20130331 Stormwater Pollution Prevention Plan 08212013 '
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Stormwater Pollution Prevention Plan
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For
. � Weber Property
Prepared For
� Northwest Regional Office
3190 - 160th Avenue SE
Bellevue, WA 98008-5452
425-649-7000
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� � Owner Developer Operator/Contractor
Randy Weber Randy Weber TBD
' � 25720 217th Avenue S.E. 25720 217th Avenue S.E. �
Maple Valley, WA 98038 Maple Valley, WA 98038 �
' �
Project Site Location
� Between NW Crystal Springs Street and Rhoton Road S.E. Yelm, Washington
Certified Erosion and Sediment Control Lead
� TBD
� SWPPP Prepared By
Barghausen Consulting Engineers, Inc.
� 18215 72nd Avenue South
Kent, WA 98032
(425) 251-6222
� Will Schuur, Design Engineer
SWPPP Preparation Date
� 6/19/2013
Approximate Project Construction Dates
� TBD
� ��FI�IED
' AUG 21 2013
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Contents
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1.0 Introduction...............................................................................................................................1
� ......................................3
2.0 Site Description ..................................................................................
�'" 2.1 Existing Conditions
...........................................................................................................3
2.2 Proposed Construction Activities.................................................................o..............e.....3
3.0 Construction StormwaterBMPs...........................................................................o...................5
� 3.1 The 12 BMP Elementse...........................................o..........................................................5
3.1.1 Element#1 —Mark Clearing Limits...................................................................5
� 3.1.2 Element#2—Establish Construction Access.....................................................5
3.1.3 Element#3 —Control Flow Rates..................................................o....................5
3.1.4 Element#4—Install Sediment Controls..a.....................................e................e...5
� 3.1.5 Element#5 — Stabilize Soils.............e.......e....................................o....................6
3.1.6 Element#6—Protect Slopes.............e......e.....................................................a....6
3.1.7 Element#7—Protect Drain Inlets..................................................e....................6
3.1.8 Element#8—Stabilize Channels and Outlets................................o..............o.....6
�" 3.1.9 Element#9—Control Pollutants............................... ..............7
' .....................e e.....
3.1.10 Element#10—Control Dewatering..............................................00..................e7
� 3.1.11 Element#11 —Maintain BMPs ....................................................°e...................7
3.1.12 Element#12—Manage the Project....................................................................7
� 3.2 Site Specific BMPs...........................e...........................................................e..................10
4.0 Construction Phasing and BMP Implementation...........e...e.................................oe.....
� 5.0 Pollution Prevention Team ......................................e............................................e..................12
5.1 Roles and Responsibilities...............................................................................................12
� 5.2 Team Members..............................................................................................e.................13
6.0 Site Inspections and Monitoring..........................................................................°e...............e.15
� 6.1 Site Inspection.........................e.......................................................................................15
6.1.1 Site Inspection Frequency .e......................e....................................................0..15
6.1.2 Site Inspection Documentation.........................................................................16
� 6.2 Stormwater Quality Monitoring......................................................................................16
6.2.1 Turbidity..................................................e........................................................16
6.2.2 pH...................................................................................................e.............0...17
� pH monitoring shall be conducted as follows:..............................................................17
7.0 Reporting and Recordkeeping ................................................................................................19
� 7.1 Recordkeeping..............................................................................................e..............0...19
7a 1.1 Site Log Book...................................................................................................19
, 7.1.2 Records Retention..........................................................................e..................19
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� 7.1.3 Access to Plans and Records...........ae....................................e......................e...19
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7.1.4 Updating the SWPPP........................................................................................20
7.2 Reporting.........................................................................................................................20
�"' 7.2.1 Discharge Monitoring Reports
u� .....o...........................a.......................................20
7.2.2 Notification of Noncompliance...............e........................................................20
� Appendix B—Construction BMPs.........................................................................................22
� APPendix C—General Permit.............................e..........o........................................................23
' Appendix D— Site Inspection Forms (and Site Log) .............................................................24
� Appendix A Site plans
■ Vicinity map (with all discharge points)
� ■ Site plan with TESC measures
Appendix B Construction BMPs
Appendix C General Permit
''� Appendix D Site Log and Inspection Forms
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�,,,, Stormwater Pollution Prevention Plan
1.0 Introduction
( �
This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES
' � Stormwater Permit requirements for the proposed Weber Property project in Yelm, Washington.
i The site is located between NW Crystal Springs Street and Rhoton Road S.E. in the city of Yelm,
' Washington. The proposed project is located on a 7.57-acre site. Currently, the site is covered
� with native and non-native vegetation, dirt roads, and a gravel parking area. The proposed
Weber Property project proposes to fill the east half of the site to the base flood elevation far
future construction while excavating the west half of the site for compensatory flood plain
� storage.
� Construction activities will include: clearing, excavation, and grading. The purpose of this
SWPPP is to describe the proposed construction activities and all temporary and permanent
I erosion and sediment control (TESC) measures, pollutions prevention measures,
� inspection/monitoring activities, and recordkeeping that will be implemented during the
proposed construction project. The objectives of the SWPPP are to:
� 1. Implement Best Management Practices (BMPs) to prevent erosion and
sedimentation, and to identify, reduce, eliminate or prevent stormwater
contamination and water pollution from construction activity.
� 2e Prevent violations of surface water quality, ground water quality, or sediment
management standards.
� 3e Control peak flow rates and velocities of stormwater runoff.
� This SWPPP used as guidance the Ecology SWPPP template downloaded from the Ecology
� website. This SWPPP is based on the Construction Stormwater General Permit and guidance
contained in the Stormwater 1Vlanagement Manual for Western Washington (SWMMWW 2012).
� The report is divided into seven main sections with several appendices that include stormwater
relted reference materials. The topics presented
� ❑ Section 1 —INTRODUCTION. This section provides a summary
description of the project, and the organization of the SWPPP
; document.
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� ❑ Section 2— SITE DESCRIPTION. This section provides a
� description of the existing site conditions, proposed construction
activities, and calculated stormwater flow rates for existing
conditions and post—construction conditions.
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❑ 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).
'� ❑ Section 4—CONSTRUCTION PHASING AND BMP
I IMPLEMENTATION. This section provides a description of the
� timing of the BMP implementation in relation to the project
schedulea
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❑ Section 5 —POLLUTION PREVENTION TEAM. This section
� identifies the appropriate contact names (emergency and non-
emergency), monitoring personnel, and the on-site temparary
� erosion and sedimentation control CESCL.
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� ❑ Section 6—INSPECTION AND MONITORING. This section
'� provides a description of the inspection and monitoring
requirements such as the parameters of concern to be monitored,
sample locations, sample frequencies, and sampling methods for
� all stormwater discharge locations from the site.
� ❑ Section 7—RECORDKEEPING. This section describes the
requirements for documentation of the BMP implementation, site
inspections, monitoring results, and changes to the implementation
;� of certain BMPs due to site factors experienced during
construction.
� Supporting documentation and standard forms are provided in the following Appendices:
� Appendix A— Site plans
Appendix B—Construction BMPs
I Appendix C—General Permit
� Appendix D— Site Log and Inspection Forms
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2.0 Site Description
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� 2.1 Existing Conditions
� The proposed Weber Property project site is located on a 7.57-acre site located within a portion
of the Northwest '/4, Section 19, Township 17 North., Range 2 East, Willamette Meridian, City of
� Yelm, Thurston County, Washington. Specifically, the site is located between NW Crystal
� � Springs Street and Rhoton Road S.E. Currently, the site consists entirely of pasture and trees.
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Under existing conditions, the site is approximately 93 percent pervious. When the project is
� complete, the site work will have added no new impervious areas.
The site topography consists of slopes ranging from 0 to 3 percent. There is a high point near the
� center of the sitea
Stormwater from the eastern portion of the site drains eastward into an existing ditch on Rhoton
� Road S.E. Stormwater from the western portion of the site drains to Yelm Creek.
Yelm Creek runs south to north along the west property line.
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(" 2.2 Proposed Construction Activities
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j Upon completion of the project, the eastern half of the site will have been raised to an elevation
� of 335 and the western half of the site will have been excavated for compensatory flood plain
storage.
� The following summarizes details regarding site areas:
■ Total site area: 7.57 acres
� ■ Percent impervious area before construction: 7 %
� ■ Percent impervious area after construction: 0 %
■ Disturbed area during construction: 4.98 acres
� ■ Disturbed area that is characterized as im ervious i.e.
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� access roads, staging, parking): 0.53 acres
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� Stormwater Pollution Prevention Plan
3.0 Construction Stormwater BMPs
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� 3.1 The 12 BMP Elements
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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 (BMP C101)
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f� 3.1.2 Element#2—Establish Construction Access
� Construction access or activities occurring on unpaved areas shall be minimized9 yet where
necessary, access points shall be stabilized to minimize the tracking of sediment onto public
roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent
� sediment from entering state waters. All wash wastewater shall be controlled on site. The
specific BMPs related to establishing construction access that will be used on this project
include:
� Stabilized Construction Entrance/Exit (BMP C 105)
� 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. The specific BMPs for flow control that sha11 be used
on this project include:
�„ Straw Wattles (BMP C235)
� 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 ar prior to being discharged to an infiltration facility.
The specific BMPs to be used for controlling sediment on this pro�ect mclude:
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Silt Fencing (B1VIP C233)
� Straw Wattles (BMP C235)
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� 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:
� Temporary and Permanent Seeding (BMP C120)
� 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 C 120)
� 3.1.7 Element#7—Protect Drain Inlets
All storm drain inlets and culverts made operable during construction shall be protected to
prevent unfiltered or untreated water from entering the drainage conveyance system. However,
� the first priority is to keep all access roads clean of sediment and keep street wash water separate
from entering storm drains until treatment can be provided. Storm Drain Inlet Protection(BMP
� C220)will be implemented for all drainage inlets and culverts that could potentially be impacted
� by sediment-laden runoff on and near the project site. The following inlet protection measures
I will be applied on this project:
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� Storm Drain Inlet Protection (BMP C220)
� 31.8 Element#8—Stabilize Channels and Outlets
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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. This project does not
�� propose any concentrated discharges to off-site areas. Site run-off will be in the form of sheet-
� flow and will be mitigated with straw wattles and silt fencing. If it becomes necessary, the
� specific BMPs for channel and outlet stabilization that shall be used on this project include:
Outlet Protection(BMP C209)
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�„ Stormwater Pollution Prevention Plan
3.1.9 Element#9—Control Pollutants
,�,,, All pollutants, including waste materials and demolition debris, that occur onsite shall be
handled and disposed of in a manner that does not cause contamination of stormwater. Good
� housekeeping and preventative measures will be taken to ensure that the site will be kept clean,
well organized, and free of debris. If required, BMPs to be implemented to control specific
� sources of pollutants are discussed below.
� Material on Hand(BMP C 150)
� The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under
the Federal regulations of the Clean Water Act (CWA).
� 3.1.10 Element#10—Control Dewatering
� Given the scope of wark on this project, dewatering should not be necessary as part of this
construction project.
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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
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tempararily 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 needede 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:
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■ 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 ex osed.
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■ Keep runoff velocities low.
"' ■ Retain sediment on site.
� ■ Thoroughly monitor site and maintain all ESC measures.
■ Schedule major earthwork during the dry season.
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In addition, project management will incorporate the key components listed below:
� As this project site is located west of the Cascade Mountain Crest, the project will be managed
according to the following key project components:
� Phasing of Construction
� ■ The construction project is being phased to the extent practicable in order
to prevent soil erosion, and, to the maximum extent possible, the transport
i of sediment from the site during construction.
� ■ Revegetation of exposed areas and maintenance of that vegetation shall be
an integral part of the clearing activities during each phase of construction,
per the Scheduling BMP (C 162).
Seasonal Work Limitations
� ■ From October 1 through Apri130, clearing, grading, and other soil
i disturbing activities shall only be permitted if shown to the satisfaction of
� the local permitting authority that silt-laden runoff will be prevented from
leaving the site through a combination of the following:
❑ Site conditions including existing vegetative coverage, slope, soil
type, and proximity to receiving waters; and
� ❑ Limitations on activities and the extent of disturbed areas; and
� ❑ Proposed erosion and sediment control measures.
■ Based on the mformation provided and/or local weather conditions, the
local permitting authority may expand or restrict the seasonal limitation on
�' site disturbance.
� ■ The following activities are exempt from the seasonal clearing and grading
limitations:
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Stormwater Pollution Prevention Plan
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❑ Routine maintenance and necessary repair of erosion and sediment
control BMPs;
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❑ 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 coardinate 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
�,n practices of erosion and sediment control. This person has the necessary
skills to:
� ❑ Assess the site conditions and construction activities that could
i 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 ar on-call
at all times.
�` ■ Whenever inspection and/ar 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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�„ Stormwater Pollution Prevention Plan
■ The SWPPP shall be modified whenever there is a change in the design,
construction, operation, or maintenance at the construction site that has, ar
'"" 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 autharity, it is determined that the SWPPP is ineffective in
eliininating 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 withm seven(7)
� days following the inspection.
� 3.2 Site Specific BMPs
Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site
� specific plan sheets will be updated annually.
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� Stormwater Pollution Prevention Plan
' 4.0 Construction Phasing and BMP
� Implementation
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• BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTNITY,A PRE-
CONSTRUCTION MEETING MUST BE HELD BETWEEN CITY OFFICIALS,THE
APPLICANT,AND THE APPLICANT'S CONSTRUCTION REPRESENTATIVE.
r,,, CONTRACTOR SHALL NOTIFY THE CITY CONSTRUCTION INSPECTION
PERSONNEL TO SCHEDULE THE PRE-CONSTRUCTION CONFERENCE ON-
� SITE.
• FLAG AND FENCE LIMITS OF CLEARING.
� ' INSTALL CONSTRUCTION ENTRANCE AND ASSOCIATED CULVERT AS
INDICATED ON PLAN.
� • INSTALL FILTER FABRIC FENCE AS INDICATED ON PLANS.
� • CLEAR AND GRUB AREAS OF THE SITE TO BE ROUGH GRADED OR FILLED
AND STABILIZE SLOPES. AREAS THAT MAY NOT BE WORKED UNTIL LATER
� SHOUI,D BE LEFT IN THE NATURAL STATE TO PREVENT EROSION.
• MAINTAIN FACILITIES AND MODIFY AS NECESSARY DEPENDING ON SITE
CONDITIONS AND STAGES OF CONSTRUCTION ACTIVITY.
� ' GRADE SITE TO FINISH GRADE AND STABILIZE ALL SLOPES.
� ' CONTRACTORS SHALL BE RESPONSIBLE FOR MAINTENANCE OF THE
i, TEMPORARY EROSION AND SEDIMENTATION CONTROL(TESC)FACILITIES
THROUGHOUT CONSTRUCTION.
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• REMOVE TEMPORARY EROSION CONTROL FACILITIES WHEN THE SITE IS
COMPLETELY STABILIZED AND APPROVED BY THE CITY OF YELM.
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' ALL TEMPORARY EROSION AND SEDIMENTATION CONTROL BMP'S SHALL
� BE REMOVED WITHIN 30 DAYS AFTER FINAL SITE STABILIZATION IS
ACHIEVED.
' COMPLETE INSPECTION PUNCHLIST.
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�.., Stormwater Pollution Prevention Plan
5.0 Pollution Prevention Team
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;� 5.1 Roles and Responsibilities
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I The pollution prevention team consists of personnel responsible far implementation of the
� SWPPP, including the following:
� ■ Certified Erosion and Sediment Control Lead(CESCL)—primary
contractor contact, responsible for site inspections (BMPs, visual
monitoring, sampling, etc.); to be called upon in case of failure of any
� ESC measures.
■ Resident Engineer—For projects with engineered structures only
� (sediment ponds/traps, sand filters, etc.): site representative for the owner
that is the project's supervising engineer responsible for inspections and
issuing instructions and drawings to the contractor's site supervisor or
� representative
■ Emergency Ecology Contact—individual to be contacted at Ecology in
� case of emergency.
■ Emergency Owner Contact—individual that is the site owner or
� representative of the site owner to be contacted in the case of an
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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.
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° � 5.2 Team Members
� Names and contact information for those identified as members of the pollution prevention team
are provided in the following table.
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� Title Name(s) Phone Number
Certified Erosion and Sediment Control Lead(CESCL) TBD �
� Resident Engineer Hal P.Grubb,P.E. (425)251-6222
Emergency Ecology Contact Staff on Duty (360)407-6242
Emergency Owner Contact Randy Weber (206)510-5563
� Non-Emergency Ecology Contact TBD �
� Monitoring Personnel TBD �
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� Stormwater Pollution Prevention Plan
6.0 Site Inspections and Monitoring
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i 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
irequirements9
� ■ Site inspections; and,
■ Stormwater quality monitaring.
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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, ar 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 mformation for the CESCL is provided m
,� 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 si�e log book or forms provided in this document. All new BMPs or design
changes will be documented in the SWPPP as soon as possible.
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'; 6.1.1 Site Inspection Frequency
� Site inspections will be conducted at least once a week and within 24 hours following any
discharge from the site. For sites with temporary stabilization measures, the site inspection
frequency can be reduced to once every month.
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6.1.2 Site Inspection Documentation
� The site inspector will record each site inspection using the site log inspection forms provided in
Appendix D. The site inspection log forms may be separated from this SWPPP document, but
''� will be maintained on-site ar 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
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6.2.1 Turbidity
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�� 1. Sampling Methods
a. Monitoring Personnel (TBD) shall conduct turbidity sampling pursuant to Condition
� S4.0 of the permit.
j 2. Sampling Frequency
� a. Sampling shall be conducted at least once every calendar week, when there is a discharge
i of stormwater (or authorized non-stormwater) from the site. Samples shall be
'� representative of the flow and characteristics of the discharge.
b. When there is no discharge during a calendar week, sampling is not required.
� c. Sam lin is not re uired outside of normal workin hours or durin unsafe conditions. If
P g q g g
i the monitoring personnei are unable to sample during a monitoring period, the Discharge
� 1Vlonitoring Report (DMR) shall include a brief explanation.
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� 3. Sampling Locations
� a. Sampling is required at all discharge points where stormwater (or authorized non-
stormwater) is discharged off site.
� b. The sampling point is identified on the SWPPP site map and shall be clearly marked in
the field with a flag, tape, stake, or other visible marker.
'; Sampling and Analysis Methods
� a. Turbidity analysis shall be performed with a calibrated turbidity meter (turbidimeter),
either on-site or at an accredited lab. The results shall be recorded in the site log book
in Nephelometric Turbidity Units (NTU).
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Parameter Units Analytical Sampling Benchmark
� Method Fre uenc Value
Turbidity NTU SM2130 or Weekly, if 25 NTU
� EPA 180.1 dischar in
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5. Turbidity Values: The benchmark value for turbidity is 25 NTU (Nephelometric Turbidity
� Units).
a. Turbidity 26—249 NTU:
� If the discharge turbidity is greater than 25 NTU, but less than 250 NTU, the CESL
shall:
� i. Review the SWPPP for compliance with Condition S9 of the Permit and make
appropriate revisions within 7 days of the discharge that exceeded the benchmark;
and
I ii. Fully implement and maintain appropriate source control and/or treatment BMPs as
� soon as possible, but within 10 days of the discharge that exceeded the benchmark;
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and
'� iii. Document BMP implementation and rnaintenance in the site log book.
a. Turbidity 250 NTU or greater, or Transparency 6 cm or less:
� If discharge turbidity is greater than or equal to 250 NTU the CESCL shall:
i. Notify Ecology by phone in accordance with Condition SS.A. of the permit; and
! ii. Review the SWPPP for compliance with Condition S9 of the permit and make
� appropriate revisions within 7 days of the discharge that exceeded the benchmark;
and
'� iii. Fully implement and maintain appropriate source control and/or treatment BMPs as
soon as possible, but within 10 days of the discharge that exceeded the benchmark;
iv. Document BMP implementation and maintenance in the site log book; and
� v. Continue to sample discharges daily until:
• tur�idity is 25 NTU (or lower); or
� the CESCL has demonstrated compliance with the water quality standard for
,� • turbidity:
� • no more than 5 NTU over background turbidity, if background is less than 50
�� NTU, or
• no more than 10 percent over background turbidity, if background is 50 NTU or
greater; or
� • the discharge stops or is eliminated.
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� 6.2.2 pH
pH monitoring shall be conducted as follows:
� 1. The pH monitoring period shall commence when the concrete is first exposed to
� precipitation and continue weekly until stormwater pH is 8.5 or less.
'� 2. During the pH monitoring period, a representative sample of stormwater shall be
obtained and pH analysis shall be conducted at least once per weeke
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3e pH monitoring shall occur in the sediment pond ar at oti�er locations that receive
� stormwater runoff from the area of significant concrete work or engineered soils prior to
discharge to surface waters.
� 4. The benchmark value for pH is 8.5 standard units. Any time sampling indicates that pH
� is 8.5 or greater, the contractor shall:
i 5. Prevent the high pH water (8.5 or above) from entering storm sewer systems or surface
waters; and,
� a. If necessary, adjust or neutralize the high pH water using an appropriate treatment
I BMP such as COZ sparging or dry ice. The operator shall consult with KeyBank and
�A shall obtain written approval from Ecology prior to using any form of chemical
�� treatment other than COZ sparging or dry ice.
6a pH analysis shall be performed on-site with a calibrated pH meter, pH test kit, or wide
� range pH indicator paper. The pH monitoring results shall be recorded in the site
logbook.
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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 ins ection form and water ualit monitorin forms included in this
, p q Y g
I SWPPP include the required information for the site log book.
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� 7.1.2 Records Retention
Records of all monitoring information (site log book, inspection reports/checklists, etc.), this
j 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
i three years following the termination of permit coverage in accordance with permit condition
� SS.C.
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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
accardance with permit condition SS.G.
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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.
�
7.2 Reporting
I� 7.2.1 Discharge Monitoring Reports
[Priar to October 2008] If cumulative soil disturbance is smaller than 5 acres: Discharge
� Monitoring Report (DMR) forms will not be submitted to Ecology because water quality
sampling is not being conducted at the site.
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�� If cumulative soil disturbance is 5 acres or larger: Discharge Monitoring Reports (DMRs) will be
submitted to Ecology monthly. Of there was no discharge during a given monitoring period, the
Permittee shall submit the form as required, with the words "No discharge" entered in the place
'� of rnonitoring results. The DMR due date is 15 days following the end of each month.
� 7.2.2 Notification of Noncompliance
If any of the terms and conditions of the permit are not met, and it causes a threat to human
� health ar the environment, the following steps will be taken in accordance with permit section
SS.Fe
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!� 1. Ecology will be immediately notified of the failure to complyo
2. Immediate action will be taken to control the noncompliance issue and to
� correct the problem. If applicable, sampling and analysis of any
noncompliance will be repeated immediately and the results submitted to
� Ecology within five (5) days of becoming aware of the violation.
�� 3. A detailed written report describing the noncompliance will be submitted
to Ecology within five (5) days, unless requested earlier by Ecology.
� In accordance with permit condition S2.A, a complete application form will be submitted to
Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General
� Permit.
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� Appendix B — Construction BMPs
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Preserving Natural Vegetation (BMP C101)
� Stabilized Construction Entrance/Exit(BMP C105)
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'' Straw Wattles (BMP C235)
Silt Fencing (BMP C233)
� Temporary and Permanent Seeding (BMP C120)
� Storm Drain Inlet Protection (BMP C220)
I Outlet Protection(BMP C209)
'� Material on Hand BMP C 150
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�, BIUIP C101: Preserving Natural Vegetation
Purpose The purpose of preserving nahual 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 requiz-ed by local governments.
� • Phase constructian to preserve natural vegetation on the project site for
as long as possible during the construction period.
� Design and Natural vegetation can be preserved in natural ciuxnps or as individual
Installation trees, shrubs and vines.
� Specifications The preservation of individual plants is more difficuit because heavy
'� equipment is generally used to remove unwanted vegetation. The points
� to remember when attempting to save individual plants are:
j� • 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 he saved. It is
preferable to lceep 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.
• GYade Changes - Changing the natuxal ground leve] 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 znajor changes in grade, it rnay become neeessary to
,� supply air to the roots of plants. This can be done by placzng a layer of
; gravel and a tile systez� over the roots before the fill is made� A tile
� system protects a tree from a raised grade. The tile system should be
� i�olume II--Construction Stormwater Pollution Prevention-Au st 2012
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� Table 4.1.'[ Source Control BMPs by SWPPP Element
� Eiement#1 Element#2 E lement#13
Element#5 Element#6 Elemeni�9 Eiement#11 Etement#12
Preserve EstablisF� ProtectLow
BMPorEtementName Sta6�7ize Protect Control Maintaln Managethe
!, VegetationJhlEark Construction 5oi[s Sbpes Pol9utants SMPs Project fmg�
;� Clearin LimRs Access Devela ment
BNfP C101: Preserving Natural Vegetation ✓
BMP C102:8uffer Zones ✓ ✓
� BMP C103:High Visibility Piasfic or FAetal f �
Fence
I BMPC105: StabilizedConstruction �
Entrance 1 Exit
i� BMP C106: Wheel Wash ✓
i 8MP C107: Construction RosdiParking f
� Ar�a Stabilization
BMP C12Q:Tempor�rand Permanent � �
Seeding
BMP C121: Mulching ✓ ✓
� BMP C122: Nets and Blankets ✓ ✓
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� BMP C123: Plastic Covering ✓
i BMP C124: Sodding ✓
� BMP C925: TopsoiIing 1 Composting ✓
BMP C12fi: Polyacryla�ride for Soil Erosion �
Protectian
� B�u1P C130: Surface Roughening ,� ✓
BMPC131: GradientTerraces ✓ ✓
,� BMP C9d0: Dust Cantrol ✓
BMP C'E50: Materiais On Nand ✓ ✓
I� BMP C951: Cnncrete Handling ✓
BMP C752: Sawcutting and Surfacing �
Pollut'soo Prevention
'� BMP C153: Material Delivery,Storage and f
Containment
IBMP C154: Concrete Was6outQrea ✓
� BMP C160: Cert'rfied Erosion and � f
���� Sediment Controi Lead
BMP C762:Scheduling ✓
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�, - , laid out on the original grade leading from a dry well az-ound the tree
trunlc. The system should then be covered with small stones to allow
� air to circulate over the raot area.
Lowering the natural ground level can ser�ously damage Crees and
shrubs. The highest percentage of the plant roots are in the upper 12
� inches of the soil and cuts af only 2-3 inches can cause serious injury.
To pratect the roots it may be necessary to terrace the immediate area
around the plants to be saved. If roots are expased, 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 fox 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
tlrainfields,power, water, and sewer linese 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 firees are:
� • Maple, Dogwood,Red alder, Western hemlock, Western red cedar,
i and Douglas fir do not readily adjust to changes in environment and
;� special care shauld be taken to protect these trees.
• The windthrow hazard of Pacific silver fir and madrona is high, while
that of Westeix� 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.
j • Thinning operations in pure or mixed stands af Grand fir, Pacific silver
�� fir,Noble fr, Sitka spruce,Westem red cedar, Western hemlock,
Pacific dogwood, and Red alder can cause serious disease problezns.
Disease can become established through damaged limbs, trunks, roots,
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yolume 11—Constructron,Stormwater-Pollution Prevention -August 2012
� 44
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� and freshly cut stumps. Diseased and weakened trees are also
susceptible 1ko insect attack.
� Maintenance Inspect flagged and/or fenced areas regularly to make sure flagging or
Standards fencing has not been removed or damaged. If the flagging or fencing
has been damaged or visibility reduced, it shall be repaired or
E � 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.
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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 anly 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 See Fi�ure 4.1.1 for details.Note: the 100' minimum length of the
Installation entrance shall be reduced to the maximum practicable size when the size
�� Specifications 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:
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'� Grab Tensile Strength(ASTM D4751) 200 psi min.
Grab Tensile Elongation(ASTM 30%m�.
� D4632)
'� Mullen Burst Strength(ASTM 400 psi min.
D3786-80a)
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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Ijolume II—Construction Stormwater Pollution Preventaon-August 2012
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� • Fencing(see BMP C 103) shall be installed as necessary to restrict
traffic to the construction entrance.
• Whenever possible,the entrance shall be conshucted 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
j 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 Quarry spalls shall be added if the pad is no longer in accordance with
Standards 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 cornpletion and site stabilization, all construction
� accesses intended as permanent access for maintenance shall be
permanently stabilized.
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� Drfveway shall meet the
requirements of the
P����9��Y
It(s recommended that the
� entrance be aowned so that
runoff drains off the pad
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Instali driveway cuhrert if there
�a roadside ditch present
� 4'—8'auam s�ails f�
Geotextile .�4.
� � ���'��:
tY min.ihickness �^�
� Prov�e full w�th of
ingressJegress area
Figure 4.1.1 —Stabilized Construction Entrance
� Approved as Ecology has approved products as able to meet the requirements of BMP
Equivalent C 105. The products did not pass through the Technology Assessment
�9 Protocol—Ecology(TAPE)process. Local jurisdictions may choose not
��r 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.ecv.wa.�programs/wq/stortnwater/newtech/equivalent.html
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� BMP C120: Temporary and Permanent Seeding
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� Purpose Seeding reduces erosion by stabilizing exposed soils.A well-esta.blished
vegetative cover is one of the most effective methods of reducing erosion.
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! 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 unti175 percent
� grass cover is established.
Between October 1 and March 30 seeding requires a cover of mulch with
straw or an erosion control blanket unti175 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 C 121: Mulchin� 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
i as pavement,riprap, gabions or geotextiles)which will prevent
� erosion.
Design and Seed retention/detention ponds as required.
Installation Install channels intended for vegetation before starting major
� Specifications earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated
� channels that will have high flows, install erosion cantrol blankets
over hydroseed. Before allowing water�o flow in vegetated
� channels, establish 75 percent vegetation cover. If vegetated
� channels cannat be established by seed before water flow; install sod
� � in the channel bottom—over hydromulch and erosion control
blankets.
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� Yolume II–Construction Stormwater Pollution Prevention-August 2012
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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: Mulchin� for
specifications.
�, • Areas that will have seeding only and not landscaping may need
' compost ar 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 i£
• 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
� variery 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 4.1.21ists the standard mix for areas requiring a temporary
vegetative cover.
� Table 4.1.2
Temporary Erosion Control Seed Mix
� %Wei ht %Purit %Germination
Chewings or annual blue grass 40 98 90
Festuca rubra var. commutata or
� Poa anna
Perennial rye- 50 98 90
� Lolium erenne
Redtop or colonial bentgrass 5 92 85
A ostrs alba or A rostzs tenuts
� White dutch clover 5 98 90
Tri olium re ens
� • Table 4.1.3 lists a recommended mix for landscaping seed.
Table 4.1.3
� Landscaping Seed Mix
! °/a Wei ht %Puri %Germination
� Perennial rye blend 70 98 90
Lolium erenne
Chewings and red fescue blend 30 98 90
� Festuca rubra var. commutata
or Festuca rubra
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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
� % Wei ht %Puri %Germination
� Dwarf tall fescue (several varieties) 45 98 90
� Festuca arundinacea var.
Dwarf perennial rye (Barclay) 30 98 90
Lolium eYenne var. barcl
�` Red fescue 20 98 90
4� Fest�ca rubra
Colonial bentgrass 5 98 90
� A Yostis tenuis
� • Table 4.1.5 lists a mix for bioswales and other internuttently wet areas.
� Table 4.1.5
� Bioswale Seed Mix*
! %Wefi ht %Purit %Germination
j� Tall or meadow fescue 75-80 98 90
Festuca arundinacea or Festuca
'I elatior
� Seaside/Creeping bentgrass 10-15 92 85
A rostis alustris
Redtop bentgrass 5-10 90 80
'' � A rostis alba or A rostis i antea
*Modified BYiargreen, Inc. Hydroseedirtg Guide Wetlands Seed Mix
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� • Table 4.1.6 lists a low-growing,relatively non-invasive seed mix
'i 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*
�'" %Wei ht %Puri %Germination
I�M Tall or meadow fescue 60-70 98 90
j Festuca arundrnacea or
Festuca elatior
� Seaside/Creeping bentgrass 10-15 98 85
A ostis alustris
�" Meadow foxtail 10-15 90 80
��� Ale ocurus ratensis
( Alsike clover 1-6 98 90
�"* Tri olium h bridum
�r� Redtop bentgrass 1-6 92 85
A rostis alba
� *Modifred Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
• Table 4.1.71ists 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.
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� Meadow Seed Mix
� %Wei ht %Purl %Germination
'!� Redtop or Oregon bentgrass 20 92 85
Agrostis alba or Agrostis
ore onensis
Red fescue 70 98 90
� Festuca rubra
White dutch clover 10 98 90
� Tri olium re ens
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Yolume II—Construction Stormwater Pollutian Prevention-August 2012
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� , • Ronghening 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. Backbiading or smoothing of slopes
greater than 4H:1 V is not allowed if they are to be seeded.
� • Restoration-based landscape practices require d.eeper incorporation
I than that provided by a simple single-pass ratotilling treatment.
� Wherever practical, initially rip the subgrade to improve long-term
permeability, infiltration, and water inflow quaiities. At a
minimum, pertnanent areas shall use soil amendments to achieve
� organic matter and permeability perfornnance defined in
engineered soil/landscape systems. For systems that are deeper
than 8 inehes complete the rototilling process in multiple lifts, or
� prepare the engineered soil system per specificatians and place to
achieve the specified depth.
• Fertilizers:
� • Conducting soil tests ta determine the exact type and quantity of
fertilizer is recornzr�ended. 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{�itrogen-phosphorus-potassiusn)
� fertilizer at a rate of 90 pounds per acre. Always use slaw-release
fertilizers because they are more efficient and have fewer
environmental impacts. Da not add fertilizez°to the hydromulch
' machine, or agitate, moz-e than 20 mxnutes before use. Toa much
�, agitation destroys the slow-release coatu�g.
• There are nuznerous products available that take the place of
� chemical fertilizers. These include severa�with seawee�extracts
that are beneficial to soil microbes and organisms. If 100 percent
� cottonseed meal is used as the mulch in hydroseed,chemical
� fertilizer inay not be necessary, Cottonseed meal provides a good
source of long-term, slow-re�ease, available nitrogen.
� • Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix:
i • On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically
Bonded Fiber Matrix (MBFM)products. Apply BFMIMBFM
� products at a minimum rate of 3,000 pounds per acre of mulch
i with approxitnately 14 percent tackifier. Achieve a minimum of 95
. � percent soil coverage during application, Numeraus products are
available commercially. Instailed products per manufacturer's
�nstructions. Most praducts require 24-36 hours to cure before
rainfall and cannot be installed on wet or saturatec� sails.
� Volume I.I—Construction Stormwater Pollution Prevention-.August 2012
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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.
i • �n slopes steeper than 2.SH: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 Reseed any seeded areas that fail to establish at least 80 percent cover
Standards (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.
i • Supply seeded areas with adequate moisture,but do not water to the
� extent that it causes runoff.
Approved as Ecology has approved products as able to meet the requirennents of BMP
Equivalent C l 20. The praducts 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.ecv.wa.�programs/wq/stormwater/newtech/equivalent.html
�
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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.
' As a temporary cover measure,mulch should be used:
� Conditions of Use
• For less than 30 days on disturbed areas that require cover.
• At all times for seeded areas, especially during the wet season and
� Yolume II—Construction Stormwater Pollution Prevention-Au st 2012
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�. Standards accuxnulation during and after each runoff pxoducing rainfall.
Sediment shall be removed when zt reaches one ha�f 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 reducang the velocity of concentrated
� stonnwater flows.
IYw
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 The receiving channel at the outlet of a culvert shall be protected from
� Installation erosion by rock lining a minimum of b feet downs�ream and extending up
Specificatzons the cham}el sides a minimum of 1—foot above the maximum tailwater
i 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�hrough
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 i percent), use 2-inch to 8-inch riprapa Minimum
� thiclrness is 1-foot.
2. For 5 to 10 fps discharge velacity at the outlet{pipe slope less than
3 percent),use 24-inch to 48-inch riprap. Mulimum thickrxess 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.
� Yolume II—ConstYUCtion Stormwater Pollution Preventiorr-Au ust 2012
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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 • Inspect and repair as needed.
Standards • Add rock as needed to maintain the intended function.
� • Clean ener dissi ater if sediment builds u .
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� BMP C220: Storm Drain Iniet 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 witb 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 fmished lawn and yard drain.
�, Table 4.2.21ists 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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7abte 4.2.2
�, Storm Drain Inlet Protection
� �'' Applicable for
Type of Inlet Emergency Pavedl Earthen
� Protection Overf[ow Surfaces Cond'[tians of Use
Drop Inlet Protection
Excavated drop inlet Yes, Earthen `Applicable for heavy flows. Easy .
� protection temparary to ma�ntain.Large area
flooding will Requirement:.30'X 30'/acre
; ` occur.: :
� Block and grayel drop. :Yes Paved or Earthen Applicabl.e far h.eavy concentxated
� inlet pxotection flows. Will not pond.
Gravel and wire drop No ' Applicable for heavy concentrat�d ;
inlet protection #1ows.Will pond..Can withstand
� ` '. ` traffic. ' ;
Catch basin filtexs Yes Paved or.Earthen k�equent maintenance re uired.
Curb Inlet Protection
� Curb inlet protection Small capacity Paved ' Used for stuxdy, more campact
with a wooden weir ouerflow.` installation.
Block and gravel curb Yes `.` Paved Stur.dy,but limited filtration. ':
� inlet protecEion
Cul�ert!In1et'Protection
Culvert inlet sediment 18 month expected life.
� trap
� Design and Excavated Drop.Inlet Protection -An excavated impoundment around the
Installation storm drain. Sediment settles out of the stormwater prior to entering the
Specifications storm drain.
� • Provide a depth of 1-2 ft as measured from the crest of the inlet
structure.
• Slope sides of excavation na 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 prevenfi standing water problems.
� • Clear the a�ea of all debrise
• 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�vhen removing structure and stabilizing area.
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Yolunze II—Construction Stormwater Pollution Prevention-August 2012
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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 %2-inch openings
over all block openings.
� • Place gravel just below the top of blocks on slopes of 2H:1 V or flatter.
• An alternative design is a gravel donut.
� Provide an inlet slope of 3H:1 V.
� •
• Provide an outlet slope of 2H:1 V.
• Provide al-foot wide level stone area between the structure and the
� inlet.
I • Use inlet slope stones 3 inches in diameter or larger.
� • Use gravel l/2-to 3/a-inch at a minimum thickness of 1-foot for the
outlet slope.
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�, Plan View A
Drain �����po °o ° •��s?o �°.
Grate o�o��°<°�<°� ����G�C��o°4`�jo���•o
� o U -.q��o��;o�a�oo.��je�j���C�`.��� a
���n �.i�-��n���o- .���c� O O�J„0�,0�0
� �ca� o,n �o0�'er�� �c=� o
`°Q°'���' �r� ��/��0��/�
��G°�oc n n��Do
���� �O o U _ �se��o a��o Concrete
� -����o�o , �- '��"�`a.`oo Block
r— g
'� ��°C���p"� �,' � � � ���°o�ra
n��� � � �1� �(1�� I �v�°C�O
,,�.. '>1���o O oo��J
`��°�og•nn •�pC�'�°c>°p`n
,��o��`o a0o� �c�o° Gravel
°C�r�'�C�� � ���'�J�C• -�? Backfili
�/� ° �cr�-�O�i.J
liG^opf?/-� (�."°j o°�� O a°-�.I°``,-�!��°"�C�J�'
� '�i�" °00� �b�UL�op ,°o°p���° �' °O°p° �
'�O`�'CJh���:��G��-c^� °O �%G��JO �� J
�.�;�OO �0�7�O�,C�OO���'� OoGC�
q c�
� �� � ���J e�� w
� �r� � A
�y5 ��OQ
���o
� Section A ' A Concrete Block- Wire Screen or
� Filter Fabric
Gravel Backfiil Overtlow
� �
'� l� Water nding Heigh
�o,���ac , -- a�Po t
n�ob o � Water', ( � � o ��Ib`",��_\,,,o
-¢�oc�� nocl i � �� C`�' ���o�
---,'-�'-- „��L1��.,.���w=��n� . F,� c_i�'"� o_a�� ��-
�\�\T\��\ \�\ \ ` , . , - \�\�\ \�\��J�\��,
����\//�\//�\//�\//�\//�\//�\ _ \//�\//�\//�\//�\//�\/�\,�
� \�����j��j�\j� Drop Inlet \j�\j��\j��\j�\\
,. /i�//��//��//� ���//��/\���i./i
��i�/j� � ��/i�/
� i�--
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
runofFfrom bypassing the inlet.A temporary dike may be necessary on the downslope side of the structure.
� 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 '/2-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 inesh is necessary.
��
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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.
r�
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
i 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
I inlet with a wooden frame and gravel.
� • Use wire mesh with %2-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 Fi�ure 4.2.9.
� • Use wire mesh with '/2-inch openings.
• Place two concrete blocks on their sides abutting the curb at either side
of the inlet opening. These are spacer blocks.
� • Place a 2x4 stud through the outer holes of each spacer block to align
the front blocks.
� • Place blocks on their sides across the front of the inlet and abutting the
spacer blocks.
• Place wire mesh over the outside vertical face. �
� • Pile coarse aggregate against the wire to the top of the barrier.
I
� 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.
�
i Yolume II-Construction Stormwater Pollution Prevention-August 2012
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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
berxn sized to sediment trap standards for protecting a culvert inlet.
� Maintenance • Inspect catch basin filters frequently, especially after stortn events.
Standards 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 Ecology has approved products as able to meet the requirements of BMP
Equivalent 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.ec�gov/programs/wq/stormwater/newtech/equivalent.html
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� Plan View
� � Back of Sidewalk A — — Catch Basin
I
� �
� 2x4 Wood Stud
� Back of Curb , Concrete Bfock
� Curb inlet
-- ---- ---
; _ - -
, ;� � > :
_ - .� � _
� � = � --� _ _ -
� � - �
_ l � �:
, , ,
�
-; -
� ; � _
- � _ -
� -� .- - -- -
�
�
, . . ,
:: .
_ : .
_ �
� - - - . -. -- - -
Wire Screen or , � .
� Filter Fabric A Concrete Block
Section A � A 3�4'prain Gravel
(20mm)
� 3�4�Drain Gravel
(20mm}
� Ponding Height
Concrete Block
Overflow __- �
� --'j -__ ___
-- ------ _ -- -= Curb Inlet
�x - --- ---
Wire Screen ar !
Fil#er Fabric
4 Wood Stud Catch Basin
�. (10�x50 Timber Stud)
� NOTES:
1.Use bEock 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 shal]allow for overFlow from severe storm event.
� 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed
from the traveled way immediately.
� Figure 4.2.9—Block and Gravel Curb fnlet Protection
�
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� Yolume II—Const��uction Stormwater Pollution Prevention-August 2012
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�, Pian View
� Back of Sidewalk
� Burlap Sacks to Catch Basin
� Qverlap onto Curb
� -- Gurb Inlet
' Back of Curb�
, '� ��
, ---- - _ . ._._. _ � ---
, -
I '''' I
� , � _
! �; .
'� �i ,i -- --
;' :......
RUNOFF ',��
-----
�� ;i
; ; ._..— .._......... ........
� `
� I
RUNOFF SPILLWAY;,;,' _..__....--_..--__ _—
� �/ \'�:.
� �%''`
;,
! - ,i r/:;
� / � .J//
,
�' „
:��,
: ,
; ,%`-.
� ' --- / //''�'/
�'` "�%" Gravef Filfed Sandbags
'�-_:_�_� �/l/ Stacked Tightly
,,-
� NOTES:
; 1.Place curb type sediment barriers on gently sloping street segments,where water can pond and allow
'� sediment to separate from runoff:
2.Sandbags of either burlap or woven'geotextile'fabric,are filled with gravel,layered and packed tightIy.
3.Leave a one sandbag gap in the top row to provide a spillway for overflow.
4.Inspect bamers a.nd remove sediment after each storm event.Sediment and gravel must be removed from
,�� the traveied way i�rzmediately.
� Figure 4.2.10-Curb and Gutter Barrier
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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 runoffvelocities of overland flow. See Fi�ure 4.2.12 for
i 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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� Joints in filter fabric shall be spliced at
posts. Use staples,wire rings or 2"x2' by 14 Ga.wire or
equivalent to attach fabric to posts equivalent, if standard
r_� — ,- _ � strength fabric used
� I I ,j--- _ ' I
/
� I I Filter fabric
C
( � ` `' � E
� I I f � I N
I I I _ �,�_�� , I _��-,
� _ '�— _ - -i u-n�= i-n;���-ii i > .
, ' ��
I �U��ii��u��l. i�;: iil�H-1�i ii i i-i�i u �i�iii��� u�—��i ° - .
�-11 �,_ c
7 I�. 6'max �-! � �--Minimum 4"x4"trench '� ���1��� �
�' I � I �"'
� j `--� Backfill trench with native soil � —�
Post spacing may be increased or 3/4"-1.5"washed gravel /
to 8'if wire backing is used \ !
� 2"x2"wood posts,steel fence
posts,or equivalent
� Figure 4.2.12-Silt Fence
Design and • Use in combination with sediment basins or other BMPs.
� Installation Maximum slope steepness (normal (perpendicular)to fence line)
Specifications • 1 H:1 V.
� • 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
� Pol meric Mesh AOS 0.60 mm maximum for slit film woven #30 sieve .0.30
Y t )
(ASTM D4751) min maa�imum for all other geotextile types(#50 sieve).
� 0.15 mm minimum for all fabric types(#100 sieve).
Water Permittivity 0.02 sec minimum
(ASTM D4491)
I� Grab Tensile Strength 1801bs.Minimum for extra strength fabric.
,I (ASTM D4632) 1001bs minimum for standard strength fabric.
I�.
Grab Tensile Strength 30%maximum
(ASTM D4632)
� Ultraviolet Resistance 70%minimum
� (ASTM D4355)
� • 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
r' backing attached.
� • Filter fabric material shall contain ultraviolet ray inhibitors and
stabilizers to provide a minunum 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 Fi�ure 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 2'h-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
' fhe 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
I 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
� volume II—Construction Stormwater Poldution Prevention-Au ust 2Q12
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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 requued
� 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
I 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 runaff 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:1 V.
� • 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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4-91
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;,� , 1. The base of both end pasts must 1oe at least 2- to 4-inches above the
top of the fitter fabric on the middle posts far ditch checics 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 b-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 f lter fabric, enabling posts to
r,,, support the filter fabric from upstrearn water pressureo
4. Install posts with the nipples facing away from the filter fabrzc.
� 5. Attac� the filter fabric to each post with three ties, all spaced
within the top 8-inches of the filter fabric. Afifiach each tie
�'^' diagonally 4S degrees through the filter fabric, with each puncture
at Ieast I-inch vertically apart. Each tie should be positioned to
hang on a post nipple when tightening ta prevent sagging.
6. Wxap approximately 6-inches of fabric around the end pasts 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
ins#allation for any deviation before compaction. Use a flat-bladed
� shovel to tuck fabric deeper into the graund if necessarya
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Peeding h�iyht tOBT SPAClNG: _ '
� mwx.24' 7'mwx.�n op�n runs _ .
, ........""" " `--...""""'Top af FabdC �
. . 4 m�x.en poolleg ar�as
• Beit
Al4aeNfab„e m �
upstra�n aid�si posl , 8• .
X
FLOW—# �
�, anv..wr..�n.re.� r toST OEPTHs -
slle r�ne�2 m 4 tleu�� �� As�nueh bdaW g►au�d
wIM A�Nes aunlny �' as�abf7a�bsw�[ound
eo pa.1.er gn�ln : .
S.
-% OMganet attechmern
100Xeanpaetl 10O%esenpfetlen . ygiyy� .
� tlW
�
� %� `�, �i �� �/
\����� \�♦ ��C�\`�������\�
�\\\\\�\f ;�\�'i\\`i;�i\�
� /�i/// ''/� '% /'/� /% '
,���j%��,� �/�\��\�����j//�\� �nr�a�naaro��u�s:
�%��\�/�� � ��i�i\�/��/\\� •Gatl�er/ebAe at poMS,r naeded.
\�\\��\ ����\����� \�\� •Wliie three ees per po�,aN wkhln mp e•of taMc.
�,. �,/��\�\\� '! \��\�/�\����/�\ •Poekbn aaehYe�agonally.punefuing hdesva�ticaRy
\�\���\�/ � \�/�\/�\�/�\�� 6 R�t6rnan of 1'OpaR.
� � � •kang eacA da on n post Npple and tlgTAsn secaraty.
TAs
� No more ihan 24"of a 36'fabric use ean�e nes(sa�ar soa wis.
is allowed above ground.
�" Roll ot sflt fence
1 . '�rw"" OP�ratton
Ir Post
tnstaned
• alter
compac6on
�Y Fabiic
O �above SNt Fence
ground
� : \ � � �� � y�•
\\�_... ,,`\�\\�i� �,�;\�\Y
��'Q`'�.
��.�°j���r.� `:��;., 'y.'%�:%'>= �`�.��
.- �- � j �t,iH�n�i �'� 200-3QOmm ��y-�\` \�i
`k;�e' ..o- v �.. �.� � ��.
: y' �c„�� ��l��it����: � ;�i '���\���� ���ii
..\i�v�\����j�:\\i�����j,i,ii/ii- �'�i�i��' i�•� f i'Y� � `���• \�
� O 'A 1 '► �l,��v�� .������� ..�����"�.':�.���. ���'�% 4��• :
.i�iy •
Hadwntal chhal poirrt 5icng blede
(76 mm+WdM� (18 mm wldtl�) Comp3eted Irutafatlon
VibraEOry pbw is not acceptable because nf hn�izontal compactinn
,�
Figure 4.2.13—Silt Fence fnstallation by 5licing Method
� Maintena�xce • Repair any daxnage immediately.
Standards Intercept and convey all evident concentrated flows uphill of the silt
� • fence to a sediment pond.
• Check the uphili 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 accurs, replace the fence or remove the
trapped sediment.
�
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Volume II—Construction Stormwater Pollution Prevention-August 2012
� 4-93
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� • Remove sediment deposits when the deposit reaches approximately
one-third the height of the silt fence, or install a second silt fence.
� • Replace filter fabric that has deteriorated due to ultraviolet breakdown.
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� BMP C235: Watfies
Purpose Wattles are temporary erosion and sediment control barriers consisting of
� straw, compost, or other material that is wrapped in biodegradable tubular
plastic or similar encasing material. They reduce the velociiy and can
spread the flow of rill and sheet runoff, and can capture and retain
�, sediment. Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet
in length. Wattles are placed in shallow trenches and staked along the
contour of disturbed or newly consriucted slopes. See Figure 4.2.14 for
�, typical construction details. WSDOT Standard Plan I-30.30-00 also
provides information on Wattles
� (http://www.wsdot.wa.gov/Design/StandardsCPlans.htm#SectionI)
Conditions of Use • Use wattles:
• In disturbed areas that require immediate erosion protection.
� • On exposed soils during the period of short construction delays, or
over winter months.
� • On slopes requiring stabilization until permanent vegetation can be
established.
� • The material used dictates the effectiveness period of the wattle.
Generally, Wattles are typically effective for one to two seasons.
� • Prevent rilling beneath wattles by properly entrenching and abutting
wattles together to prevent water from passing between them.
Design Criteria • Install wattles perpendicular to the flow direction and parallel to the
� slope contour.
• Narrow trenches should be dug across the slope on contour to a depth
of 3- to 5-inches on clay soils and soils with gradual slopes. On loose
� soils, steep slopes, and areas with high rainfall,the trenches should be
dug to a depth of 5-to 7-inches, or 1/2 to 2/3 of the thickness of the
wattle.
� • Start building trenches and installing wattles from the base of the slope
and work up. Spread excavated material evenly along the uphill slope
� and compacted using hand tamping or other methods.
• Construct trenches at intervals of 10-to 25-feet depending on the
steepness of the slope, soil type, and rainfall. The steeper the slope the
� closer together the trenches.
� • Install the wattles snugly into the trenches and abut tightly end to end.
� Do not overlap the ends.
• Install stakes at each end of the wattle, and at 4-foot centers along
' � entire length of wattle.
Volume II—Construction Stormwater Pollution Prevention-August 2012
4-95
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• If required, install pilot holes for the stakes using a straight bar to drive
- holes through the wattle and inta the soil.
• Wooden stakes should be approximately 3/4 x 3/4 x 24 inches min.
� Willow cuttings or 3/S-inch rebar can also be used for stakes.
� • Stakes should be driver�through the middle of the wattle, leaving 2 to
3 inches of the stake protruding above the wattle.
Maintenance • Wattles may require maintenance to ensure they are in contact with
� Standards soil and thoroughly entrenched, especially after significant rainfall on
steep sandy soils.
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4-96
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� �
�-------.....- ---...._..._�
� � 1 i (1.2m) ;"
��+- .� I , ,� `/\,1�'.
, '�. � � ..
��;�: :,
Straw Rolls Must , � --
Be Placed Alang �`: � v�� ;,;,,,,�;' ',
� //'�S,J - ` ..,
Sfope Contours � \`
,�, Adjaceni rolls shall
;��; - tighily abut
//, ,� _`
. ,
/� i
/ �! �:.,� ' r �1j:��� / ''i�_�_/"
�I/ / ,/ ^x/x�Sa"'=:..,'�y' ?.
� �i:�z:y � /.—;� `� i ', j
�:�. � �y�� �;�r` � :
7��
> � �:
� \,f� �, +,..
�� � :- �,, � • � �
� ����� j 10'-25'(3-Brtl) -- ' 1 � '';:,`i.!
\/.\�\ :`�" � �', ,.
%
� �\i\ ��';- ,
\�\ - - , �'�\J�� --
� \/,/ „ ;j\\ `
�\�
\�j/\��\
Spacing Depends �
on Soil Type and /���/� Sadiment,organic matter,
Stope Steepness � � ��% __
���� / -- and native seeds are
� <�/�� / captured behind the ro31s.
�; r
����\�.
•,�� ;
� y �i��
i�� —�l
%°—��' �:,
� J, i ` 3.'_5"(75-125mm}
\ ,�....
:.��� � � / \' /`//�:=� 8"-10"DIA.
,!,\\\\ �� �� _ 1_�- ;,, `�\\���\ � i,:,�(200-250mm)
/
� ��� � ! ,_
:!� �� � r,.
�-�, ?_ V � --/ ���
Live Stake <:;, ,� : - � l;
�; >
�;.. � �•
---� >>,- � ��•��.
� _. `_ _-_ `'��. �� .�..,....
- �-� fb.
, '�:��`\. 1" X 1" Stake
�
l/i�� not to scale {25 x 25mm)
r, ��.
� T
NOTE: �
l.Straw roll installation requires the ptacement and secure staking of fhe roll in a trench,3"-5"(75-125snm}
deep,dug on contour. runoff must not be allowed to run under or around roll.
� Figure 4.2.14—Wattles
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Volume II—Construction Stormwater Pollution Prevention-August 2012
4-97
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'� Stormwater Pollution Prevention Plan
Appendix C — General Permit
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� Stormwater Pollution Prevention Plan
� 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 ar
� practices.
d. The following shall be noted:
� i. locations of BMPs inspected,
I 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
I� sheen shall be noted, as applicable.
f A description of any water quality monitaring performed during
� inspection, and the results of that monitoring.
ga 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
24 12433.007.doc
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� Stormwater Pollution Prevention Plan
� 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 SS.F of the permit.
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� Site Inspection Form
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25 12433.007.doc
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� Stormwater Pollution Prevention Plan
� 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:
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Inspection of BMPs
� Element 1: Mark Clearing Limits
BMP e
� Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
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� BMP:
Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
�
� Element 2: Establish Construction Access
BMPe
Location Inspected Functioning problem/Corrective Action
�
Y N Y N NIP
�
BMPe
� Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
'�
Element 3: Control Flow Rates
� BMP:
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� Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
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� BMP:
I Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
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� Element 4: Install Sediment Controls
BMPe
� Inspected Functioning
Location y N Y N NIP Problem/Corrective Action
�
BMP:
�„ Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
�
BMP:
' � Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
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' � BMP:
� Location Insp�ct�d �unNio NIP problem/Corrective Action
�
� BMP:
� Location Inspected Functioning problem/Corrective Action
' ' Y N Y N NIP
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Element S: Stabilize Soils
� BMP:
Inspected Functioning
Location y N Y N NIP problem/Corrective Action
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� BMP:
Location Inspected Functioning probiem/Corrective Action
Y N Y N NIP
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� BMP:
Inspected Functioning
Location y N Y N NIP Problem/Corrective Action
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BMPe
Location Inspected Functioning problem/Corrective Action
� Y N Y N NIP
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Element 6: Protect Slopes
� BMPa
Inspected Functioning
Location Y N Y N NIP problem/Corrective Action
'
BMP:
��
Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
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� BMP:
Location Inspected Functioning problem/Corrective Action
' Y N Y N NIP
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� Element 7: Protect Drain Inlets
BMP:
Inspected Functioning
� Location y N Y N NIP problem/Corrective Action
�
BMPa
� Location InsplctN Y nNioNiP problem/Corrective Action
�
� BMP:
Location Inspected Functioning problem/Corrective Action
� Y N Y N NIP
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Element 8: Stabilaze Channels and Outlets
� BMP:
Inspected Functioning
� Location y N Y N NIP Problem/Corrective Action
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� BMPe
Location Inspected Functioning problem/Corrective Action
� Y N Y N NIP
,�
BMPa
Location Inspected Functioning problem/Corrective Action
� Y N Y N NIP
�
BMP:
Inspected Functioning
� Location Y N Y N NIP Problem/Corrective Action
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� Element 9: Control Pollutants
BMP:
� Inspected Functioning
Location y N Y N NIP Problem/Corrective Action
� ��
BMP:
� Location Inspected Functioning problem/Corrective Action
Y N Y N NIP
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� Element 10: Control Dewatering
BMP:
Inspected Functioning
Location y N Y N NIP Problem/Corrective Action
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'� BMP:
� Location InsplctN �unNioNIP problem/Corrective Action
� �
BMP:
'' � Inspected Functioning
Location Y N Y N NIP Problem/Corrective Action
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� Stormwater Dischar es From the Site
Observed? Problem/Corrective Action
Y ❑N
� Location
Turbidity
� Discoloration
Sheen
Location
�* Turbidity
Disco�oration
Sheen
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� Stormwater Pollution Prevention Plan
� Water Quali Monitorin
Was any water quality monitoring conducted? ❑ Yes ❑ No
If water quality monitoring was conducted, record results here:
�
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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 re airs, maintenance, or installations made as a result of the ins ection.
Were Photos Taken? ❑ Yes ❑ No
� If hotos taken, describe hotos below:
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