HomeMy WebLinkAboutRS_SWPPP_170712_v1
Prepared for:
iCap Lakeview, LLC
3535 Factoria Blvd
Suite 500
Bellevue, WA 98006
Prepared by:
CPH Consultants
Bryce Bessette and
Jamie Schroeder, PE
11431 Willows Road NE
Suite 120
Redmond, WA 98052
July 12, 2017
Stormwater Pollution and Prevention Plan (SWPPP)
Senza Lakeview Subdivision
3907 Park Avenue N
City of Renton, Washington
Stormwater Pollution Prevention Plan
For Senza Lakeview
Prepared For
iCAP Lakeview, LLC
3535 Factoria Blvd. SE, Suite 500
Bellevue, WA 98006
425-278-9030
Owner Developer Operator/Contractor
iCAP Lakeview, LLC
3535 Factoria Blvd. SE, Suite 500
Bellevue, WA 98006
P: (425) 278-9030
iCAP Lakeview, LLC
3535 Factoria Blvd. SE, Suite 500
Bellevue, WA 98006
P: (425) 278-9030
TBD
Project Site Location
3907 Park Ave N.
Renton, WA 98056
Certified Erosion and Sediment Control Lead
Raymond Coglas, PE
1805 136th Pl Northeast, Suite 201
Bellevue, WA 98005
P: (425) 449-4704
F: (425) 449-4711
SWPPP Prepared By
CP|H Consultants
Jamie Schroeder, P.E.
Bryce Bessette, P.E.
11431 Willows Road NE, Suite 120
Redmond, WA 98052
P: (425) 285-2390
SWPPP Preparation Date
July 6, 2017
Approximate Project Construction Dates
August, 2017
August, 2019
Senza Lakeview Stormwater Pollution Prevention Plan
CPH Project No. 0139-15-001 July 6, 2017
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Contents
1.0 Introduction ......................................................................................................................... 4
2.0 Site/Project Description ...................................................................................................... 6
2.1 Existing Conditions ......................................................................................................... 6
2.2 Proposed Construction Activities ................................................................................... 7
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…………………………………… 8
3.1.3 Element #3 – Control Flow Rates ........................................................................... 9
3.1.4 Element #4 – Install Sediment Controls ............................................................... 10
3.1.5 Element #5 – Stabilize Soils ................................................................................. 10
3.1.6 Element #6 – Protect Slopes ................................................................................. 10
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 ........................................................................... 11
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 ....................................................................................................... 16
4.0 Construction Phasing and BMP Implementation .............................................................. 17
5.0 Pollution Prevention Team ..................................................................................................... 18
5.1 Roles and Responsibilities ............................................................................................ 18
5.2 Team Members ............................................................................................................. 18
6.0 Site Inspections and Monitoring……………………………………………………………..18
6.1 Site Inspection ............................................................................................................... 19
6.1.1 Site Inspection Frequency ..................................................................................... 19
6.1.2 Site Inspection Documentation ............................................................................. 19
6.2 Stormwater Quality Monitoring .................................................................................... 20
6.2.1 Turbidity .............................................................................................................. 20
6.2.2 pH ......................................................................................................................... 20
7.0 Reporting and Recordkeeping........................................................................................... 22
7.1 Recordkeeping .............................................................................................................. 22
7.1.1 Site Log Book ....................................................................................................... 22
7.1.2 Records Retention ................................................................................................. 22
7.1.3 Access to Plans and Records................................................................................. 22
7.1.4 Updating the SWPPP ............................................................................................ 22
7.2 Reporting....................................................................................................................... 23
7.2.1 Discharge Monitoring Reports .............................................................................. 23
7.2.2 Notification of Noncompliance............................................................................. 23
7.2.3 Permit Application and Changes .......................................................................... 23
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Appendix A – Erosion Control Plans
Appendix B – Construction BMPs
Appendix C – General Permit
Appendix D – Site Inspection Forms (and Site Log)
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1.0 Introduction
This Stormwater Pollution Prevention Plan (SWPPP) has been prepared for the Senza Lakeview
single-family development project located in Renton, Washington. Senza Lakeview proposes to
provide 17 new homes, frontage improvements to Lake Washington Blvd N., N. 40th St., and
Park Ave N., water and sewer utilities, and storm drainage mitigation facilities. The project is
located at 3907 Park Ave N. within Section 32, Township 24N, Range 5E, W.M. Snohomish
County, Washington. This site is approximately 3.83 acres.
Construction activities will include approximately 2.29 acres of new impervious area in the form
of asphalt driveways and drive aisles, new sidewalks, and building roofs. 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 record keeping 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 water 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.
This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology
website and modifying to be specific for this project. This SWPPP was prepared based on the
requirements set forth in the Construction Stormwater General Permit and 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 1 – 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
(SWMMWW 2005).
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▪ 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 – Erosion Control Plans
Appendix B – Construction BMPs
Appendix C – General Permit
Appendix D – Site Inspection Forms (and Site Log)
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2.0 Site/Project Description
2.1 Existing Conditions
The project area consists of 4 parcels totaling 3.83 acres (SC tax parcel #’s: 3342700415,
3342700420, 3342700425, 3342700427). The project is located at 3907 Park Ave n., Renton,
WA 98056 within Section 32, Township 24N, Range 5E, W.M.
The site is currently occupied by three single-family residences. Access to the existing homes are
provided by a gravel driveway that connects to N. 40th St. A number of trees of varying type,
age, and health conditions exist on the site along with various brushes and grass cover.
The soils of the area are characterized generally by the Natural Resource Conservation Services
(NRCS) as Alderwood gravelly sandy loam (AgC) and Indianola loamy sand (InC). Refer to
Appendix A of the TIR for a site specific geotechnical report along with the NRCS data. Refer to
Figure 3 in the TIR Appendix for a map of the existing site conditions and existing drainage
basins.
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2.2 Proposed Construction Activities
The proposed development will create a total of 17 single-family homes. In addition, the project
will include frontage improvements to Lake Washington Blvd N., N. 40th St., and Park Ave N.,
including the pavement widening, curb and gutter, sidewalk and landscaping. The overall project
will create and/or replace a total of approximately 2.29 acres of impervious surfaces.
The proposed construction activities include site preparation, TESC installation, pavement and
sidewalk construction, utility installation, stormwater conveyance system design, and water
quality vault excavation. The schedule and phasing of BMPs during construction is provided in
Section 4.0.
The site qualifies for the Direct Discharge Exemption as the flowpath from the project site
discharge point is less than a half mile to the 100-year floodplain of Lake Washington. All of the
storm water runoff from the improved site will be collected, controlled, and released to the
existing 18” concrete pipe located at the intersection of Lake Washington BLVD N and N 40th
St. A series of on-site catch basin inlets and underground pipes will collect and convey surface
water runoff westerly within proposed road right-of-way for the majority of the developed site to
a Contech water quality vault for water quality treatment.
The developed site is required to provide Basic Water Quality treatment in addition to Level 1
(i.e., basic) flow control per current City of Renton surface water standards. Water quality storm
volumes are proposed to be treated with a Contech StormFilter vault in the northwest corner of
the site. The runoff from the frontage improvements and half street grind and overlay along Park
Ave N. will be treated by a Contech StormFilter catchbasin system near the corner of Park Ave
N. and N. 40th St.
Stormwater runoff volumes were calculated using the Western Washington Hydrology Model
2012 (WWHM). Water quality treatment was sized using the 2-year treatment volume.
The following summarizes details regarding the site conditions:
▪ Total site area: 3.83 acres
▪ Percent impervious area before construction: 10.2 %
▪ Percent impervious area after construction: 53.4 %
▪ Disturbed area during construction: 4.65 acres
▪ Disturbed area that is characterized as impervious
(i.e., access roads, staging, parking): 2.29 acres
▪ 2-year stormwater runoff peak flow prior to construction
(existing): 0.12 cfs
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▪ 50-year stormwater runoff peak flow prior to construction
(existing): 0.36 cfs
▪ 2-year stormwater runoff peak flow after construction 1.10 cfs
▪ 50-year stormwater runoff peak flow after construction 2.32 cfs
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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:
• Preserving Natural Vegetation Purpose (BMP C101)
• Construction Fence (BMP C103)
Tree protection will be provided for all trees to remain, including all trees adjacent to the
work and outside the construction limits as noted on the drawings. The upstream
boundaries of the site will be lined with construction fencing.
3.1.2 Element #2 – Establish Construction Access
Construction access shall be stabilized to minimize the tracking of sediment onto public roads;
street sweeping shall be employed to prevent sediment from entering state waters. The specified
BMPs related to establishing construction access that will be used on the project include:
• Stabilized Construction Entrance (BMP C105)
Construction access shall be established to prevent tracking any sediment onto City or
State roads or onto the adjacent property. One construction entrance will be provided.
3.1.3 Element #3 – Control Flow Rates
In order to protect the properties and waterways downstream of the project site, stormwater
discharges from the site will be controlled during construction. Flow rates during construction
are proposed to be controlled using the temporary interceptor ditches, rock check dams, and a
temporary sediment pond. In general, discharge rates of stormwater from the site will be
controlled where increases in impervious area or soil compaction during construction could lead
to downstream erosion, or where necessary to meet local agency stormwater discharge
requirements. BMPs related to establishing construction access that will be used on the project
include:
• Temporary Interceptor Ditches (BMP C200)
• Rock Check Dams (BMP C207)
• Temporary Sediment Trap (BMP C240)
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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:
• Outlet Protection (BMP C209)
• Storm Drain Inlet Protection (BMP C220)
• Silt Fence (BMP C233)
Outlet protection, storm drain inlet protection, and silt fence will be placed as shown on the plans
or as directed by the City inspector.
In addition, sediment will be removed from paved areas in 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 wash off of sediments from adjacent streets in runoff.
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 vaults or detention tanks) can be used during the
construction phase.
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:
• Topsoiling (BMP C125)
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,
protected with sediment trapping measures, and where possible, be located away from storm
drain inlets, waterways, and drainage channels.
3.1.6 Element #6 – Protect Slopes
All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes
erosion. The following specific BMPs will be used to protect slopes for this project:
• Temporary and Permanent Seeding (BMP C120)
• Pipe Slope Drain (BMP C204)
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Minimal construction is proposed for wet weather season and slope protection can be established
with final landscaping.
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. Storm
Drain Inlet Protection (SWMMWW 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
Curb Inlet Protection:
• Silt Fence wrapped over inlet
• Catch Basin Filters
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:
• Interceptor Dike and Swale (BMP C200)
• Check Dams (BMP C207)
• Outlet Protection (BMP C209)
• Storm Drain Inlet Protection (BMP C220)
• Gravel Filter Berm (BMP C232)
• Sediment Trap (BMP C240)
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 1A, 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 stream banks, slopes, and downstream reaches shall be provided at
the outlets of all conveyance systems. Refer to the Temporary and Erosion Sediment Control
Plans for placement and location of these facilities.
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. If
required, BMPs to be implemented to control specific sources of pollutants are discussed below:
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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.
• Contaminated surfaces shall be cleaned immediately following any discharge or spill
incident.
Chemical storage:
• Any chemicals stored in the construction areas will conform to the appropriate source
control BMPs listed in Volume IV of the Ecology stormwater manual. In Western
WA, all chemicals shall have cover, containment, and protection provided on site, per
BMP C153 for Material Delivery, Storage and Containment in SWMMWW 2005
• Application of agricultural chemicals, including 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’ recommendations for application procedures
and rates shall be followed.
Demolition:
• Dust released from demolished sidewalks, buildings, or structures will be controlled
using Dust Control measures (BMP C140).
• Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris
will be protected 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).
Concrete and grout:
• Process water and slurry resulting from concrete work will be prevented from
entering downstream surface waters by implementing Concrete Handling measures
(BMP C151).
Sanitary wastewater:
• Portable sanitation facilities will be firmly secured, regularly maintained, and emptied
when necessary.
Solid Waste:
• Solid waste will be stored in secure, clearly marked containers.
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Other:
• Other BMPs will be administered as necessary to address any additional pollutant
sources on site.
As per the Federal regulations of the Clean Water Act (CWA) and according to Final Rule 40
CFR Part 112, as stated in the National Register, a Spill Prevention, Control, and
Countermeasure (SPCC) Plan is required for construction activities. The Contractor shall
prepare an SPCC Plan according to the Washington State Department of Transportation
(WSDOT) Requirements (see the WSDOT Standard Specifications for Road, Bridge, and
Municipal Construction 2004) to address an approach to prevent, respond to, and report spills or
releases to the environment that could result from construction activities. This Plan must:
• Be well thought out in accordance with good engineering;
• Achieve three objectives - prevent spills, contain a spill that occurs, and clean up the
spill;
• Identify the name, location, owner, and type of facility;
• Include the date of initial operation and oil spill history;
• Name the designated person responsible;
• Show evidence of approval and certification by the person in authority; and
• Contain a facility analysis.
3.1.10 Element #10 – Control Dewatering
Any potential 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. Channels will be stabilized, per Element #8. Clean, non-
turbid dewatering water will not be routed through stormwater sediment ponds, and will be
discharged directly to downstream systems in a manner that does not cause erosion, flooding, or
a violation of State water quality standards in receiving waters. 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.
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 C151)
Concrete shall be managed in accordance with City and SWDOT standards. No washing out of
concrete trucks shall be permitted on the project site.
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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 BMP’s specifications. Visual
monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours
of any rainfall event that causes a 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.
• 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.
In addition, project management will incorporate the key components listed below:
Phasing of Construction:
• The construction project is being phased to the extent practicable in order to prevent
excessive 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 (C162).
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:
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▪ 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:
▪ 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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• 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 BMPs
Site Specific BMPs are shown on the Temporary Erosion and Sediment Control Plan and details
in Appendix A. The Certified Erosion and Sediment Control Lead will promptly implement one
or more alternate BMP’s after the first sign that existing BMPs are ineffective or failing.
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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 for 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 dry season is considered to be from May 1 to September 30 and the wet
season is considered to be from October 1 to April 30. Most earthwork construction is
anticipated to be completed during the dry season.
• Estimated Construction start date 08 / 01 / 2017
• Mobilize equipment on site: 08 / 01 / 2017
• Mobilize and store all ESC 08 / 01 / 2017
• Install ESC measures: 08 / 02 / 2017
• Install stabilized construction entrance: 08 / 02 / 2017
• Begin clearing and grubbing: 08 / 05 / 2017
• Wet Season Starts: 10 / 01 / 2017
• Site grading begins: 08 / 10 / 2017
• Install Sanitary Sewer and Storm Drainage: 08 / 28 / 2017
• Install Water System: 08 / 28 / 2017
• Parking and roadway paving 09 / 15 / 2017
• Final landscaping and planting begins: 07 / 06 / 2018
• Permanent erosion control measures (hydroseeding): 11 / 27 / 2017
• Estimate of Building Construction finish date: 10 / 01 / 2018
• Wet Season Starts: 10 / 01 / 2018
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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. Go to the following website to get the name and number for the Ecology
contact information: http://www.ecy.wa.gov/org.html.
• 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) Raymond Coglas, PE (425) 449-4704
Resident / Project Engineer Jamie Schroeder, PE 425-285-2390
Emergency Ecology Contact Ecology Office 425-649-7000
Emergency Owner Contact Levi Rowse 425-278-9030
Non-Emergency Ecology Contact Jamie Schroeder, PE 425-285-2390
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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 name 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
rainfall event which causes a discharge of stormwater from the site by a Certified Erosion and
Sediment Control Lead (CESCL). For sites with temporary stabilization measures, the site
inspection frequency can be reduced to once every month.
6.1.2 Site Inspection Documentation
The site inspector will record each site inspection using the site log inspection forms provided in
Appendix C. 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.
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6.2 Stormwater Quality Monitoring
6.2.1 Turbidity Sampling
Monitoring requirements for the proposed project will include turbidity sampling to monitor site
discharges for water quality in compliance with the 2005 Construction Stormwater General
Permit (Appendix C). Sampling will be done with a turbidity meter or transparency tube and
conducted at all site 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 C). The key
benchmark values that require action include 25 NTU (equivalent to 32 cm transparency) and
250 NTU (equivalent to 6 cm transparency) for turbidity. If the 25 NTU benchmark for turbidity
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 make revisions to the
SWPPP as necessary.
3. Sample the 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 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.
2. Continue daily sampling until the turbidity is less than 25 NTU.
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 that are taken in the site log book
and in monthly discharge monitoring reports.
6.2.2 pH Sampling
Stormwater runoff will be monitored for pH starting on the first day of any activity that includes
more than 40 cubic yards of poured or recycled concrete, or after the application of any
“Engineered Soils” such as, cement treated base, cement kiln dust, fly ash, etc. This does not
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include fertilizers. For concrete work, pH monitoring will start the first day concrete is poured
and continue until 3 weeks after the last pour. For engineered soils, the pH monitoring period
begins when engineered soils are first exposed to precipitation and continue until the area is fully
stabilized.
Stormwater samples will be collected daily from all points of discharge from the site and
measured for pH using a calibrated pH meter, pH test kit, or wide range pH indicator paper. If
the measured pH is 8.5 or greater, the following steps will be conducted:
1. Prevent the high pH water from entering storm drains or surface water.
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.
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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;
• 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.B, and S9.B.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,
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.
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7.2 Reporting
7.2.1 Discharge Monitoring Reports
Water quality sampling results will be submitted to Ecology monthly on Discharge Monitoring
Report (DMR) forms in accordance with permit condition S5.B. If there was no discharge
during a given monitoring period, the form will be submitted with the words “no discharge”
entered in place of the monitoring results. If a benchmark was exceeded, a brief summary of
inspection results and remedial actions taken will be included. If sampling could not be
performed during a monitoring period, a DMR will be submitted with an explanation of why
sampling could not be performed.
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.
Any time turbidity sampling indicates turbidity is 250 nephelometric turbidity units (NTU) or
greater or water transparency is 6 centimeters or less, the Ecology regional office will be notified
by phone within 24 hours of analysis as required by permit condition S5.A (see Section 5.0 of
this SWPPP for contact information).
In accordance with permit condition S4.D.5.b, the Ecology regional office will be notified if
chemical treatment other than CO2 sparging is planned for adjustment of high pH water (see
Section 5.0 of this SWPPP for contact information).
7.2.3 Permit Application and Changes
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.
Appendix A – Erosion and Sediment Control Plans
Appendix B – Construction BMPs
The following includes a list of the BMPs to be implemented on the site. The fact sheets provide
a descriptive narrative and construction/installation details for each BMP.
• Preserving Natural Vegetation Purpose (BMP C101)
• High Visibility Fence (BMP C103)
• Stabilized Construction Entrance (BMP C105)
• Wheel Wash (BMP C106)
• Temporary and Permanent Seeding (BMP C120)
• Topsoiling (BMP C125)
• Dust Control (BMP C140)
• Concrete Handling (BMP C151)
• Sawcutting and Surfacing Pollution Prevention (BMP C152)
• Contractor Erosion and Spill Control Lead (BMP C160)
• Scheduling (BMP C162)
• Interceptor Dike and Swale (BMP C200)
• Pipe Slope Drain (BMP C204)
• Check Dams (BMP C207)
• Outlet Protection (BMP C209)
• Storm Drain Inlet Protection (BMP C220)
• Gravel Filter Berm (BMP C232)
• Silt Fence (BMP C233)
• Sediment Trap (BMP C240)
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BMP C101: Preserving Natural Vegetation
Purpose The purpose of preserving natural vegetation is to reduce erosion wherever
practicable. Limiting site disturbance is the single most effective method
for reducing erosion. For example, conifers can hold up to about 50
percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to
the ground after the storm.
Conditions of Use Natural vegetation should be preserved on steep slopes, near perennial
and intermittent watercourses or swales, and on building sites in wooded areas.
• As required by local governments.
• Phase construction to preserve natural vegetation on the project site for
as long as possible during the construction period.
Design and Installation Specifications
Natural vegetation can be preserved in natural clumps or as individual trees, shrubs and vines.
The preservation of individual plants is more difficult because heavy
equipment is generally used to remove unwanted vegetation. The points
to remember when attempting to save individual plants are:
• Is the plant worth saving? Consider the location, species, size, age, vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees.
• Fence or clearly mark areas around trees that are to be saved. It is
preferable to keep ground disturbance away from the trees at least as
far out as the dripline.
Plants need protection from three kinds of injuries:
• Construction Equipment - This injury can be above or below the
ground level. Damage results from scarring, cutting of roots, and
compaction of the soil. Placing a fenced buffer zone around plants to
be saved prior to construction can prevent construction equipment injuries.
• Grade Changes - Changing the natural ground level will alter grades,
which affects the plant's ability to obtain the necessary air, water, and
minerals. Minor fills usually do not cause problems although
sensitivity between species does vary and should be checked. Trees can typically tolerate fill of 6 inches or less. For shrubs and other
plants, the fill should be less.
When there are major changes in grade, it may become necessary to
supply air to the roots of plants. This can be done by placing a layer of
gravel and a tile system over the roots before the fill is made. A tile system protects a tree from a raised grade. The tile system should be
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laid out on the original grade leading from a dry well around the tree trunk. The system should then be covered with small stones to allow
air to circulate over the root area.
Lowering the natural ground level can seriously damage trees and
shrubs. The highest percentage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area
around the plants to be saved. If roots are exposed, construction of
retaining walls may be needed to keep the soil in place. Plants can also
be preserved by leaving them on an undisturbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the
plant.
• Excavations - Protect trees and other plants when excavating for
drainfields, power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with
hand tools or with power augers. If it is not possible to route the trench
around plants to be saved, then the following should be observed:
Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint if roots will be exposed for more than 24-hours.
Backfill the trench as soon as possible.
Tunnel beneath root systems as close to the center of the main trunk to
preserve most of the important feeder roots.
Some problems that can be encountered with a few specific trees are:
• Maple, Dogwood, Red alder, Western hemlock, Western red cedar,
and Douglas fir do not readily adjust to changes in environment and
special care should be taken to protect these trees.
• The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hemlock is moderate. The danger of windthrow
increases where dense stands have been thinned. Other species (unless
they are on shallow, wet soils less than 20 inches deep) have a low
windthrow hazard.
• Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other
hand, they thrive in high moisture conditions that other trees would
not.
• Thinning operations in pure or mixed stands of Grand fir, Pacific silver
fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock, Pacific dogwood, and Red alder can cause serious disease problems.
Disease can become established through damaged limbs, trunks, roots,
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and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack.
Maintenance
Standards
Inspect flagged and/or fenced areas regularly to make sure flagging or
fencing has not been removed or damaged. If the flagging or fencing
has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored.
• If tree roots have been exposed or injured, “prune” cleanly with an
appropriate pruning saw or lopers directly above the damaged roots
and recover with native soils. Treatment of sap flowing trees (fir,
hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier.
BMP C102: Buffer Zones
Purpose Creation of an undisturbed area or strip of natural vegetation or an
established suitable planting that will provide a living filter to reduce soil
erosion and runoff velocities.
Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Vegetative
buffer zones can be used to protect natural swales and can be incorporated
into the natural landscaping of an area.
Critical-areas buffer zones should not be used as sediment treatment areas. These areas shall remain completely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow the use of the
expanded area for removal of sediment.
Design and Installation Specifications
• Preserving natural vegetation or plantings in clumps, blocks, or strips
is generally the easiest and most successful method.
• Leave all unstable steep slopes in natural vegetation.
• Mark clearing limits and keep all equipment and construction debris
out of the natural areas and buffer zones. Steel construction fencing is
the most effective method in protecting sensitive areas and buffers.
Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective.
• Keep all excavations outside the dripline of trees and shrubs.
• Do not push debris or extra soil into the buffer zone area because it
will cause damage from burying and smothering.
• Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal
permits or approvals.
Maintenance
Standards
Inspect the area frequently to make sure flagging remains in place and the
area remains undisturbed. Replace all damaged flagging immediately.
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BMP C103: High Visibility Fence
Purpose 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, exits, or internal roads.
4. Protect areas where marking with survey tape may not provide
adequate protection.
Conditions of Use To establish clearing limits plastic, fabric, 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 Installation Specifications
High visibility plastic fence shall be composed of a high-density
polyethylene material and shall be at least four feet in height. Posts 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.
If appropriate install fabric silt fence in accordance with BMP C233 to
act as high visibility fence. Silt fence shall be at least 3 feet high and
must be highly visible to meet the requirements of this BMP.
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 Standards If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored.
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BMP C105: Stabilized Construction Entrance / Exit
Purpose Stabilized Construction entrances are established to reduce the amount of
sediment transported onto paved roads by vehicles or equipment. This is done by constructing a stabilized pad of quarry spalls at entrances and
exits for construction sites.
Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering
or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site.
For residential construction provide stabilized construction entrances for each residence, rather than only at the main subdivision entrance.
Stabilized surfaces shall be of sufficient length/width to provide vehicle access/parking, based on lot size/configuration.
On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional
stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take
place; additional materials will enable the contractor to install them where needed.
Design and Installation
Specifications
See Figure 4.1.1 for details. Note: the 100’ minimum length of the entrance shall be reduced to the maximum practicable size when the size
or configuration of the site does not allow the full length (100’).
Construct stabilized construction entrances with a 12-inch thick pad of 4-
inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do not use crushed concrete, cement,
or calcium chloride for construction entrance stabilization because these products raise pH levels in stormwater and concrete discharge to surface
waters of the State is prohibited.
A separation geotextile shall be placed under the spalls to prevent fine
sediment from pumping up into the rock pad. The geotextile shall meet the following standards:
Grab Tensile Strength (ASTM D4751) 200 psi min.
Grab Tensile Elongation (ASTM D4632) 30% max.
Mullen Burst Strength (ASTM D3786-80a) 400 psi min.
AOS (ASTM D4751) 20-45 (U.S. standard sieve size)
• Consider early installation of the first lift of asphalt in areas that will
paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large
concrete pours, excess concrete is often available for this purpose.
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• Fencing (see BMP C103) shall be installed as necessary to restrict
traffic to the construction entrance.
• Whenever possible, the entrance shall be constructed on a firm,
compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance.
• Construction entrances should avoid crossing existing sidewalks and back of walk drains if at all possible. If a construction entrance must
cross a sidewalk or back of walk drain, the full length of the sidewalk and back of walk drain must be covered and protected from sediment
leaving the site.
Maintenance Standards
Quarry spalls shall be added if the pad is no longer in accordance with
the specifications.
• If the entrance is not preventing sediment from being tracked onto
pavement, then alternative measures to keep the streets free of sediment shall be used. This may include replacement/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash.
• Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be
cleaned by washing down the street, except when high efficiency sweeping is ineffective and there is a threat to public safety. If it is
necessary to wash the streets, the construction of a small sump to contain the wash water shall be considered. The sediment would then
be washed into the sump where it can be controlled.
• Perform street sweeping by hand or with a high efficiency sweeper. Do
not use a non-high efficiency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches.
• Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately.
• If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see BMP C103) shall be installed to
control traffic.
• Upon project completion and site stabilization, all construction
accesses intended as permanent access for maintenance shall be permanently stabilized.
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Figure 4.1.1 – Stabilized Construction Entrance
Approved as
Equivalent
Ecology has approved products as able to meet the requirements of BMP
C105. The products did not pass through the Technology Assessment
Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for
review on Ecology’s website at
http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html
BMP C106: Wheel Wash
Purpose Wheel washes reduce the amount of sediment transported onto paved
roads by motor vehicles.
Conditions of Use When a stabilized construction entrance (see BMP C105) is not preventing
sediment from being tracked onto pavement.
• Wheel washing is generally an effective BMP when installed with careful attention to topography. For example, a wheel wash can be
detrimental if installed at the top of a slope abutting a right-of-way
where the water from the dripping truck can run unimpeded into the
street.
Driveway shall meet the requirements of the permitting agency
It is recommended that the entrance be crowned so that runoff drains off the pad
Provide full width of ingress/egress area
12” min. thickness
Geotextile
4’ – 8” quarry spalls
Install driveway culvert if there is a roadside ditch present
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• Pressure washing combined with an adequately sized and surfaced pad with direct drainage to a large 10-foot x 10-foot sump can be very
effective.
• Discharge wheel wash or tire bath wastewater to a separate on-site
treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval.
• Wheel wash or tire bath wastewater should not include wastewater
from concrete washout areas.
Design and Installation Specifications
Suggested details are shown in Figure 4.1.2. The Local Permitting Authority may allow other designs. A minimum of 6 inches of asphalt treated base (ATB) over crushed base material or 8 inches over a good
subgrade is recommended to pave the wheel wash.
Use a low clearance truck to test the wheel wash before paving. Either a
belly dump or lowboy will work well to test clearance.
Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water.
Midpoint spray nozzles are only needed in extremely muddy conditions.
Wheel wash systems should be designed with a small grade change, 6- to
1-inches for a 10-foot-wide pond, to allow sediment to flow to the low side of pond to help prevent re-suspension of sediment. A drainpipe with a 2- to 3-foot riser should be installed on the low side of the pond to allow
for easy cleaning and refilling. Polymers may be used to promote
coagulation and flocculation in a closed-loop system. Polyacrylamide
(PAM) added to the wheel wash water at a rate of 0.25 - 0.5 pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time. If PAM is already being used for dust or erosion control and is being applied
by a water truck, the same truck can be used to change the wash water.
Maintenance Standards The wheel wash should start out the day with fresh water.
The wash water should be changed a minimum of once per day. On large earthwork jobs where more than 10-20 trucks per hour are expected, the
wash water will need to be changed more often.
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Figure 4.1.2 – Wheel Wash
Notes:
1. Asphalt construction entrance 6 in. asphalt treated base (ATB). 2. 3-inch trash pump with floats on the suction hose.
3. Midpoint spray nozzles, if needed. 4. 6-inch sewer pipe with butterfly valves. Bottom one is a drain. Locate top pipe’s invert 1 foot above bottom
of wheel wash. 5. 8 foot x 8 foot sump with 5 feet of catch. Build so the sump can be cleaned with a trackhoe.
6. Asphalt curb on the low road side to direct water back to pond. 7. 6-inch sleeve under road.
8. Ball valves. 9. 15 foot. ATB apron to protect ground from splashing water.
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stable driving surface and to stabilize any areas that have eroded.
Following construction, these areas shall be restored to pre-construction
condition or better to prevent future erosion.
Perform street cleaning at the end of each day or more often if necessary.
BMP C120: Temporary and Permanent Seeding
Purpose Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion.
Conditions of Use Use seeding throughout the project on disturbed areas that have reached
final grade or that will remain unworked for more than 30 days.
The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1.
Between July 1 and August 30 seeding requires irrigation until 75 percent
grass cover is established.
Between October 1 and March 30 seeding requires a cover of mulch with
straw or an erosion control blanket until 75 percent grass cover is established.
Review all disturbed areas in late August to early September and complete
all seeding by the end of September. Otherwise, vegetation will not
establish itself enough to provide more than average protection.
• Mulch is required at all times for seeding because it protects seeds from heat, moisture loss, and transport due to runoff. Mulch can be applied on top of the seed or simultaneously by hydroseeding. See BMP C121: Mulching for specifications.
• Seed and mulch, all disturbed areas not otherwise vegetated at final site stabilization. Final stabilization means the completion of all soil disturbing activities at the site and the establishment of a permanent
vegetative cover, or equivalent permanent stabilization measures (such
as pavement, riprap, gabions or geotextiles) which will prevent
erosion.
Design and Installation
Specifications
Seed retention/detention ponds as required.
Install channels intended for vegetation before starting major
earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated
channels that will have high flows, install erosion control blankets
over hydroseed. Before allowing water to flow in vegetated channels, establish 75 percent vegetation cover. If vegetated channels cannot be established by seed before water flow; install sod
in the channel bottom—over hydromulch and erosion control
blankets.
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• Confirm the installation of all required surface water control measures to prevent seed from washing away.
• Hydroseed applications shall include a minimum of 1,500 pounds per
acre of mulch with 3 percent tackifier. See BMP C121: Mulching for
specifications.
• Areas that will have seeding only and not landscaping may need compost or meal-based mulch included in the hydroseed in order to
establish vegetation. Re-install native topsoil on the disturbed soil
surface before application.
• When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. To overcome this, consider increasing seed quantities by up to 50 percent.
• Enhance vegetation establishment by dividing the hydromulch operation into two phases:
1. Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift.
2. Phase 2- Install the rest of the mulch and tackifier over the first lift.
Or, enhance vegetation by:
1. Installing the mulch, seed, fertilizer, and tackifier in one lift.
2. Spread or blow straw over the top of the hydromulch at a rate of
800-1000 pounds per acre.
3. Hold straw in place with a standard tackifier.
Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost
may be offset by the reduced need for:
• Irrigation.
• Reapplication of mulch.
• Repair of failed slope surfaces.
This technique works with standard hydromulch (1,500 pounds per
acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum).
• Seed may be installed by hand if:
• Temporary and covered by straw, mulch, or topsoil.
• Permanent in small areas (usually less than 1 acre) and covered
with mulch, topsoil, or erosion blankets.
• The seed mixes listed in the tables below include recommended mixes for both temporary and permanent seeding.
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• Apply these mixes, with the exception of the wetland mix, at a rate of 120 pounds per acre. This rate can be reduced if soil
amendments or slow-release fertilizers are used.
• Consult the local suppliers or the local conservation district for
their recommendations because the appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the
local authority may be used.
• Other mixes may be appropriate, depending on the soil type and
hydrology of the area.
• Table 4.1.2 lists the standard mix for areas requiring a temporary vegetative cover.
Table 4.1.2 Temporary Erosion Control Seed Mix
% Weight % Purity % Germination
Chewings or annual blue grass
Festuca rubra var. commutata or Poa anna
40 98 90
Perennial rye - Lolium perenne 50 98 90
Redtop or colonial bentgrass
Agrostis alba or Agrostis tenuis
5 92 85
White dutch clover
Trifolium repens
5 98 90
• Table 4.1.3 lists a recommended mix for landscaping seed.
Table 4.1.3 Landscaping Seed Mix
% Weight % Purity % Germination
Perennial rye blend Lolium perenne 70 98 90
Chewings and red fescue blend
Festuca rubra var. commutata
or Festuca rubra
30 98 90
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• Table 4.1.4 lists a turf seed mix for dry situations where there is no need for watering. This mix requires very little maintenance.
Table 4.1.4 Low-Growing Turf Seed Mix
% Weight % Purity % Germination
Dwarf tall fescue (several varieties)
Festuca arundinacea var.
45 98 90
Dwarf perennial rye (Barclay) Lolium perenne var. barclay 30 98 90
Red fescue
Festuca rubra
20 98 90
Colonial bentgrass
Agrostis tenuis
5 98 90
• Table 4.1.5 lists a mix for bioswales and other intermittently wet areas.
Table 4.1.5
Bioswale Seed Mix*
% Weight % Purity % Germination
Tall or meadow fescue
Festuca arundinacea or Festuca
elatior
75-80 98 90
Seaside/Creeping bentgrass
Agrostis palustris
10-15 92 85
Redtop bentgrass
Agrostis alba or Agrostis gigantea
5-10 90 80
* Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
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• Table 4.1.6 lists a low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Apply
this mixture at a rate of 60 pounds per acre. Consult Hydraulic Permit
Authority (HPA) for seed mixes if applicable.
Table 4.1.6
Wet Area Seed Mix*
% Weight % Purity % Germination
Tall or meadow fescue
Festuca arundinacea or
Festuca elatior
60-70 98 90
Seaside/Creeping bentgrass
Agrostis palustris
10-15 98 85
Meadow foxtail
Alepocurus pratensis
10-15 90 80
Alsike clover Trifolium hybridum 1-6 98 90
Redtop bentgrass Agrostis alba 1-6 92 85
* Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
• Table 4.1.7 lists a recommended meadow seed mix for infrequently
maintained areas or non-maintained areas where colonization by native
plants is desirable. Likely applications include rural road and utility right-of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter
months. Consider the appropriateness of clover, a fairly invasive
species, in the mix. Amending the soil can reduce the need for clover.
Table 4.1.7
Meadow Seed Mix
% Weight % Purity % Germination
Redtop or Oregon bentgrass
Agrostis alba or Agrostis
oregonensis
20 92 85
Red fescue
Festuca rubra
70 98 90
White dutch clover
Trifolium repens
10 98 90
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• Roughening and Rototilling:
• The seedbed should be firm and rough. Roughen all soil no matter
what the slope. Track walk slopes before seeding if engineering
purposes require compaction. Backblading or smoothing of slopes
greater than 4H:1V is not allowed if they are to be seeded.
• Restoration-based landscape practices require deeper incorporation than that provided by a simple single-pass rototilling treatment.
Wherever practical, initially rip the subgrade to improve long-term
permeability, infiltration, and water inflow qualities. At a
minimum, permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper
than 8 inches complete the rototilling process in multiple lifts, or
prepare the engineered soil system per specifications and place to
achieve the specified depth.
• Fertilizers:
• Conducting soil tests to determine the exact type and quantity of
fertilizer is recommended. This will prevent the over-application
of fertilizer.
• Organic matter is the most appropriate form of fertilizer because it provides nutrients (including nitrogen, phosphorus, and potassium) in the least water-soluble form.
• In general, use 10-4-6 N-P-K (nitrogen-phosphorus-potassium)
fertilizer at a rate of 90 pounds per acre. Always use slow-release
fertilizers because they are more efficient and have fewer environmental impacts. Do not add fertilizer to the hydromulch machine, or agitate, more than 20 minutes before use. Too much
agitation destroys the slow-release coating.
• There are numerous products available that take the place of
chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent
cottonseed meal is used as the mulch in hydroseed, chemical
fertilizer may not be necessary. Cottonseed meal provides a good
source of long-term, slow-release, available nitrogen.
• Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix:
• On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically
Bonded Fiber Matrix (MBFM) products. Apply BFM/MBFM
products at a minimum rate of 3,000 pounds per acre of mulch
with approximately 10 percent tackifier. Achieve a minimum of 95
percent soil coverage during application. Numerous products are available commercially. Installed products per manufacturer’s
instructions. Most products require 24-36 hours to cure before
rainfall and cannot be installed on wet or saturated soils.
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Generally, products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer.
• BFMs and MBFMs provide good alternatives to blankets in most
areas requiring vegetation establishment. Advantages over
blankets include:
• BFM and MBFMs do not require surface preparation.
• Helicopters can assist in installing BFM and MBFMs in remote areas.
• On slopes steeper than 2.5H:1V, blanket installers may require ropes and harnesses for safety.
• Installing BFM and MBFMs can save at least $1,000 per acre compared to blankets.
Maintenance
Standards
Reseed any seeded areas that fail to establish at least 80 percent cover
(100 percent cover for areas that receive sheet or concentrated flows). If
reseeding is ineffective, use an alternate method such as sodding, mulching, or nets/blankets. If winter weather prevents adequate grass
growth, this time limit may be relaxed at the discretion of the local
authority when sensitive areas would otherwise be protected.
• Reseed and protect by mulch any areas that experience erosion after
achieving adequate cover. Reseed and protect by mulch any eroded area.
• Supply seeded areas with adequate moisture, but do not water to the
extent that it causes runoff.
Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP
C120. The products did not pass through the Technology Assessment Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing
prior to consideration for local use. The products are available for review on
Ecology’s website at
http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html
BMP C121: Mulching
Purpose Mulching soils provides immediate temporary protection from erosion.
Mulch also enhances plant establishment by conserving moisture, holding
fertilizer, seed, and topsoil in place, and moderating soil temperatures.
There is an enormous variety of mulches that can be used. This section discusses only the most common types of mulch.
Conditions of Use As a temporary cover measure, mulch should be used:
• For less than 30 days on disturbed areas that require cover.
• At all times for seeded areas, especially during the wet season and
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Design and Installation
Specifications
Sod shall be free of weeds, of uniform thickness (approximately 1-inch thick), and shall have a dense root mat for mechanical strength.
The following steps are recommended for sod installation:
• Shape and smooth the surface to final grade in accordance with the
approved grading plan. The swale needs to be overexcavated 4 to 6 inches below design elevation to allow room for placing soil amendment and sod.
• Amend 4 inches (minimum) of compost into the top 8 inches of the
soil if the organic content of the soil is less than ten percent or the
permeability is less than 0.6 inches per hour. See http://www.ecy.wa.gov/programs/swfa/organics/soil.html for further information.
• Fertilize according to the supplier's recommendations.
• Work lime and fertilizer 1 to 2 inches into the soil, and smooth the
surface.
• Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water flow. Wedge strips securely
into place. Square the ends of each strip to provide for a close, tight fit.
Stagger joints at least 12 inches. Staple on slopes steeper than 3H:1V.
Staple the upstream edge of each sod strip.
• Roll the sodded area and irrigate.
• When sodding is carried out in alternating strips or other patterns, seed
the areas between the sod immediately after sodding.
Maintenance Standards
If the grass is unhealthy, the cause shall be determined and appropriate
action taken to reestablish a healthy groundcover. If it is impossible to establish a healthy groundcover due to frequent saturation, instability, or some other cause, the sod shall be removed, the area seeded with an
appropriate mix, and protected with a net or blanket.
BMP C125: Topsoiling / Composting
Purpose Topsoiling and composting provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in
itself, topsoiling and composting are an integral component of providing
permanent cover in those areas where there is an unsuitable soil surface
for plant growth. Use this BMP in conjunction with other BMPs such as
seeding, mulching, or sodding.
Native soils and disturbed soils that have been organically amended not
only retain much more stormwater, but they also serve as effective
biofilters for urban pollutants and, by supporting more vigorous plant
growth, reduce the water, fertilizer and pesticides needed to support
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installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris.
Conditions of
Use
• Permanent landscaped areas shall contain healthy topsoil that reduces
the need for fertilizers, improves overall topsoil quality, provides for
better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation.
• Leave native soils and the duff layer undisturbed to the maximum
extent practicable. Stripping of existing, properly functioning soil
system and vegetation for the purpose of topsoiling during
construction is not acceptable. Preserve existing soil systems in undisturbed and uncompacted conditions if functioning properly.
• Areas that already have good topsoil, such as undisturbed areas, do not
require soil amendments.
• Restore, to the maximum extent practical, native soils disturbed during
clearing and grading to a condition equal to or better than the original site condition’s moisture-holding capacity. Use on-site native topsoil, incorporate amendments into on-site soil, or import blended topsoil to
meet this requirement.
• Topsoiling is a required procedure when establishing vegetation on
shallow soils, and soils of critically low pH (high acid) levels.
• Beware of where the topsoil comes from, and what vegetation was on site before disturbance, invasive plant seeds may be included and could
cause problems for establishing native plants, landscaped areas, or
grasses.
• Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum
conditions for establishing grasses. Use commercially available
mycorrhiza products when using off-site topsoil.
Design and Installation
Specifications
Meet the following requirements for areas requiring disruption and
topsoiling:
• Maximize the depth of the topsoil wherever possible to provide the
maximum possible infiltration capacity and beneficial growth
medium. Topsoil shall have:
• A minimum depth of 8-inches. Scarify subsoils below the topsoil
layer at least 4-inches with some incorporation of the upper
material to avoid stratified layers, where feasible. Ripping or re-
structuring the subgrade may also provide additional benefits
regarding the overall infiltration and interflow dynamics of the soil system.
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• A minimum organic content of 10% dry weight, and 5% organic matter content in turf areas. Incorporate organic amendments to a
minimum 8-inch depth except where tree roots or other natural
features limit the depth of incorporation.
• A pH between 6.0 and 8.0 or matching the pH of the undisturbed soil.
• If blended topsoil is imported, then fines should be limited to 25
percent passing through a 200 sieve.
• Accomplish the required organic content and pH by either returning
native topsoil to the site and/or incorporating organic amendments.
• To meet the organic content use compost that meets the definition of “composted materials” in WAC 173-350-220. This code is
available online at:
http://apps.leg.wa.gov/WAC/default.aspx?cite=173-350-220.
The compost must also have an organic matter content of 35% to 65%, and a carbon to nitrogen ratio below 25H:1V.
The carbon to nitrogen ratio may be as high as 35H:1V for
plantings composed entirely of plants native to the Puget Sound
Lowlands region.
• For till soils use a mixture of approximately two parts soil to one part compost. This equates to 4 inches of compost mixed to a depth of 12 inches in till soils. Increasing the concentration of compost
beyond this level can have negative effects on vegetal health, while
decreasing the concentrations can reduce the benefits of amended
soils.
• Gravel or cobble outwash soils, may require different approaches. Organics and fines easily migrate through the loose structure of
these soils. Therefore, the importation of at least 6 inches of
quality topsoil, underlain by some type of filter fabric to prevent
the migration of fines, may be more appropriate for these soils.
• The final composition and construction of the soil system will result in
a natural selection or favoring of certain plant species over time. For
example, incorporation of topsoil may favor grasses, while layering
with mildly acidic, high-carbon amendments may favor more woody
vegetation.
• Allow sufficient time in scheduling for topsoil spreading prior to
seeding, sodding, or planting.
• Take care when applying top soil to subsoils with contrasting textures.
Sandy topsoil over clayey subsoil is a particularly poor combination,
as water creeps along the junction between the soil layers and causes the topsoil to slough. If topsoil and subsoil are not properly bonded,
water will not infiltrate the soil profile evenly and it will be difficult to
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establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least
6 inches.
• Field exploration of the site shall be made to determine if there is
surface soil of sufficient quantity and quality to justify stripping. Topsoil shall be friable and loamy (loam, sandy loam, silt loam, sandy clay loam, and clay loam). Avoid areas of natural ground water
recharge.
• Stripping shall be confined to the immediate construction area. A 4-
inch to 6-inch stripping depth is common, but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping.
• Do not place topsoil while in a frozen or muddy condition, when the
subgrade is excessively wet, or when conditions exist that may
otherwise be detrimental to proper grading or proposed sodding or seeding.
• In any areas requiring grading remove and stockpile the duff layer and
topsoil on site in a designated, controlled area, not adjacent to public
resources and critical areas. Stockpiled topsoil is to be reapplied to
other portions of the site where feasible.
• Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than
one pile in proximity to areas where topsoil will be used.
Stockpiling of topsoil shall occur in the following manner:
• Side slopes of the stockpile shall not exceed 2H:1V.
• Between October 1 and April 30:
• An interceptor dike with gravel outlet and silt fence shall
surround all topsoil.
• Within 2 days complete erosion control seeding, or covering
stockpiles with clear plastic, or other mulching materials.
• Between May 1 and September 30:
• An interceptor dike with gravel outlet and silt fence shall
surround all topsoil if the stockpile will remain in place for a
longer period of time than active construction grading.
• Within 7 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials.
• When native topsoil is to be stockpiled and reused the following
should apply to ensure that the mycorrhizal bacterial, earthworms, and
other beneficial organisms will not be destroyed:
1. Re-install topsoil within 4 to 6 weeks.
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2. Do not allow the saturation of topsoil with water.
3. Do not use plastic covering.
Maintenance
Standards
• Inspect stockpiles regularly, especially after large storm events.
Stabilize any areas that have eroded.
• Establish soil quality and depth toward the end of construction and once established, protect from compaction, such as from large machinery use, and from erosion.
• Plant and mulch soil after installation.
• Leave plant debris or its equivalent on the soil surface to replenish
organic matter.
• Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides, rather than continuing to implement
formerly established practices.
BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection
Purpose Polyacrylamide (PAM) is used on construction sites to prevent soil erosion.
Applying PAM to bare soil in advance of a rain event significantly reduces
erosion and controls sediment in two ways. First, PAM increases the soil’s
available pore volume, thus increasing infiltration through flocculation
and reducing the quantity of stormwater runoff. Second, it increases flocculation of suspended particles and aids in their deposition, thus reducing stormwater runoff turbidity and improving water quality.
Conditions of Use PAM shall not be directly applied to water or allowed to enter a water
body.
In areas that drain to a sediment pond, PAM can be applied to bare soil under the following conditions:
• During rough grading operations.
• In Staging areas.
• Balanced cut and fill earthwork.
• Haul roads prior to placement of crushed rock surfacing.
• Compacted soil roadbase.
• Stockpiles.
• After final grade and before paving or final seeding and planting.
• Pit sites.
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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
Installation
Specifications
• Vegetate or mulch areas that will not receive vehicle traffic. In areas
where planting, mulching, or paving is impractical, apply gravel or
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. 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 C126) 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 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. Use of PAM could be a 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.
• 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.
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• 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 of paved roadways 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
Standards
Respray area as necessary to keep dust to a minimum.
BMP C150: Materials on Hand
Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unexpected heavy summer rains. Having
these materials on-site reduces the time needed to implement BMPs when
inspections indicate that existing BMPs are not meeting the Construction
SWPPP requirements. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard.
Conditions of Use • Construction projects of any size or type can benefit from having
materials on hand. A small commercial development project could
have a roll of plastic and some gravel available for immediate
protection of bare soil and temporary berm construction. A large earthwork project, such as highway construction, might have several
tons of straw, several rolls of plastic, flexible pipe, sandbags,
geotextile fabric and steel “T” posts.
• Materials are stockpiled and readily available before any site clearing,
grubbing, or earthwork begins. A large contractor or developer could keep a stockpile of materials that are available for use on several
projects.
• If storage space at the project site is at a premium, the contractor could
maintain the materials at their office or yard. The office or yard must
be less than an hour from the project site.
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Design and Installation
Specifications
Depending on project type, size, complexity, and length, materials and quantities will vary. A good minimum list of items that will cover
numerous situations includes:
Material
Clear Plastic, 6 mil
Drainpipe, 6 or 8 inch diameter
Sandbags, filled
Straw Bales for mulching,
Quarry Spalls
Washed Gravel Geotextile Fabric
Catch Basin Inserts
Steel “T” Posts
Silt fence material
Straw Wattles
Maintenance Standards • All materials with the exception of the quarry spalls, steel “T” posts,
and gravel should be kept covered and out of both sun and rain.
• Re-stock materials used as needed.
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. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate
concrete, concrete process water, and concrete slurry from entering waters
of the state.
Conditions of Use Any time concrete is used, utilize these management practices. Concrete
construction projects include, but are not limited to, the following:
• Curbs
• Sidewalks
• Roads
• Bridges
• Foundations
• Floors
• Runways
Design and
Installation
• Wash out concrete truck chutes, pumps, and internals into formed
areas only. Assure that washout of concrete trucks is performed off-
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Specifications site or in designated concrete washout areas. Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or
streams. Refer to BMP C154 for information on concrete washout
areas.
• Return unused concrete remaining in the truck and pump to the originating batch plant for recycling. Do not dump excess concrete on site, except in designated concrete washout areas.
• Wash off hand tools including, but not limited to, screeds, shovels,
rakes, floats, and trowels into formed areas only.
• Wash equipment difficult to move, such as concrete pavers in areas that do not directly drain to natural or constructed stormwater conveyances.
• Do not allow washdown from areas, such as concrete aggregate
driveways, to drain directly to natural or constructed stormwater
conveyances.
• Contain washwater and leftover product in a lined container when no formed areas are available,. Dispose of contained concrete in a manner
that does not violate ground water or surface water quality standards.
• Always use forms or solid barriers for concrete pours, such as pilings,
within 15-feet of surface waters.
• Refer to BMPs C252 and C253 for pH adjustment requirements.
• Refer to the Construction Stormwater General Permit for pH
monitoring requirements if the project involves one of the following
activities:
• Significant concrete work (greater than 1,000 cubic yards poured concrete or recycled concrete used over the life of a project).
• The use of engineered soils amended with (but not limited to)
Portland cement-treated base, cement kiln dust or fly ash.
• Discharging stormwater to segments of water bodies on the 303(d)
list (Category 5) for high pH.
Maintenance Standards
Check containers for holes in the liner daily during concrete pours and
repair the same day.
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BMP C152: Sawcutting and Surfacing Pollution Prevention
Purpose 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. Concrete
spillage or concrete discharge to surface waters of the State is prohibited. Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from entering waters of the State.
Conditions of Use Utilize these management practices anytime sawcutting or surfacing
operations take place. Sawcutting and surfacing operations include, but
are not limited to, the following:
• Sawing
• Coring
• Grinding
• Roughening
• Hydro-demolition
• Bridge and road surfacing
Design and
Installation
Specifications
• Vacuum slurry and cuttings during cutting and surfacing operations.
• 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 including stormwater systems. This may require temporarily blocking catch basins.
• Dispose of collected slurry and cuttings in a manner that does not
violate ground water or surface water quality standards.
• Do not allow process water generated during hydro-demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems.
Dispose process water in a manner that does not violate ground water
or surface water quality standards.
• Handle and dispose cleaning waste material and demolition debris in a manner that does not cause contamination of water. Dispose of
sweeping material from a pick-up sweeper at an appropriate disposal
site.
Maintenance Standards Continually monitor operations to determine whether slurry, cuttings, or
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.
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BMP C160: Certified Erosion and Sediment Control Lead
Purpose The project proponent designates at least one person as the responsible
representative in charge of erosion and sediment control (ESC), and water
quality protection. The designated person shall be the Certified Erosion
and Sediment Control Lead (CESCL) who is responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements.
Conditions of Use A CESCL shall be made available on projects one acre or larger that
discharge stormwater to surface waters of the state. Sites less than one
acre may have a person without CESCL certification conduct inspections; sampling is not required on sites that disturb less than an acre.
• The CESCL shall:
• Have a current certificate proving attendance in an erosion and
sediment control training course that meets the minimum ESC training and certification requirements established by Ecology (see
details below).
Ecology will maintain a list of ESC training and certification
providers at:
http://www.ecy.wa.gov/programs/wq/stormwater/cescl.html
OR
• Be a Certified Professional in Erosion and Sediment Control
(CPESC); for additional information go to: www.cpesc.net
Specifications • Certification shall remain valid for three years.
• The CESCL shall have authority to act on behalf of the contractor or
developer and shall be available, or on-call, 24 hours per day
throughout the period of construction.
• The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL.
• A CESCL may provide inspection and compliance services for
multiple construction projects in the same geographic region.
Duties and responsibilities of the CESCL shall include, but are not limited
to the following:
• Maintaining permit file on site at all times which includes the
Construction SWPPP and any associated permits and plans.
• Directing BMP installation, inspection, maintenance, modification,
and removal.
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• Updating all project drawings and the Construction SWPPP with changes made.
• Completing any sampling requirements including reporting results
using WebDMR.
• Keeping daily logs, and inspection reports. Inspection reports should include:
• Inspection date/time.
• Weather information; general conditions during inspection and
approximate amount of precipitation since the last inspection.
• A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted:
1. Locations of BMPs inspected.
2. Locations of BMPs that need maintenance.
3. Locations of BMPs that failed to operate as designed or intended.
4. Locations of where additional or different BMPs are required.
• Visual monitoring results, including a description of discharged
stormwater. The presence of suspended sediment, turbid water,
discoloration, and oil sheen shall be noted, as applicable.
• Any water quality monitoring performed during inspection.
• General comments and notes, including a brief description of
any BMP repairs, maintenance or installations made as a result
of the inspection.
• Facilitate, participate in, and take corrective actions resulting from inspections performed by outside agencies or the owner.
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
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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 Considerations • Minimize construction during rainy periods.
• 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.
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BMP C200: Interceptor Dike and Swale
Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the
top or base of a disturbed slope or along the perimeter of a disturbed
construction area to convey stormwater. Use the dike and/or swale to
intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the construction site.
Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed
to an erosion control facility which can safely convey the stormwater.
• Locate upslope of a construction site to prevent runoff from entering disturbed area.
• When placed horizontally across a disturbed slope, it reduces the
amount and velocity of runoff flowing down the slope.
• Locate downslope to collect runoff from a disturbed area and direct
water to a sediment basin.
Design and Installation
Specifications
• Dike and/or swale and channel must be stabilized with temporary or permanent vegetation or other channel protection during construction.
• Channel requires a positive grade for drainage; steeper grades require
channel protection and check dams.
• Review construction for areas where overtopping may occur.
• Can be used at top of new fill before vegetation is established.
• May be used as a permanent diversion channel to carry the runoff.
• Sub-basin tributary area should be one acre or less.
• Design capacity for the peak flow from a 10-year, 24-hour storm,
assuming a Type 1A rainfall distribution, for temporary facilities. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model. For facilities that will also serve on
a permanent basis, consult the local government’s drainage
requirements.
Interceptor dikes shall meet the following criteria:
Top Width 2 feet minimum.
Height 1.5 feet minimum on berm.
Side Slope 2H:1V or flatter.
Grade Depends on topography, however, dike system minimum is
0.5%, and maximum is 1%. Compaction Minimum of 90 percent ASTM D698 standard proctor.
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Horizontal Spacing of Interceptor Dikes:
Average Slope Slope Percent Flowpath Length
20H:1V or less 3-5% 300 feet
(10 to 20)H:1V 5-10% 200 feet
(4 to 10)H:1V 10-25% 100 feet (2 to 4)H:1V 25-50% 50 feet
Stabilization depends on velocity and reach
Slopes <5% Seed and mulch applied within 5 days of dike
construction (see BMP C121, Mulching).
Slopes 5 - 40% Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap or other measures to avoid erosion.
• The upslope side of the dike shall provide positive drainage to the dike
outlet. No erosion shall occur at the outlet. Provide energy dissipation
measures as necessary. Sediment-laden runoff must be released through a sediment trapping facility.
• Minimize construction traffic over temporary dikes. Use temporary
cross culverts for channel crossing.
Interceptor swales shall meet the following criteria:
Bottom Width 2 feet minimum; the cross-section bottom shall be level.
Depth 1-foot minimum.
Side Slope 2H:1V or flatter.
Grade Maximum 5 percent, with positive drainage to a
suitable outlet (such as a sediment pond).
Stabilization Seed as per BMP C120, Temporary and Permanent Seeding, or BMP C202, Channel
Lining, 12 inches thick riprap pressed into the bank
and extending at least 8 inches vertical from the
bottom.
• Inspect diversion dikes and interceptor swales once a week and after
every rainfall. Immediately remove sediment from the flow area.
• Damage caused by construction traffic or other activity must be
repaired before the end of each working day.
Check outlets and make timely repairs as needed to avoid gully formation. When the area below the temporary diversion dike is permanently
stabilized, remove the dike and fill and stabilize the channel to blend with
the natural surface.
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BMP C204: Pipe Slope Drains
Purpose To use a pipe to convey stormwater anytime water needs to be diverted
away from or over bare soil to prevent gullies, channel erosion, and
saturation of slide-prone soils.
Conditions of Use Pipe slope drains should be used when a temporary or permanent
stormwater conveyance is needed to move the water down a steep slope to
avoid erosion (Figure 4.2.4).
On highway projects, pipe slope drains should be used at bridge ends to
collect runoff and pipe it to the base of the fill slopes along bridge approaches. These can be designed into a project and included as bid
items. Another use on road projects is to collect runoff from pavement and
pipe it away from side slopes. These are useful because there is generally a
time lag between having the first lift of asphalt installed and the curbs,
gutters, and permanent drainage installed. Used in conjunction with sand bags, or other temporary diversion devices, these will prevent massive
amounts of sediment from leaving a project.
Water can be collected, channeled with sand bags, Triangular Silt Dikes,
berms, or other material, and piped to temporary sediment ponds.
Pipe slope drains can be:
• Connected to new catch basins and used temporarily until all
permanent piping is installed;
• Used to drain water collected from aquifers exposed on cut slopes and take it to the base of the slope;
• Used to collect clean runoff from plastic sheeting and direct it away
from exposed soil;
• Installed in conjunction with silt fence to drain collected water to a controlled area;
• Used to divert small seasonal streams away from construction. They
have been used successfully on culvert replacement and extension
jobs. Large flex pipe can be used on larger streams during culvert
removal, repair, or replacement; and,
• Connected to existing down spouts and roof drains and used to divert
water away from work areas during building renovation, demolition,
and construction projects.
There are now several commercially available collectors that are attached to the pipe inlet and help prevent erosion at the inlet.
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Design and Installation
Specifications
Size the pipe to convey the flow. The capacity for temporary drains shall be
sufficient to handle the peak volumetric flow rate calculated using a 10-
minute time step from a 10-year, 24-hour storm event, assuming a Type 1A
rainfall distribution. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model.
Consult local drainage requirements for sizing permanent pipe slope drains.
• Use care in clearing vegetated slopes for installation.
• Re-establish cover immediately on areas disturbed by installation.
• Use temporary drains on new cut or fill slopes.
• Use diversion dikes or swales to collect water at the top of the slope.
• Ensure that the entrance area is stable and large enough to direct flow
into the pipe.
• Piping of water through the berm at the entrance area is a common
failure mode.
• The entrance shall consist of a standard flared end section for culverts
12 inches and larger with a minimum 6-inch metal toe plate to prevent
runoff from undercutting the pipe inlet. The slope of the entrance shall
be at least 3 percent. Sand bags may also be used at pipe entrances as a
temporary measure.
• The soil around and under the pipe and entrance section shall be
thoroughly compacted to prevent undercutting.
• The flared inlet section shall be securely connected to the slope drain
and have watertight connecting bands.
• Slope drain sections shall be securely fastened together, fused or have gasketed watertight fittings, and shall be securely anchored into the soil.
• Thrust blocks should be installed anytime 90 degree bends are utilized.
Depending on size of pipe and flow, these can be constructed with
sand bags, straw bales staked in place, “t” posts and wire, or ecology blocks.
• Pipe needs to be secured along its full length to prevent movement.
This can be done with steel “t” posts and wire. A post is installed on
each side of the pipe and the pipe is wired to them. This should be
done every 10-20 feet of pipe length or so, depending on the size of the pipe and quantity of water to divert.
• Interceptor dikes shall be used to direct runoff into a slope drain. The
height of the dike shall be at least 1 foot higher at all points than the
top of the inlet pipe.
• The area below the outlet must be stabilized with a riprap apron (see BMP C209 Outlet Protection, for the appropriate outlet material).
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• If the pipe slope drain is conveying sediment-laden water, direct all
flows into the sediment trapping facility.
• Materials specifications for any permanent piped system shall be set
by the local government.
Maintenance Standards
Check inlet and outlet points regularly, especially after storms.
The inlet should be free of undercutting, and no water should be going
around the point of entry. If there are problems, the headwall should be
reinforced with compacted earth or sand bags.
• The outlet point should be free of erosion and installed with appropriate outlet protection.
• For permanent installations, inspect pipe periodically for vandalism and
physical distress such as slides and wind-throw.
• Normally the pipe slope is so steep that clogging is not a problem with
smooth wall pipe, however, debris may become lodged in the pipe.
Figure 4.2.4 – Pipe Slope Drain
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Figure 4.2.6 – Detail of Level Spreader
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/or 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.
• Do not place check dams 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.
• Construct rock check dams from appropriately sized rock. The rock
used must be large enough to stay in place given the expected design
flow through the channel. 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.
• Check dams may also 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.
• Place check dams perpendicular to the flow of water.
• The dam should form a triangle when viewed from the side. This
prevents undercutting as water flows over the face of the dam rather
than falling directly onto the ditch bottom.
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• Before installing check dams impound and bypass upstream water flow away from the work area. Options for bypassing include pumps,
siphons, or temporary channels.
• 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.
• 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 2H:1V 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.
• Use filter fabric foundation under a rock or sand bag check dam. If a
blanket ditch liner is used, filter fabric is not necessary. A piece of
organic or synthetic blanket cut to fit will also work for this purpose.
• 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 4.2.7 depicts a typical rock check dam.
Maintenance Standards Check dams shall be monitored for performance and sediment
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.
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Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C207. The products did not pass through the Technology Assessment
Protocol – Ecology (TAPE) process. Local jurisdictions may choose not
to accept this product approved as equivalent, or may require additional
testing prior to consideration for local use. The products are available for review on Ecology’s website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html
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Figure 4.2.7 – Rock Check Dam
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Standards accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the height of the
dam.
• Anticipate submergence and deposition above the triangular silt dam
and erosion from high flows around the edges of the dam. Immediately repair any damage or any undercutting of the dam.
BMP C209: Outlet Protection
Purpose Outlet protection prevents scour at conveyance outlets and minimizes the
potential for downstream erosion by reducing the velocity of concentrated
stormwater flows.
Conditions of use Outlet protection is required at the outlets of all ponds, pipes, ditches, or other conveyances, and where runoff is conveyed to a natural or manmade
drainage feature such as a stream, wetland, lake, or ditch.
Design and Installation Specifications
The receiving channel at the outlet of a culvert shall be protected from
erosion by rock lining a minimum of 6 feet downstream and extending up the channel sides a minimum of 1–foot above the maximum tailwater elevation or 1-foot above the crown, whichever is higher. For large pipes
(more than 18 inches in diameter), the outlet protection lining of the
channel is lengthened to four times the diameter of the culvert.
• Standard wingwalls, and tapered outlets and paved channels should also be considered when appropriate for permanent culvert outlet protection. (See WSDOT Hydraulic Manual, available through
WSDOT Engineering Publications).
• Organic or synthetic erosion blankets, with or without vegetation, are
usually more effective than rock, cheaper, and easier to install. Materials can be chosen using manufacturer product specifications. ASTM test results are available for most products and the designer can
choose the correct material for the expected flow.
• With low flows, vegetation (including sod) can be effective.
• The following guidelines shall be used for riprap outlet protection:
1. If the discharge velocity at the outlet is less than 5 fps (pipe slope
less than 1 percent), use 2-inch to 8-inch riprap. Minimum
thickness is 1-foot.
2. For 5 to 10 fps discharge velocity at the outlet (pipe slope less than
3 percent), use 24-inch to 48-inch riprap. Minimum thickness is 2 feet.
3. For outlets at the base of steep slope pipes (pipe slope greater than
10 percent), an engineered energy dissipater shall be used.
• Filter fabric or erosion control blankets should always be used under
riprap to prevent scour and channel erosion.
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• New pipe outfalls can provide an opportunity for low-cost fish habitat improvements. For example, an alcove of low-velocity water can be
created by constructing the pipe outfall and associated energy
dissipater back from the stream edge and digging a channel, over-
widened to the upstream side, from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shelter during high flows. Bank stabilization, bioengineering, and habitat features
may be required for disturbed areas. This work may require a HPA.
See Volume V for more information on outfall system design.
Maintenance Standards • Inspect and repair as needed.
• Add rock as needed to maintain the intended function.
• Clean energy dissipater if sediment builds up.
BMP C220: Storm Drain Inlet Protection
Purpose Storm drain inlet protection prevents coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area.
Conditions of Use Use storm drain inlet protection at inlets that are operational before
permanent stabilization of the disturbed drainage area. Provide protection
for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless conveying runoff entering catch basins to a sediment pond or trap.
Also consider inlet protection for lawn and yard drains on new home
construction. These small and numerous drains coupled with lack of
gutters in new home construction can add significant amounts of sediment into the roof drain system. If possible delay installing lawn and yard drains until just before landscaping or cap these drains to prevent sediment from
entering the system until completion of landscaping. Provide 18-inches of
sod around each finished lawn and yard drain.
Table 4.2.2 lists several options for inlet protection. All of the methods for storm drain inlet protection tend to plug and require a high frequency of maintenance. Limit drainage areas to one acre or less. Possibly provide
emergency overflows with additional end-of-pipe treatment where
stormwater ponding would cause a hazard.
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Table 4.2.2
Storm Drain Inlet Protection
Type of Inlet
Protection
Emergency
Overflow
Applicable for Paved/ Earthen
Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet protection Yes, temporary flooding will occur
Earthen Applicable for heavy flows. Easy to maintain. Large area Requirement: 30’ X 30’/acre
Block and gravel drop inlet protection Yes Paved or Earthen Applicable for heavy concentrated flows. Will not pond. Gravel and wire drop inlet protection No Applicable for heavy concentrated flows. Will pond. Can withstand traffic. Catch basin filters Yes Paved or Earthen Frequent maintenance required.
Curb Inlet Protection Curb inlet protection with a wooden weir Small capacity overflow Paved Used for sturdy, more compact installation. Block and gravel curb inlet protection
Yes Paved Sturdy, but limited filtration.
Culvert Inlet Protection Culvert inlet sediment trap 18 month expected life.
Design and Installation Specifications
Excavated Drop Inlet Protection - An excavated impoundment around the storm drain. Sediment settles out of the stormwater prior to entering the storm drain.
• Provide a depth of 1-2 ft as measured from the crest of the inlet
structure.
• Slope sides of excavation no steeper than 2H:1V.
• 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.
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• Build a temporary dike, if necessary, 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 4.2.8.
• Provide a height of 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 ½-inch openings
over all block openings.
• Place gravel just below the top of blocks on slopes of 2H:1V or flatter.
• An alternative design is a gravel donut.
• Provide an inlet slope of 3H:1V.
• Provide an outlet slope of 2H:1V.
• Provide a1-foot wide level stone area between the structure and the
inlet.
• Use inlet slope stones 3 inches in diameter or larger.
• Use gravel ½- to ¾-inch at a minimum thickness of 1-foot for the outlet slope.
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Figure 4.2.8 – 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.
• Use a hardware cloth or comparable wire mesh with ½-inch openings.
• Use coarse aggregate.
• Provide a 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.
• Overlap the strips if more than one strip of mesh is necessary.
Ponding Height
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 downslope side of the structure.
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• Place coarse aggregate over the wire mesh.
• Provide at least a 12-inch depth of gravel over the entire inlet opening
and extend at least 18-inches on all sides.
Catchbasin Filters – Use inserts designed by manufacturers for
construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance requirements combine 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.
• Provides 5 cubic feet of storage.
• Requires dewatering provisions.
• Provides a high-flow bypass that will not clog under normal use at a
construction site.
• Insert the catchbasin filter 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.
• Use wire mesh with ½-inch openings.
• Use 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 a curb
inlet with concrete blocks and gravel. See Figure 4.2.9.
• Use wire mesh with ½-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
4.2.10.
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• 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.
Maintenance Standards • Inspect catch basin filters frequently, especially after storm events. Clean and replace clogged inserts. For systems with clogged stone filters: pull away the stones from the inlet and clean or replace. 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.
Approved as
Equivalent
Ecology has approved products as able to meet the requirements of BMP
C220. The products did not pass through the Technology Assessment
Protocol – Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for
review on Ecology’s website at
http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html
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Figure 4.2.9 – Block and Gravel Curb Inlet Protection
A
Plan View
Wire Screen orFilter Fabric Catch Basin
Curb Inlet
Concrete Block
Ponding Height
Overflow
2x4 Wood Stud(100x50 Timber Stud)
Concrete Block
Wire Screen orFilter Fabric
Curb Inlet
¾" Drain Gravel(20mm)
¾" Drain Gravel(20mm)Section A - A
Back of Curb Concrete Block
2x4 Wood Stud
Catch BasinBack of Sidewalk
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.
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Figure 4.2.10 – Curb and Gutter Barrier
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BMP C232: Gravel Filter Berm
Purpose A gravel filter berm is constructed on rights-of-way or traffic areas within
a construction site to retain sediment by using a filter berm of gravel or
crushed rock.
Conditions of Use Where a temporary measure is needed to retain sediment from rights-of-way or in traffic areas on construction sites.
Design and
Installation
Specifications
• Berm material shall be ¾ to 3 inches in size, washed well-grade gravel
or crushed rock with less than 5 percent fines.
• Spacing of berms:
− Every 300 feet on slopes less than 5 percent
− Every 200 feet on slopes between 5 percent and 10 percent
− Every 100 feet on slopes greater than 10 percent
• Berm dimensions:
− 1 foot high with 3H:1V side slopes
− 8 linear feet per 1 cfs runoff based on the 10-year, 24-hour design
storm
Maintenance Standards • Regular inspection is required. Sediment shall be removed and filter
material replaced as needed.
BMP C233: Silt Fence
Purpose 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 4.2.12 for
details on silt fence construction.
Conditions of Use Silt fence may be used downslope of all disturbed areas.
• 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.
• Silt fence is not intended to treat concentrated flows, nor is it intended
to treat substantial amounts of overland flow. Convey any
concentrated flows through the drainage system to a sediment pond.
• Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything
deeper than sheet or overland flow.
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Figure 4.2.12 – Silt Fence
Design and
Installation Specifications
• Use in combination with sediment basins or other BMPs.
• Maximum slope steepness (normal (perpendicular) to fence line)
1H:1V.
• Maximum sheet or overland flow path length to the fence of 100 feet.
• Do not allow 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 4.2.3):
Table 4.2.3 Geotextile Standards
Polymeric Mesh AOS (ASTM D4751) 0.60 mm maximum for slit film woven (#30 sieve). 0.30 mm maximum for all other geotextile types (#50 sieve).
0.15 mm minimum for all fabric types (#100 sieve).
Water Permittivity (ASTM D4491) 0.02 sec-1 minimum
Grab Tensile Strength (ASTM D4632) 180 lbs. Minimum for extra strength fabric.
100 lbs minimum for standard strength fabric.
Grab Tensile Strength
(ASTM D4632)
30% maximum
Ultraviolet Resistance
(ASTM D4355)
70% minimum
• Support standard strength fabrics with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the
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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.
• One-hundred 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.
• Refer to Figure 4.2.12 for standard silt fence details. Include the
following standard Notes for silt fence on construction plans and specifications:
1. The contractor shall install and maintain temporary silt fences at
the locations shown in the Plans.
2. Construct silt fences in areas of clearing, grading, or drainage prior
to starting those activities.
3. The silt fence shall have a 2-feet min. and a 2½-feet max. height above the original ground surface.
4. The filter fabric shall be sewn together at the point of manufacture
to form filter fabric lengths as required. Locate all sewn seams at
support posts. 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.
5. Attach the filter fabric on the up-slope side of the posts and secure with staples, wire, or in accordance with the manufacturer's
recommendations. Attach the filter fabric to the posts in a manner
that reduces the potential for tearing.
6. Support the filter fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic
mesh is used, fasten the mesh securely to the up-slope side of the
posts with the filter fabric up-slope of the mesh.
7. Mesh 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 the same level of ultraviolet radiation as the
filter fabric it supports.
8. Bury the bottom of the filter fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of
the filter fabric, so that no flow can pass beneath the fence and
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scouring cannot occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the
ground 3-inches min.
9. Drive or place the fence posts into the ground 18-inches min. A
12–inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18-inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H:1V
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.
10. Use wood, steel or equivalent posts. The spacing of the support
posts shall be a maximum of 6-feet. Posts shall consist of either:
• Wood with dimensions of 2-inches by 2-inches wide min. and a 3-feet min. length. Wood posts shall be free of defects such as knots, splits, or gouges.
• No. 6 steel 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.
• Other steel posts having equivalent strength and bending
resistance to the post sizes listed above.
11. Locate silt fences 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.
12. If the fence must cross contours, with the exception of the ends of the fence, place gravel check dams perpendicular to the back of the
fence to minimize concentrated flow and erosion. The slope of the
fence line where contours must be crossed shall not be steeper than
3H:1V.
• Gravel check dams shall be approximately 1-foot deep at the
back of the fence. Gravel check dams 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.
• Gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. Gravel
check dams shall be located every 10 feet along the fence
where the fence must cross contours.
• Refer to Figure 4.2.13 for slicing method details. Silt fence installation using the slicing method specifications:
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1. The base of both end posts must be at least 2- to 4-inches above the top of the filter 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.
2. Install posts 3- to 4-feet apart in critical retention areas and 6- to 7-feet apart in standard applications.
3. Install posts 24-inches deep on the downstream side of the silt
fence, and as close as possible to the filter fabric, enabling posts to
support the filter fabric from upstream water pressure.
4. Install posts with the nipples facing away from the filter fabric.
5. Attach the filter fabric to each post with three ties, all spaced within the top 8-inches of the filter fabric. Attach each tie
diagonally 45 degrees through the filter fabric, with each puncture
at least 1-inch vertically apart. Each tie should be positioned to
hang on a post nipple when tightening to prevent sagging.
6. Wrap approximately 6-inches of fabric around the end posts and secure with 3 ties.
7. No more than 24-inches of a 36-inch filter fabric is allowed above
ground level.
Compact the soil immediately next to the filter 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. Check and correct the silt fence
installation for any deviation before compaction. Use a flat-bladed
shovel to tuck fabric deeper into the ground if necessary.
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Figure 4.2.13 – Silt Fence Installation by Slicing Method
Maintenance Standards
• Repair any damage immediately.
• Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment pond.
• 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.
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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 on-site, 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.
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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 Installation Specifications
• See Figures 4.2.16 and 4.2.17 for details.
• If permanent runoff control facilities are part of the project, they
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 Q2/0.00096 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.
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Surface area determinedat top of weir
Note: Trap may be formed by berm or bypartial or complete excavation
Discharge to stabilizedconveyance, outlet, orlevel spreader
¾" - 1.5"Washed gravel
Geotextile
Flat Bottom
1' Min. Overflow
1' Min.
4' Min.
RipRap2"-4" Rock
1' Min.
1.5' Min.
3.5'-5'
3H
:
1
V
M
a
x
.
• 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 Standards
• Sediment shall be removed from the trap when it reaches 1-foot in
depth.
• Any damage to the pond embankments or slopes shall be repaired.
Figure 4.2.16 – Cross Section of Sediment Trap
Figure 4.2.17 – Sediment Trap Outlet
Native soil orcompacted backfill
Geotextile
Min. 1' depth2"-4"' rock
Min. 1' depth 3/4"-1.5"washed gravel
6' Min.
1' Min. depth overflow spillway
Appendix C – General Permit
The approved NPDES General Construction Permit will be provided prior to the
beginning of construction.
STATE OF WASHINGTON
DEPARTMENT OF ECOLOGY
PO Box 47600 • Olympia, WA 98504-7600 • 360-407-6000
711 for Washington Relay Service • Persons with a speech disability can call 877-833-6341
February 13, 2017
Levi Rowse
iCap Lakeview, LLC
3535 Factoria Blvd SE Ste 500
Bellevue, WA 98006-1298
RE: Coverage under the Construction Stormwater General Permit
Permit number: WAR305059
Site Name: Senza Lakeview
Location: 3907 Park Ave N
Renton County: King
Disturbed Acres: 434
Dear Mr. Rowse:
The Washington State Department of Ecology (Ecology) received your Notice of Intent for coverage
under Ecology's Construction Stormwater General Permit (permit). This is your permit coverage
letter. Your permit coverage is effective on February 13,2017. Please retain this permit coverage
letter with your permit (enclosed), stormvitater pollution prevention plan (SWPPP), and site log
book. These materials are the official record of permit coverage for your site.
Please take time to read the entire permit and contact Ecology if you have any questions.
Appeal Process
You have a right to appeal coverage under the general permit to the Pollution Control Hearing Board
(PCHB) within 30 days of the date of receipt of this letter. This appeal is limited to the general
permit's applicability or non-applicability to a specific discharger. The appeal process is governed by
chapter 43.21B RCW and chapter 371-08 WAC. "Date of receipt" is defined in RCW 43.21B.001(2).
To appeal, you must do the following within 30 days of the date of receipt of this letter:
• File your appeal and a copy of the permit cover page with the PCHB (see addresses below).
Filing means actual receipt by the PCHB during regular business hours.
• Serve a copy of your appeal and the permit cover page on Ecology in paper form -
by mail or in person (see addresses below). E-mail is not accepted.
You must also comply with other applicable requirements in chapter 43.2IB RCW and
chapter 371-08 WAC.
Levi Rowse
February 13, 2017
Page 2
Address and Location Information:
Street Addresses:
Department of Ecology
Attn: Appeals Processing Desk
300 Desmond Drive SE
Lacey, WA 98503
Mailing Addresses:
Department of Ecology
Attn: Appeals Processing Desk
PO Box 47608
Olympia, WA 98504-7608
Pollution Control Hearings Board (PCHB)
1111 Israel Road SW, Suite 301
Tumwater, WA 98501
Pollution Control Hearings Board
PO Box 40903
Olympia, WA 98504-0903
Electronic Discharge Monitoring Reports (WQWebDMR)
This permit requires that Pennittees submit monthly discharge monitoring reports (DMRs) electronically
using Ecology's secure online system, WQWebDMR. To sign up for WQWebDMR go to:
www.ecy.wa.gov/programs/wq/permits/paris/webdmr.html. If you have questions, contact the portal staff
at (360) 407-7097 (Olympia area), or (800) 633-6193/option 3, or email WQWebPortal@ecy.wa.gov.
Ecology Field Inspector Assistance
If you have questions regarding stormwater management at your construction site, please contact
Greg Stegman of Ecology's Northwest Regional Office in Bellevue at greg.stegman@ecy.wa.gov or
(425) 649-7019.
Questions or Additional Information
Ecology is committed to providing assistance. Please review our web page at:
www.ecy.wa.gov/programs/wq/stormwater/construction. If you have questions about the
construction stormwater general permit, please contact RaChelle Stane at rcla461@ecy.wa.gov or
(360) 407-6556.
Sincerely,
Bill Moore, P.E., Manager
Program Development Services Section
Water Quality Program
Enclosure
Appendix D – 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 remedial actions
required to bring the site back into compliance, as well as a schedule of
implementation.
i. 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 S5.F of the permit.
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 BMPs
Element 1: Mark Clearing Limits
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 2: Establish Construction Access
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 3: Control Flow Rates
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 4: Install Sediment Controls
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action
Y N Y N NIP
Element 5: Stabilize Soils
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 6: Protect Slopes
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action
Y N Y N NIP
Element 7: Protect Drain Inlets
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 8: Stabilize Channels and Outlets
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 9: Control Pollutants
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Element 10: Control Dewatering
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
BMP:
Location Inspected Functioning Problem/Corrective Action Y N Y N NIP
Stormwater Discharges From the Site
Observed? Problem/Corrective Action Y N
Location
Turbidity
Discoloration
Sheen
Location
Turbidity
Discoloration
Sheen
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: