology.
2. The authorization specifies either an individual or a position having responsibility for
the overall operation of the regulated facility, such as the position of plant manager,
superintendent, position of equivalent responsibility, or an individual or position
having overall responsibility for environmental matters.
C. Changes to authorization. If an authorization under paragraph G2.13.2 above is no longer
accurate because a different individual or position has responsibility for the overall
operation of the facility, a new authorization satisfying the requirements of paragraph
G23.2 above shall be submitted to Ecology prior to or together with any reports,
information, or applications to be signed by an authorized representative.
D. Certification. Any person signing a document under this section shall make the following
certification:
"I certify under penalty of law, that this document and all attachments were
prepared under my direction or supervision in accordance with a system
designed to assure that qualified personnel properly gathered and evaluated
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the information submitted. Based on my inquiry of the person or persons who
manage the system, or those persons directly responsible for gathering
information, the information submitted is, to the best of my knowledge and
belief, true, accurate, and complete. I am aware that there are significant
penalties for submitting false information, including the possibility of fine and
imprisonment for knowing violations."
G3. RIGHT OF INSPECTION AND ENTRY
The Permittee shall allow an authorized representative of Ecology, upon the presentation of
credentials and such other documents as may be required by law:
A. To enter upon the premises where a discharge is located or where any records shall be
kept under the terms and conditions of this permit.
B. To have access to and copy - at reasonable times and at reasonable cost - any records
required to be kept under the terms and conditions of this permit.
C. To inspect - at reasonable tunes - any facilities, equipment (including monitoring and
control equipment), practices, methods, or operations regulated or required under this
permit.
D. To sample or monitor - at reasonable times - any substances or parameters at any location
for purposes of assuring permit compliance or as otherwise authorized by the Clean
Water Act.
G4. GENERAL PERMIT MODIFICATION AND REVOCATION
This permit may be modified, revoked and reissued, or terminated in accordance with the
provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance,
or termination include, but are not limited to, the following:
A. When a change which occurs in the technology or practices for control or abatement of
pollutants applicable to the category of dischargers covered under this permit;
B. When effluent limitation guidelines or standards are promulgated pursuant to the CWA or
Chapter 90.48 RCW, for the category of dischargers covered under this permit;
C. When a water quality management plan containing requirements applicable to the
category of dischargers covered under this permit is approved; or
D. When information is obtained which indicates that cumulative effects on the environment
from dischargers covered under this permit are unacceptable.
G5. REVOCATION OF COVERAGE UNDER THE PERMIT
Pursuant with Chapter 43.21B RCW and Chapter 173-226 WAC, the Director may terminate
coverage for any discharger under this permit for cause. Cases where coverage may be
terminated include, but are not limited to, the following:
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A. Violation of any term or condition of this permit;
B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully all
relevant facts;
C. A change in any condition that requires either a temporary or permanent reduction or
elimination of the permitted discharge;
D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090;
E. A determination that the permitted activity endangers human health or the environment,
or contributes to water quality standards violations;
F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and
Chapter 173-224 WAC;
G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226-
130(5), when applicable.
The Director may require any discharger under this permit to apply for and obtain coverage
under an individual permit or another more specific general permit. Permittees who have
their coverage revoked for cause according to WAC 173-226-240 may request temporary
coverage under this permit during the time an individual permit is being developed, provided
the request is made within ninety (90) days from the time of revocation and is submitted
along with a complete individual permit application form.
G6. REPORTING A CAUSE FOR MODIFICATION
The Permittee shall submit a new application, or a supplement to the previous application,
whenever a material change to the construction activity or in the quantity or type of discharge
is anticipated which is not specifically authorized by this permit. This application shall be
submitted at least sixty (60) days prior to any proposed changes. The filing of a request by
the Permittee for a permit modification, revocation and reissuance, or termination, or a
notification of planned changes or anticipated noncompliance does not relieve the Permittee
of the duty to comply with the existing permit until it is modified or reissued.
G7. COMPLIANCE WITH OTHER LAWS AND STATUTES
Nothing in this permit shall be construed as excusing the Permittee from compliance with
any applicable federal, state, or local statutes, ordinances, or regulations.
G8. DUTY TO REAPPLY
The Permittee shall apply for permit renewal at least 180 days prior to the specified
expiration date of this permit.
G9. TRANSFER OF GENERAL PERMIT COVERAGE
Coverage under this general permit is automatically transferred to a new discharger,
including operators of lots/parcels within a common plan of development or sale, if:
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A. A written, signed agreement (Transfer of Coverage Form) between the current discharger
(Permittee) and new discharger containing a specific date for transfer of permit
responsibility, coverage, and liability is submitted to the Director; and
B. The Director does not notify the current discharger and new discharger of the Director's
' intent to revoke coverage under the general permit. If this notice is not given, the transfer
is effective on the date specified in the written agreement.
When a current discharger (Permittee) transfers a portion of a permitted site, the current
discharger shall also submit an updated application form (NOI) to the Director indicating the
remaining permitted acreage after the transfer. When a current discharger (Permittee)
transfers all portions of a permitted site to one or more new dischargers, the current
discharger shall also submit a notice of termination (NOT) form to the Director.
G10. REMOVED SUBSTANCES
Collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in the
course of treatment or control of stormwater shall not be resuspended or reintroduced to the
final effluent stream for discharge to state waters.
G11. DUTY TO PROVIDE INFORMATION
The Permittee shall submit to Ecology, within a reasonable time, all information which
Ecology may request to determine whether cause exists for modifying, revoking and
reissuing, or terminating this permit or to determine compliance with this permit. The
Permittee shall also submit to Ecology upon request, copies of records required to be kept by
this permit [40 CFR 122.41(h)].
G12.OTHER REQUIREMENTS OF 40 CFR
All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by
reference.
G13. ADDITIONAL MONITORING
Ecology may establish specific monitoring requirements in addition to those contained in this
permit by administrative order or permit modification.
G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS
Any person who is found guilty of willfully violating the terms and conditions of this permit
shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of
up to ten thousand dollars ($10,000) and costs of prosecution, or by imprisonment in the
discretion of the court. Each day upon which a willful violation occurs may be deemed a
separate and additional violation.
Any person who violates the terms and conditions of a waste discharge permit shall incur, in
addition to any other penalty as provided by law, a civil penalty in the amount of up to ten
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thousand dollars ($10,000) for every such violation. Each and every such violation shall be a
separate and distinct offense, and in case of a continuing violation, every day's continuance
shall be deemed to be a separate and distinct violation.
G15. UPSET
Definition — "Upset" means an exceptional incident in which there is unintentional and
temporary noncompliance with technology -based permit effluent limitations because of
factors beyond the reasonable control of the Permittee. An upset does not include
noncompliance to the extent caused by operational error, improperly designed treatment
facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or
improper operation.
An upset constitutes an affirmative defense to an action brought for noncompliance with such
technology -based permit effluent limitations if the requirements of the following paragraph
are met.
A Permittee who wishes to establish the affirmative defense of upset shall demonstrate,
through properly signed, contemporaneous operating logs or other relevant evidence that: 1)
an upset occurred and that the Permittee can identify the cause(s) of the upset; 2) the
permitted facility was being properly operated at the time of the upset; 3) the Permittee
submitted notice of the upset as required in condition S5.F; and 4) the Permittee complied
with any remedial measures required under this permit.
In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset
has the burden of proof.
G16. PROPERTY RIGHTS
This permit does not convey any property rights of any sort, or any exclusive privilege.
G17. DUTY TO COMPLY
The Permittee shall comply with all conditions of this permit. Any permit noncompliance
constitutes a violation of the Clean Water Act and is grounds for enforcement action; for
permit termination, revocation and reissuance, or modification; or denial of a permit renewal
application.
G18. TOXIC POLLUTANTS
The Permittee shall comply with effluent standards or prohibitions established under Section
307(a) of the Clean Water Act for toxic pollutants within the time provided in the regulations
that establish those standards or prohibitions, even if this permit has not yet been modified to
incorporate the requirement.
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G19. PENALTIES FOR TAMPERING
The Clean Water Act provides that any person who falsifies, tampers with, or knowingly
renders inaccurate any monitoring device or method required to be maintained under this
permit shall, upon conviction, be punished by a fine of not more than $10,000 per violation,
or by imprisonment for not more than two years per violation, or by both. If a conviction of
a person is for a violation committed after a first conviction of such person under this
Condition, punishment shall be a fine of not more than $20,000 per day of violation, or
imprisonment of not more than four (4) years, or both.
G20. REPORTING PLANNED CHANGES
The Permittee shall, as soon as possible, give notice to Ecology of planned physical
alterations, modifications or additions to the permitted construction activity, which will result
A. The permitted facility being determined to be a new source pursuant to 40 CFR
122.29(b);
B. A significant change in the nature or an increase in quantity of pollutants discharged,
including but not limited to: for sites 5 acres or larger, a 20% or greater increase in
acreage disturbed by construction activity;
C. A change in or addition of surface water(s) receiving stormwater or non-stormwater from
the construction activity; or
D. A change in the construction plans and/or activity that affects the Permittee's monitoring
requirements in Special Condition S4.
Following such notice, permit coverage may be modified, or revoked and reissued pursuant
to 40 CFR 122.62(a) to specify and limit any pollutants not previously limited. Until such
modification is effective, any new or increased discharge in excess of permit limits or not
specifically authorized by this permit constitutes a violation.
G21. REPORTING OTHER INFORMATION .
Where the Permittee becomes aware that it failed to submit any relevant facts in a permit
application, or. submitted incorrect information in a permit application or in any report to
Ecology, it shall promptly submit such facts or information.
G22. REPORTING ANTICIPATED NON-COMPLIANCE
The Permittee shall give advance notice to Ecology by submission of a new application or
supplement thereto at least forty-five (45) days prior to commencement of such discharges,
of any facility expansions, production increases, or other planned changes, such as process
modifications, in the permitted facility or activity which may result in noncompliance with
permit limits or conditions. Any maintenance of facilities, which might necessitate
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unavoidable interruption of operation and degradation of effluent quality, shall be scheduled
during non -critical water quality periods and carried out in a manner approved by Ecology.
G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT
Any discharger authorized by this permit may request to be excluded from coverage under
the general permit by applying for an individual permit. The discharger shall submit to the
Director an application as described in WAC 173-220-040 or WAC 173-216-070, whichever
is applicable, with reasons supporting the request. These reasons shall fully document how an
individual permit will apply to the applicant in a way that the general permit cannot. Ecology
may make specific requests for information to support the request. The Director shall either
issue an individual permit or deny the request with a statement explaining the reason for the
denial. When an individual permit is issued to a discharger otherwise subject to the
construction stormwater general permit, the applicability of the construction stormwater
general permit to that Permittee is automatically terminated on the effective date of the
individual permit.
G24. APPEALS
A. The terms and conditions of this general permit, as they apply to the appropriate class of
dischargers, are subject to appeal by any person within 30 days of issuance of this general
permit, in accordance with Chapter 43.2113 RCW, and Chapter 173-226 WAC.
B. The terms and conditions of this general permit, as they apply to an individual discharger,
are appealable in accordance with Chapter 43.21B RCW within 30 days of the effective
date of coverage of that discharger. Consideration of an appeal of general permit
coverage of an individual discharger is limited to the general permit's applicability or
nonapplicability to that individual discharger. I
C. The appeal of general permit coverage of an individual discharger does not affect any
other dischargers covered under this general permit. If the terms and conditions of this
general permit are found to be inapplicable to any individual discharger(s), the matter
shall be remanded to Ecology for consideration of issuance of an individual permit or
permits.
G25. SEVERABILITY
The provisions of this permit are severable, and if any provision of this permit, or application
of any provision of this permit to any circumstance, is held invalid, the application of such
provision to other circumstances, and the remainder of this permit shall not be affected
thereby.
G26. BYPASS PROHIBITED
A. Bypass Procedures
Bypass, which is the intentional diversion of waste streams from any portion of a
treatment facility, is prohibited for stormwater events below the design criteria for
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stormwater management. Ecology may take enforcement action against a Permittee for
bypass unless one of the following circumstances (1, 2, 3 or 4) is applicable.
1. Bypass of stormwater is consistent with the design criteria and part of an approved
management practice in the applicable stormwater management manual.
2. Bypass for essential maintenance without the potential to cause violation of permit
limits or conditions.
Bypass is authorized if it is for essential maintenance and does not have the potential
to cause violations of limitations or other conditions of this permit, or adversely
impact public health.
3. Bypass of stormwater is unavoidable, unanticipated, and results in noncompliance of
this permit.
This bypass is permitted only if:
a. Bypass is unavoidable to prevent loss of life, personal injury, or severe property
damage. "Severe property damage" means substantial physical damage to
property, damage to the. treatment facilities which would cause them to become
inoperable, or substantial and permanent loss of natural resources which can
reasonably be expected to occur in the absence of a bypass;
b. There are no feasible alternatives to the bypass, such as the use of auxiliary
treatment facilities, retention of untreated wastes, maintenance during normal
periods of equipment downtime (but not if adequate backup equipment should
have been installed in the exercise of reasonable engineering judgment to prevent
a bypass which occurred during normal periods of equipment downtime or
preventative maintenance), or transport of untreated wastes to another treatment
facility; and
c. Ecology is properly notified of the bypass as required in Special Condition S5.F
of this permit.
4. A planned action that would cause bypass of stormwater and has the potential to
result in noncompliance of this permit during a storm event.
The Permittee shall notify Ecology at least thirty (30) days before the planned date of
bypass. The notice shall contain:
a. a description of the bypass and its cause;
b. an analysis of all known alternatives which would eliminate, reduce, or mitigate
the need for bypassing;
c. a cost-effectiveness analysis of alternatives including comparative resource
damage assessment;
d. the minimum and maximum duration of bypass under each alternative;
e. a recommendation as to the preferred alternative for conducting the bypass;
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f. the projected date of bypass initiation;
g. a statement of compliance with SEPA;
h. a request for modification of water quality standards as provided for in WAC 173-
201A-110, if an exceedance of any water quality standard is anticipated; and
i. steps taken or planned to reduce, eliminate, and prevent reoccurrence of the
bypass.
5. For probable construction bypasses, the need to bypass is to be identified as early in
the planning process as possible. The analysis required above shall be considered
during preparation of the Stormwater Pollution Prevention Plan (SWPPP) and shall
be included to the extent practical. In cases where the probable need to bypass is
determined early, continued analysis is necessary up to and including the construction
period in an effort to minimize or eliminate the bypass.
Ecology will consider the following prior to issuing an administrative order for this
type bypass:
a. If the bypass is necessary to perform construction or maintenance -related
activities essential to meet the requirements of this permit.
b. If there are feasible alternatives to bypass, such as the use of auxiliary treatment
facilities, retention of untreated wastes, stopping production, maintenance during
normal periods of equipment down time, or transport of untreated wastes to
another treatment facility.
c. If the bypass is planned and scheduled to minimize adverse effects on the public
and the environment.
After consideration of the above and the adverse effects of the proposed bypass and
any other relevant factors, Ecology will approve, conditionally approve, or deny the
request. The public shall be notified and given an opportunity to comment on bypass
incidents of significant duration, to the extent feasible. Approval of a request to
bypass will be by administrative order issued by Ecology under RCW 90.48.120.
B. DutyDpty to Mitigate
The Permittee is required to take all reasonable steps to minimize or prevent any
discharge or sludge use or disposal in violation of this permit that has a reasonable
likelihood of adversely affecting human health or the environment.
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APPENDIX A — DEFINITIONS
AKART is an acronym for "all known, available, and reasonable methods of prevention, control,
and treatment." AKART represents the most current methodology that can be reasonably
required for preventing, controlling, or abating the pollutants and controlling pollution associated
with a discharge.
A-12plicable TAML means a TMDL for turbidity, fine sediment, high pH, or phosphorus, which
has been completed and approved by EPA prior to November 16, 2005, or prior to the date the
operator's complete permit application is received by Ecology, whichever is later.
Applicant means an operator seeking coverage under this permit.
Best Manazement Practices (BMPs) means schedules of activities, prohibitions of practices,
maintenance procedures, and other physical, structural and/or managerial practices to prevent or
reduce the pollution of waters of the state. BMPs include treatment systems, operating
procedures, and practices to control: stormwater associated with construction activity, spillage
or leaks, sludge or waste disposal, or drainage from raw material storage.
Buffer means an area designated by a local jurisdiction that is contiguous to and intended to
protect a sensitive area
Bypass means the intentional diversion of waste streams from any portion of a treatment facility.
Calendar Week (same as Week) means a period of seven consecutive days starting on Sunday.
Certified Erosion and Sediment Control Lead (CESCL) means a person who has current
certification through an approved erosion and sediment control training program that meets the
minimum training standards established by Ecology (see BMP C160 in the SW`W.
Clean Water Act (CWA) means the Federal Water Pollution Control Act enacted by Public Law
92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq.
Combined Sewer means a sewer which has been designed to serve as a sanitary sewer and a
storm sewer, and into which inflow is allowed by local ordinance.
Common plan of development or sale means a site where multiple separate and distinct
construction activities may be taking place at different times on different schedules, but still
under a single plan. Examples include: 1) phased projects and projects with multiple filings or
lots, even if the separate phases or filings/lots will be constructed under separate contract or by
separate owners (e.g., a development where lots are sold to separate builders); 2) a development
plan that may be phased over multiple years, but is still under a consistent plan for long-term
development; and 3) projects in a contiguous area that may be unrelated but still under the same
contract, such as construction of a building extension and a new parking lot at the same facility.
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If the project is part of a common plan of development or sale, the disturbed area of the entire
plan shall be used in determining permit requirements.
Composite Sample A mixture of grab samples collected at the same sampling point at different
times, formed either by continuous sampling or by mixing discrete samples. May be "time -
composite" (collected at constant time intervals) or "flow -proportional" (collected either as a
constant sample volume at time intervals proportional to stream flow, or collected by increasing
the volume of each aliquot as the flow increases while maintaining a constant time interval
between the aliquots.
Construction Activity means land disturbing operations including clearing, grading or excavation
which disturbs the surface of the land. Such activities may include road construction,
construction of residential houses, office buildings, or industrial buildings, and demolition
activity.
Demonstrably Equivalent means that the technical basis for the selection of all stormwater BMPs
is documented within a SWPPP, including:
1. The method and reasons for choosing the stormwater BMPs selected;
2. The pollutant removal performance expected from the BMPs selected;
3. The technical basis supporting the performance claims for the BMPs selected,
including any available data concerning field performance of the BMPs selected;
4. An assessment of how the selected BMPs will comply with state water quality
standards; and
5. An assessment of how the selected BMPs will satisfy both applicable federal
technology -based treatment requirements and state requirements to use all known,
available, and reasonable methods of prevention, control, and treatment (AKART).
Department means the Washington State Department of Ecology.
Detention means the temporary storage of stormwater to improve quality and/or to reduce the
mass flow rate of discharge.
De-waterinjz means the act of pumping ground water or stormwater away from an active
construction site.
Director means the Director of the Washington Department of Ecology or his/her authorized
representative.
Discharger means an owner or operator of any facility or activity subject to regulation under
Chapter 90.48 RCW or the Federal Clean Water Act.
Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundry
wastes from residences, buildings, industrial establishments, or other places, together with such
ground water infiltration or surface waters as may be present.
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Engineered soils The use of soil amendments including, but not limited, to Portland cement
treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil
characteristics.
Equivalent BMPs means operational, source control, treatment, or innovative BMPs which result
in equal or better quality of stormwater discharge to surface water or to ground water than BMPs
selected from the SWMM.
Erosion means the wearing away of the land surface by running water, wind, ice, or other
geological agents, including such processes as gravitational creep.
Erosion and Sediment Control BMPs means BMPs that are intended to prevent erosion and
sedimentation, such as preserving natural vegetation, seeding, mulching and matting, plastic
covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are
synonymous with stabilization and structural BMPs.
Final Stabilization (same as fully stabilized or full stabilization) means the establishment of a
permanent vegetative cover, or equivalent permanent stabilization measures (such as riprap,
gabions or geotextiles) which prevents erosion.
Ground Water means water in a saturated zone or stratum beneath the land surface or a surface
water body.
I_niection well means a "well" that is used for the subsurface emplacement of fluids. (see Well)
Jurisdiction means a political unit such as a city, town or county; incorporated for local self-
government.
National Pollutant Discharge Elimination System (NPDES) means the national program for
issuing, modifying, revoking and reissuing, terminating, monitoring, and enforcing permits, and
imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the
Federal Clean Water Act, for the discharge of pollutants to surface waters of the state from point
sources. These permits are referred to as NPDES permits and, in Washington State, are
administered by the Washington Department of Ecology.
Notice of Intent (NOI) means the application for, or a request for coverage under this general
permit pursuant to WAC 173-226-200.
Notice of Termination (NOT) means a request for termination of coverage under this general
permit as specified by Special Condition S 10 of this permit.
Operator means any party associated with a construction project that meets either of the
following two criteria:
1. The party has operational control over construction plans and specifications, including the
ability to make modifications to those plans and specifications; or
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2. The party has day-to-day operational control of those activities at a project which are
necessary to ensure compliance with a SWPPP for the site or other permit conditions (e.g., they
are authorized to direct workers at a site to carry out activities required by the SWPPP or comply
with other permit conditions).
Ou all. means the location where stormwater leaves the site. It also includes the location where
stormwater is discharged to a surface waterbody within a site, but does not include discharges to
on -site stormwater treatment/infiltration devices or storm sewer systems.
Permittee means individual or entity that receives notice of coverage under this general permit.
pH means a liquid's acidity or alkalinity. A pH of 7 is defined as neutral. Large variations above
or below this value are considered harmful to most aquatic life.
pH Monitoring Period means the time period in which the pH of stormwater runoff from a site
shall be tested a minimum of once every seven days to determine if stormwater is above pH 8.5.
Point Source means any discernible, confined, and discrete conveyance, including but not
limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, and container from
which pollutants are or may be discharged to surface waters of the state. This term does not
include return flows from irrigated agriculture. (See Fact Sheet for further explanation.)
Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage,
garbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials,
radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and
industrial, municipal, and agricultural waste. This term does not include sewage from vessels
within the meaning of section 312 of the CWA, nor does it include dredged or fill material
discharged in accordance with a permit issued under section 404 of the CWA.
Pollution means contamination or other alteration of the physical, chemical, or biological
properties of waters of the state; including change in temperature, taste, color, turbidity, or odor
of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into
any waters of the state as will or is likely to create a nuisance or render such waters harmful,
detrimental or injurious to the public health, safety or welfare; or to domestic, commercial,
industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild
animals, birds, fish or other aquatic life.
Receiving Water means the waterbody at the point of discharge. If the discharge is to a storm
sewer system, either surface or subsurface, the receiving water is the waterbody that the storm
sewer system discharges to. Systems designed primarily for other purposes such as for ground
water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return
flows that coincidentally convey stormwater are considered the receiving water.
Representative means a stormwater or wastewater sample which represents the flow and
characteristics of the discharge. Representative samples may be a grab sample, a time -
proportionate composite sample, or a flow proportionate sample. Ecology's Construction
Stormwater Monitoring Manual provides guidance on representative sampling.
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Sanitary Sewer means a sewer which is designed to convey domestic wastewater.
Sediment means the fragmented material that originates from the weathering and erosion of rocks
or unconsolidated deposits, and is transported by, suspended in, or deposited by water.
Sedimentation means the depositing or formation of sediment.
Sensitive area means a waterbody, wetland, stream, aquifer recharge area, or channel migration
zone.
SEPA (State Environmental Policy Act) means the Washington State Law, RCW 43.21C.020,
intended to prevent or eliminate damage to the environment.
Significant Amount means an amount of a pollutant in a discharge that is amenable to available
and reasonable methods of prevention or treatment; or an amount of a pollutant that has a
reasonable potential to cause a violation of surface or ground water quality or sediment
management standards.
Significant Concrete Work means greater than 1000 cubic yards poured concrete or recycled
concrete.
Significant Contributor of Pollutants means a facility detellluned by Ecology to be a contributor
of a significant amount(s) of a pollutant(s) to waters of the state of Washington.
Site means the land or water area where any "facility or activity" is physically located or
conducted.
Source Control BMPs means physical, structural or mechanical devices or facilities that are
intended to prevent pollutants from entering stormwater. A few examples of source control
BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over
storage and working areas, and directing wash water and similar discharges to the sanitary sewer
or a dead end sump.
Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as,
temporary and permanent seeding, vegetative covers, mulching and matting, plastic covering and
sodding. See also the definition of Erosion and Sediment Control BMPs.
Storm Drain means any drain which drains directly into a storm sewer system, usually found
along roadways or in parking lots.
Storm Sewer System means a means a conveyance, or system of conveyances (including roads
with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade
channels, or storm drains designed or used for collecting or conveying stormwater. This does
not include systems which are part of a combined sewer or Publicly Owned Treatment Works
(POTW) as defined at 40 CFR 122.2.
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Stormwater means that portion of precipitation that does not naturally percolate into the ground
or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater
drainage system into a defined surface water body, or a constructed infiltration facility.
Stormwater Management Manual (SWMM or Manual means the technical manual published by
Ecology for use by local governments that contain descriptions of and design criteria for BMPs
to prevent, control, or treat pollutants in stormwater.
Stormwater Pollution Prevention Plan (SWPPP) means a documented plan to implement
measures to identify, prevent, and control the contamination of point source discharges of
stormwater.
Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and
all other surface waters and water courses within the jurisdiction of the state of Washington.
Total Maximum Daily Load (TIIDL) means a calculation of the maximum amount of a pollutant
that a waterbody can receive and still meet state water quality standards. Percentages of the total
maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of the
allowable loads of a single pollutant from all contributing point and nonpoint sources. The
TMDL calculations shall include a "margin of safety" to ensure that the waterbody can be
protected in case there are unforeseen events or unknown sources of the pollutant. The
calculation shall also account for seasonable variation in water quality.
Treatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few
examples of treatment BMPs are detention ponds, oil/water separators, biofiltration, and
constructed wetlands.
Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm.
transparency tube. The transparency tube is used to estimate the relative clarity or transparency
of water by noting the depth at which a black and white Secchi disc becomes visible when water
is released from a value in the bottom of the tube. A transparency tube is sometimes referred to
as a "turbidity tube".
Turbidi The clarity of water expressed as nephelometric turbidity units (NTU) and measured
with a calibrated turbidimeter.
Waste Load Allocation (WLA) means the portion of a receiving water's loading capacity that is
allocated to one of its existing or future point sources of pollution. WLAs constitute a type of
water quality based effluent limitation (40 CFR 130.2(h)).
Water Quality means the chemical, physical, and biological characteristics of water, usually with
respect to its suitability for a particular purpose.
Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR
Subpart 122.2 within the geographic boundaries of Washington State and "waters of the state" as
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defined in Chapter 90.48 RCW which include lakes, rivers, ponds, streams, inland waters,
underground waters, salt waters, and all other surface waters and water courses within the
jurisdiction of the state of Washington.
Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the
largest surface dimension. (see Injection Well)
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APPENDIX B — ACRONYMS
AKART All Known, Available, and Reasonable Methods of Prevention, Control, and
Treatment
BMP Best Management Practice
CESCL Certified Erosion and Sediment Control Lead
CFR
Code of Federal Regulations
CKD
Cement Kiln Dust
cm
Centimeters
CTB
Cement Treated Base
CWA
Clean Water Act
DMR Discharge Monitoring Report
EPA Environmental Protection Agency
ESC Erosion and Sediment Control
NOI Notice of Intent
NOT Notice of Termination
NPDES National Pollutant Discharge Elimination System
NTU Nephelometric Turbidity Unit
RCW Revised Code of Washington
SEPA
State Environmental Policy Act
SW1VIM
Stormwater Management Manual
SWPPP
Stormwater Pollution Prevention Plan
TMDL
Total Maximum Daily Load
UIC . Underground Injection Control
USC United States Code
USEPA United States Environmental Protection Agency
WAC Washington Administrative Code
WQ Water Quality
WWHM Western Washington Hydrology Model
Stormwater Pollution Prevention Plan
Appendix E — Site Inspection Forms (and Site Log)
The results of each inspection shall be summarized in an inspection report or checklist
that is entered into or attached to the site log book. It is suggested that the inspection
report or checklist be included in this appendix to keep monitoring and inspection
information in one document, but this is optional. However, it is mandatory that this
SWPPP and the site inspection forms be kept onsite at all times during construction, and
that inspections be performed and documented as outlined below.
At a minimum, each inspection report or checklist shall include:
a. Inspection date/times
b. Weather information: general conditions during inspection,
approximate amount of precipitation since the last inspection,
and approximate amount of precipitation within the last 24 hours.
C. A summary or list of all BMPs that have been implemented,
including observations of all erosion/sediment control structures or
practices.
d. The following shall be noted:
i. locations of BMPs inspected,
ii. locations of BMPs that need maintenance,
iii. the reason maintenance is needed,
iv. locations of BMPs that failed to operate as designed or
intended, and
V. locations where additional or different BMPs are needed, and
the reason(s) why
e. A description of stormwater discharged from the site. The presence
of suspended sediment, turbid water, discoloration, and/or oil
sheen shall be noted, as applicable.
f. A description of any water quality monitoring performed during
inspection, and the results of that monitoring.
g. General comments and notes, including a brief description of any
BMP repairs, maintenance or installations made as a result of the
inspection.
h. A statement that, in the judgment of the person conducting the site
inspection, the site is either in compliance or out of compliance
with the terms and conditions of the SWPPP and the NPDES
permit. If the site inspection indicates that the site is out of
compliance, the inspection report shall include a summary of the
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Stormwater Pollution Prevention Plan
remedial actions required to bring the site back into compliancc. as
well as a schedule of implementation.
Name, title, and signature of person conducting the site inspection;
and the following statement: "I certify under penalty of law that
this report is true, accurate, and complete, to the best of my
knowledge and belief'.
When the site inspection indicates that the site is not in compliance with any terms and
conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop,
contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance;
correct the problem(s); implement appropriate Best Management Practices (BMPs),
and/or conduct maintenance of existing BMPs; and achieve compliance with all
applicable standards and permit conditions. In addition, if the noncompliance causes a
threat to human health or the environment, the Permittee shall comply with the
Noncompliance Notification requirements in Special Condition S51 of the permit.
n
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Stormwater Pollution Prevention Plan
Site Inspection Form
General Information
Project Name:
Inspector Name: Title:
CESCL #
Date: Time:
Inspection Type: ❑ After a rain event
❑ Weekly
❑ Turbidity/transparency benchmark exceedance
❑ Other
Weather
Precipitation Since last inspection In last 24 hours
Description of General Site Conditions:
Inspection of BDTPs
Element]: Mark Clearing Limits �
BMP:.
�.i..-+_�r.i _ `-'*4_ - _. _s-£
Location Inspected Functioning
Y N FTY7N NIP
f—]
I: '.
Inspected Functioning
Location Y N Y N NIP
Element 2: Establish Construction Access
BMP:
Location
Location
Inspected
Y N
Inspected
Y N
Functioning
Y N NIP
Functioning
Y N NIP
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
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Stormwater Pollution Prevention Plan
Element 3: Control Flow Rates
BMP:
Inspected Functioning
Location Y N Y N NIP
BMP:
Inspected Functioning
Location Y N Y N NIP
Element 4: Install Sediment Controls
BMP:
Location
Inspected Functioning
Y N Y N I NIP
BMP:
Location Inspected Functioning
Y N Y N NIP
BMP:
Location
BMP:
Location
BMP:
Location
Inspected
Y N
Inspected
Y N
Inspected
Y N
Functioning
Y 7N NIP
Functioning
Y N NIP
Functioning
[—Y—N-] NIP
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Con-ective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
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Stormwater Pollution Prevention Plan
Element S: Stabilize Soils
BMP:
Location Inspected
Y N
BMP:
Location Inspected
Y N
BMP:
Inspected
Location I, N
BMP:
Location Inspected
Y N
Element 6: Protect Slopes
BMP:
Location Inspected
Y N
BMP:
Location
BMP:
Location
Inspected
Y N
Inspected
Y N
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
E F:�]
Functioning
Y N NIP
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
41
Stormwater Pollution Prevention Plan
Element 7: Protect Drain Inlets
BMP:
Inspected Functioning
Location y N Y N NIP
BMP:
Location Inspected Functioning
Y N FY 7N NIP
BMP:
Inspected Functioning
Location y N Y N NIP
Element 8: Stabilize Channels and Outlets
BMP:
Inspected Functioning
Location y N FTY N NIP
BMP:
Problem/Corrective Action
Problem/Corrective Action'
Problem/Corrective Action
Problem/Corrective Action
Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
BMP:
Inspected Functioning;
Location y N Y N NIP Problem/Corrective Action
BMP:
Inspected Functioning
Location y N Y N NIP Problem/Corrective Action F
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Stormwater Pollution Prevention Plan
Element 9: Control Pollutants
BMP:
Inspected
Location I, N
BMP:
Location Inspected
Y N
Element 10: Control Dewatering
BMP:
Inspected
Location Y N
BMP:
Location
BMP:
Location
Inspected
Y N
Inspected
Y N
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
Functioning
Y N NIP
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
Problem/Corrective Action
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Stormwater Pollution Prevention Plan
Location
Turbidity
Discoloration
Sheen
Location
Turbidity
Discoloration
Sheen'
Stormwater Discharges From the Site
Observed?
Y a Problem/Corrective Action
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Stormwater Pollution Prevention Plan
Water Quality Monitoring
Was any water quality monitoring conducted? ❑ Yes ❑ No
If water quality monitoring was conducted, record results here:
If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6
cm or less, was Ecology notified by phone within 24 hrs?
❑ Yes ❑ No
If Ecology was notified, indicate the date, time, contact name and phone number
below:
Date:
Time:
Contact Name:
Phone #:
General Comments and Notes
Include BMP repairs, maintenance, or installations made as a result of the inspection.
Were Photos Taken? ❑ Yes ❑ No
If photos taken, describe photos below:
45