HomeMy WebLinkAbout03396 - Technical Information Report - Stormwater Pollution Prevention Plan Stormtil�ater Pollution Prevention Plan
I
�
Stormwater Pollution Prevention Plan
p� for the
� Fairfield Development Project
M
Prepared For:
The Fairfield Development Project at the Landing
Renton, Washington
Owner Developer Operator/Contractor
Dan Milich Rick Remsing Fairfield Development, LP
5510 Morehouse Drive 19401 40th Avenue West 19401 40th Avenue West
#200 #280 #280
San Diego, CA 92121 Lynnwood, WA 98036 Lynnwood, WA 98036
Prepared By:
Kleinfelder
2405 140th Avenue NE, Suite A101
Bellevue, Washington 98005
(425) 562-4200
Kathryn Brown, Environmental Scientist
Kleinfelder Project No. 67057
November 8, 2Q06 �� ;��,
i�Y vFrieNTON "-Y
�CEIV�n �F�
_,;°�
;��V � " Z� ; .
UNAUTHORIZED USE OR COPYING OF THIS DOCUMENT IS STRICTLY PROHIBITEC BY ANYONE OTHER THAN THE
CLfENT FOR THE SPECIFIC PROJECT.
33��
Stormwater Po!lution Prevention Plan
TABLE OF CONTENTS
1.0 INTRODUCTION...................................................................................................1
2.0 SITE DESCRiPTION.............................................................................................3
2.1 EXISTING CONDITIONS ...........................................................................3
2.2 PROPOSED CONSTRUCTION ACTIVITIES.............................................3
3.0 CONSTRUCTION STORMWATER BMPS...........................................................5
3.1 THE 12 BMP ELEMENTS ..........................................................................5
3.1.1 Element#1 — Mark Ciearing Limits...................................................5
3.1.2 Element#2 — Establish Construction Access ...................................5
3.1.3 Element#3 — Control Flow Rates.....................................................6
3.1.4 Element#4 — Install Sediment Controls............................................7
' 3.1.5 Element#5 — Stabilize Soils.............................................................8
3.1.6 Element#6 — Protect Slopes............................................................9
3.1.7 Element#7 — Protect Drain Inlets.....................................................9
3.1.8 Element#8 — Stabilize Channels and Outlets ..................................9
3.1.9 Element#9 — Control Pollutants.....................................................10
3.1.10 Element #10 — Control Dewatering...............................................12
3.1.11 Element #11 — Maintain BMPs .....................................................12
3.1.12 Element #12 — Manage the Project ..............................................12
_ 3.2 SITE SPECIFIC BMPS.............................................................................15
4.0 CONSTRUCTION PHASING AND BMP IMPLEMENTATION ...........................16
. ',
5.0 POLLUTION PREVENTION TEA............................................................................17
5.1 ROLES AND RESPONSIBILITIES...........................................................17
5.2 TEAM MEMBERS ....................................................................................17
6.0 SITE INSPECTIONS AND MONITORING...............................................................18
6.1 SITE INSPECTION ..................................................................................18
6.1.1 Site Inspection Frequency..............................................................19
6.1.2 Site Inspection Documentation.......................................................19
6.2 STORMWATER QUALITY MONITORING...............................................19
�
7.0 REPORTING AND RECORDKEEPING .......................................21 �
......................
7.1 RECORDKEEPING..................................................................................21
7.1.1 Site Logbook ..................................................................................21
� 7.1.2 Records Retention..........................................................................21
7.1.3 Access to Plans and Records....................... .........21 �
.........................
7.1.4 Updating the SWPPP.....................................................................21
7.2 REPORTING............................................................................................22
7.2.1 Discharge Monitoring Reports........................................................22
7.2.2 Notification of Noncompliance........................................................22
7.2.3 Permit Application and Changes ....................................................22
67057/SEA6R213.doc Page i of ii November 8,2006
Copyright 2006 Kleinfelder,Inc.
Stormwater Pollution Prevention Plan
APPENDICIES
Appendix A — Site plans
Appendix B — Construction BMPs
Appendix C —Alternative Construction BMP list
Appendix D — General Permit
Appendix E — Site Log and Inspection Forms
Appendix F — Engineering Calculation
� ;
� �
� ,
,
i �
C ,
� i
I � �
'i � ,
I , �
67057/SEA6R213.doc Page ii of ii November 8,2006
Copyright 2�06 Kleinfelder, Inc.
Storm.�✓aier Pollution Preventicn Plan
1.0 INTRODUCTION
This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the
NPDES stormwater permit requirements for the Fairfield construction project at the
Landing in Renton, Washington. The project is located in lot 2 of the Landing property
bordered by Logan Avenue North and Park Avenue North, Garden Avenue North and
North 10th Street in Renton, Washington. The existing site consists of approximately 8
acres being redeveloped as general retail space, a poured concrete underground
garage and construction of mid-rise apartment buildings, and landscaping.
Construction activities will include excavation, grading, relocation of onsite
services/utilities, construction of a generaf retail space, a poured concrete underground
garage and construction of mid-rise apartment buildings. The purpose of this SWPPP is
to describe the proposed construction activities and all temporary and permanent
erosion and sediment control (TESC) measures, pollution prevention measures,
inspection/monitoring activities, and record keeping that will be implemented during the
proposed construction project. The objectives of the SWPPP are to:
. 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.
. Prevent violations of surface water quality, ground water quality, or sediment
management standards.
. Prevent, during the construction phase, adverse water quality impacts including
impacts on beneficial uses of the receiving water by controlling peak flow rates
and volumes of stormwater runoff at the Permittee's outFalls and downstream of
the outfalls.
This SWPPP was prepared In accordance with the requirements set forth in the
Construction Stormwater General Permit, Stormwater Management Manual for Western
Washington (SWMMVWI! 2005). The report is divided into seven main sections with
several appendices that include stormwater related reference materials. The topics
presented in the each of the main sections are:
. Section 1 — INTRODUCTION. This section provides a summary description of
the project, and the organization of the SWPPP document.
67057;SEA5R213.doc Page 1 0'22 November 8,2005
Copyrignt 2006 Kleir,felder, Inc
Storm�vater PoNution Prevention Plan
. Section 2 — SITE DESCRIPTION. This section provides a detailed description of
the existing site conditions, proposed construction activities, and calculated
stormwater flow rates for existing conditions and post—construction conditions.
. Section 3 — CONSTRUCTION BMPs. This section provides a detailed
description of the BMPs to be implemented based on the 12 required elements of
the SWPPP (SWMMWW 2005).
. Section 4 — CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This
section provides a description of the timing of the BMP implementation in relation
to the project schedule.
. Section 5 — POLLUTION PREVENTION TEAM. This section identifies the
appropriate contact names (emergency and non-emergency), monitoring
personnel, and the onsite temporary erosion and sedimentation control inspector
. Section 6 — INSPECTION AND MONITORING. This section provides a
description of the inspection and monitoring requirements such as the
parameters of concern to be monitored, sample locations, sample frequencies,
and sampling methods for all stormwater discharge locations from the site.
. Section 7 — RECORDKEEPING. This section describes the requirements for
documentation of the BMP implementation, site inspections, monitoring results,
and changes to the implementation of certain BMPs due to site factors
experienced during construction.
Supporting documentation and standard forms are provided in the following
Appendices:
6705"SEA5R213 doc Page 2 of 22 November 8,2��6
Copyrig7t 200o Kleinfelder, Inc
Stormwater Po!lution Prevention Plan
2.0 SITE DESCRIPTION
2.1 EXISTING CONDITIONS
The project is bounded by Logan Avenue North, Park Avenue North, Garden Avenue
North and North 10th Street in Renton, Washington. The existing site consists of
approximately 8 acres being redeveloped as general retail space, a poured concrete
underground garage, construction of mid-rise apartment buildings, and landscaping. A
site vicinity map is provided in Appendix A. The site is relatively flat and ranges in
elevation from approximately 27 to 30 feet above mean sea level (msl) with no trending
slope. The project site is underlain by 5 to 15 feet of fill, which consists primarily of
varying proportions of silt, sand and gravel. The fill is underlain by highly variable,
discontinuous layers and lenses of soft and loose alluvial and lacustrine soils extending
depths of approximately 40 to 110 feet below ground surface (bgs).
Site stormwater drainage runs through a series of catch basins and subsurface storm
drains from the northwest side of the property to the northeast (See Appendix A). The
city system discharges to Lake Washington. At the point of discharge, Lake
Washington is not listed as a Category 5 polluted water of the state under the State's
Clean Water Act Section 303(d) list.
There are no critical areas on the site such as high erosion risk areas, wetlands,
streams, or steep slopes (potential landslide area).
2.2 PROPOSED CONSTRUCTION ACTIVITIES
The proposed development includes construction of a general retail space, a poured
concrete underground garage and construction of mid-rise apartment buildings. New
sanitary, electrical, gas, and storm drain utilities will also be constructed.
Construction activities will include site preparation, TESC installation, site-wide grading,
excavation for building foundations, and paving. The schedule and phasing of BMPs
during construction is provided in Section 4.0.
Stormwater runoff volumes were calculated using Stormshed, which utilized the Santa
Barbara Urban Hydrograph Method (SBUH). The temporary sedimentation pond that
will be used during construction was designed using the existing 10-year storm event for
Phase 1 and Phase 2. In the developed conditions, no detention will be provided due to
the site's proximity to Lake Washington. Water quality treatment will be provided two-
� 67057/SEA6R213.doc Page 3 of 22 November 8,2006
Copyright 2006 Kleinfelder, Inc.
Stormwater Pollution Prevention Plan
three cartridge Catch Basin StormFiiters sized to treat the 6-month, 24-hour storm of the
private road and its surrounding area between Phase 1 and Phase 2.
The following summarizes details regarding site areas:
. Total site area: 7.8 acres
. Percent impervious area before construction: 95 %
. Percent impervious area after construction: 65 %
. Disturbed area during construction: 7.7 acres
. Disturbed area that is characterized as impervious
(i.e., access roads, staging, parking): 3.9 acres
. 2-year stormwater runoff peak flow prior to construction
(existing): 3.4 cfs
. 10-year stormwater runoff peak flow prior to construction
(existing): 5.1 cfs
• 2-year stormwater runoff peak flow during construction: 1.4 cfs
. 10-year stormwater runoff peak flow during construction: 3.1 cfs
. 2-year stormwater runoff peak flow after construction: 3.2 cfs
. 10-year stormwater runoff peak flow after construction: 4.9 cfs -
All stormwater flow calculations are provided in Appendix F.
6 i OSi!SEA6R213 dx Page 4 of 22 Ncvember 8,2�06
Copyright 2006 Kleinfelder, Inc.
Stormwater Pol/ution Prevention Plan
3.0 CONSTRUCTION STORMWATER BMPS
3.1 THE 12 BMP ELEMENTS
Provided below are descriptions of the 12 Ecology-required Best Management Practice
elements for western Washington SWPPPs. Excluded BMPs include a brief narrative
providing justification for the exclusion. Ecology fact sheets that include specifications
and installation requirements for each selected BMP are included in Appendix B.
Alternate BMPs are included in Appendix C as a quick reference tool for the onsite
inspector in the event the BMP(s) described below are deemed ineffective or
inappropriate during construction to satisfy the requirements set forth in the General
NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues
that may cause a violation{s) of the NPDES Construction Stormwater permit (as
provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly
initiate the implementation of one or more of the alternative BMPs listed in Appendix C
after the first sign that existing BMPs are ineffective or failing.
3.1.1 Element#1 — Mark Clearing Limits
To protect adjacent properties and to reduce the area of soil exposed to construct'ton,
the limits of construction will be clearly marked before land-disturbing activities begin.
Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be
clearly delineated, both in the field and on the plans. In general, natural vegetation and
native topsoil shall be retained in an undisturbed state to the maximum extent possible.
The BMPs relevant to marking the clearing limits that will be applied for this project
include:
. High Visibility Plastic or Metal Fence (BMP C103)
A metal chain link fence at least three feet high will be used to restrict clearing to
approved limits, limit construction traffic to designated construction entrances or roads,
protect areas with marking or survey tape, and restrict the access of the general public
to the work site
Alternate BMPs for marking clearing limits are included in Appendix C.
3.1.2 Element#2— Establish Construction Access
Construction access and activities occurring on unpaved areas shall be minimized, 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
57057/SEA6R213.doc Page 5 of 22 November 8,20D6
Copyright 2006 Kleinfelder, Inc.
Stormwater Pollufion Prevention Plan
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 (BMP C105)
. Construction Road/Parking Area Stabilization (BMP 107)
Sediment will be controlled from entering into the street and paved surfaces. Sediment
will be removed from trucks and equipment prior to leaving the site by installing a rock
construction access road (Appendix A). If the action of the vehicle traveling over the
rocks is not sufficient to remove the majority of the sediment, then the contractor will
install a tire wash facility. If sediment is still tracked to paved surfaces, street-sweeping
vehicles will be used. The stabilized entrance will be in place prior to the start of
construction activities.
Alternate construction access BMPs are included in Appendix C.
� 3.9.3 Element#3— Control F/ow 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 shall be used on this project include:
. Temporary Sediment Pond (BMP C241)
A temporary sediment pond will be located on the northwest side of the property (see
Appendix A). A proposed sump and gravel filter for pumping stormwater water will be
located approximately 60 feet southwest of the sediment pond. Water from the
temporary sediment ponds will be discharged into the storm water sewer located along
Garden Avenue North. Interceptor swales and rock check dams will also be used as
flow control measures.
Alternate flow control BMPs are included in Appendix C.
The project site is located west of the Cascade Mountain Crest. As such, the project
must comply with Minimum Requirement 7 (Ecology 2005}.
Discharge rates of stormwater from the site will be controlled where increases in
impervious area or soil compaction during construction could lead to downstream
67057lSEA6R213.doc Page 6 of 22 November 8,2006
Copyright 2006 Kleinfelder,Inc.
Stormwater Po!lution Prevention Plan
erosion, or where necessary to meet local agency stormwater discharge requirements
(e.g. discharge to combined sewer systems).
3.1.4 Element#4— Install Sediment Controls
All stormwater runoff from disturbed areas shall pass through an appropriate sediment
removal BMP before leaving the construction site or prior to being discharged to an
infiltration facility. The specific BMPs to be used for controlling sediment on this project
include:
. Silt Fence (BMP C233)
• Storm Drain Inlet Protection (BMP C220)
. Temporary Sediment Pond (BMP C241)
A silt fence will be used around the perimeter of the stockpilelstaging area on the
project site (Appendix A) to limit movement of sediment offsite. Catch basin inserts will
be used to limit the amount of sediment entering the stormwater sewer system.
Alternate sediment control BMPs are included in Appendix C.
In addition, sediment will be removed from paved areas in and adjacent to construction
work areas manually or using mechanical sweepers, as needed, to minimize tracking of
sediments on vehicle tires away from the site and to minimize wash off of sediments
from adjacent streets in runoff.
If permanent stormwater BMPs are used to control sediment discharge during
construction, the structures will be protected from excessive sedimentation with
adequate erosion and sediment control BMPs. Any accumulated sediment shall be
removed after construction is complete and the permanent stormwa�er BMP will be
restabilized with vegetation per applicable design requirements once the remainder of
the site has been stabilized.
67057/SEA6R213.doc Paoe 7 of 22 November 8,2oos
Copyright 20�6 Kleinfelder, Inc.
Stormwater Pollution Prevention Plan
The followin BMPs wiil be im lemented as end-of-pipe sediment controls as required
9 P
to meet permitted turbidity limits in the site discharge(s). Prior to the implementation of
these technologies, sediment sources and erosion control and soil stabilization BMP
efforts will be maximized to reduce the need for end-of-pipe sedimentation controls.
. Temporary Sediment Pond (BMP C241)
. Construction Stormwater Filtration (BMP C251}
. Construction Stormwater Chemical Treatment (BMP C250) (implemented only
with prior written approval from Ecology).
3.1.5 Elemenf#5— Stabilize Soils
Exposed and unworked soils shall be stabilized with the application of effective BMPs to
prevent erosion throughout the life of the project. The specific BMPs for soil
stabilization that shall be used on this project include:
. Plastic Covering (BMP C123)
. Dust Control (BMP C140)
During wet weatt�er-season (November 1 through April 30) the time of disturbed soil
exposure will not exceed 48 hours. From May 1 to October 31 the time of exposure
should not exceed 7 days. Exposed soil must be covered a# the end of a construction
week and also at the threat of rain. Covers may include straw, wood fiber mulch,
compost, and plastic sheeting or equivalent. Stabilize all areas within 7 days of reaching
final grade. Seed or sod any areas to remain unworked for more than 30 days. Dust
from clearing grading, and other construction activities shall be minimized at all times.
Any dust suppressants used must be pre-approved by the director. Petrochemical dust
suppressants are prohibited. Watering the site to suppress dust will be performed such
that sediment is kept out of the public drainage system.
Alternate soil stabilization BMPs are included in Appendix C.
The project site is located west of the Cascade Mountain Crest. As such, no soils shall
remain exposed and unworked for more than 7 days during the dry season (May 1 to
September 30} and 2 days during the wet season (October 1 to April 30). Regardless of
the time of year, all soils shall be stabilized at the end of the shift before a holiday or
weekend if needed based on weather forecasts.
67057/SEA6R213.doc Page 8 of 22 November 8,2006
Copyright 2006 Kleinfelder, Inc.
Sformwater Pollution Prevention P/an.
In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles
will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized
from erosion, protected with sediment trapping measures, and where possible, be
located away from storm drain inlets, waterways, and drainage channels.
3.1.6 E/ement#6— Protect Slopes
All cut and fill slopes will be designed, constructed, and protected in a manner that
minimizes erosion. The following specific BMPs will be used to protect slopes for this
project:
• Plastic Covering (BMP C123)
Cut and fill slopes that are steeper than 2H:1V and equa{ to or greater than four feet in
height, they shall be protected by plastic covering.
Alternate slope protection BMPs are included in Appendix C.
3.1.7 Element#7— Protect Drain /nlets
All storm drain inlets and culverts made operable during construction shall be protected
-to prevent unfiltered or untreated water from entering the drainage conveyance system.
However, the first priority is to keep all access roads clean of sediment and keep street
wash water separate from entering storm drains until treatment can be provided. Storm
Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and
culverts that could potentially be impacted by sediment-laden runoff on and near the
project site. The following inlet protection measures will be applied on this project:
. Catch Basin Filters
If the BMP options listed above are deemed ineffective or inappropriate during
construction to satisfy the requirements set forth in the General NPDES Permit
(Appendix D), or if no BMPs are listed above but deemed necessary during
construction, the Certified Erosion and Sediment Control Lead shall implement one or
more of the alternative BMP inlet protection options listed in Appendix C.
j 3.1.8 Elemenf#8— Stabilize Channels and Outlefs
All temporary on-site conveyance channels shall be de�igned, constructed, and
stabilized to prevent erosion from the expected peak 10 minute velocity of flow from a
Type 1A, 10-year, 24-hour recurrence interval storm for the developed condition. No
specific BMPs for channel and outlet stabilization are prescribed for this project:
67057/SEA6R213.doc Page 9 of 22 November 8,2006
Copyright 2006 Kleinfelder, Inc.
Storm�n�afer PoNution Prevention Plan
. No BMPs to be impiemented
Treated water will be discharged from the temporary sediment pond to the storm sewer.
Alternate channel and outlet stabilization BMPs are included in Appendix C.
3,1.9 Element#9— Control Pol/utanfs
All pollutants, including waste materials and demolition debris, that occur onsite shall be
handled and disposed of in a manner that does not cause contamination of stormwater.
Good housekeeping and preventative measures will be taken to ensure that the site will
be kept clean, well organized, and free of debris. If required, BMPs to be implemented
to control specific sources of pollutants are discussed below.
Vehicles, construction equipment, andlor petroleum product storage/dispensing:
. All vehicles, equipment, and petroleum product storage/dispensing areas will be
inspected regularly to detect any leaks or spills, and to identify maintenance
needs to prevent leaks or spills.
. On-site fueling tanks and petroleum product storage containers shall include
secondary containment.
. Spill prevention measures, such as drip pans, will be used when conducting
maintenance and repair of vehicles or equipment.
. In order to perform emergency repairs on site, temporary plastic will be placed
beneath and, if raining, over the vehicle.
. Contaminated surfaces shall be cleaned immediately following any discharge or
spill incident.
Chemical stora.qe:
. Any chemicals stored in the construction areas will conform to the appropriate
source control BMPs listed in Volume fV of the Ecology stormwater manual. In
Western WA, all chemicals shall have cover, containment, and protection
provided on site, per BMP C153 for Material Delivery, Storage and Containment
in SWMMWW 2005
. Application of agricultural chemicals, including fertilizers and pesticides, shall be
conducted in a manner and at application rates that will not result in loss of
chemical to stormwater runoff. Manufacturers' recommendations for application
procedures and rates shall be followed.
6705%!SEA6R213.doc Page 1 D of 22 November 8. 2006
Copy�ight 2005 Kieinfelder, Inc.
Stormwafer Pollution Prevention Plan
Excavation spoils and dewatering wasfe:
. Dewatering BMPs and BMPs specific to the excavation (including handling of
contaminated soils) are discussed under Element 10.
Demolition:
. Dust released from demolished sidewalks, buildings, or structures will be
controlled using Dust Control measures (BMP C140).
• Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or
debris will be protected using Storm Drain Inlet Protection (BMP C220 as
described above for Element 7).
. Process water and slurry resulting from concrete work will be prevented from
entering the waters of the State by implementing Concrete Handling measures
(BMP C151).
Sanitary wastewater.
. Portable sanitation facilities will be firmly secured, regularly maintained, and
emptied when necessary.
• Wheel wash or tire bath wastewater shall be discharged to a separate on-site
treatment system or to the sanitary sewer as part of Wheel Wash implementation
(BMP C106).
Solid Waste:
. Solid waste will be stored in secure, clearly marked containers.
The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC)
Plan under the Federal regulations of the Clean Water Act (CWA}.
5 r�57'SEA6R213.doc Page 1 1 of 22 November 8,2006
Copyright 2005 Kleinfelder, Inc.
Stormwater Pollution Prevention Plan
3.1.10 Element#10— Control Dewatering
� All dewatering water from open cut excavations, foundation work, trenching, or
underground vaults shali be handled and discharged in a controlled manner. Clean,
non-turbid dewatering water will be discharged to the City of Renton storm water sewer
system in a manner that does not cause erosion, flooding, or a violation of State water
quality standards in the receiving water. BMPs to be used for sediment trapping and
turbidity reduction include the following:
. Temporary Sediment Pond or Collection Tank (BMP C241).
Alternate dewatering control BMPs are included in Appendix C.
3.1.11 Element #19 — Maintain BMPs
All temporary and permanent erosion and sediment control BMPs shall be maintained
and repaired as needed to assure continued performance of their intended function.
Maintenance and repair shall be conducted in accordance with each particular BMP's
specifications. Visual monitoring of the BMPs will be conducted at least once every
calendar week and within 24 hours of any rainfall event that causes a discharge from
the site. If the site becomes inactive, and is temporarily stabilized, the inspection
frequency will be reduced to once every month.
All temporary erosion and sediment control BMPs shall be removed within 30 days after
the final site stabilization is achieved or after the temporary BMPs are no longer
needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil
resulting from removal of BMPs or vegetation shall be permanently stabilized.
3.1.12 Element#12— Manage the Project
Erosion and sediment control BMPs for this project have been designed based on the
following principles:
. Design the project to fit the existing topography, soils, and drainage patterns.
• Emphasize erosion control rather than sediment control.
. Minimize the extent and duration of the area exposed.
. Keep runoff velocities low.
. Retain sediment on site.
. Thoroughly monitor site and maintain all ESC measures.
. Schedule major earthwork during the dry season.
67057lSEA5R2^3.doc Page 12 of 22 November 8,2006
Copyrigh?2006 Kleinfelder, Inc.
Stormwater Po!lution Prevention Plan
In addition, project management will incorporate the key components listed below:
Phasinc�of Construction
. The construction project is being phased to the extent practicable in order to
prevent soil erosion, and, to the maximum extent possible, the transport of
sediment from the site during construction.
. Revegetation of exposed areas and maintenance of that vegetation shall be an
integral part of the clearing activities during each phase of construction, per the
Scheduling BMP (C162).
Seasonal Work Limitations �
. From October 1 through April 30, clearing, grading, and other soil disturbing
activities shall only be permitted if shown to the satisfaction of the local permitting
authority that silt-laden runoff will be prevented from leaving the site through a
combination of the following:
o Site conditions including existing vegetative coverage, slope, soil type,
and proximity to receiving waters; and
o Limitations on activities and the extent of disturbed areas; and
o Proposed erosion and sediment control measures.
. Based on the information provided and/or local weather conditions, the local
permitting authority may expand or restrict the seasonal limitation on site
disturbance.
. The following activities are exempt from the seasonal clearing and grading
limitations:
o Routine maintenance and necessary repair of erosion and sediment
control BMPs;
o 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
o 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
57�57/SEA6R213.doc Page 13 of 22 November 8, 2�D5
Copyright 20�o Kleinfelder. Inc.
Stormwater Pollution Prevention Plan
o Care has been taken to coordinate with utilities, other construction
projects, and the local jurisdiction in preparing this SWPPP and
scheduling the construction work.
Inspection and Monitorinq
. All BMPs shall be inspected, maintained, and repaired as needed to assure
continued perFormance of their intended function. Site inspections shall be
conducted by a person who is knowledgeable in the principles and practices of
erosion and sediment control. This person has the necessary skills to:
o Assess the site conditions and construction activities that could impact the
quality of stormwater, and
o Assess the effectiveness of erosion and sediment control measures used
to control the quality of stormwater discharges.
. A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all
times.
. Whenever inspection and/or monitoring reveals that the BMPs identified in this
SWPPP are inadequate, due to the actual discharge of or potential to discharge
a significant amount of any pollutant, appropriate BMPs or design changes shall
be implemented as soon as possible.
Maintaininp an Updated Construc�ion SWPPP
. This SWPPP shall be retained on-site or within reasonable access to the site.
. The SWPPP shall be modified whene�er there is a change in the design,
construction, operation, or maintenance at the construction site that has, or could
have, a significant effect on the discharge of pollutants to waters of the state.
. The SWPPP shall be modified if, during inspections or investigations conducted
by the owner/operator, or the applicable local or state regulatory authority, it is
determined that the SWPPP is ineffective in eliminating or significantly
minimizing pollutants in stormwater discharges from the site. The SWPPP shall
be modified as necessary to include additional or modified BMPs designed to
correct problems identified. Revisions to the SWPPP shall be completed within
seven (7) days following the inspection.
67057/SEA6R213.doc Page 14 of 22 November 8, 2006
Copyright 2006 Kleinfelder; Inc.
Sformwater Pollution Prevention Plan ��,
3.2 SITE SPECIFfC BMPS
Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A.
These site specific plan sheets will be updated as appropriate.
67057;5EA5R213.doc Page 15 of 22 November 8,2006
Copyrig7t 2006 Kleinfelder, Inc.
Stormwater Po!lution Preventio,� PJan
4.0 CONSTRUCTION PHASING AND BMP IMPLEMENTATION
. Dry Season starts: 05 / 01 / 2007
57057/SEA6R213 doc Page 15 of 22 November 8,2005
Copyright 20G6 Kfeinfefder. Inc.
Stormwater Pollution Prevention Plan
5.0 POLLUTION PREVENTION TEA
5.1 ROLES AND RESPONSIBILITIES
The pollution prevention team consists of personnel responsible for implementation of
the SWPPP, including the following:
. Certified Erosion and Sediment Control Lead (CESCL) — primary contractor
contact, responsible for site inspections (BMPs, visual monitoring, sampling,
etc.); to be called upon in case of failure of any ESC measures.
. Resident Engineer — For projects with engineered structures only (sediment
ponds/traps, sand filters, etc.): site representative for the owner that is the
project's supervising engineer responsible for inspections and issuing instructions
and drawings to the contractor's site supervisor or representative
. Emergency Ecology Contact — individual to be contacted at Ecology in case of
emergency.
. Emergency Owner Contact — individual that is the site owner or representative of
the site owner to be contacted in the case of an emergency.
. Monitoring Personnel — personnel responsible for conducting water quality
monitoring; for most sites this person is also the Certified Erosion and Sediment
Control Lead.
5.2 TEAM MEMBERS
Names and contact information for those identified as members of the pollution
prevention team are provided in the following table.
Title Name(s) Phone Number
Certified Erosion and Sediment Control Lead Katie Brown (425)301-2836
(CESCL} Scott Andrews (425)577-1218
Scott Darst (425)922-3675
Resident Engineer Richard Craiger (425) 640-9242 �
i
Emergency Ecology Contact Christopher Dew (425)649-4484
Emergency Owner Contact Richard Craiger (425)640-9242
Monitoring Personnel Scott Andrews (425) 577-1218
, Scott Darst � (425) 922-3675
' �?057;SEA6R213.doc Page 17 of 22 November 8,2006
Copyright 2006 KVeinfelder, Inc.
Stormwater Pollution Prevention Plan
6.0 SITE INSPECTIONS AND MONITORINGMonitoring 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 logbook will be maintained for all on-
site construction activities and will include:
. A record of the implementation of the SWPPP and other permit requirements;
. Site inspections; and,
. Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site logbook. This SWPPP may
function as the site logbook if desired, or the forms may be separated and included in a
separate site logbook. However, if separated, the site logbook 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. Site inspections will be conducted by a persor� -
who is knowledgeable in the principles and practices of erosion and sediment control.
The onsite inspector will have the skills to assess the potential for water quality impacts
as a result of the type of construction activities occurring on site, and the knowledge of
the appropriate and effective ESC measures needed to control the quality of stormwater
discharges.
All BMPs will be inspected, maintained, and repaired as needed to assure continued
performance of their intended function. The inspector will be a Certified Erosion and
Sediment Control Lead (CESCL) per BMP C160. The name and contact information for
the CESCL is provided in Section 5 of this SWPPP.
Site inspection will occur in all areas disturbed by construction activities and at all
stormwater discharge points. Stormwater will be examined for the presence of
suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will
evaluate and document the effectiveness of the installed BMPs and determine if it is
necessary to repair or replace any of the BMPs to improve the quality of stormwater
discharges. All maintenance and repairs will be documented in the site log book or
5705�;SEA5R213 doc Pa�e 18 of 22 N�vember 8.2005
Copyright 20�5 Kleinfelder, Inc.
Stormwater Pollution Prevention Plan
forms provided in this document. All new BMPs or design changes wiil be documented
in the SWPPP as soon as possible.
6.1.� Site Jnspection Frequency
Site inspections will be conducted at least once a week and within 24 hours following
any rainfall event which causes a discharge of stormwater from the site. For sites with
temporary stabilization measures, the site inspection frequency can be reduced to once
every month.
6.1.2 Site Inspecfion Documentation
The site inspector will record each site inspection using the site log inspection forms
provided in Appendix E. The site inspection log forms may be separated from this
SWPPP document, but will be maintained on-site or within reasonable access to the site
and be made available upon request to Ecology or the local jurisdiction.
6.2 STORMWATER QUALITY MONITORING
Monitoring requirements for the proposed project will include turbidity sampling to
monitor site discharges for water quality compliance with the 2005 Construction
Stormwater General Permit (Appendix D). Sampling will be cc�nducted at all discharge
points at least once per calendar week.
Turbidity monitoring will follow the analytical methodologies described in Section S4 of
the 2005 Construction Stormwater General Permit (Appendix D). The key turbidity
benchmark values that require action are 25 NTU and 250 NTU. If the 25 NTU
benchmark for turbidity is exceeded, the following steps will be conducted:
. Ensure all BMPs specified in this SWPPP are installed and functioning as
intended.
. Assess whether additional BMPs should be implemented, and document
revisions to the SWPPP as necessary.
. Sample discharge location daily until the analysis results are less than 25 NTU
(turbidity) or greater than 32 cm (transparency).
. If the turbidity is greater than 25 NTU but less than 250 NTU for more than 3
days, additional treatment BMPs will be implemented within 24 hours of the third
consecutive sample that exceeded the benchmark value. Additional treatment
j BMPs to be considered will include, but are not limited to, off-site treatment,
infiltration, filtration and chemical treatment.
67057/SEA6R213.doc Page 19 of 22 November 8,2006
Copyright 2006 Kleinfelder,Inc.
Stormwater Pollution Prevention Plan
If the 250 NTU benchmark for turbidity is exceeded at any time, the following steps will
be conducted:
. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this
SWPPP for contact information).
. Continue daily sampling until the turbidity is less than 25 NTU (or transparency is
greater than 32 cm).
. Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration
and chemical treatment within 24 hours of the first 250 NTU exceedance.
. Implement additional treatment BMPs as soon as possible, but within 7 days of
the first 250 NTU exceedance.
. Describe inspection results and remedial actions taken in the site logbook and in
monthly discharge monitoring reports as described in Section 7.0 of this SWPPP.
67057/SEA5R213.doc Page 20 of 22 November 8,2006
Copyright 2006 Kleinfelder, Inc.
�
( Stormwater Pollution Prevention P(an
I
7.0 REPORTING AND RECORDKEEPING
I7.1 RECORDKEEPING
I 7.1.1 Site Logbook
A site logbook will be maintained for all on-site construction activities and will include:
�
I . A record of the implementation of the SWPPP and other permit requirements;
• Site inspections; and,
I • Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site logbook.
7.1.2 Records Retention
Records of all monitoring information (site log book, inspection reports/checklists, etc.),
this Stormwater Pollution Prevention Plan, and any other documentation of compliance
with permit requirements will be retained during the life of the construction project and
for a minimum of three years following the termination of permit coverage in accordance
with permit condition SS.C.
7.1.3 Access to Plans and Records
� The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be
retained on site or within reasonable access to the site and will be made immediately
I� available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be
provided to Ecology within 14 days of receipt of a written request for the SWPPP from
Ecology. Any other information requested by Ecology will be submitted within a
reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the
public when requested in writing in accordance with permit condition SS.G.
7.1.4 Updating fhe 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
5�057%SEA6R213.doc Page 21 of 22 November fi. 20�5
Copyn�ht 20�5 Klein`eld�r. Inc.
Stormwater Pollution Prevention P/an
additional or modified BMPs are necessary to correct problems identified, and an
updated timeline for BMP implementation will be prepared.
7.2 REPORTING
7.2.1 Discharge Monitoring Reports
Discharge Monitoring Report (DMR) forms will be submitted to monthly to the
Department of Ecology.
7.2.2 Notification of Noncompliance
If any of the terms and conditions of the permit are not met, and it causes a threat to
human health or the environment, the following steps will be taken in accordance with
permit section S5.F:
. Ecology will be immediately notified of the failure to comply.
. 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.
. A detailed written report describing the noncompliance will be submitted to
Ecology within five (5) days, unless requested earlier by Ecology.
Any time turbidity sampling indicates turbidity is 250 nephelometric turbidity units (NTU)
or greater or water transparency is 6 centimeters or less, the Ecology regional office will
be notified by phone within 24 hours of analysis as required by permit condition SS.A
(see Section 5.0 of this SWPPP for contact information).
7,2.3 Permit Application and Changes
In accordance with permit condition S2.A, a complete application form will be submitted
to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the
General Permit.
67057/SEA5R213.doc Paae 22 of 22 November 8.2�D5
Copyright 20D6 Kleinfeider, Inc. r
I
�
Stormwater Po!lution Prevention Plan
APPENDIX A - SITE PLANS
�
il �
�:
E
r. �-
'- �I
_ l :
i �
I
i
I_ .I
�
I •
i_
�
i__l
i
I'
�; �
�f' � �� 27th St N E 2�
_._. , VJ fjs _..
D cS
'' c`� D NE 24th St f -
�
d ! m `�
a
m = m �r
L a k e � ;,� � �, a / ,
�.
�� W a s h i n g f o n � `�� " < � i Z
�� rzn rn Q ,'- �
� NE t 6th St m `� Q
04�,Qa�� � � c
O,. 'e� z Z ,,`-�
s �`e s Downstream s': �t� �2tn st "' '� �
�' B Ma�+►� Sample Location� ``� �
�
�: o
a �
� t cc pa� , soo �,
�'�
� S 115ih PI �� rO�eCt �;. � � ,�� �
°�° S 117th St �. Z SI t@ �z 9t ,�� St m
�. ha w
� m � o �, z
cn d "` c�o � � 900 � d �
o � s �D S m y m z z � w a �
Q � �
D �y � w Z � Q � Y Upstrea�n z � D
� ; � � z ��—Sample`�ocation Q �� �
cn a � z � � ,� m
L y O
� � � Q'N 5th St = �� �
ao
S � ,� � N 4th St z � � ME 4th S# NE 4th S#
< Q � � ? o
�Q `° c D � 3rqr St Q 900 ` ab
���0�9 � Z A►rPort Way S ��s�, � �Bs plti 3Cd St
� S, � S Tobin St � �f � Mt OHvet
N �
S � Q a� � C�t�Y
�� Sf S 2nd St �� v, Renton 169
`S� 3rd p� 900 S 3rd St J 3 5' `
m �
Co�yright�1988-200"M-crosoH Corp.anGfor its suppl�rers.All-ights resened. http:;lwwvr.rk�osoft.wm'mapDoint ���
2 Cooyrighl 2D00 Cy Geographic Data Technology,Inc Aii nghts reserved.�.20DG Nav gation Te�hndogies.All rghis reserveA. '�
€Copyrigh[2000 by Compusearch Mlcromarkeling Data arW Systems Ltd. �
� I�
Not to Sca/e
Sample Location Ma� FIGURE
KLEINFELDER Fairfield Development
The Landing 7
PROJECT NO. 75990 November 2006 Renton, Washington
ATTACHED IMAGES:
ATTACHED XREFS:
CAD FILE: G:175990\ LAYOUT: Layoutl
LJ .
•'r
� � � . .�.,"♦ �\ ..
�G j
� �yy , � \�...: �,,,�/' e .
` /t%
`° � " _ / �
�_ � , �
� a> ';; '�/'�,
� . " � `�`, ',,', �,j f,
�,,'�� ,.. `; i
N � s / j �, �\•�� � .
� � '� ��� ���`��
' ' j� /��� � at� .
n . �`/ �l°�, d� � i',
� �� � � i � � � ���
� ,1 � �� • %� °°`�,d oa���'' ' '
� ��,� , � ����_� ,,
i � �,
� �ti ;,`'
,v / ' i /1.r '.r 1 ;
� �/ ,'F/
/,, / % i ` ,:- ` `� �` �
/ � ,,
Y% � i �'`h^ � � " t�
Y �i / ,e�/,� �/�/xf��/�/� � , � � :�J��
t �j �" ��'1��'� �� /' , � ��. r �� a..
/. �,A /� �/� /'�:� �1�� /! 1�}, ���`�� �` 1(n
,
/ 0 / / , / .,� � 7 7� t
c� � ✓��'�� / f/ ,�' �
� / `, � J��'// '� ' n," �
, ��� ,✓`•� �( ��;!%% � ��\�, ^�, 1
? �' /; \/ i.; , , �
� I� F y,F 4.Ci `�"��t://. . �,�;���\ i� 1 � �'u'A�`V .. � .
x �'v.•
i �
�/� ��'� r ,� ��_� � :.� �� .�e �
�� � r .� � rd /� .. ..
I. �� �@' � /~ ��J� �' \ \ �,, � 1.
� , '" •/✓ � � ��/'� • � � , i�`
� � � � �. f /� �I �y _ � � A
� �. , �f� . . �
� `� �
�, . .� _ , .l,l � .i %�� � � � `���
; r.� .L� � ��. �� ,r ,�� � �' �.
,, h. �', 1 1 � ;� ,�" � ,�
� 1 ♦ �, ,� �
.� f/' ` ', MF. 4..Af�llil , `7�`� ��e`• ' .
��J-�, '•,� L .w ^��J` �y y,;.rV�'�tn I � \ � �1 y� .'
�. `� w q
� �
\\\ � �' � � '', � `�� �
� �`.; �„ � ` � �,n,�. � i
�. ,{;; `.� � � , k
� 1 � ,1�� , ,`,
�� � '" :" i �; �,���, � \ �� ; �
< � � , �r�r � ;,,, ,' �
r �,� r. � � ��� . � ��,��,A � ��� � � �;� ��
° �. (y �, � ` � f ,;� +�
�,,�„ ��� `,• \ t��:.+'/ � �/ � ,'.� ` „��.v �'��Y ..
,,, � �� ; �,,.� . , , ,� �. Socapio
� � .. , � ` . �� • � ,� , ,. 1 �Tl�l M� � _ L t #2
_
�;�-�. � ` � �,� ���t�� � ' �` ' `��, �.r,' �, � ;, , �:,�'�� ,�'ti n
.. . ,
_. y� .s . . � ,. � ..... � 1
. � r � �� �. �� - r.;.:� � � ..�..� �`�t .q ��� i r� a�y������r��� ��T � ��.�S�; � ,
� k
. t � ) �\ 9 � � � `� � t����.��'" �?,�`{��" iM 4 f'\ �\ K\. �.� .
/ .
,� , ,� � r �., x �y - �W '� ::: � `t°�.�,��Q� b � ��`� {'G� "i � �. �:".
�j� r f ��� �j� �� 1.., �YIJA`E 'r � �.�""""� " �`�,1 J""`� ,, ` , � ` .�\
�1'', �
�
F . ,.^^"�"� �• `Ar ��
� �' '� �,,°� � + '� �u ,�" �, � �; ���'"� ,� � p�� t�� '� � � �.�'�
"f�. '�
� � i , 1`� � � � j '��,.. li �� ��i <�� � � i"+ Utl+� . ���'�q.�i � � �� � iV� ,� i
r^.�
� r C�`I 'I��..�. . '
. .� � ' ,• ��. � �/ • w .� �� � .�., � . '� ��Gw,,,�""'� �r' .e:. .;w�. sq�.,, ,� r"' , I
��
,I�.�� IiF� � I -•' �� 4" I� I' \ `,`
, �� ' � 1 �k . r . ` M���P f �. ' �l( .
� . � � � � b t"i - b**"�^t� -lx^/ a s�!. .-wt �. 1 . ,
, C '� � a :.�!�;�`" � ��=�� � , �.�� �'�� f �� /e
...
- .�.., � .� ,.�� . �� - � ,4. ���� �� `. _, Sam
.., � � ... w��a.114 1 �x-` '.ri J�., �w°� F
, � 1 .. ��� s .� � �- —
, , a �r �} , � �� ;', , , . � a
� � , �� � � � ,� ,�4� , ,,, „ � � `� ,\ �t Location #1
i��� . ;t � ��'y. 1 � � �.�{� " .�; � � aa�� � .�,asV�'�i " ,��,, �f� �,��,. � �M r +���� ��� �
� ��. �� 1���� 1 � � 'i�` a N l. ' �t����v � � 1
% .� , i �+I �� �� f�-- �� ',. i. N .};'SY �'1 I� Sd I {�§ 6 �'
�� � .
�Y � '}b � �^A
/� ��, • - I t,'�i ,�a �h"1�4 '�� � �q. � � .icL. C'!'��Z}��},ft�'I%" 1 e5 .� �,��., .
-� � ��� i��� `-td 1� I '\ I i�i -II�� �i�'���1,�.. ! , `1
-- � i �. , � �M';;� l \ � ?s�,u:�;r- { ie�� ���" \ ,��,,
- �+:� I t� �dn�i � M� �� 1 f��` I � \ i.,. � a��.� �R 4� I
� I�� i I i j,, 1 � I ' \��'1 ' �, `�i � 1 �
.
�
' i �, I l l I � � �'�. � �.u. i ` ,�� �� 1�, 't
II�' I 1'� , F i t �' ".�"' ,...- �, `� '`'y�
I � �� tk��i ��f,. 14: \ \\`
��I I I �� I I II I I y I �� .� f � 1 u� 1 �� � \ �
�I ��I i l � r iy�" U." \ 4 ,
�� iI I � 1 � VA a
i .
I �'I I� �'d �I�� 'i I • ,�,,;r,� . i ..
� t p II I � /r,'�ja'�'rt�N���� ��"� �� � y p���.
1 ll 1`\ \ I i... .., `� ��.� �
�°I � I� I ��fl� \1' �' F`y�V�l �'��� ��� t.
"' " ` �i .`, �,i ..._...� p Mr t yi��� � �„ ..�\ . !
{ � �� k \
1 � � � �Q
.
.
I I � �� , ���11 , , .�: �,�. �
,, � � - , �
.� � � R.�.�� � �� ���� �� ���k° �� '.
Ii� � �` f
� 7+, _ , ' ��"! �ry �4 :�.r R r � � � I _���4
L �� � � �� �� �x' ��.� * � � � ��
-�
I �. �I � � � � . t . -
. . I I t'I I � a ,�. 'I 4 ��. .
� � \ . ''- �, I l
; I � � .. ......... i ,. ��� ,.�
� �I I II i���� , �� ... . . . 6 ...!' KI �� ,
,a. I `
� � 4
� i �� �
....... i. .
i �
� � ii i��'I, �r * ��it� a
,
. i yfi: ,�.'��� � a! 1 � �' �� .
;:. .
.\
�_ �
,.
"` i � 1 . �r�.,� �. = .
..� ,� �,1 .. �7� •.a
I wx x h .k. 1�t
.
. :': ., .r� .�..... .�,.1 �. ' ...�. . - �
I v � ,
y .; I ,� . ,�t ..:.
� �
.,.
� � ' � � i 1 - A ' ." '��R..� .,� T "� _ .
�
,. ; ..� �.�„� .� ... ..
�. . I . . f n '.. ,�- ' 1 .�� .-' .
� �
,—� .-. � . � �., ���.'. ... ., . ...
r
�`, ,
� i , �.,. - `��
r -...�.�.���,.r� j � ". .:'M ., . • . .. ' S �
�.� . '.:'..
.. 4 - ... . . �_��F I ..:x y ��` .
�
I
�. �.._.. .,�. '�° - __ t
_ . ..,,....,. �� �.. � I � �, , . ,y, \"^,
�
'r r `
r _. ._ ,�_. ,,. ,.. ,. �° r . ., ",. . `
�
, _ 1, _ - 4 A �
, I � � '
. .. .,. .. .,.a � ..I�r Ip, � � - y r 1`
�,„:
_ _ �_.,
„-
� r � ' ' � •t � :. �R
�„�.7�"�,"'�`�'�`m`��'Yy""_1 * I " A ^ . �
. '�j � - — e � ,
, ,..
.
� � , , � ;;,
,
. �. � ., .
II� �I �i �.Y.� � II � ... � . . :�.F�. � .
� � �III i � , �
�'/�//' r I I J�'
✓ . �. �. : � " ' ��.
� ,\\
I I i � � I I I al y,� ,
i i t,1 1`5
l.1' f �I
i
1 I I
I i
1 ��� � � , �� �
o ,00 ; , '
'�� '� � � ,�� �
Scale in Feet
,
Figure
DRAWN BY: J.Stewart gite Plan with Sarrple Locations K L E 1 N F E L D E R
REVISED BY:
-- --- __ —
CHECKED BY: 2405 140th Avenue NE,Suite A101 �
—___—_____ Fairtield Development Bellevue,WA 98005-1877
DATE: �APPROVED BY: The Landin9 PH:(425)562-4200 FAX:(425)562-4201
November 2006 Renton,Washington www.kleinfelder.com
—_ __ —— - _ -- ---- —
� PROJECT NO. 75990 I FILE NAME: Site Plan.dwg
StormwaterPollution Prevention Plan
APPENDIX B — CONSTRUCTION BMPS
High Visibility Plastic or Metal Fence (BMP C103)
Stabilized Construction Entrance (BMP C105)
Construction Road/Parking Area Stabilization (BMP C107)
Temporary Sediment Pond (BMP C241)
Construction Stormwater Filtration (BMP C251)
Concrete Handling (BMP C151)
Silt Fence (BMP C233) I
� Storm Drain Inlet Protection (BMP C220)
Plastic Covering (BMP C123)
Dust Control (BMP C140)
�
BMP C103: High Visibility Plastic or Metal Fence
Purpose Fencing is intended to: (1) restrict clearing to approved limits; (2)prevent
disturbance of sensitive areas,their buffers, and other areas required to be
left undisturbed; (3) limit construction traffic to designated construction
entrances or roads; and, (4)protect areas where marking with survey tape
may not provide adequate protection.
Conditions of Use To establish clearing limits,plastic or metal fence may be used:
• At the boundary of sensitive areas,their buffers, and other areas
required to be left uncleared.
• As necessary to control vehicle access to and on the site.
Design and • High visibility plastic fence shall be composed of a high-density
Installation polyethylene material and shall be at least four feet in height. Posts
Specifications for the fencing shall be steel or wood and placed every 6 feet on
center(maximum) or as needed to ensure rigidity. The feneing shall
be fastened to the post every s� inches with a polyethylene tie. On
long continuous lengths of fencing, a tension wire or rope shall be
used as a top stringer to prevent sagging between posts. The fence
color shall be high visibility orange. The fence tensile strength shall
be 3601bs./ft. using the ASTM D4595 testing method.
• Metal fences shall be designed and installed according to the
manufacturer's specifications.
• Metal fences shall be at least 3 feet high and must be highly visible.
• Fences shall not be wired or stapled to trees.
Maintenance • If the fence has been damaged or visibility reduced, it shall be
Standards repaired or replaced immediately and visibility restored.
4-6 Volume ll- Construction Stormwater Pollufion Prevention February 2005
BMP C105: Stabilized Construction Entrance
Purpose Construction entrances are sta.bilized to reduce the amount of sediment �
transported onto paved roads by vehicles or equipment by constructing a
stabilized pad of quarry spalls at entrances to construction sites.
Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving
a construction site and traveling on paved roads or other paved areas
within 1,000 feet of the site.
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 i.nitial Construction SWPPP. It is
difficult to determine exactly where access to these projects will take
place; additional ma.terials will enable the contractor to install them where
needed.
Design and • See Figure 4.2 for details. Note: the 100' minimum length of the
Installation entrance shall be reduced to the maximum practicable size when the
Specifications size or configuration of the site does not allow the full length(100').
• A separation geotextile shall be placed under the spalls to prevent
fine sediment from pumping up into the rock pad. The geotextile
shall meet the following standards:
Grab Tensile Strength (ASTM D4751) 200 psi min.
Grab Tensile Elongation (ASTM b4632) 30% max. ,
, Mullen Burst Strength(ASTM D3786-80a) 400 psi min.
AOS (ASTM D4751) 20-45(U.S. standard sieve size)
• Consider early installation of the first lift of asphalt in areas that will
paved;this can be used as a stabilized entrance. Also consider the
installation of excess concrete as a stabilized entrance. During large
concrete pours, excess concrete is often available for this purpose.
• Hog fuel (wood-based mulch) may be substituted for or combined with
quarry spalls in azeas that will not be used for permanent roads. Hog
fuel is generally less effective at stabilizing construction entrances and
should be used only at sites where the amount of traff c is very limited.
Hog fuel is not recommended for entrance stabilization in urban areas.
The effectiveness of hog fuel is highly variable and it generally
requires more maintenance than quarry spalls. The inspector may at
' any time require the use of quarry spalls if the hog fuel is not
preventing sediment from being tracked onto pavement or if the hog
fuel is being carried onto pavement. Hog fuel is prohibited in
permanent roadbeds because organics in the subgrade soils cause
degradation of the subgrade support over time.
• Fencing (see BMPs C 103 and C 104)shall be installed as necessary to
restrict traffic to the construction entrance.
4-8 Volume !1— Construction Stormwater Pollution Prevention February 2005
• Whenever possible,the entrance sball be constructed on a firm,
compacted subgrade. This can substantially increase the effectiveness
of the pad and reduce the need for maintenance.
Maintenance • Quarry spalls(or hog fuel) shall be added if the pad is no longer in
Standards accordance with the specifications.
• If the entrance is not preventing sediment from being tracked onto
pavement,then alternative measures to keep the streets free of
sediment shall be used. This may include 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 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 shall be considered.
The sediment would then be washed into the sump where it can be
controlled.
• Any quarry spalls that are loosened from the pad, which end up on the
roadway shall be removed immediately.
• If vehicles are entering or e�uting the site at points other than the
construction entrance(s), fencing(see BMPs C103 and C104) shall be
installed to control traffic.
• Upon project completion and site stabilization, all construction
accesses intended as permanent access for maintenance shall be
permanently stabilized.
Drivewey shaB mee�the
requ'vemenis ot ihe
partnittinp apenq
k is recommanded that
the entrance 6e
crowned so that rurq((
�d drains off the pad
P
Eps� i
'°o.
3�
i
!
Instal driveway aHert
M there Is a roadside
ditch present
4�•g"q�arTY SPalls
Geotextib
12'min.thickness_� ,fi� /���\�
� Provide fuli witlM of
ingress/egress erea
Figure 4.2- Stabilized Construction Entrance
February 2005 Volume 11- Construction Storm�vater Pollution Prevention 4-9
BMP C107: Construction Road/Parking Area Stabilization
Purpose Stabilizing subdivision roads,parking areas, and other onsite vehicle
transportation routes immediately after grading reduces erosion caused by
construction traffic or runoff.
Conditions of Use ' Roads or parki.ng areas shall be stabilized w�herever they are constructed,
whether permanent or temporary, for use by construction traffic.
• Fencing(see BN1Ps C103 and C104) shall be installed, if necessary,to
limit the access of vehicles to only those roads and parking areas that
are stabilized.
Design and • On areas that will receive asphalt as part of the project,�install the first
Installation lift as soon as possible.
Specifications A 6-inch depth of 2-to 4-inch crushed rock,gravel base,or crushed
• surfacing base course shall be applied immediately after grading or
utility installation. A 4-inch course of asphalt treated base (ATB)may
also be used, or the road/parking area may be paved. It may also be
possible to use cement or calcium chloride for soil stabilization. If
cement or cement kiln dust is used for roadbase stabilization,pH
monitoring and BMPs are necessary to evaluate and minimize the
effects on stormwater. If the area will not be used for permanent roads,
parking areas, or structures, a 6-inch depth of hog fuel may also be
used,but this is likely to require more maintenance. Whenever
possible, construction roads and parking areas shall be placed on a firm, '.
compacted subgrade.
• Temporary road gradients sha11 not exceed 15 percent. Roadways shall
be carefully graded to drain. Drainage ditches shall be provided on each
side of the roadway in the case of a crowned secrion, or on one side in the
case of a super-elevated section. Drainage ditches shall be directed to a
sediment control BMP.
• Rather than relying on ditches,it may also be possible to grade the road
so that runoff sheet-flows into a heavily vegetated area with a well-
developed topsoil. Landscaped areas are not adequate. If this area has at
least 50 feet of vegetation, then it is generally preferable to use the
vegetation to treat ru.noff,rather than a sediment pond or trap. The 50
feet shall not include wetlands. If runoff is allowed to sheetflow through
adjacent vegetated areas, it is vital to design the roadways and pazking
areas so that no concentrated runoff is created.
• Storm drain inlets shall be protected to prevent.sediment-laden water
- -
entering the storm drai.n system(see BMP C220).
hlaintenance • Inspect stabilized azeas regularly,especially after large storm events.
Standards . Crushed rock, gravel base,hog fuel, etc. shall be added as required to
maintain a stable driving surface and to stabilize any areas that have
eroded.
• Following construction,these areas shall be restored to pre-construction �
condition or better to prevent future erosion.
4-12 Volume ll- Construcrion Stormwater Po!lution PrevPn.tion February 2L�05
BMP C241: Temporary Sediment Pond
Purpose Sediment ponds remove sediment from runoff originating from disturbed
areas of the site. Sediment ponds are typically designed to remove
sediment no smaller than medium silt (0.02 mm). Consequently, they
usually reduce turbidity only slightly.
Conditions of Use Prior to leaving a construction site, stormwater runoff must pass through a
sediment pond or other appropriate sediment removal best management
practice.
A sediment pond shall be used where the contributing drainage area is 3
acres or more. Ponds must be used in conjunction with erosion control
practices to reduce the amount of sediment flowing into the basin.
Design and • Sediment basins must be installed only on sites where failure of the
Installation structure would not result in loss of life,damage to homes or
Specifications buildings, or interruption of use or service of public roads or utilities.
Also, sediment traps and ponds are attractive to children and can be
very dangerous. Compliance with local ordinances regarding health
and safety must be addressed. If fencing of the pond is required, the
type of fence and its location shall be shown on the ESC plan.
• Structures having a maximum storage capacity at the top of the dam of
10 acre-ft(435,600 ft3) or more are subject to the Washington Dam
Safety Regulations (Chapter 173-175 WAC).
• See Figure 4.24, Figure 4.25, and Figure 4.26 for details.
• If permanent runoff control facilities are part of the project, they
should be used for sediment retention. The surface area requirements
of the sediment basin must be met. This may require enlarging the
permanent basin to comply with the surface area requirements. If a
permanent control structure is used, it may be advisable to partially
restrict the lower orifice with gravel to increase residence time while
still allowing dewatering of the basin.
• Use of infiltration facilities for sedimentation basins during
construction tends to clog the soils and reduce their capacity to
infiltrate. If infiltration facilities are to be used,the sides and bottom
of the facility must only be rough excavated to a minimum of 2 feet ��
above final grade. Final grading of the infiltration facility shall occur I
only when all contributing drainage areas are fully stabilized. The I',
infiltration pretreatment facility should be fully constructed and used I
with the sedimentation basin to help prevent clogging. '
• Determining pond Geometry
Obtain the discharge from the hydrologic calculations of the peak flow
for the 2-year runoff event(QZ). The 10-year peak flow shall be used
if the project size, expected timing and duration of construction, or
downstream conditions wanant a higher level of protection. If no
hydrologic analysis is required,the Rational Method may be used.
February 2005 Volume ll-Construction Stormwater Po!lution Prevention 4-105
_
I '
Deterinine the required surface area at the top of the riser pipe with the
equation:
SA = 2 x Q2/0.00096 or
2080 square feet per cfs of inflow
See BMP C240 for more information on the derivation of the surface �'
area calculation.
The basic geometry of the pond can now be determ.ined using the
following design criteria:
• Required surface area SA(from Step 2 above) at top of riser.
• Mini.mum 3.5-foot depth from top of riser to bottom of pond.
• Maximum 3:1 interior side slopes and maximum 2:1 exterior slopes.
The interior slopes can be increased to a maximum of 2:1 if fencing is
provided at or above the maximum water surface.
• One foot of freeboard between the top of the riser and the crest of the
emergency spillway.
• Flat bottom.
• Minunum 1-foot deep spillway.
• Length-to-width ratio between 3:1 and 6:1.
• Sizing of Discharge Mechanisms.
The outlet for the basin consists of a combination of principal and
emergency spillways. These outlets must pass the peak runoff expected
from the contributi.ng drainage area for a 100-year storm. If, due to site �
conditions and basin geometry,a sepazate emergency spill-way is not
feasible,the principal spillway must pass the entire peak runoff expected
from the 100-yeaz storm. However, an attempt to provide a separate
emergency spillway should always be made. The runoff calculations
should be based on the site conditions during construction. The flow
through the dewatering orifice cannot be utilized when calculating the
100-year storm elevarion because of its potential to become clogged;
therefore, available spillway storage must begin at the principal spillway
riser crest.
The pri.ncipal spillway designed by the procedures contained in this
standard will result i.n some reduction in the peak rate of ru.noff.
However,the riser outlet design will not adequately control the basin
discharge to the predevelopment discharge limitations as stated in
_ _ _ Minimum-Requirement�7: Flow.Control.--Howeuer, if the basin for a
permanent stormwater detention pond is used for a temporary
sedimentation basin,the control structure for the permanent pond can be
used to maintain predevelopment dischazge li.mitations. The size of the
basin,the expected life of the construction project,the anticipated
downstream effects and the anticipated weather conditions during
construction, should be considered to determine the need of additional
discharge control. See Figure 4.28 for riser inflow curves.
4-106 Volume 11—Construction Stormwater Pollution Prevention February 2005
Key divider into sbpe '—�
to prevent flow T��: ;.
arour�Oj�� 4.3 -Sediment iser D� il
The pond length shall be 3 to 6
times the ma�dmum pond widih � � ���,���,
i � ' � `°
S�in��
� � Y.� /
� -��
� ,—>
'' ` Por�length,� supp ----� �.ry
Infiow �p � • f
Sift f�ce or �, ; i : Discharge to stabdzed
� V equivalent dnrider � � i conveyance,ou8et,or
;' r i t'. ; level spreader
`__�T, , �' �� �{ �f:
�_~--� /
!
�
Note:Pond may be fomied by berm or
by partial or complete excavation ti
Figure 4.24-Sediment Pond Plan View
Riser Pipe
(principal spilMray) Crest of
open at top with emergency spillway 6'min.Wfdth
trash radc �
E�i � i ,:�,k. Embankment compacted 95°k
���)_�C Dewatering device �, r —-- -. rvious materials such as
���— `'s (see riser detail) _ ��,� _ �`� gravel or Gean sand shall
�� � 'c = '�-=-_'_-=�- _�i not be used
����` _ � � ��'!=:--v�:_'-_-=`�-_=__`
'-�: _ � �--==_--------- �
`� 4 . �...-.. . "' "_ ..
��I �"i i�--�. ��f i�-.� =ttf=������i ���_
'I'� ���1N1—�� � �] � �t--{����c-�t E�71 � � .�,,��'I�'1?-
T!����_ , Tl:.� '�
�:'�l��r r� • ,. :�� Dischargetostab�l¢ed
Vlifre-backed sitt fence pewatering ��te base cornreyance outlet or
staked haybales wrapped p�{�ce (see riser detail) tevei spreader
with filter fabric,or
equivalent divider
Figure 4.25-Sediment Pond Cross Section
Polyethylene cap Prrnride adequate
strapping
Perforated poyethylene = Cortugated
drainage tubing,d�ameter _
min.2"larger than ' m���
dewatering orifice. =
Tubing shall comply = 3.5"min.
- ��'g� Dewaterin orifice,scheduFe,
with ASTM F667 and _ �p�pling Tadc weld 40�eel stub m in
AASHTO M294 _
' Diameter as per ca�ulations
=:,
���1F/11
� 6"fnifl. r�-�
L'--- -"�
16"min. � Altematively,metal stakes
� Concrete base and wire may be used to
preverY fldatio�
�2X riser dia.Min.-�-I
Figure 4.26-Sediment Pond Riser Detail
February 2005 Volume !1-C�nstruction Stormwater Pollution Prevention 4-107
1D0 —
72 54 48
�
�
I 42
1 S 36
i 33
i
30
2T
24 �
m
21 �
v
c
� 18
m
a
L
m
a
m �� 15
m
...
u
a
3
�
a , �2
�
10
I
I �
(
1
��� HEAD IN FEET (m easu�red from crest of riser) ��
Qwe�r=9.739 DHg��
dor�t�ce=3.782 DzH��
Q i� cfs, D end H irt feet
Siope change oecurs at weir=orifice transition
Figure 4.27-Riser Inflow Curves
4-108 Volume I!- Construction Stormwafer PoUution Prevention Februarv 2005
Principal Spillway: Determine the required diameter for the principal
spillway(riser pipe). The diameter shall be the minimum necessary to
pass the pre-developed 10-year peak flow(Qlp). Use Figure 4.28 to
deternune this diameter(h= 1-foot). Note:A per•manent control structure
� may be used instead of a temporary riser•.
Emergency O�erflow Spillway: Deternune the required size and design �
of the emergency overflow spillway for the developed 100-year peak flow
using the method contained in Volume III.
Dewatering Orifice: Determine the size of the dewatering orifice(s)
(minimum 1-inch diameter) using a modified version of the discharge
equation for a vertical orifice and a basic equation for the area of a circular
orifice. Determine the required area of the orifice with the following
equation:
AS�2h�o.5
A° 0.6x3600Tg°�5
where Ao = orifice area(square feet)
AS = pond surface area(square feet)
h = head of water above orifice(height of riser in feet) '
T = dewatering time (24 hours)
g = - acceleration of gravity(32.2 feetlsecond2)
Convert the required surface area to the required diameter p of the orifice:
D= 24x A° =13.54x Ao
�
The vertical,perforated tubing connected to the dewatering orifice must be
at least 2 inches larger in diameter than the orifice to improve flow
characteristics. The size and number of perforations in the tubing should
be large enough so that the tubing does not restrict flow. The orifice
should control the flow rate.
• Additional Design Specifications
The pond shall be divided i.nto two roughly equal volume cells by a
permeable divider that will reduce turbulence while allowing
movement of water between cells. The divider shall be at least one-
half the height of the riser and a minimum of one foot below the top of
the riser. Wire-backed, 2-to 3-foot high, extra strength filter fabric
supported by treated 4"x4"s can be used as a divider. Altematively,
� staked straw bales wrapped with filter fabric (geotextile)may be used.
If the pond is more than 6 feet deep, a different mechanism must be
proposed. A ripra.p embankment is one acceptable method of
separation for deeper ponds. Other designs that satisfy the intent of
February 2005 Volume ll— Construcfion Stormwater Po!lution Pr�vention 4-109
this provision are allowed as long as the divider is permeable,
structurally sound, and designed to prevent erosion under or around '
the barrier.
To aid in determining sediment depth, one-foot intervals shall be
prominently marked on the riser.
� If an embankment of more than 6 feet is proposed,the pond must '
comply with the criteria contained in Volume III regarding dam safety
for detention BMPs.
• The most common structural failure of sedimentation basins is caused
by piping.• Piping refers to two phenomena: (1) water seeping through
fine-grained soil, eroding the soil grain by grain and forming pipes or
tunnels; and, (2)water under pressure flowing upward through a
granular soil with a head of sufficient magnitude to cause soil grains to
lose contact and capability for support.
T'he most critical construction sequences to prevent piping will be:
1. Tight connections between riser and barrel and other pipe
connections.
2. Adequate anchoring of riser.
3. Proper soil compaction of the embankment and riser footing.
4. ��roper construction of anti-seep devices. ,
Maintenance • Sediment shall be removed from the pond when it reaches 1-foot in
Standards depth.
� Any damage to the pond embankments or slopes shall be repaired.
4-110 Volume ll— Constructi�n Storrrrwater Pollution Prevenfion February 2005
BMP C251: Construction Stormwater Filtration
Purpose Filtration removes sediment from runoff originating from disturbed areas
of the site.
Conditions of Use Traditional BMPs used to control soil erosion and sediment loss from sites
under development may not be adequate to ensure compliance with the
water quality standard for turbidity in the receiving water. Filtration may
be used in conjunction with gravity settling to remove sediment as small
as fine silt(0.5 µm). The reduction in turbidity will be dependent on the
particle size distribution of the sediment in the stormwater. In some
circumstances, sedimentation and filtration may achieve compliance with
the water quality standard for turbidity.
Unlike chemical treatment,the use of construction stormwater filtration
does not require approval from Ecology.
Filtration may also be used in conjunction with polymer treatment in a
portable system to assure capture of the flocculated solids.
Design and Background Information
Installation
Specifications Filtration with sand media has been used for over a century to treat water
and wastewater. The use of sand filtration for treatment of storrnwater
has developed recently, generally to treat runoff from streets, parki.ng lots,
and residential areas. The application of filtration to construction
stormwater treatment is currently under development.
Two types of filtration systems may be applied to construction stormwater
treatment: rapid and slow. Rapid sand filters are the typical system used
for water and wastewater treatment. They can achieve relatively high
hydraulic flow rates, on the order of 2 to 2Q gpm/sf, because they have
automatic backv��ash systems to remove accumulated solids. In contrast,
slow sand filters have very low hydraulic rates, on the order of 0.02
gpm/sf,because they do not have backwash systems. To date, slow sand
filtration has generally been used to treat stormwater. Slow sand filtration
is mechanically simple in comparison to rapid sand filtration but requires a
much larger filter area.
Filtration Eqnipment. Sand media filters are available with automatic
backwashing features that can filter to 50 µm particle size. Screen or baj
filters can filter down to 5 µm. Fiber wound filters can remove particles
down to 0.5 µm. Filters should be sequenced from the largest to the
smallest pore opening. Sediment removal efficiency will be related to �
particle size distribution in the stormwater. �'�
Treatment Process Description. Stormwater is collected at interception I
point(s) on the site and is diverted to a sediment pond or tank for removal '�
of large sediment and storage of the stormwater before it is treated by the
February 2005 Volume !J- Construcfion Stormwater Pollution Prevenfion 41?7
filtration system. The stormwater is pumped from the trap,pond, or tank
through the filtration system in a rapid sand filtration system. Slow sand �.
filtration systems are designed as flow through systems using gravity.
If large volumes of concrete are being poured,pH adjustment may be
necessary.
Maintenance Rapid sand filters typically have automatic backwash systems that are
Standards triggered by a pre-set pressure drop across the filter. If the backwash
water volume is not large or substantially more turbid than the stormwater
stored in the holding pond or tank, backwash return to the pond or tank
may be appropriate. However, land application or another means of
treatment and disposal may be necessary.
• Screen, bag, and fiber filters must be cleaned andlor replaced when
they become clogged.
• Sediment shall be removed from the storage and/or treatment ponds as
necessary. Typically, sediment removal is required once or twice
duri.ng a wet season and at the decommissioning of the ponds.
, -- - . _. . .
, � I
'� ,
!
. _,
i
i
4-118 Volume 1!- Construction Stormwater Pollution Prevention February 2005
BMP C151: Concrete Handling
Purpose Concrete work can generate process water and slurry that contain fine
particles and high pH, both of which can violate water quality standards in
the receiving water. This BMP is intended to minimi�e and eliininate
concrete process water and slurry from entering waters of the state.
Conditions of Use Any time concrete is used,these management practices shall be utilized.
Concrete construction projects include, but are not limited to,the
following:
• Curbs
• Sidewalks
• Roads
• Bridges
• Foundations
• Floors
• Runways
Design and • Concrete truck chutes, pumps, and internals shall be washed out only
Installation into formed areas awaiting installation of concrete or asphalt.
Specifications Unused concrete remaining in the truck and pump shall be returned to
• the originating batch plant for recycling.
• Hand tools including, but not limited to, screeds, shovels, rakes, floats,
and trowels shall be washed off only into formed areas awaiting
installation of concrete or asphalt.
• Equipment that cannot be easily moved, such as concrete pavers, shall
only be washed in areas that do not directly drain to natural or
constructed stormwater conveyances.
• Washdown from areas such as concrete aggregate driveways shall not
drain directly to natural or constructed stormwater conveyances.
• When no formed areas are available, washwater and leftover product
shall be contained in a lined container. Contained concrete shall be
disposed of in a manner that does not violate groundwater or surface
water quality standards.
Maintenance Containers shall be checked for holes in the liner daily during concrete
Standards pours and repaired the same day.
February 2�05 V�lume Il— Construction Stormwater Potlu�ion Prevention 4-43
BMP C233: Siit Fence
1
Purpose Use of a silt fence reduces the transport of coarse sediment from a
construction site by providing a temporary physical barrier to sediment
and reducing the runoff velocities of overland flow. See Figure 4.19 for
details on silt fence construction.
Conditions of Use Silt fence may be used downslope of all disturbed areas.
• Silt fence is not intended to treat concentrated flows,nor is it intended
to treat substantial amounts of overland flow. Any concentrated flows
must be conveyed through the drainage system to a sediment pond.
The only circumstance in which overland flow can be treated solely by
a silt fence,rather than by a sediment pond,is when the area draining
to the fence is one acre or less and flow rates are less than 0.5 cfs.
• Silt fences should not be constructed in streams or used in V-shaped
ditches. They are not an adequate method of silt control for anything
deeper than sheet or overland flow.
Joints in fifter fabric shall be spliced at
posts.Use staples,wire rings or 2°x2•by 14 Ga.wire or
equivalent to attach fabric to posts equivalent,if standard
strength fabric used
I I - Ffter fabric
II I =
II I E
N
I ( � :.
I �
f I � � _'
i C
� �-6'max-� T� Minimum 4"x4'trench �� E
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 4.19—Silt Fence
Design and e ��age area of 1 acre or less or in combination with sediment basin
Installation in a larger site.
Specifications
� Ma�mum slope steepness (normal (perpendicular)to fence line) 1:l.
• Ma�cimum sheet or overland flow path length to the fence of 100 feet.
• No flows greater than 0.5 cfs.
• The geote�rtile used shall meet the following standards. All geotextile
properties listed below are mi.nimum average roll values (i.e., the test
result for any sampled roll in a lot shall meet or exceed the values
shown in Table 4.10):
4-94 Volume N-Construction Sformwater Po!lutien Prevention February 2005
Table 4.10
Geotextile Standards
Polymeric Mesh AOS 0.60 mm maximum for slit film wovens(#30 sieve). 030
(ASTM D4751) mm maximum far all other geotextile types(#50 sieve).
0.15 mm minimum for all fabric types(#100 sieve).
Water Permittivity 0.02 sec'minimum
(ASTM D4491)
Grab Tensile Strength 1801bs. Minimum for extra sixength fabric.
(ASTM D4632) 1001bs min;mum for standard strength fabric.
Grab Tensile Strength 30%m�ivnum
(ASTM D4632)
U7traviolet Resistance 70%m;nimum
(ASTM D4355)
• Standard strength fabrics shall be supported with wire mesh, chicken
wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the
strength of the fabric. Silt fence materials are available that have
synthetic mesh backing attached.
• Filter fabric material shall contain ultraviolet ray inhibitors and
stabilizers to provide a minimum of six months of expected usable
construction life at a temperature range of 0°F. to 120°F.
• 100 percent biodegradable silt fence is available that is strong, long
I�sting, and can be left in place after the proje�t is completed, if �
permitted by local regulations.
• Standard Notes for construction plans and specifications follow. Refer
to Figure 4.19 for standard silt fence details.
The contractor shall install and maintain temporary silt fences at the
locations shown in the Plans. The silt fences shall be constructed in
the areas of clearing, grading,or drainage priar to starting those
activities. A silt fence shall not be considered temporary if the silt
fence must function beyond the life of the contract. The silt fence
shall prevent soil carried by runoff water from going beneath,through,
or over the top of the silt fence,but shall allow the water to pass
through the fence.
The n�mum height of the top of silt fence shall be 2 feet and the '
m�imum height shall be 21/2 feet above the original ground surface. �
The geote�tile shall be sewn together at the point of manufacture, or at
an approved location as deternvned by the Engineer, to form geotextile
lengths as required. All sewn seams shall be located at a support post.
Alternatively,two sections of silt fence can be overlapped,provided
the Contractor can demonstrate,to the satisfaction of the Engi.neer, that
the overlap is long enough and that the adjacent fence sections are
close enough together to prevent silt laden water from escaping
through the fence at the overlap.
February 2005 Volume tl— Construction Stormv✓ater Pollution Prevention 4-95
The geoteatile shall be attached on the up-slope side of the posts and
support system with staples,wire,or in accordance with the '
manufacturer's recommendations. The geotextile shall be attached to
the posts in a manner that reduces the potential for geotextile tearing at
the staples,wire, or other connection device. Silt fence back-up
support for the geotextile in the form of a wire or plastic mesh is
dependent on the properties of the geotextile selected for use. If wire
or plastic back-up mesh is used, the mesh shall be fastened securely to
the up-slope of the posts with the geotextile being up-slope of the
mesh back-up suppart.
The geote�ile at the bottom of the fence shall be buried in a trench to
a minimum depth of 4 inches below the ground surface. The trench
shall be backfilled and the soil tamped in place over the buried portion
of the geote�ile, such that no flow can pass beneath the fence and
scouring can not occur. When wire or polymeric back-up support
mesh is used,the wire or polymeric mesh shall eatend into the trench a
minimum of 3 inches.
The fence posts shall be placed or driven a minimum of 18 inches. A
minimum depth of 12 inches is allowed if topsoil or other soft
-suligrade soil is no�present and a minimum depth of 18 inches cannot
be reached. Fence post depths shall be increased by 6 inches if the
fence is located on slopes of 3:1 or steeper and the slope is
- perpendicular to the fence. If required post depths carulot be obtained;
the posts shall be adequately secured by bracing or guying to prevent �
overturning of the fence due to sediment loading.
Silt fences shall be located on contour as much as possible, except at
the ends of the fence,where the fence shall be tumed uphill such that
the silt fence captures the runoff water and prevents water from
flowing around the end of the fence.
If the fence must cross contours, with the exception of the ends of the
fence,gravel check dams placed perpendicular to the back of the fence
shall be used to minimi�e concentrated flow and erosion along the
back of the fence. The gravel check dams shall be appro�mately 1-
. foot deep at the back of the_fence. It shall be continued perpendicular
to the fence at the same elevation until the top of the check dam
intercepts the ground surface behind the fence. The gravel check dams
shall consist of crushed surfacing base course, gravel backfill for
- --- - - --walls,or-shoulder-ballast.--�'he grave��heck dams shall be located
every 10 feet along the fence where the fence must cross contours.
The slope of the fence line where contours must be crossed shall not
be steeper than 3:1.
Wood, steel or equivalent posts shall be used Wood posts shall have
minimum dimensions of 2 inches by 2 inches by 3 feet minimum
length,and shall be free of defects such as knots,splits, or gouges. �
496 Volume 1!—Construction Storn�.water Polluti�n Pr�venti�n Februar}�2�05
Steel posts shall consist of either size No. 6 rebar or larger,ASTM A
120 steel pipe with a minimum diameter of 1-inch, U, T, L, or C shape
steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts
having equivalent strength and bending resistance to the post sizes
listed. The spacing of the support posts shall be a maximum of 6 feet.
Fence back-up support, if used, shall consist of steel wire with a
m�imum mesh spacing of 2 inches,or a prefabricated polymeric
� mesh. The strength of the wire or polymeric mesh shall be equivalent
to or greater than 1801bs. grab tensile strength. The polymeric mesh
must be as resistant to ultraviolet radiation as the geotextile it supports.
• Silt fence installation using the slicing method specification details
follow. Refer to Figure 4.20 for slicing method details.
The base of both end posts must be at least 2 to 4 inches above the top
of the silt fence fabric on the m.iddle posts for ditch checks to drain
properly. Use a hand level or string level, if necessary,to mark base
points before installation.
Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet
apart in standard applications.
Install posts 24 inches deep on the do��nstream side of the silt fence,
and as close as possible to the fabric,enabling posts to support the
fabric from upstream water pressure.
Install posts with the nipples facing away from the silt fence fabric.
Attach the fabric to each post with three ties, all spaced within the top
8 inches of the fabric. Attach each tie diagonally 45 degrees through
the fabric, with each puncture at least 1 inch vertically apart. In
addition, each tie should be positioned to hang on a post nipple when
tightening to pre�ent sagging.
Wrap approximately 6 inches of fabric around the end posts and secure
with 3 ties.
No more than 24 inches of a 36-inch fabric is allov�red above ground
level.
The rope lock system must be used in all ditch check applications.
The installation should be checked and corrected for any deviation
before compaction. Use a flat-bladed shovel to tuck fabric deeper into
the ground if necessary.
Compaction is vitally important for effective results. Compact the soil
immediately next to the silt fence fabric with the front wheel of the
tractor, skid steer, or roller exerting at least 60 pounds per square inch.
Compact the upstream side first and then each side twice for a total of
four trips.
February 2005 Volume I!—Construction Stormwater Pollution Prevenfion 4-97
• Any damage shall be repaired immediately.
Maintenance If concentrated flows are evident uphill of the fence,they must be
Standards �
intercepted and conveyed to a sediment pond.
• It is important to check the uphill side of the fence for signs of the
fence clogging and acting as a barrier to flow and then causing
channelization of flows parallel to the fence. If this occurs, replace the
fence or remove the trapped sediment.
• Sediment deposits shall either be removed when the deposit reaches
approximately one-third the height of the silt fence,or a second silt
fence shall be installed.
• If the filter fabric (geotextile) has deteriorated due to ultraviolet
breakdown, it shall be re laced.
Vwndfaa Milht POST SPAGWG: � �
,nafG Y4� T a�afL se sy�n rae�s �
........».... .. .........._...�ot Fsbdc
. 6'esax..a pooW�g ai�fs
AetaeA talth b . $8�
vpstrrsw NA�M yeR �..8.
f
Fiow�
om.owr.sek.tda st r POST GEPTM:
sxe anw 2 a su�n.a }: Ns inuaA Mfwr�e�ad
wta�awiea aweBnG � as taLefo abew greead �
bo P.s.t.xl��br � .
t00%e 1BGXewp��cd�e � � .��taQeeteneeR
ap Cndas+fengh.
l;\\�\���\\ \��//�\�\�\\��\\ _ _ '
//\/\�j\\ ���i%�/��/i , _ �
��\��\�\/� \ �\\�\\�\��\
/���������� �\������\��/�� A17hGtiFrEN'(OES�S: .- : ��, . .
//�/j� � \�!'�j/\����\� •Gauier►aene at paam,�neseea
/
/j\�/\�j�\�/ � ��i//�//�ji\ •u�zeereetbsperp�.atveat�r+taps'dta�tc.
//�\�\/��/ � j%j/j%\�� ♦�md'�tls�.Punar'rte'g hoFas�uraey
\ � \ ��\�\\�\�
No more Eltan 24'at a 36'fabric �u�a�sea�����e+���r
�Q.ort,.►e. _:. .:: `
� IS 8fbW8t2�bOYB�}TOUfId. �
Rol of s7t fenca
1- �� _�
�
�
S�
�„���,
Fahrtc
�abnYe Sit feAce
�
� � _' �.� t�-�--
� � 1�i�� r �d�v —�_ a'-?v i`h�`' '���"s�y
_. . . __ . . _ . `���.�'�. . . . f pa�.� ���.1� t�.�y,.
�' � i -���. ��' 2flb-3{R3lY1tn �i �'.� iv.v
:�, �r" ` ��lE/ib" . t �� �{ .���,�� v"�;!i
E`� `��/'�������.' t .y` � � Y��� �r�
���,�.��.C'�/a�s�i�bi,i.6��;g. ��i� 5���.\�.�. ` : ` �3'i ✓i� �'
• o.� ��r ��s`�� ' �� : < . � �'�`�� �O
r�y �
liort�d�P� Slcing Dleds
ft�+^��t? (7 B mm wldth},
Canpboed kffieletlon
�Ik7iSt01��ClW S If�8GCA�lBh�B b@C7USE�Of��74Ei2DfK,R{CSfi7'1(38CffOR
Figure 4.20-Silt Fence Installation by Slicing Method
4-98 Vo1umP 1/-Co.n�truction Storr.�rrafsr Pollution Prsventicn Febrr:ary 2C05
BMP C220: Storm Drain Inlet Protection
�
Purpose To prevent coarse sediment from entering drainage systems prior to 'I
permanent stabilization of the disturbed area.
Conditions of Use Where storm drain inlets are to be made operational before permanent
stabilization of the disturbed drainage area. Protection should be provided
for all storm drain 'vilets downslope and within 500 feet of a disturbed or
construction area,unless the runoff that enters the catch basin will be
conveyed to a sediment pond or trap. Inlet protection may be used
anywhere to protect the drainage system. It is likely that the drainage
system will still require cleaning.
Table 4.9 lists several options for inlet protection. All of the methods for
storm drain inlet protection are prone to plugging and require a high
frequency of maintenance. Drainage areas should be limited to 1 acre or
less. Emergency overflows may be required where stormwater ponding
would cause a hazard. If an emergency overflow is provided, additional
end-of-pipe treatment may be required.
Table 4.9
_ - Storm Drain Inlet Protetion
Appiicable for
Type of Inlet Emergency Paved! Earthen
Protection Overflow Surfaces Conditions of Use � �-
Dro Inlet Protection
Excavated drop inlet Yes, Earthen Applicable for heavy flows. Easy
protection temporary to maintain. Large area I
flooding will R.equirement: 30'X 30'/acre �
occur
Block and gravel drop Yes Paved or Earthen Applicable for heavy concentrated
inlet protection flows. Will not pond.
Gravel and wire drop No Applicable for heavy concentrated
inlet protection flows. Will pond. Can withstand
traffic.
Catch basin filters Yes Paved or Earthen Fre uent maintenance re uired.
Curb Inlet Protection
Curb inlet protection Small capacity Paved Used for sturdy, more compact
with a wooden weir overflow installation.
Block and gravel curb Yes Paved Sturdy,but li.mited filtration.
inlet protection
Culvert Inlet Protection
Culvert inlet sediment 18 month expected life.
tra
',
4-82 volcrrne!!- Constiz.�ction Stormwater Po.►!ut%on Prs��en,tion Fe�w-z�y 2ee�
Design and Excavated Drop Inlet Pf-otection -An excavated impoundment around the
Installation storm drain. Sediment settles out of the stormwater prior to entering the
Specifications storm drain.
• Depth 1-2 ft as measured from the crest of the inlet structure.
• Side Slopes of excavation no steeper than 2:1.
• Minimum volume of excavation 35 cubic yards.
• Shape basin to fit site with longest dimension oriented toward the
longest inflow area.
• Install provisions for draining to prevent standing water problems.
• Clear the area of all debris.
• Grade the approach to the inlet uniformly.
• Drill weep holes into the side of the inlet.
• Protect weep holes with screen wire and washed aggregate.
• Seal weep holes when removing structure and stabilizing area.
• It may be necessary to build a temporary dike to the down slope side
of the structure to prevent bypass flow.
Block and Gravel Filter-A barrier formed around the storm drain inlet
with standard concrete blocks and gravel. See Figure 4.14.
• Height 1 to 2 feet above inlet.
• Recess the first row 2 inches into the gound 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 1/z-inch openings
over all block openings.
• Place gravel just below the top of blocks on slopes of 2:1 or flatter.
• An alternative design is a gravel donut.
• Inlet slope of 3:1.
• Outlet slope of 2:1.
• 1-foot wide level stone area between the shucture and the inlet.
• Inlet slope stones 3 inches in diameter or larger.
• Outlet slope use gravel l/z-to %4-inch at a minimum thickness of 1-foot.
February 2005 Volume 11- Consfruction Stormwater Pollution Prevention 483
,
Plan View A
Drain
Grate . .0,�4��b��q�.(�o 0 o�Qo�o�
o a�:�o O o O �f�o O•,�'°o•°
� od�o�od�o� oQ�oOA � o
�.
o �Oo�'oCS• .o :�'��A?oo
�o�o �.Q °o°�v
a�°�O' e:0��°o Concrete
� �p ° o. oo:
ar,,�."'o ��� oo Block
:��°�o� ��0�� Q �°°�
0
���0 0����0 �
o.�°.
oa�o
o °
O'4 0.00 � ° °O po
e 0,�°0; o ° Gravel -
. •fJ�>,'Q,lJo � �o Backfill
o p�
o� �o° . �o° �o
�,O��Q�°O�D 'OO�p� ° �. °•O�O�
Vo���' �a` 800����40
� .�000� .�o<�ood
r'�
��,s5�5�oQ0 1�1
h�
Section A � A Concrete Block Wire Screen or
Filter Fabric
Gravel Backfiil �Overffow
Water Ponding Height
;•Q ,•�
�a Water�
�\�\\�\\�\\ \\.\\ \\ \\ \\ \\ \\�\\�\\�\\���
�/��/%/��/��/���/j��/� Drop Inlet �\��\��\�/���/�\�//\/\/,
���/i�/��/j��/j ��/��/\���/%�/i �
��%/j _.�/i�/
Notes:
1. Drop inlet sediment barriers are to be used for smail, nearly level drainage areas.(less than 5%)
2. Excavate a basin of sufficient size adjacent to the drop inlet.
3.The top of the strucnue(ponding height)must be well below the ground elevation downslope to prevent
runoff from bypassing the inlek A temporary dike may be necessary on the dowslope side of the struchae.
Figure 4.14-Biock and Gravel Filter
Gravel and Wire Mesh Filter -A gravel barrier placed over the top of the
inlet. This structure does not provide an overflow.
• Hardware cloth or comparable wire mesh with 1/2-inch openings.
• Coarse aggregate.
• Height 1-foot or more, l8 inches wider than inlet on all sides.
• Place wire mesh over the drop inlet so that the wire extends a
minimum of 1-foot beyond each side of the inlet structure.
• If more than one strip of inesh is necessary, overlap the strips.
• Place coarse aggregate over the vvire mesh.
• The depth of the gravel should be at least 12 inches over the entire ;
inlet opening and e�end at least 18 inches on all sides.
4-84 �/nl��ma!!- Genstn.��ti�n. Sto,m,�:h�afer Pc!tutiC;l Aro�ion�:C;t Febn,z�;�ee5
Catchbasin Filters-Inserts should be designed by the manufacturer for
use at construction sites. The limited sediment storage capacity increases
the amount of inspection and maintenance required,which may be daily
for heavy sediment loads. The maintenance requirements can be reduced
by combining a catchbasin filter with another type of inlet protection.
This type of inlet protection provides flow bypass without overflow and
therefore may be a better method for inlets located along active rights-of-
way.
• 5 cubic feet of storage. ,
• Dewatering provisions.
• High-flow bypass that will not clog under normal use at a construction
site.
• The catchbasin filter is inserted in the catchbasin just below the
grating.
Curb Inlet Profection with Wooden Weir-Barrier formed around a curb
inlet with a wooden frame and gravel.
• Wue mesh with %2-inch openings.
• Extra strength filter cloth.
• Construct a frame.
• Attach the wire and filter fabric to the frame.
• Pi1e coarse washed aggregate against wire/fabric. _
• Place weight on frame anchors.
Block and Grm�el Curb Inlet Protection-Barrier formed around an inlet
with concrete blocks and gravel. See Figure 4.14.
• Wire mesh with 1/z-inch openings.
s Place two concrete blocks on their sides abutting the curb at either side
of the inlet opening. These are spacer blocks.
• Place a 2x4 stud through the outer holes of each spacer block to align
the front blocks.
• Place blocks on their sides across the front of the inlet and abutting the
spacer blocks.
• Place wire mesh over the outside vertical face.
• Pile coarse aggregate against the wire to the top of the barrier.
Curb and Gutter Sedinzent Barrier- Sandbag or rock berm(riprap and
aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure
4.16.
• Construct a horseshoe shaped berm, faced with coarse aggregate if
using riprap, 3 feet high and 3 feet wide, at least 2 feet from the i.nlet.
• Construct a horseshoe shaped sedimentation trap on the outside of the
berm sized to sediment trap sta.ndards for protecting a cul��ert inlet.
February 2005 Volume J!-Construction Stormwater Pol/ution Prevention 4-85
Maintertance • Catch basin filters should be inspected frequently, especially after
Standards storm events. If the insert becomes clogged, it should be cleaned or
replaced.
• For systems using stone filters: If the stone filter becomes clogged
with sediment,the stones must be pulled away from the inlet and
cleaned or replaced. Since cleaning of gravel at a construction site
may be difficult, an alternative approach would be to use the clogged
stone as fill and put fresh stone around the inlet.
• Do not wash sediment into storm drains while cleaning. Spread all
excavated material evenly over the surrounding land area or stockpile
and stabilize as appropriate.
'
�-= -
4-86 Volume I!—ronstivct10F1 StG�!'.^.?4Y2ter Po!l:.�t6�n P;�venticn February 2CC5
Plan View
Back of Sidewalk /4 Catch Basin
I
I
ac4 V1bod Stud
Back of Curb Caxrete Block
Curb Inlet
o °�o. •�
ao °.
A C�'�
� O•O
.,,e •�. . p� •
- � ��Q�
(� ,9pQ� /� a�l�—oO
J�r'� •p. I � Qp Y,'�Q�, Op •O.
p� �$�y �p�. .���' �
P)Q e �O + Q'
� � '
v �81� R . 'R . R 4 � V' � '•
'• °�O O�• �,O�' '� �,O.'��'p O� � �0��� '�O 0p �O�••
��'� '• G A-o��4 • ��0,� , ��°d�Z� Ak7�" �
o°v�D�'�Po�°p �v=���o�.�r ,qop-o op �p�,p��.o,�t�p.
°�°_ °e SJq o�� , �°o o. � �oo ��' oo � �e�S�o $'
+-'�O �C°ap� gQp ' ��0�,� Qp 'O •�Cp�;FCop.
�J ' •1J til Wo�b
Wire Screen r A
Ffter Fabric ���e g��
Section A - A '�"Drain Gravel
(20mm)
S/."Drain Gravel
(20mm)
Ponding Height
Concrete Block
Overfl
� . - . . � a ,,%,,%
� � c�rb�n�et �,;.
1Mre Screen or \\������\�/\�/\/� \\���
Filter Fabric ����/���/�� \//�
4 UU�od Stud �\ Catch Basin \/'
(100x50 Timber Stud) \\�•
\�/
NOTES:
1. Use block and gravel type sedimerrt barrier when curb inlet is located in gerrtly sloping strcet segment,
where water can por�d and allow sediment to separate from runoff.
2. Barrier shall allow for overflanr from severe storm everrt.
3. Insped barriers and remove sediment after each storm event. Sediment and gravel must be removed
from the traveled way immediately.
Figure 4.15—Block and Gravel Curb Inlet Protection
February 2005 Volume 1!—Construction Stormwater Pollution Prevention 4-87
Plan View
Back of Sidewalk
Burlap Sacks to Catch Basin
Overlap onto Curb
Curb Inlet
Back of Curb
RUNOFF
RUNOFF SPILLWAY
Gravel Filled Sandbags
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 tightly.
3.Leave a one sandbag gap in the top row to provide a spillway for overflow.
4.Inspect barriers and remove sediment after each storm event.Sediment and gravel must be removed from
the traveled way immediately.
Fi ure 4.16—Curb and Gutter Barrier
�-. .
4-88 Volume!!—Gonsfiucfio.n Stormwater?o!lutio.n Pre��enfion Feb�u�!}�2G�Q5
BMP C123: Plastic Covering
Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
Conditions of • Plastic covering may be used on disturbed areas that require cover
Use measures for less than 30 days,except as stated below.
• Plastic is particularly useful for protecting cut and fill slopes and
stockpiles. Note: The relatively rapid breakdown of most polyethylene
sheeting makes it unsuitable for long-term(greater than six months)
applications.
• Clear plastic sheeting can be used over newly-seeded areas to create a
greenhouse effect and encourage grass growth if the hydroseed was
insta.11ed too late in the season to establish 75 percent grass cover, or if
the wet season started earlier than normal. Clear plastic should not be
used for this purpose during the summer months because the resulting
high temperatures can kill the grass.
• Due to rapid runoff caused by plastic sheeting,this method shall not be
used upslope of areas that might be adversely impacted by
concentrated runoff. Such areas include steep and/or unstable slopes.
o While plastic is inexpensive to purchase,the added cost of installation,
maintenance,removal, and disposal make this an expensive material,
up to $1.5�-2.00 per square yard.
• Whenever plastic is used to protect slopes, water collection measures
must be installed at the base of the slope. T'hese measures include
plastic-covered berms,channels, and pipes used to covey clean
rainwater away from bare soil and disturbed areas. At no time is clean
runoff from a plastic covered slope to be mixed with dirty runoff from
a project.
• Other uses for plastic include:
1. Temporary ditch liner;
2. Pond liner in temporary sediment pond;
3. Liner for bermed temporary fuel storage area if plastic is not
reactive to the type of fuel being stored;
_ 4. Emergency_�lope protection during heavy rains;and,- -
5. Temporary drainpipe ("elephant trunk") used to direct water.
4-26 Vp1JmE? !1— (1nn.ctnlrtinR .Ctnrmv�atgr Pnll�rfinn Pra�ian�ipn FAhr�ra�i?nn�
Design and • Plastic slope cover must be installed as follows:
Installativn 1. Run plastic up and down slope, not across slope;
Specifications
2. Plastic may be installed perpendicular to a slope if the slope length
is less than 10 feet;
3. Minimum of 8-inch overlap at seams;
4. On long or wide slopes, or slopes subject to wind, all seams should
be taped;
5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench
at the top of the slope and backfill with soil to keep vvater from
flowing underneath; �
6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and pound a wooden stake through each to hold them in
place;
7. Inspect plastic for rips,tears, and open seams regularly and repair
immediately. This prevents high velocity runoff from contacting
bare soil which causes ektreme erosion;
8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
• Plastic sheeting shall have a rrLnimum thickness of 0.06 millimeters.
• If erosion at the toe of a slope is likely, a gravel berm, riprap, or other
suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
Maintenance • Tom sheets must be replaced and open seams repaired.
Standards
• If the plastic begins to deteriorate due to ultraviolet radiation, it must
be completely removed and replaced.
• When the plastic is no longer needed, it shall be completely removed.
• Dispose of old tires appropriately.
February 2005 Volume 11— Construction Stormtivater PoUution Preveniion 4-27
BMP C140: Dust Control
Purpose Dust control prevents wind transport of dust from disturbed soil surfaces
onto roadways, drainage ways, and surface waters.
Conditions of Use • In areas (including roadways) subject to surface and air movement of
dust where on-site and off-site impacts to roadways, drainage ways, or
surface waters are likely.
Design and • Vegetate or mulch areas that will not receive vehicle traffic. In areas
Installation where planting, mulching, or paving is impractical, apply gravel or
Specifccations landscaping rock.
• Limit dust generation by clearing only those areas where immediate
activity will take place, leaving the remaining area(s) in the original
condition, if stable. Maintain the original ground cover as long as
practical.
• Construct natural or artificial windbreaks or windscreens. These may
be designed as enclosures for small dust sources.
• Sprinkle the site with water until surface is wet. Repeat as needed. To
prevent carryout of mud onto street, refer to Stabilized Construction
Entrance (BNIP C105).
• Irrigation water can be used for dust control. Irrigation systems should
be installed as a first step on sites where dust control is a concern. `` �
• Spray exposed soil areas with a dust palliative,following the
manufacturer's instructions and cautions regarding handling and
application. Used oil is prohibited from use as a dust suppressant.
Local governments may approve other dust palliatives such as calcium
chloride or PAM.
• PAM(BMP C126) added to water at a rate of 0.5 lbs. per 1,000
gallons of water per acre and applied from a water truck is more
effective than water alone. This is due to the increased infiltration of
water into the soil and reduced evaporation. In addition, small soil
' particles are bonded together and are not as easily transported by wind.
Adding PAM may actually reduce the qua.ntity of water needed for
dust control, especially in eastern Washington. Since the wholesale '
cost of PAM is about$ 4.00 per pound,this is an e�tremely cost-
_ effective dust control method. - -
Techniques that can be used for unpaved roads and lots include:
• Lower speed limits. High vehicle speed increases the amount of dust
stirred up from unpaved roads and lots.
• Uggrade the road surface strength by improving particle size, shape,
and mineral types that make up the surface and base materials. �
440 Volume/!- Gonstruction Stor.m.water PoL►!�tion Pre�ente�n Fehrla�2�05
• Add surface b avel to reduce the source of dust emission. Limit the
amount of fine particles (those smaller than .075 mm)to 10 to 20
, percent.
• Use geotextile fabrics to increase the strength of new roads or roads
undergoing reconstruction.
• Encourage the use of alternate,paved routes, if available.
• Restrict use by tracked vehicles and heavy trucks to prevent damage to ,
road surface and base. '
• Apply chemical dust suppressants using the admix method,blending
the product with the top few inches of surface material. Suppressants
may also be applied as surface treatments.
• Pave unpaved permanent roads and other trafficked areas.
• Use vacuum street sweepers. '
• Remove mud and other dirt promptly so it does not dry and then turn '
into dust. �
• Limit dust-causing work on windy days.
• Contact your local Air Pollution Control Authority for guidance and ,
training on other dust control measures. Compliance with the local Air
Pollution Control Authority constitutes compliance with this BMP.
I Maintenance Respray area as necessary to keep dust to a minimum. I'
Standards
�
, February 2005 Volume I!— Construction Stormwafer Pollution Prevention 4-41
Pacific dogwood, and Red alder can cause serious disease problems.
Disease can become esta.blished through damaged limbs,trunks, roots,
and freshly cut stumps. Diseased and weakened trees are also
susceptible to insect attack.
Maintenance • Inspect flagged and/or fenced areas regularly to make sure flagging or
Standards fencing has not been removed or da.maged. If the flagging or fencing
has been damaged or visibility reduced, it shall be repaired or
replaced immediately and visibility restored.
• If tree roots have been exposed or injured, "prune" cleanly vvith 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.
�
4-4 Volume!!— Construction Stormwater Pollution Prevention February 20Jb
Stormwater Pollut;on Prevention Plan
Appendix C — Alternative BMPs �'
The following includes a list of possible alternative BMPs for each of the 12 elements
not described in the main SWPPP text. This list can be referenced in the event a BMP '�
for a specific element is not functioning as designed and an alternative BMP needs to
be implemented.
Element#1 - Mark Clearing Limits
Preserving Natural Vegetation (C101)
Buffer Zones (C102) �'�
Stake and Wire Fence (C104) I
Element#2 - Establish Construction Access
Water Bars (C203)
Element#3 - Control Flow Rates
Element#4 - Install Sediment Controls
— Straw Bale Barrier (C230) _ _ .
Brush Barrier (C231)
Gravel Filter Berm (C232)
Vegetated Strip (C234)
Straw Wattles (C235) '
Construction Stormwater Chemical Treatment (C250)
Element#5 - Stabilize Soils
Temporary and Permanent Seeding (C120)
Mulching (C121} ,
Nets and Blankets (C122)
Sodding (C124)
Topsoiling (C125)
Polyacrylamide for Soil Erosion Protection (C126)
Surface Roughening (C130)
Gradient Terraces (C131)
Small Project Construction Stormwater Pollution Prevention Plan (C108)
�
Stormwater Pollution Prevention Plan
Element#6 - Protect Slopes
Temporary and Permanent Seeding (C120)
Surface Roughening (C130)
GradientTerraces (C131)
Interceptor Dike and Swale (C200)
Grass-Lined Channels (C201)
Pipe Slope Drains (C205)
Level Spreader (C206)
Check Dams (C207)
Triangular Silt Dike (Geotextile-Encased Check Dam) C208)
Straw Wattles (C235)
Element#8 - Stabilize Channels and Outlets
Grass-Lined Channels (C201)
Channel Lining (C202)
Level Spreader (C206)
Check Dams (C207)
Triangular Silt Dike (Geotextile-Encased Check Dam) C208)
Outlet Protection (C209)
Element#10 - Control Dewatering
Construction Stormwater Chemical Treatment (C250)
, � ,
� II
i -
'
_;
BMP C102: Buffer Zones
Purpose An undisturbed area or strip of natural vegetation ar an established
suitable planting that will provide a living filter to reduce soil erosion and
runoff velocities.
Co�:ditiofas of Use Natural buffer zones are used along streams,v�Tetlands and other bodies of
water that need protection from erosion and sedimentation. Vegetative
buffer zones can be used to protect natural swales and can be incorporated
into the natural landscaping of an area.
Critical-areas buffer zones should not be used as sediment treatment areas.
These areas shall remain completely undisturbed. The local permitting
authority may expand the buffer widths temporarily to allow the use of the
expanded area for removal of sediment.
Design and • Preserving natural vegetation or plantings in clumps, blocks, or strips
Installation is generally the easiest and most successful method.
Specifications Leave all unstable steep slopes in natural vegetation.
.
• Mark clearing limits and keep all equipment and construction debris
out of the natural areas. Steel construction fencing is the most
effective method in protecting sensitive areas and buffers.
Alternatively, wire-backed silt fence on steel posts is marginally
effective. Flagging alone is typically not effective.
• Keep all excavations outside the dripline of trees and shrubs.
• Do not push debris or extra soil into the buffer mne area because it
will cause damage from burying and smothering.
• Vegetative buffer zones for streams, lakes or other waterways shall be
established by the local permitting authority or other state or federal
pernuts or approvals.
Maintenance • Inspect the area frequently to make sure flagging remains in place
Standards and the area remains undisturbed.
�
February 2005 Volume ll- Construction Stormwafer Pollution Prevention 4-5
BMP C104: Stake and Wire Fence �
Purpose Fencing is intended to: (1)restrict clearing to approved limits; (2)prevent
disturbance of sensitive areas,their buffers, and other areas required to be
left undisturbed; (3) limit construction tra�ic to designated construction
entrances or roads; and, (4)protect any areas where marking with survey ,
tape may not provide adequate protection.
Conditions of Use To establish cleari.ng limits, stake or wire fence may be used:
• At the boundary of sensitive areas,their buffers, and other areas
required to be left uncleared.
• As necessary,to control vehicle access to and on the site.
Design and • See Figure 4.1 for details.
Installation More substantial fencing shall be used if the fence does not prevent
Specifications • encroachment into those areas that are not to be disturbed.
Maintenance • If the fence has been damaged or visibility reduced, it shall be
Standards repaired or replaced immediately and visibility restored.
Survey Flagging Baling Wire Do Not Nail or Staple
�re to Trees
3' MIN.
10'-20'
- Metal
Fence Post
—I I I !I I—I I I—I I I—I 1 I—I I I I f-1 I 1—i I f—I I I— I I—I i�Z.; MIN.
� _�
Figure 4.1 –Stake and Wire Fence
�
February 2005 Volume 1!– Construction Stormwater Pollution Prevention 4-7
BMP C203: Water Bars
Purpose A small ditch or ridge of material is constructed diagonally across a road
or right-of-way to divert stormwater runoff from the road surface, wheel
tracks, or a shallow road ditch.
Conditions of use Clearing right-of-way and construction of access for power lines,pipelines,
and other similar installations often require long narrow right-of-ways over
sloping terrain. Disturbance and compaction promotes gully formation in ',
these cleared strips by increasing the volume and velocity of runoff. Gully
formation may be especially severe in tire tracks and ruts. To prevent
gullying, runoff can often be diverted across the width of the right-of-way to
undisturbed areas by using small predesigned diversions.
• Give special consideration to each individual outlet area, as well as to �'
the cumulative effect of added diversions. Use gravel to stabilize the
diversion where significant vehicular traffic is anticipated.
Design and Height: 8-inch minimum measured from the channel bottom to the ridge top
Installation
Specifications
• Side slope of channel: 2:1 maximum; 3:1 or flatter when vehicles will
cross.
• Base width of ridge: 6-inch minimum.
• Locate them to use natural drainage systems and to discharge into well
vegetated stable areas.
• Guideline for S acin :
Slo e % S acin ft
� <5 125
5 - 10 100
- 10 - 20 75
20 - 35 50
> 35 Use rock lined ditch
• Grade of water bar and angle: Select angle that results in ditch slope
� less than 2 percent.
• Install as soon as the clearing and grading is complete. Reconstruct
when construction is complete on a section when utilities are being
� installed.
• Compact the ridge when installed.
• Stabilize, seed and mulch the portions that are not subject to traffic.
Gravel the areas crossed bv vehicles.
,
February 20D5 Volume ll— Construcfion Stormwater Pollution Prevenfion 4-65
Maintenance Periodically i.nspect right-of-way diversions for wear and after every heavy
Standards rainfall for erosion damage. �
• Immediately remove sediment from the flow area and repair the dike.
a Check outlet areas and make timely repairs as needed.
• When permanent road drainage is established and the area above the
temporary right-of-way diversion is permanently sta.bilized, remove
the dike and fill the channel to blend with the natural ground, and
appropriately stabilize the disturbed area.
, .
�� . :
��'�`•
�
,-
,I ;
;
,
r
II� 4-66 Votume!!—Constructi�n Stermw?fsr P�!lu�ron Preven.t6on Februar,r 2005
BMP C230: Straw Bale Barrier II�
Purpose To decrease the velocity of sheet flows and intercept and detain small !
amounts of sediment from disturbed areas of limited e�ctent,preventing ',
sediment from leaving the site. See Figure 4.17 for details on straw bale
barriers. '
Conditions of Use Below disturbed areas subject to sheet and rill erosion.
• Straw bales are among the most used and least effective BMPs. The
best use of a straw bale is hand spread on the site.
• Where the size of the drainage area is no greater than 1/4 acre per 100
feet of barrier length; the ma�mum slope length behind the barrier is
100 feet; and the maximum slope gradient behind the barrier is 2:1.
• Where effectiveness is required for less than three months.
• Under no circumstances should straw bale 6arriers be constructed I
in streams, channels, or ditches.
• Straw bale barriers should not be used where rock or hard surfaces
prevent the full and uniform anchoring of the barrier.
Design and Bales shall be placed in a single row,lerigthwise on the contour,with ends
Installation of adjacent bales tightly abutting one another.
Specifuations All bales shall be either wire-bound or sh-ing-tied. Straw bales shall be
installed so that bindings are oriented around the sides rather than along
the tops and bottoms of the bales in order to prevent deterioration of the
bindings.
• The barrier shall be entrenched and backfilled A trench shall be
excavated the width of a bale and the length of the proposed barrier to
a minimum depth of 4 inches. The trench must be deep enough to
remove all grass and other material that might allow underflow. After
the bales are staked and chinked(filled by wedging},the excavated
soil shall be backfilled against the barrier. Backfill soil shall conform '
to the ground level on the downhill side and shall be built up to 4
inches against the uphill side of the barrier.
• Each bale shall be securely anchored by at least two stakes or re-bars
driven through the bale. The first stake in each bale shall be driven
toward the previously laid bale to force the bales together. Stakes or
re-bars shall be driven deep enough into the ground to securely anchar
the bales. Stakes should not ea�tend above the bales but instead should
be driven in flush with the top of the bale for safety reasons.
N • The gaps between the bales shall be chinked(filled by wedging)with
straw to prevent water from escaping between the bales. Loose straw
scattered over the area immediately uphill from a straw bale barrier
tends to increase barrier efficiency. Wedging must be done carefully
in order not to separate the bales.
'I ! February 2005 Volume!!- Construction Sformwater PoUution Prevention 4-89
111aintenance • Straw bale barriers shall be inspected iminediately after each runoff-
Standards producing rainfall and at least daily during prolonged rainfall.
• Close attention shall be paid to the repair of damaged bales, end runs,
and undercutting beneath bales.
• Necessary repairs to barriers or replacement of bales shall be
accomplished promptly.
• Sediment deposits should be removed after each runoff-producing
rainfall. They must be removed when the level of deposition reaches
approximately one-half the height of the barrier.
• Any sediment deposits remaining in place after the straw bale barrier
is no longer required shall be dressed to conform to the existing grade,
prepared and seeded.
• Straw bales used as a temporary straw bale barrier shall be removed
after project completion and stabilization to prevent sprouting of
unwanted vegetation.
;
;
� _ _ �
'
4-90 4/0!!��?e!!-G�n�truct;�� crerm.!Na}sr Pe!lutio� P!�4�@flfi�n Fe@��an�20�5
Section A - A
s�-s�
(1.5-1.8m) ��\/ / ' \/�\/�\
�jj/�///�� %/�//��/�
Ponding Height �
1 S�O �/
/���/���/�/i\ 4E(1 Omm)MinBmum
\�///�//�� � into Soil
Angle Stake Toward
Previous Bale to
Section B - B A Provide Tight Fit
, � ,
'�, i. % � �, �. A /, i. � . i� �/
Wooden Stake
or Rebar Driven
Through Bale.
Plan ��\ LL �
/
B B
NOTES: I�
1.The straw bales shall be placed on slope contour. I�I
2.Bales to be placed in a row with the ends tighfly abutting.
3.Key in bales to prevent erosion or flow under bales.
Figure 4.17 Straw Bale Barrier ,
�I�
, �
February 2005 Volume ll— Construction Stormwater Pollution Prevention 4-91
BMP C231: Brush Barrier
Purpose The purpose of brush barriers is to reduce the transport of coarse sediment
from a construction site by providing a temporary physical barrier to
sediment and reducing the runoff velocities of overland flow.
Conditions of Use . Brush barriers may be used downslope of all disturbed areas of less
than one-quarter acre. �
• Brush barriers are not intended to treat concentrated flows,nor are I
they i.ntended ta treat substantial amounts of overland flow. Any
concentrated flows must be conveyed through the drainage system to a
sediment pond. The only circumstance in which overland flow can be
treated solely by a barrier,rather than by a sediment pond, is when the
area draining to the barrier is small.
• Brush barriers should only be installed on contours.
Design and • Height 2 feet(minimum)to 5 feet(maximum).
Installation . width 5 feet at base(minimum) to 15 feet (maximum).
Specifications
• Filter fabric(geotextile) may be anchored over the brush berm to ,
enhance the filtration ability of the barrier. Ten-ounce burlap is an '�
_ _adequate alternative to filter fabric. I
• Chipped site vegetation, composted mulch, or wood-based mulch(hog
fuel) can be used to construct brush barriers.
• A 100 percent biodegradable installation can be constructed using 10-
ounce burlap held in place by wooden stakes. Figure 4.18 depicts a
typical brush barrier.
Maintenance • There shall be no signs of erosion or concentrated runoff under or
Standards around the barrier. If concentrated flows are bypassing the barrier, it
must be expanded or augmented by toed-in filter fabric.
• The dimensions of the banier must be maintained.
If required, drape filter fabric
over brush and secure in 4'k4" `�
min.trench with compacted `` _
backfill.
�
'� , � _-- .
� :.��'��� �.-.,��-..
� ��- �
.`-� :. _ �--`-�
�--- - --.._.
� � �Anchor dawnhill edge o�
� , ~�' fitter fabric with stakes,
�� ,i�:"� ��
` sandbags,or equivalent.
���:: �'':'r�� +��
u��'4' �-"�,�
�2'M�.Height
Min.5'wide brush barrier with •
max.6"diameter woody debris.
Altematively topsoil strippings
may be used to form the barrier.
�.
Figure 4.18— Brush Barrier
¢92 �/p111/nP 1(— Cnn�fr»ntinn .Ctnrm�ni�for�nll�,rt;n�r� P;n�.o��:�? c�ui G3f y ZOOJ�
BMP C232: Gravel Filter Berm
Purpose A gravel filter berm is constructed on rights-of-way or traffic areas «�ithin
a construction site to retain sediment by using a filter berm of gra��el or
crushed rock.
Conditions of Use Where a temporary measure is needed to retain sediment from rights-of-
way or in traffic areas on construction sites.
Design and • Berm material shall be 3/4 to 3 inches in size, «•ashed well-grade gravel
Installation or crushed rock with less than 5 percent fines.
Specifications
• Spacing of berms:
— Every 300 feet on slopes less than 5 percent
— Every 200 feet on slopes between 5 percent and 10 percent
— Every 100 feet on slopes greater than 10 percent
• Berm dimensions:
— 1 foot high with 3:1 side slopes
— 8 linear feet per 1 cfs runof�based on the 10-year, 24-hour design
storm
Maintenance • Regular inspection is required. Sediment shall be removed and filter
Standards material replaced as needed.
February 2005 Volume !I— Constructron Stormwater Pollution Prevention 4-93
BMP C234: Vegetated Strip
Purpose Vegetated strips reduce the transport of coarse sediment from a
construction site by providing a temporary physical banier to sediment
and reducing the runoff velocities of overland flow.
Conditions of Use Vegetated strips may be used downslope of all disturbed areas.
.
• Vegetated strips are not intended to treat concentrated flows, nor are
they intended to treat substantial amounts of overland flow. Any
concentrated flows must be conveyed through the drainage system to a
sediment pond. The only circumstance in which overland flow can be
treated solely by a strip,rather than by a sediment pond, is when the
following criteria are met(see Table 4.11):
Table 4.11
Ve etated Stri s
Avera e Slo e Slo e Percent Flo ath Len th
1.SH:1 V or less 67%or less 100 feet
2H:1 V or less 50%or less 115 feet
4H:1V or less 25%or less ; 150 feet
6H:1V or less 16.7%or less 200 feet
lOH:1V or less 10%or less i 250 feet
Design and • The vegetated strip shall consist of a min;mum of a 25-foot wide
Installation continuous strip of dense vegetation with a permeable topsoil. Grass-
Specifications covered, landscaped areas are generally not adequate because the
volume of sediment overwhelms the grass. Ideally, vegetated strips
shall consist of undisturbed native grow�th with a well-developed soil
that allows for infiltration of runoff.
• The slope within the strip shall not exceed 4H:1 V.
• The uphill boundary of the vegetated strip shall be delineated with
clearing limits.
Maintenance • Any areas damaged by erosion or construction activity shall be seeded �,
Standards immediately and protected by mulch. �
• If more than 5 feet of the original vegetated strip width has had ''
vegetation removed or is being eroded,sod must be installed. '
• If there are indications that concentrated flows axe traveling across the
buffer, surface water controls must be installed to reduce the flows
entering the buffer, or additional perimeter protection must be
installed.
_ ,
February 2005 Volume I!- Construction Sformwater PolJution Prevenfion 4-99
BMP C235: Straw Wattles
Purpose Straw wattles are temporary erosion and sediment control barriers
consisting of straw that is wrapped in biodegradable tubular plastic or
similar encasing material. They reduce the velocity and can spread the
flow of rill and sheet runoff, and can capture and retain sediment. Straw
wattles are typicaily 8 to 10 inches in diameter and 25 to 30 feet in length.
The wattles are placed in shallow trenches and staked along the contour of
disturbed or newly constructed slopes. See Figure 4.21 for typical
construction details. '
Conditions of Use • Disturbed areas that require immediate erosion protection.
� Exposed soils during the period of short construction delays, or over
winter months.
� On slopes requiring stabilization until permanent vegetation can be
established.
• Straw wattles are effective for one to two seasons.
• If conditions are appropriate, wattles can be staked to the ground using
��illow cuttings for added revegetation.
• Rilli.ng can occur�beneath wattles if not properly entrenched and water
can pass between wattles if not tightly abutted together.
Design Criteria • It is critical that wattles are installed 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 rai.nfall,the trenches should be
dug to a depth of 5 to 7 inches, or ll2 to 2/3 of the thickness of the
wattle.
• Start building trenches and installing wattles from the base of the slope
and work up. Excavated material should be spread evenly along the
uphill slope and compacted using hand ta.mping or other methods.
• Construct trenches at contour intervals of 3 to 30 feet apart depending
on the steepness of the slope, soil type, and rai.nfall. 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.
• If required, install pilot holes for the stakes using a straight bar to drive
holes through the wattle and into the soil.
• At a minimum,wooden stakes should be approximately 3/4 x 3/4 x 24
inches. Willou�cuttings or 3/8-inch rebar can also be used for stakes. �
4-��� 1/o1u .m.e 1!-Gon.crn�rtinh Ctnrrr7y�ata�Pnllirtjnn Pray,ionti�r7 Fchr�,r�,�?nn�
Maintenance • Stakes should be driven through the middle of the wattle, leaving 2 to 3
Standards inches of the stake protruding above the wattle.
• Wattles may require maintenance to ensure they are in contact with soil
and thoroughly entrenched, especially after significant rainfall on steep
sandy soils.
• Inspect the slope after significant storms and repair any areas where
wattles are not tightly abutted or water has scoured beneath the wattles.
3-4 _�
`� � (1.2m)
� � � ���
Straw Rolls Idust �\��� •. "
Be Placed Alang \/�\ � � �
\
Slope Contours /�� � Adjacent rolls shall
� � ` tightly abut�
/ �> \
//\ C!��
�\�\�\`. � �
,�..
�� \� � � �
'�\��i`� 10'-25'(3-8m) �/
���
� '���\i, / j � �
.��\
,�/\� �j\
\/
Spacing Depends �
on Soil Type and � ,/��v� Sediment,organic matter,
Slope Steepness �i� and native seeds are
\��\/�� �captured behind the rolls.
.,
\���\
\
. �/��T
3"-5"(75-125mm)
%�
\ � �/�\� 8'-10'DIA.
�/� , � ��/��� � (2U0-25Dmm)
\i\\ • \/
\
Live Stake �,�
—�Y ,�\� /�� �\/�
' ��� 1" X 1" Stake
� not to scale (25 x 25mm)
� ��
�
IvTOTE: � •
1.Straw roll installation requires the placement and secure staldng of the roll in a trench,3"•5"(75-125mm)
deep,dug on contour. runoff must not be allowed to r�undez or azound roll.
Figure 4.21 -Straw Wattles
February 2005 Vo(ume ll—Construction Stormwater Pollution Prevenfion 4-101
�
BMP C250: Construction Stormwater Chemical Treatment
Purpose Turbidity is difficult to control once fine particles are suspended in
stormwater runoff from a construction site. Sedimentation ponds are
effective at removing larger particulate matter by gravity settling, but are
ineffective at removing smaller particulates such as clay and fine silt.
Sediment ponds are typically designed to remove sediment no smaller than
medium silt(0.02 mm). Chemical treatment may be used to reduce the
turbidity of stormwater runoff.
Conditions of Use Chemical treatment can reliably provide exceptional reductions of
turbidity and associated pollutants. Very high turbidities can be reduced
to levels comparable to what is found in streams during dry weather.
Traditional BMPs used to control soil erosion and sediment loss from sites
under development may not be adequate to ensure compliance with the
water quality standard for turbidity in the receiving water. Chemical
treatment may be required to protect streams from tbe impact of turbid
stormwater discharges, especially when construction is to proceed through
the wet season.
Formal written approval from Ecology and the Local Permitting
Authority is required for the use of chemical treatment regardless of
site size. The intention to use Chemical Treatment shall be indicated
on the Notice of Intent for coverage under the General Construction
Permit. Chemical treatment systems should be designed as part of the
Construction SWPPP, not after the fact. Chemical treatment may be
used to correct problem sites in limited circumstances with formal
written approval from Ecology and the Local Permitting Authority.
The SEPA review authority must be notified at the application phase of
the project review(or the time that the SEPA determination on the project
is performed)that chemical treatment is proposed if it is added after this
stage, an addendum will be necessary and may result in project approval
delay.
Design and See Appendix II-B for background information on chemical treatment.
Installation
Specifications Criteria for Chemical Treatment Product Use: Chemically treated
stormwater discharged from construction sites must be nonto�c to aquatic
organisms. The following protocol shall be used to evaluate chemicals
proposed for stormwater treatment at construction sites. Authorization to
use a chemical in the field based on this protocol does not relieve the
applicant from responsibilit��for meeting all discharge and receiving
water criteria applicable to a site.
• Treatment chemicals must be appro��ed by EPA for potable water use.
• Petroleum-based polymers are prohibited.
February 2005 Volume 11- Construction Stormwater Pollution Prevenfion 4-111
• Prior to authorization for field use,jar tests shall be conducted to
demonstrate that turbidity reduction necessary to meet the receiving
water criteria can be achieved. Test conditions, including but not
limited to raw water quality and jar test procedures, should be
indicative of field conditions. Although these small-scale tests cannot
be expected to reproduce performance under field conditions,they are
indicative of treatment capability.
• Prior to authorization for field use,the chemically treated stormwater
shall be tested for aquatic toxicity. Applicable procedures defined in
Chapter 173-205 WAC, Whole Effluent Toxicity Testing and Limits,
shall be used. Testing shall use stormwater from the construction site
at which the treatment chemical is proposed for use or a water solution
using soil from the proposed site.
• The proposed maximum dosage shall be at least a factor of five lower
than the no observed effects concentration(NOEC).
• The approval of a proposed treatment chemical shall be conditional,
subject to full-scale bioassay monitoring of treated stormwater at the
construction site where the proposed treatment chemical is to be used.
o Treatment chemicals that-have aiready passed the above testing
protocol do not need to be reevaluated. Contact the Department of
Ecology Regional OfFice for a list of treatment chemicals that have
been evaluated and are currently approved for use. I
Treatment System Design Considerations: The design and operation of
a chemical treatment system should take into consideration the factors that
determine optimum, cost-effective performance. It may not be possible to '
fully incorporate all of the classic concepts into the design because of
practical limitations at construction sites. Nonetheless, it is important to
recognize the following:
• The right chemical must be used at the right dosage. A dosage that is
either too low or too high will not produce the lowest turbidity. There
is an optimum dosage rate. This is a situation where the adage "adding
more is always better" is not the case.
• 'The coagulant must be mixed rapidly into the water to insuze proper
dispersion.
• A flocculation step is important to increase the rate of settling, to
produce the lowest turbidity, and to keep the dosage rate as low as
_ - -- - _
possible.
• Too little energy input into the water during the flocculation phase
results in flocs that are too small and/or insuf�iciently dense. Too
much energy can rapidly destroy floc as it is formed.
4-912 Volume ll-Consiruction Stormwater Pollution Prevention Februarv 2005
• Since the volume of the basin is a determinant in the amount of energy
per unit volume,the size of the energy input system can be too small
relative to the volume of the basin.
• Care must be taken in the design of the withdrawal system to minimize
outflow velocities and to prevent floc discharge. The discharge should
be directed through a physical filter such as a vegetated swale that
would catch any unintended floc discharge.
Treatment System Design: Chemical treatment systems shall be
designed as batch treatment systems using either ponds or portable trailer-
mounted tanks. Flow-through continuous treatment systems are not
allowed at this time.
A chemical treatment system consists of the stormwater collection system
(either temporary diversion or the permanent site drainage system), a
storage pond,pumps, a chemical feed system, treatment cells,and
interconnecting piping.
The treatment system shall use a minimum of two lined treatment cells.
Multiple treatment cells allow for clarification of treated water while other
cells are being filled or emptied. Treatment cells may be ponds or tanks.
Ponds with constructed earthen embankments greater than six feet high
require special engineeri.ng analyses. Portable tanks may also be suitable
for some sites.
The following equipment should be located in an operations shed:
• the chemical injector;
• secondary containment for acid, caustic, buffering compound, and
treatment chemical;
• emergency shower and eyewash, and ,
• monitoring equipment which consists of a pH meter and a
turbidimeter.
Sizing Criteria: The combination of the storage pond or other holding
area and treatment capacity should be large enough to treat stormwater
during multiple day storm events. It is recommended that at a minimum
the storage pond or other holding area should be sized to hold 1.5 times
the runoff volume of the 10-year,24-hour storm event. Bypass should be
provided around the chemical treatment system to accommodate extreme
storm events. Runoff volume shall be calculated using the methods
presented in Volume 3, Chapter 2. If no hydrologic analysis is required
far the site,the Rational Method may be used.
Primary settling should be encouraged in the storage pond. A forebay
with access for maintenance may be beneficial.
There are two opposing considerations in sizing the treatment cells. A
larger cell is able to treat a larger volume of water each time a batch is
February 2005 Volume ll-Construcfion Stormwater Pollution Prevention 4-113
processed. However,the larger the cell the longer the time required to
empty the cell. A larger cell may also be less effective at flocculation and
therefore require a longer settling time. The simplest approach to sizing
the treatment cell is to multiply the allowable discharge flow rate times the
desired drawdown time. A 4-hour drawdown time allows one batch per
cell per 8-hour work period, given 1 hour of flocculation followed by two
hours of settling.
The pernussible discharge rate governed by potential downstream effect
can be used to calculate the recommended size of the treatment cells. The
following discharge flow rate lim.its shall apply:
• If the discharge is directly or indirectly to a stream, the discharge flow
rate shall not exceed 50 percent of the peak flow rate of the 2-year, 24-
hour event for all storm events up to the 10-yeaz, 24-hour event.
• If discharge is occurring during a storm event equal to or greater than
the 10-year, 24-hour event,the allowable discharge rate is the peak
flow rate of the 10-year, 24-hour even� �
• Discharge to a stream should not increase the stream flow rate by more
than 10 percent.
_- - _ _ __ _ -
• If the discharge is directly to a lake, a major receiving water listed in
Appendix C of Volume I, or to an infiltration system,there is no
discharge flow limit. ,
• If the discharge is to a municipal storm drainage system, the allowable
discharge rate may be lixnited by the capacity of the public system. It
may be necessary to clean the municipal storm drainage system prior
to the start of the discharge to prevent scouring solids from the
drainage system.
• Runoff rates shall be calculated using the methods presented in
Volume 3, Chapter 2 for the predeveloped condition. If no hydrologic
analysis is required for the site,the Rational Method may be used.
Maintenance Monitoring: The following monitoring shall be conducted. Test results
Standards shall be recorded on a daily log kept on site:
Operational Monitoring
• pH, conductivity(as a surrogate for alkalinity),turbidity and
temperature of the untreated stormwater
• Total volume treated and discharged
• Discharge tune and flow rate
• Type and amount of chemical used for pH adjustment
• Amount of polymer used for treatment
• Settling time
4114 Vo�ume 11—Construction Stormwater Pollution Prevention February 2005
Compliance Monitorin�
• pH and turbidity of the treated stormwater
• pH and turbidity of the receiving water
Biomonitorin�
Treated stormwater shall be tested for acute (lethal}toxicity. Bioassays
shall be conducted by a laboratory accredited by Ecology, unless
otherwise approved by Ecology. The performance standard for acute
tozicity is no statistically significant difference in survival between the
control and 100 percent chemically treated stormwater.
Acute toxicity tests shall be conducted with the following species and
protocols:
• Fathead minnow, Pimephales promelas (96 hour static-renewal test,
method: EPA/600/4-90/027F). Rainbow trout, Oncorhynchus mykiss
(96 hour static-renewal test, method: EPA/600/4-90/027F) may be
used as a substitute for fathead minnow.
• Daphnid, Ceriodaphnia dubia, Daplznia pulex, or Daphnia magna(48
hour static test, method: EPA/600/4-90/027F).
All toxicity tests shall meet quality assurance criteria and test conditions in
the most recent versions of the EPA test method and Ecology Publication
#WQ-R-95-80,Laboratory Guidance and Whole Effluent To�city Test
Review Criteria.
Bioassays shall be performed on the first five batches and on ever}�tenth
batch thereafter, or as otherwise approved by Ecology. Failure to meet the
performance standard shall be immediately reported to Ecology.
Discharge Compliance: Prior to discharge, each batch of treated
stormwater must be sampled and tested for compGance with pH and
turbidity limits. These limits may be established by the water quality
standards or a site-specific discharge pernut. Sampling and testing for
other pollutants may also be necessary at some sites. Turbidity must be
within 5 NTUs of the background turbidity. Background is measured in
the receiving water,upstream from the treatment process discharge point.
pH must be within the range of 6.5 to 8.5 standard units and not cause a
change in the pH of the receiving water of more than 0.2 standard units. It
is often possible to discharge treated stormwater that has a lower turbidity
than the receiving water and that matches the pH.
Treated stormwater samples and measurements shall be taken frorn the
discharge pipe or another location representative of the nature of the
treated stormwater discharge. Samples used for determining compliance
with the water quality standards in the receiving water shall not be taken
February 2005 Volume !1- Construction Stormwater Pollution Prevention 4-915
from the treatment pond prior to decanting. Compliance with the water
quality standards is determined in the receiving water.
Operator Training: Each contractor who intends to use chemical
treatment shall be trained by an experienced contractor on an active site
for at least 40 hours.
Standard BMPs: Surface stabilization BMPs should be implemented on
site to prevent significant erosion. All sites shall use a truck wheel wash
to prevent tracking of sediment off site.
Sediment Removal And Disposal:
• Sediment shall be removed from the storage or treatment cells as
necessary. Typically, sediment removal is required at least once
during a wet season and at the decommissioning of the cells.
Sediment rema.ining in the cells between batches may enhance the
settling process and reduce the required chemical dosage.
• Sediment may be incorporated into the site away from drainages.
, _. _._ _.. _
�.
i
4116 Volume 1!— Construction Stormwater Pollution Prevention February 2005
BMP C120: Temporary and Permanent Seeding
Purpose Seeding is intended to reduce erosion by stabilizing exposed soils. A
well-established vegetative cover is one of the most effective methods of
reducing erosion.
Conditions of Use ' Seeding may be used throughout the project on disturbed areas that
have reached final grade or that will remain unworked for more than
30 days.
• Channels that will be vegetated should be installed before major
earthwork and hydroseeded with a Bonded Fiber Matrix. The
vegetation should be well established(i.e.,75 percent cover)before
water is allowed to flow in the ditch. With channels that will have
high flows, erosion control blankets should be installed over the
hydroseed. If vegetation cannot be established from seed before water
is allowed in the ditch, sod should be installed in the bottom of the
ditch over hydromulch and blankets.
• Retention/detention ponds should be seeded as required.
• Mulch is required at all times because it protects seeds from heat,
moisture loss, and transport due to runoff.
• All disturbed areas shall be reviewed in late August to early September
and all seeding should be completed by the end of September.
Otheru�ise,vegetation will not establish itself enough to provide more
than average protection.
• At fmal site stabilization,all disturbed areas not otherwise vegetated or
stabilized shall be seeded and mulched. Final stabilization means the
completion of all soil disturbing activities at the site and the
establishment of a permanent vegetative cover, or equivalent
permanent stabilization measures (such as pavement, riprap, gabions
or geotextiles)which will prevent erosion.
Design and • Seeding should be done during those seasons most conducive to
Installation growth and will vary with the climate conditions of the region.
Specifications Local experience should be used to determine the appropriate
seeding periods.
• The optimum seeding windows for westem Washington are April 1
through June 30 and September 1 through October 1. Seeding that
occurs between July 1 and August 30 will require irrigation until 75
percent grass cover is established. Seeding that occurs between
October 1 and March 30 will require a mulch or plastic cover until
75 percent grass cover is established.
• To prevent seed from being washed away,confirm that all required
surface water control measures have been installed.
February 2005 Volume i!- Construction Stormwater Pollution Prevention 413
• The seedbed should be fum and rough. All soil should be roughened
no matter what the slope. If compaction is required for engineering
purposes, slopes must be track walked before seeding. Backblading or
smoothi.ng of slopes greater than 4:1 is not allowed if they are to be
seeded.
• New and more effective restoration-based landscape practices rely on
deeper incorporation than that pro��ided by a simple single-pass
rototilling treatment. Wherever practical the subgrade should be
initially ripped to improve long-term permeability, infiltration, and
water inflow qualities. At a rrLnimum,permanent areas shall use soil
amendments to achieve organic matter and permeability performance
defined in engineered soiUlandscape systems. For systems that are
deeper than 8 inches the rototilling process should be done i.n multiple
lifts, or the prepared soil system shall be prepared properly and then
placed to achieve the specified depth.
• Organic matter is the most appropriate form of"fertilizer" because it
provides nutrients (including nitrogen,phosphorus, and potassium) in
the least water-soluble form. A natural system typically releases 2-10
percent of its nutrients annually. Chemical fertilizers have since been
formulated to simulate what-organic matter does naturally.
• In general, 10-4-6 N-P-K(nitrogen-phosphorus-potassium) fertilizer
can be used at a rate of 90 pounds per acre. Slow-release fertilizers '
should always be used because they are more efficient and have fewer
environmental impacts. It is recommended that areas being seeded for
final landscaping conduct soil tests to determine the exact type and
quantity of fertilizer needed. This will prevent the over-application of
fertilizer. Fertilizer should not be added to the hydromulch machine
and agitated more than 20 minutes before it is to be used. If agitated
too much,the slow-release coating is destroyed.
• There are numerous products available on the market that take the
place of chemical fertilizers. These include several with seaweed
extracts that are beneficial to soil microbes and organisms. If 100
percent cottonseed meal is used as the mulch in hydroseed, chemical
fertilizer may not be necessary. Cottonseed meal is a good source of
long-term, slow-release, available nitrogen.
• Hydroseed applications shall include a minimum of 1,500 pounds per
acre of mulch with 3 percent ta.ckifier. Mulch may be made up of 100
percent: cotEonseed meal; fibers made of wood, recycled cellulose,
hemp, and kenaf; compost; or blends of these. Tackifier shall be plant-
based, such as guar or alpha plantago, or chemical-based such as
polyacrylamide or polymers. Any mulch or tackifier product used
shall be installed per manufacturer's instructions. Generally, mulches
come in 40-50 pound bags. Seed and fertilizer are added at time of
application. '
4-14 Volume I!—Construction Stormwater Pollution Prevention February 2005
• Mulch is always required far seeding. Mulch can be applied on top of
the seed or simultaneously by hydroseeding.
• On steep slopes, Bonded Fiber Matrix(BF1V� or Mechanically Bonded
Fiber Matr� (MBF1V�products should be used. BFM/MBFM
products are applied at a minimum rate of 3,000 pounds per acre of
mulch with approximately 10 percent tackifier. Application is made
so that a minimum of 95 percent soil coverage is achieved. Numerous
products are available commercially and should be installed per
manufacturer's instructions. Most products require 24-36 hours to
cure before a rainfall and cannot be installed on wet or saturated soils.
Generally,these products come in 40-�0 pound bags and include all
necessary ingredients except for seed and fertilizer.
BFMs and MBFMs have some advantages over blankets:
• No surface preparation required; i
• Can be installed via helicopter in remote areas; 'i
• On slopes steeper than 2.5:1, blanket installers may need to be roped ,
and harnessed for safety; '
• They are at least $1,000 per acre cheaper installed.
In most cases,the shear strength of blankets is not a factor when used on
slopes, only when used in channels. BFMs and MBFMs are good ,
alternatives to blankets in most situations where vegetation establishment ',
is the goal. '
• 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. One way to
overcome this is to increase seed quantities by up to 50 percent. ,
s Vegetation establishment can also be enhanced 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.
An alternative is to install the mulch, seed,fertilizer, and tackifier i.n one
lift. Then, spread or blow straw over the top of the hydromulch at a rate of
about 800-1000 pounds per acre. 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: '
1. Irrigation
2. Reapplication of mulch
' 3. Repair of failed slope surfaces '
February 2005 Volume I!- Consiruction Stormwater Pollutron?revention 4-15
This technique works with standard hydromulch(1,500 pounds per acre
minimum)and BFM/MBFMs(3,000 pounds per acre minimum}. �
• Areas to be permanently landscaped shall provide a healthy topsoil
that reduces the need for fertilizers, improves overall topsoil quality,
provides for better vegetal health and vitality,improves hydrologic
characteristics, and reduces the need for irrigation. This can be
accomplished in a number of ways:
Recent research has shown that the best method to improve till soils is
to amend these soils with compost. The optirnum mixture is
appro�mately two parts soil to one part compost. This equates to 4
inches of compost mixed to a depth of 12 inches in till soils. Increasing
the concentration of compost beyond this level can have negative
effects on vegetal health, while decreasing the concentrations can
reduce the benefits of amended soils. Please note: The compost should
meet specifications for Grade A quality compost in Ecology
Publication 94-038.
Other soils, such as gravel or cobble outwash soils, may require
different approaches. Organics and fines easily migrate through the
loose structure of these soils. Therefore, the importation of at least 6
inches of quality topsoil, underlain by some type of filter fabric to
prevent the migration of fines,may be more appropriate for these soils.
Areas that already have good topsoil, such as undisturbed areas, do not
require soil amendments.
• Areas that will be seeded only and not landscaped may need compost
or meal-based mulch included in the hydroseed in order to establish
vegetation. Native topsoil should be re-installed on the disturbed soil
surface before application.
• Seed that is installed as a temporar��measure may be installed by hand
if it will be covered by straw,mulch, or topsoil. Seed that is installed
as a permanent measure may be installed by hand on small areas
(usually less than 1 acre)that will be covered with mulch, topsoil, or
erosion blankets. The seed mixes listed below include recommended
mixes for both temporary and permanent seeding. These mixes,with
the exception of the wetland mix, shall be applied at a rate of 120
pounds per acre: This rate can be reduced if soil amendments or slow-
release fertilizers are used. Local suppliers or the local conservation
district should be consulted for their recommendations because the
appropriate mix depends on a variety of factors, including location,
exposure, soil type, slope, and expected foot traffic. Alternative seed
mixes approved by the local authority may be used.
4-16 Volume 11- Construction Stor.mwater PollutiQn Prevention Fehrua!;2�J5
Table 4.1 represents the standard mix for those areas where just a
temporary vegetative cover is required.
Table 4.1
Tem ora Erosion Controi Seed Mix
%We' ht %Puri %Germination
Chew�ings or annual blue grass 40 98 90
Festuca rubra var. commutata or Poa cmna
Perennial rye- 50 98 90
Lolium erenne
Redtop or colonial bentgrass 5 92 85
A ostis alba or A astis tenuis
White dutch clover 5 98 90
Tri olium re ens
Table 4.2 provides just one recommended possibility for landscaping seed.
Table 4.2
Landsca in Seed Mix
%Wei ht %Puri %Germina6on
Perennial rye blend 70 98 90
Lolium erenne
Chewings and red fescue blend 30 98 90
Festuca subra var. commutata
or Festuca rubra
This turf seed mix in Table 4.3 is for dry situations where there is no need
for much water. The advantage is that this mix requires very little
maintenance.
Table 4.3
Low-Growin Turf Seed Mix
% We' ht %Puritv %Germina6on
Dwarf tall fescue(several varieties) 45 98 90
Festuca arundinacea var.
Dwarf perennial rye(Barclay) 30 98 90
Lolium erenne var. barcl
Red fescue. 20 98 90
Festuca rubra
Colonial bentgrass 5 98 90
A astis tenuis
Table 4.4 presents a mix recommended for bioswales and other
intermittently wet areas.
Table 4.4
Bioswale Seed Mix"
%We' ht %Puritv %Germination I
Tall or meadow fescue 75-80 98 90 '
Festuca arundinacea or Festuca elalior
Seaside/Creeping bentgrass 10-15 92 85
A ostis alustrrs
Redtop benterass 5-10 90 80
A ostis alba or A ostis i antea
*Modified Bricmgreen, Inc. Hydroseeding Guide Wetlands Seed Mix
February 2005 Volume 1!—Construcfion Stormwater Po!lution Prevention 4-17
T'he seed mix shown in Table 4.5 is a recominended low-growing,
relatively non-invasive seed mix appropriate for very wet areas that are
not regulated wetlands. Other mixes may be appropriate, depending on
the soil type and hydrology of the area. Recent research suggests that
bentgrass(agrostis sp.) should be emphasized in wet-area seed mixes.
Apply this mixture at a rate of 60 pounds per acre.
Table 4.5
Wet Area Seed Mix*
%VVei ht %Puri %Germination
Tall or meadow fescue 60-70 98 90
Festuca arundinacea or
Festuca elatior
Seaside/Creeping bentgrass 10-15 98 85
A ostis alustris
Meadow foxtail 10-15 90 80
Ale ocurus ralensis
Alsike clover 1-6 98 90
Tri olium bridum
Redtop bentgrass 1-6 92 85
A ostis alba
*Modified Briargreen,Inc. Hydroseeding Guide Wetlands Seed Mix
The meadow seed mix in Table 4.6 is recom.mended for areas that will be
maintained infrequently or not at all and 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. The
appropriateness of clover in the m'v�may need to be considered,as this can
be a fairly invasive species. If the soil is amended, the addition of clover
may not be necessary.
Tabie 4.6
Meadow Seed Mix
%R'ei ht %Puri %Germination
Redtop or Oregon bentgrass 20 92 85
A ostis alba or A ostis ore onensis
Red fescue 70 98 90
Festuca rubra
White dutch clover 10 98 90
Tri olium re ens
Maintenance • Any seeded areas that fail to establish at least 80 percent cover(100
Standards percent cover for areas that receive sheet or concentrated flows) shall
be reseeded. If reseeding is ineffective, an altemate method, such as
sodding,mulching, or nets/blankets, shall be used. 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.
¢18 t/Qfrrmg I(- rnnctn�rfi�n .CtCf�n�q��atar PpllwifiCrJ Prn.ionf:n� Fohrur���2G1��
• After adequate cover is achieved, any areas that experience erosion
shall be reseeded and protected by mulch. If the erosion problem is
drainage related, the problem shall be fixed and the eroded area
reseeded and protected by mulch.
• Seeded areas shall be supplied with adequate moisture, but not watered
to the extent that it causes runoff.
February 2005 Volume !!—Construction SFormwafer Pollution Prevention 419
- �
BMP C121: Mulching 'I
Purpose The purpose of mulching soils is to provide irrunediate 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. Only the most common types are discussed in this
section.
Conditions of Use As a temporary cover measure, mulch should be used:
• On disturbed areas that require cover measures for less than 30 days.
_ • As a cover for seed dnring the wet season and during the hot summer
months.
• During the wet season on slopes steeper than 3H:1V with more than 10
feet of vertical relief.
• Mulch may be applied at any time of the year and must be refreshed
periodically.
Design and For mulch materials, application rates, and specifications, see Table 4.7.
Installation Note: Thicknesses may be increased for disturbed areas in or near
Specifications sensitive areas or other azeas highly susceptible to erosion.
Mulch used within the ordinary high-water mark of surface waters should
be selected to minimi�e potential flotation of organic matter. Composted '
organic materials have higher specific gravities (densities)than straw,
wood, or chipped material.
Maintenance • The thickness of the cover must be maintained.
Standards �y areas that experience erosion shall be remulched and/or protected
• with a net or blanket. If the erosion problem is drainage related, then
the problem shall be fixed and the eroded area remulched.
�~
¢20 Volume !1—Constrt�ction Starmvvarer?ol.l�rtinn pre�Ar�t�r,r� FAr,�,��.2r�r��
Table 4.7
Mulch Standards and Guidelines
Mulch Application
Material Qualit+F Standards Rates Remarks II
Straw Air-dried;free from 2"-3"thick;5 Cost-effective protection when applied with adequate I
undesirable seed and bales per 1000 sf thiclmess. Hand-application generally requires greater I
coarse material. or 2-3 tons per thickness than blown straw.The thiclmess of straw may be
acre reduced by half when used in conjunction with seeding. In ,
windy areas straw must be held in place by crimping,usine a '
tacldfier,or covering with netting. Blown straw always has
to be held in place v«th a tackifier as even light winds will
blow it away. Straw,however,has several deficiencies that
should be considered when selecting mulch materials.It
often introduces and/or encourages the propagation of weed
species and it has no significant long-term benefits. Straw
should be used only if mulches with long-term benefits are
unavailable locally. It shouid also not be used within the
ordinary high-water elevation of surface waters(due to
flotation).
Hydromulch No grow�th Approx.25-30 Shall be applied w�th hydromulcher. Shall not be used
inhibiting factors. lbs per 1000 sf v�2thout seed and tackifier unless the application rate is at
or 1500 -2000 least doubled Fibers longer than about'/<-1 inch clog
lbs per acre hydromulch equipment. Fibers should be kept to less than 3/4
�- inch.
Composted No visible water or 2°thick min.; More effective control can be obtained by increasing
Mulch and dust during approx. 100 tons thiclmess to 3". Excellent mulch for protecting final grades -
Compost handling. Must be per acre(approx. imtil landscaping because it can be directly seeded or tilled
purchased from 8001bs per yard) into soil as an amendment Composted mulch has a coarser
supplier with Solid size gradation than compost.It is more stable and practical
Waste Handling to use in wet areas and during rainy weather conditions.
Permit(unless
exempt).
Chipped Site Average size shall 2"minim� This is a cost-effective way to dispose of debris from
Vegetation be several inches. thicl�ess clearing and grubbing,and it eliminates the problems
Gradations from associated with bumiug. Generally, it should not be used on
fines to 6 inches in slopes above approx. 10%because of its tendency to be
length for tex-ture, ixansported by runoff. It is not recommended within 200
variation,and feet of surface waters. If seeding is expected shortly after
interlocking mulch,the decomposition of the chipped vegetation may tie
properties. up nutrients important to grass establishment.
Wood-based No visible water or 2"thick;approx. This material is often called"hog or hogged fuel." It is
Mulch dust during 100 tons per acre usable as a material for Stabilized Construction Entrances
handling. Must be (approx.8001bs. (BMP C105)and as a mulch. The use of mulch ultimately
purchased from a per cubic yard) improves the organic matter in the soil. Special caution is
supplier with a Solid advised regarding the source and composition of v�rood-
Waste Handling based mulches. Its preparation typically does not provide
Permit or one any weed seed control,so evidence of residual vegetation in
exempt from solid its composition or known inclusion of weed plants or seeds
���aste regu.lations. should be monitored and prevented(or minimi�ed).
February 2005 Volume I!—Construction Stormwater Pollution Prevention 4-21
BMP C122: Nets and Blankets
Purpose Erosion control nets and blankets are intended to prevent erosion and hold
seed and mulch in place on steep slopes and in channels so that vegetation
can become well established. In addition, some nets and blankets can be
used to permanently reinforce turf to protect drainage ways during high
flows. Nets (commonly called matting) are strands of material woven into
an open,but high-tensile strength net(for example, coconut fiber matting).
Blankets are strands of material that are not tightly woven, but instead
form a layer of interlocking fibers,typically held together by a
biodegradable or photodegradable netting(for example, excelsior or straw
blankets). They generally have lower tensile strength than nets, but cover
the ground more completely. Coir(coconut fiber) fabric comes as both
nets and blankets.
Conditions of Use Erosion control nets and blankets should be used:
• To aid permanent vegetated stabilization of slopes 2H:1 V or greater
and with more than 10 feet of vertical relief.
• For drainage ditches and swales (highly recommended). The
application of appropriate netting or blanket to drainage ditches and
swales can protect bare soil from channelized runoff while vegeta.tion
is established. Nets and blankets also can capture a great deal of
sediment due to their open, porous structure. Synthetic nets and
blankets can be used to permanently stabilize channels and may ;
provide a cost-effective, environmentally preferable alternative to `
riprap. 100 percent synthetic blankets manufactured for use in ditches
may be easily reused as temporary ditch liners.
Disadvantages of blankets include:
• Surface preparation required;
• On slopes steeper than 2.5:1, blanket installers may need to be roped
and harnessed for safety;
• They cost at least$4,000-6,000 per acre installed.
Advantages of blankets include:
• Can be irisfalled without mobilizing special equipment;
• Can be installed by anyone with minimal training;
• Can be installed in stages or phases as the project progresses;
• Seed and fertilizer can be hand-placed by the installers as they
progress down the slope;
• Can be installed in any weather;
• There are numerous types of blankets that can be designed with
various parameters in mind. Those parameters include: fiber blend, '
mesh strength, longevity,biodegradability, cost, and availability. �
4-22 Vc�lume!1— Constnl�tion Storm.water Pol.lufi�n Prev?!?ti�n FPbruary 20C�5
Design and • See Figure 4.4 and Figure 4.5 for typical orientation and installation of '
Installation blankets used in channels and as slope protection. Note: these are
Specifications typical only; all blankets must be installed per manufacturer's ,
insta.11ation instructions.
• Installation is critical to the effectiveness of these products. If good
ground contact is not achieved, runoff can concentrate under the
product,resulting in significant erosion.
• Installation of Blankets on Slopes:
l. Complete final grade and track walk up and down the slope.
2. Install hydromulch with seed and fertilizer.
3. Dig a small trench, approximately 12 inches wide by 6 inches deep
along the top of the slope. _
4. Install the leading edge of the blanket into the small trench and
staple approximately every 18 inches. NOTE: Staples are
metal,"U"-shaped, and a minimum of 6 inches long. Longer ,
staples are used in sandy soils. Biodegradable stakes are also �'
available.
5. Roll the blanket slowly down the slope as installer walks
backwards. NOTE: The blanket rests against the installer's legs.
Staples are installed as the blanket is unrolled. It is critical that the
proper staple pattern is used for the blanket being installed. The ,
blanket is not to be allowed to roll down the slope on its own as I�
this stretches the blanket making it impossible to maintain soil '
contact. In addition, no one is allowed to walk on the blanket after
it is in place.
6. If the blanket is not long enough to cover the entire slope length,
the trailing edge of the upper blanket should overlap the leading
edge of the lower blanket and be stapled. On steeper slopes, this
overlap should be installed in a small trench, stapled, and covered
with soiL
• With the variety of products available, it is impossible to cover all the
details of appropriate use and installation. Therefore, it is critical that
the design engineer consults the manufacturer's information and that a
site visit takes place in order to insure that the product specified is
appropriate. Information is also available at the following web sites:
l. WSDOT: http://www.wsdot.wa.�ov/eesc/environmentaU
2. Texas Transportation Institute:
http://www.dot.state.tx.us/insdtdot/or�chart/cmd/erosion/contents.
htm
February 2005 Volume !!—Consfrucfion Stormwater Pollution Prevention 4-23
• Jute matting must be used in conjunction with mulch(BMP C121).
Excelsior,woven straw blankets and coir(coconut fiber)blankets may
be i.nstalled without mulch. There are many other types of erosion
control nets and blankets on the market that may be appropriate in
certain circumstances.
• In general, most nets (e.g.,jute matting) require mulch in order to
prevent erosion because they have a fairly open structure. Blankets
typically do not require mulch because t11ey usually provide complete
protection of the surface.
• Extremely steep, unstable,wet,or rocky slopes are often appropriate
candidates for use of synthetic blankets, as are riverbanks, beaches and
other high-energy environments. If synthetic blankets are used,the
soil should be hydromulched first.
• 100 percent biodegradable blankets are available for use in sensitive
areas. These organic blankets are usually held together with a paper or
fiber mesh and stitching which may last up to a year.
• Most netting used with blankets is photodegradable,meaning they
break down under sunlight(not UV stabilized). However,this process
can take months or years even under biight sun. Once vegetation is
established, sunlight does not reach the mesh. It is not uncommon to
find non-degraded netting still in place several years after installation.
This can be a problem if maintenance requires the use of mowers or
ditch cleaning equipment. In addition, birds and small animals can
become trapped in the netting.
Maintenance • Good contact with the ground must be ma.intained, and erosion must
Standards not occur beneath the net or blanket.
� Any areas of the net or blanket that are damaged or not in close contact
with the ground shall be repaired and stapled.
• If erosion occurs due to poorly controlled drainage,the problem shall
be fixed and the eroded area protected.
(.
4-24 Volume Il— Cons�ruction Stormwater PeUution ProE�ention Fearuary 2005
* � P
�
//�// �r � �
/j�� //� //��j��j \i�� �.' • //�\//�//
\��\��\� �\�\\��\ �� � '�'� ��\��\��\��\
///////// ��/////// //// �//�//�//�/
� �\ �\ � (15Anm1 \ �\ � 6'(150nvn1 \/
Lnngitudnal Anchor Trench 7ertninal Slope and Channel Anchor Trench
,� *Y�
*�
� � �
� *
� � � � Sfake at 3'-5' �
* �: (1-1.Sm)intervals. �
� P *
� P � �
� �� �
� � �
�
�' / \�������������
������\��\�
//�/ Check slot at 25'(7.6m)intervals
P ������ Isometric View
� �,/��������/i
P �
� v 6(150mn)
�
� � � � • ' i:�r�%
/�\�\�\� f .�r.�� . \��\��\ ••s � ����\��\
//\��//��/\��/\�j/\�j. \/\\�\ �/\�j/\�� n�,;,m> \��/�\��/���
/
Initial Channel Anchor Trench Intermittent Chedc Sbt
N07'ES:
1.Check slots to be eonstruefcd per manufactiaecs speciBcations. �
2.SWong m stapliag kyout per manufactuiecs specifieationc. �.
Figure 4.4—Channel Installation
Slope surface shall be smooth before ,
placement for prop�sal corrtact.
If there is a berm at the
Stapling pattem as per top d slope,anchor
• �;��•.�.�.;.._, . upslope of the berm.
manuFaciurer's recommendations. �' •.,..
� ��' .:
Min.2' i � _. ::-�`.... �
Oveliap � �
i i �
�I�I Andior in 6'k6"min.Trench
� i �„� and staple at 12' irrtervals.
i ��
. � Min.6"ove+iap.
.`�>� , I�'
— .:�' �
:';•. •
'��=111��������II��.�������b � maaxP.�sspaang.
'—'��i I I�I r–i i�---��
Bring material down to a level area,tum
Do not strdch blanketslmattings tight- the end�der 4"and staple at 12"irrtervals.
albwthe rolfs to mold to any irreg�arities.
Fw slopes less than 3H:1V,rolls Lime,fertil¢e,and seed beFore instaAation.
may be placed in horizontal strips. P�anting of shrubs,Vees,etc.Should ocair
after installation. ;
Figure 4.5—Slope Installation I!
February 2005 Volume 11—Construction Stormwater Pollution Prevention 4-25
� I
I '.
BMP C124: Sodding _
Purpose The purpose of sodding is to establish permanent turf for immediate
erosion protection and to stabilize drainage ways where concentrated
overland flow will occur.
Conditions o.f'Use Sodding may be used in the following areas:
• Disturbed areas that require short-term or long-term cover.
• Disturbed areas that require imm�diate vegetative cover.
• All waterways that require vegetative lining. Waterways may also be
seeded rather than sodded,and protected with a net or blanket.
Design and Sod shall be free of weeds, of uniform thickness(approximately 1-inch
Installation thick), and shall have a dense root mat for mechanical strength.
Specifications
The following steps are recommended for sod installation:
• Shape and smooth the surface to final grade in accordance with the
approved grading plan. The swale needs to be overexcavated 4 to 6
inches below_design elevation to allow room for placing soil
amendment and sod.
• Amend 4 inches(minimum) of compost into the top 8 inches of the
soil if the organic content of the soil is less than ten percent or the ; �
permeability is less than 0.6 inches per hour. Compost used should '
meet Ecology publication 94-038 specifications for Crrade A quality
compost.
• Fertilize according to the supplier's recommendations.
- • Work lime and fertilizer 1 to 2 inches into the soil, and smooth the
surface.
• Lay strips of sod beginning at the lowest area to be sodded and
perpendicular to the direction of water flow. Wedge strips securely
into place. Square the ends of each strip to provide for a close,tight
fit. Stagger joints at least 12 i.nches. Staple on slopes steeper than
3H:1 V. Staple the upstream edge of each sod strip.
• Roll the sodded area and irrigate.
• When sodding is carried out in alternating strips or other patterns, seed
the areas between the sod immediately after sodding.
Maintenance If the grass is unhealthy, the cause shall be determined and appropriate
Standards action taken to reestablish a healthy groundcover. If it is impossible to
establish a healthy groundcover due to frequent saturation,instability, or
some other cause,the sod shall be removed, the area seeded with an
appropriate mix, and protected with a net or blanket.
4-28 Vofume 1!-Constn_�ction Stor.mwater Potlution Preve.^.tion FeCruary 2���
BMP C125: Topsoiling
Purpose To provide a suitable growth medium for final site stabilization with
��egeta.tion. While not a permanent cover practice in itself, topsoiling is an
integral component of providing permanent cover in those areas where
there is an unsuitable soil surface for plant growth. Native soils and
disturbed soils that have been organically amended not only reta.in much
more stormwater, but they also serve as effective biofilters for urban
pollutants and, by supporting more vigorous plant growth, reduce the
water, fertilizer and pesticides needed to support installed landscapes.
Topsoil does not include any subsoils but only the material from the top
several inches including organic debris.
Conditions of • Native soils should be left undisturbed to the maximum e�ent
Use practicable. Native soils disturbed during clearing and grading should
be restored,to the maximum e�ctent practicable,to a condition where
moisture-holding capacity is equal to or better than the original site
conditions. This criterion can be met by using on-site native topsoil,
incorporating amendments into on-site soil, or importirig blended
topsoil.
• Topsoiling is a required procedure when establishing vegetation on
shallow soils, and soils of critically low pH (high acid) levels.
• Stripping of existing,properly functioning soil system and vegetation
for the purpose of topsoiling during construction is not acceptable. If ,
an existing soil system is functioning properly it shall be preserved in
its undisturbed and uncompacted condition.
• Depending on where the topsoil comes from, or what vegetation was
on site before disturbance, invasive plant seeds may be included and
could cause problems for establishing native plants, landscaped areas,
or grasses.
• Topsoil from the site will contain mycorrhizal bacteria that are
necessary for healthy root growth and nutrient transfer. These native
mycorrhiza are accli.mated to the site and will provide optimum
conditions for establishing grasses. Commercially available
mycorrhiza products should be used when topsoil is brought in from �,
off-site. I
Design and if topsoiling is to be done,the following items should be considered:
Installation ����e depth of the topsoil wherever possible to provide the
Specifuations • maximum possible infiltration capacity and beneficial growth
medium. Topsoil depth shall be at least 8 inches with a minimum
organic content of 10 percent dry weight and pH between 6.0 and 8.0
or matching the pH of the undisturbed soil. This can be accomplished
either by returning native topsoil to the site and/or i.ncorporating
organic amendments. Organic amendments should be incorporated to
a minimum 8-inch depth except where tree roots or other natural
February 2005 Volume !I— Construction Stormv✓ater Pollution Prevention 4-29
features lurut the depth of incorporation. Subsoils below the 12-inch ,
depth should be scar�ed at least 2 inches to avoid stratified layers,
where feasible. The decision to either layer topsoil over a subgrade or
incorporate topsoil into the underlying layer may vary dependi.ng on
the planting specified.
• If blended topsoil is imported,then fines should be limited to 25
percent passing through a 200 sieve.
• The final composition and construction of the soil system will result in
a natural selection or favoring of certain plant species over time. For
example,recent practices have shown that i.ncorporation of topsoil
may favor grasses, while layering with mildly acidic, high-carbon
amendments may favor more woody vegetation.
• Locate the topsoil stockpile so that it meets specifications and does not
interfere with work on the site. It may be possible to locate more than
one pile in proximity to azeas where topsoil will be used.
• Allow sufficient time in scheduling for topsoil to be spread prior to
seeding, sodding, or planting.
• Care must be taken not to apply to subsoil if the two soils have
- - -__ _
contrasting textures. Sandy topsoil over clayey subsoil is a
particularly poor combination, as water creeps along the junction
between the soil layers and causes the topsoil to slough.
• If topsoil and subsoil are not properly bonded,water will not infiltrate I
the soil profile evenly and it will be difficult to establish vegetation.
The best method to prevent a lack of bonding is to actually work the
topsoil into the layer below for a depth of at least 6 inches.
• R.ipping or re-structuring the subgrade may also provide additional
benefits regarding the overall infiltration and interflow dynamics of
the soil system.
• Field exploration of the site shall be made to determine if there is
surface soil of sufficient quantity and quality to justify stripping.
Topsoil shall be friable and loamy(loam, sandy loam, silt loam, sandy
clay loam, clay loam). Areas of natural ground water recharge should
be avoided.
• Stripping shall be confined to the immediate construction area. A 4-to
6- inch stripping depth is common, but depth may vary depending on
- the particular soil. Ajl surface runoff control structures shall be in
place prior to stripping.
Stockpiling of topsoil shall occur in the followi.ng manner:
• Side slopes of the stockpile shall not exceed 2:1.
• An interceptor dike v��ith gravel outlet and silt fence shall surround all
' topsoil stockpiles betvveen October 1 and April 30. Between May 1
4-30 Volume 1!—Construction Stormwater P�Ilcrtion Prs��sn�n Fe!�r�.�ary 20J5
and September 30, an interceptor dike with gravel outlet and silt fence
shall be installed if the stockpile will remain in place for a longer
period of time than active construction grading.
• Erosion control seeding or coveri.ng with clear plastic or other
mulching materials of stockpiles shall be completed within 2 days
(October 1 through April 30) or 7 days (May 1 through September 30)
of the formation of the stockpile. Native topsoil stockpiles shall not be
covered with plastic.
• Topsoil shall not be placed while in a frozen or muddy condition,
when the subgrade is excessively wet, or when conditions exist that
may otherwise be detrimental to proper grading or proposed sodding
or seeding.
• Previously established grades on the areas to be topsoiled shall be
maintained according to the approved plan.
• When native topsoil is to be stockpiled and reused the following
should apply to ensure that the mycorrhizal bacterial, earthworms, and
other beneficial organisms will not be destroyed:
1. Topsoil is to be re-installed within 4 to 6 weeks;
2. Topsoil is not to become saturated with water;
3. Plastic cover is not allowed.
Maintenance • Inspect stockpiles regularly, especially after large storm events.
Standards Stabilize any areas that have eroded.
'
February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-31
BMP C126: Polyacrylamide for Soil Erosion Protection
Purpose Polyacrylamide(PAM) is used on construction sites to prevent soil
erosion.
Applying PAM to bare soil in advance of a rain event significantly reduces
erosion and controls sediment in two ways. First,PAM increases the
soil's available pore volume,thus increasing infiltration through
flocculation and reducing the quantity of stormwater runoff. Second, it
increases flocculation of suspended particles and aids in their deposition,
thus reducing stormwater nxnoff turbidity and improving water quality.
Conditions of Use PAM shall not be directly applied to water or allowed to enter a water
body.
In areas that drain to a sediment pond, PAM can be applied to bare soil
under the following conditions:
• During rough grading operations.
• Staging areas.
• Balanced cut and fill earthwork.
• Haul roads prior to placement of crushed rock surfacing.
• Compacted soil roadbase.
• Stockpiles.
• After fina.l grade and before paving or fmal seeding and planting.
• Pit sites.
• Sites having a winter shut down. In the case of winter shut down, or
where soil will remain unworked for several months,PAM should be
used together with mulch.
Design and P�M may be applied in dissolved form with water, or it may be applied in
Installation dry, granular or powdered form. The preferred application method is the
Specifications dissolved form.
PAM is to be applied at a maximum rate of 2/3 pound PAM per 1000
gallons water{80 mg/L)per 1 acre of bare soil. Table 4.8 can be used to
determine the PAM and water application rate for a disturbed soil azea.
Higher concentrations of PAM do not provide any additional effectiveness.
Table 4.8
PAM and Water A lication Rates
Disturbed Area ac PAM bs VVater al
0.50 033 500
1.00 0.66 1,000
_ 1.50 1.00 1,500
2.00 1.32 2,000
2.50 1.65 2,500
3.00 2.00 3,000
3.50 2.33 3,500
4.00 2.65 4,000
4.50 3.00 4,500
5.00 3.33 5,000
'
4-32 Vo/ume !!— Constrac.tion StQrm�vat�r p��/r�ti�� p�PVP�t�nn Foh�,,��y 2p��
The Prefened Method:
• Pre-measure the area where PAM is to be applied and calculate the
amount of product and water necessary to provide coverage at the
specified application rate(2/3 pound PAM/1000 gallons/acre). ,
• PAM has infuute solubility in water, but dissolves very slowly. �,
Dissolve pre-measured dry granular PAM with a known quantity of !
clean water in a bucket several hours or overnight. Mechanical mixing I
will help dissolve the PAM. Always add PAM to water- not water to
PAM.
• Pre-fill the water truck about 1/8 full with water. The water does not '
have to be potable, but it must have relatively low turbidity-in the '
range of 20 NTU or less. '
• Add PAM/Water mixture to the truck
• Completely fill the water truck to specified volume.
• Spray PAM/Water mixture onto dry soil until the soil surface is I
unifortnly and completely wetted.
An Alternate Method:
PAM may also be applied as a powder at the rate of 5 lbs. per acre. This
must be applied on a day that is dry. For areas less than 5-10 acres, a
hand-held"organ grinder"fertilizer spreader set to the smallest setting will
work. Tractor-mounted spreaders will work for larger areas.
The following shall be used for application of PAM:
• PAM shall be used in conjunction with other BMPs and not in place of
other BMPs.
. • Do not use PAM on a slope that flows directly into a stream or
wetland. The stormwater runoff shall pass through a sediment control
BMP prior to discharging to surface waters.
• Do not add PAM to water discharging from site.
• When the total drainage area is greater than or equal to 5 acres, PAM
treated areas shall drain to a sediment pond.
• Areas less than 5 acres shall drain to sediment control BMPs, such as a
minimum of 3 check dams per acre. The total number of check dams
used shall be maximized to achieve the greatest amount of settlement
of sediment prior to discharging from the site. Each check dam shall
be spaced evenly in the drainage channel through which stormwater
flows are discharged off-site.
• On all sites,the use of silt fence shall be maximized to limit the
discharges of sediment from the site.
• All areas not being actively worked shall be covered and protected
from rainfall. PAM shall not be the only cover BMP used.
February 2005 Volume !I- Construcfion Sformwafer Pollution Preventron 4-33
• PAM can be applied to wet soil, but dry soil is preferred due to less
sediment loss.
• PAM will work when applied to saturated soil but is not as effective as
applications to dry or damp soil.
• Keep the granular PAM supply out of the sun. Granular PAM loses its
effectiveness in three months after exposure to sunlight and air.
• Proper application and re-application plans are necessary to ensure
total effectiveness of PAM usage.
• PAM,combined with��ater, is very slippery and can be a safety
hazard. Care must be taken to prevent spills of PAM powder onto
paved surfaces. During an application of PAM, prevent over-spray
from reaching pavement as pavement will become slippery. If PAM
powder gets on skin or clothing, wipe it off with a rough towel rather
than washing with water-this only makes cleanup messier and take
longer.
• Some PAMs are more to�c and carcinogenic than others. Only the
most environmentally safe PAM products should be used.
The specific PAM copolymer formulation must be anionic. Cationic
PAM shall not be used in any application because of l�nown
aquatic togicity problems. Only the highest drinking water grade
PAM,certified for compliance with ANSUNSF Standard 60 for
drinking water treatment, will be used for soil applications. Recent
media attention and hi interest in PAM has resulted in some
�
entrepreneurial exploitation of the term "polymer." All PAM are
polymers, but not all polymers are PAM, and not all PAM products
comply with ANSUNSF Standard 60. PAM use shall be reviewed and
approved by the local permitting authority. The Washington State
Department of Transportation(WSDOT)has listed approved PAM
products on their web page.
• PAM designated for these uses should be "water soluble" or "linear"or
"non-crosslinked". Cross-linked or water absorbent PAM,
polymerized in highly acidic (pH<2) conditions, are used to maintain
soil moisture content.
• The PAM anionic charge density may vary from 2-30 percent; a value
of 18 percent is typical. Studies conducted by the United States
_ _ _ __ Department of Agriculture(USDA)/ARS demonstrated that soil
stabilization was optimized by using very high molecular weight(12-
1 S mg/mole),highly anionic (>20%hydrolysis)PAM.
• PAM tackifiers are available and being used in place of gua.r and alpha
planta.go. Typically, PAM tackifiers should be used at a rate of no
more than 0.5-1 lb. per 1000 gallons of water in a hydromulch
machine. Some tackifier product instructions say to use at a rate of 3—
4-34 �/ol��tne !1—Construct1011 StOfR')W.8tg�PCll�,ff�nrt Pra�ianfi^^ FE�'���fy 2�.,�.
5 lbs. per acre,which can be too much. In addition,pump problems
can occur at higher rates due to increased viscosity.
Maintenance • PAM may be reapplied on actively worked areas after a 48-hour
Standards period.
• Reapplication is not required unless PAM treated soil is disturbed or
unless turbidity levels show the need for an additional application. If
PAM treated soil is left undisturbed a reapplication may be necessary
after two months. More PAM applications may be required for steep
slopes, silty and clayey soils (LTSDA Classification Type "C" and"D"
soils), long grades, and high precipitation areas. When PAM is
applied first to bare soil and then covered with straw, a reapplication
may not be necessary for several months.
• Loss of sediment and PAM may be a basis for penalties per RCW
90.48.080.
February 2005 Volume !1- Construction Stormwater Pollution Prevention 4-35
BMP C130: Surface Roughening
Purpose Surface roughening aids i.n the establishment of vegetative cover, reduces �
runoff velocity, increases infiltration, and provides for sediment trapping
through the provision of a rough soil surface. Horizontal depressions are
created by operati.ng a tiller or other suitable equipment on the contour or ',
by leaving slopes in a roughened condition by not fine grading them. '
Conditions for • All slopes steeper than 3:1 and greater than 5 vertical feet require
Use surface roughening. '
• Areas with grades steeper than 3:1 should be roughened to a depth of 2
to 4 inches prior to seeding. '
• Areas that will not be stabilized immediately may be roughened to
reduce runoff velocity until seeding takes place.
• Slopes with a stable rock face do not require roughening.
• Slopes where mowing is planned should not be excessively roughened.
Design rrnd There are different methods for achieving a roughened soil surface on a
Installation slope, and the selection of an appropriate method depends upon the type of
Specifications slope. Roughening methods include stair-step grading, grooving, contour
furrows, and tracking. See Figure 4.6 for tracking and contour furrows.
Factors to be considered in choosing a method are slope steepness, mowing
requirements, and whether the slope is formed by cutting or filling.
• Disiurbed areas that will not require mowing may be stair-step graded,
grooved, or left rough after filling.
• Stair-step grading is particularly appropriate in soils containing large
amounts of soft rock. Each "step" catches material that sloughs from
above,and provides a level site where vegetation can become
established. Sta.irs should be wide enough to work with standard earth
moving equipment. Stair steps must be on contour or gullies will form
on the slope.
• Areas that will be mowed(these areas should have slopes less steep
than 3:1)may have small furrows left by disking,harrowi.ng,raking, ar
seed-planting machinery operated on the contour.
• Crraded areas with slopes greater than 3:1 but less than 2:1 should be
roughened before seeding. This can be accomplished in a variety of
ways, including "track walking," or driving a crawler tractor up and
down the slope, leavi.ng a pattern of cleat imprints pazallel to slope
contours.
• Tracking is done by operating equipment up and down the slope to
leave horizontal depressions in the soil.
Maintenance • Areas that are graded in this manner should be seeded as quickly as
Standards possible.
• Regular inspections should be made of the area. If rills appear,they
' should be re-graded and re-seeded irrunediately.
4-36 Vo/ume!1- Construction St�r..mwa�er Po!lUtIQR P�?!�?!1tlOR F�hr;,lg�,.2nn�
Tracking �. �.
�-� �. a.
�. � o. �,�o. �. � .
�.
�, a�. �.�.a,� �.
a. �, �,� �. o.
�.� � �. �, a
�.�. �. �- � �.�. �. �, a,
�.�. � � �, cs. o. �. �. �.
o.� g c,, �. �� e �.
,a ��' �. �. �. �. �' �. �
c �'�a �. a. �. �' a, �,
� o,a� � o. a � a �,
a. o,a @ � � �. o. �,
� o, o. �' a � �
�a. �_ � �. 8 �
o' -�. 8 8 �
�. o. � �,
� g � �a.
�° a' �, o.'�' ca.
�, �' o. a I
� o' @ �i o.
� �. � � ra
� � � �
o. a c�.
a a � e o.
�. � �. ca-
�. B �. p.
O 0. a �. O.
� � � a
�. �, � �� a. ,.
. � a, � a. � �' �
'TRACKING'with machinery up and down a, � a�, �,o, �,
the slope provides grooves that will catch �' � a �' �'
�. �. �, �. �.
seed, rainfall and reduce runoff. \ � �' � �`
o. �"
\
_ //\��\�
Contour Furrows \��/\�j\�
ii��//�� ��
� -
.�j��\� /�\j�\
50' 6"min� �j��%�\/��%/��%� '
(15m (150mm} �\\�\ '
//\�i\�i\��\ /��
\/\\�\\�\
\//\//\\���\�� Max mu m
\\�i\\j/\��\ 1
Grooves Will Catch Seed, �\�j��j��j�
Fand Dec ease Runoff.11 ./\\�\��\��\��� / // //\\
�\��\��\�� j�j��\��j��
/�����\/����������/��� �/�.
,��j�\,�
Figure 4.6—Surface Roughening by Tracking and Contour Furrows
February 2005 Volume !!— Construction Stormwafer Pollution Prevention 4-37
BMP C131: Gradient Terraces
Purpose Gradient terraces reduce erosion damage by intercepting surface runoff
and conducting it to a stable outlet at a non-erosive velocity.
Conditions of Use • Gradient terraces normally are limited to denuded land having a water
erosion problem. They sbould not be constructed on deep sands or on
soils that are too stony, steep, or shallow to pernut practical and
economical installation and maintenance. Gradient terraces may be
used only where suitable outlets are or will be made available. See
Figure 4.7 for gradient terraces.
Design and • The maximum spacing of gradient terraces should be deternuned by
Installation the followi.ng method:
Specifications
VI = (0.8)s+ y
Where: VI =vertical interval in feet
s = land rise per 100 feet, expressed i.n feet
y =a soil and cover variable with values from 1.0 to 4.0
Values of"y" are influenced by soil erodibility and cover practices.
The lower values are applicable to erosive soils where little to no
residue is left on the surface. The higher value is applicable only to
erosion-resistant soils where a large amount of residue(1%z tons of
straw/acre equivalent) is on the surface.
• The minimum constructed cross-section.should meet the design
dimensions.
• The top of the constructed ridge should not be lower at any point than
the design elevation plus the specified overfill for settlement. The
opening at the outlet end of the terrace should have a cross section
equal to that specified for the terrace chanri�l.
• Channel grades may be either uniform or variable with a ma�mum
grade of 0.6 feet per 100 feet length. For short distances, terrace
grades may be increased to unprove alignment. The channel velocity
should not exceed that which is nonerosive for the soil type with the
planned treatment.
• All gradient terraces should have adequate outlets. Such an outlet may
- - - be a grassed waterway,vegetated area,or tile outlet. In all cases the
, outlet must convey runoff from the terrace or terrace system to a point
where the outflow will not cause damage. Vegetative cover should be
used in the outlet channel.
• The design elevation of the water surface of the terrace should not be
lower than the design elevation of the water surface in the outlet at �
, their junction,when both are operating at desi�flow.
4-38 VplUmP Il—COl►St�U�tln� Sfprm�,yatar Pnlliitinn Prc�iiar�tinr� Fghn,r���2���
• Vertical spacing detemuned by the above methods may be increased
as much as 0.5 feet or 10 percent,whichever is greater,to provide
better alignment or location,to avoid obstacles,to adjust for
equipment size, or to reach a satisfactory outlet.
• The drainage area above the top should not exceed the area that would
be drained by a terrace with normal spacing.
• T'he terrace should have enough capacity to handle the peak runoff
expected from a 2-year, 24-hour design storm without overtopping.
• The terrace cross-section should be proportioned to fit the land slope.
The ridge height should include a reasonable settlement factor. The
ridge should have a minimum top width of 3 feet at the design height.
The minimum cross-sectional area of the terrace channel should be
8 square feet for land slopes of 5 percent or less, 7 square feet for
slopes from 5 to 8 percent, and 6 square feet for slopes steeper than
8 percent. The terrace can be constructed wide enough to be
maintained using a small cat.
Maintenance • Maintenance should be performed as needed. Terraces should be
Standards inspected regularly; at least once a year, and after large storm events.
Siope to adequate outlet�
10' min. � ��' ��,`� ��
y�, t� ���/ f
9�C� f ��i���f��/ i
5�, � ��'����`�, �
�� t
� !`��1 �v'��5� 1
a�' �r� : �;l f
��' `��'%�'' � °
�,��'`� —— _.�
- -- -
,\1���� - - �._ __ —
Figure 4.7 -Gradient Terraces
February 2005 Volume fl— Construction Stormwater Pollution Prevention 4-39
BMP C201: Grass-Lined Channels
Purpose To provide a channel with a vegetative lining for conveyance of runoff.
See Figure 4.7 for typical grass-lined chaunels.
Conditions of Use This practice applies to construction sites where concentrated runoff need:
to be contained to prevent erosion or flooding.
• When a vegetative lini.ng can provide sufficient stability for the
channel cross section and at lower velocities of water (normally
e 's that the chann e ar e r 11 �
dependent on grad ). Tlu means el slop s e g ne a }
less than 5 percent and space is available for a relatively large cross
section.
• Typical uses include roadside ditches,channels at property boundaries,
outlets for diversions, and other cha�els and drainage ditches in low
areas.
• Channels that will be vegetated should be installed before major
earthwork and hydroseeded with a bonded fiber matrix(BFIv�. The
vegetation should be well established(i.e., 75 percent cover)before
water is allowed to flow in the ditch. With charmels that will have
high flows, erosion control blankets should be installed over the
hydroseed. If vegetation cannot be established from seed before water
is allowed in the ditch, sod should be installed in the bottom of the
ditch in lieu of hydromulch and blankets.
Design and Locate the channel where it can conform to the topography and other
Installation features such as roads.
Specifications Locate them to use natural drainage systems to the greatest extent
• possible.
• Avoid sharp changes in alignment ar bends and changes in grade.
• Do not reshape the landscape to fit the drainage channel.
• The ma�cimum design velocity shall be based on soil conditions, type
of vegetation, and method�f revegetation, but at no times shall
velocity exceed 5 feet/second. The channel shall not be overtopped by
the peak runoff from a 10-year, 24-hour storm, assuming a Type lA
rainfall distribution." Alternatively, use 1.6 times the 10-year, 1-hour
flow indicated by an approved continuous runoff model to deternune a
flow rate which the channel must contain.
• Where the grass-lined channel will also function as a permanent
stormwater conveyance facility, consultant the drainaQe conveyance
requirements of the local government with jurisdiction.
• An estabGshed grass or vegetated lining is required before the channel
can be used to convey stormwater, unless stabilized with nets or
, blankets.
February 2005 Volume I!- C�nstruction Stormwater Poflution Prevention 4-59
• If design velocity of a channel to be vegetated by seeding exceeds 2
ft/sec, a temporary channel liner is required. Geotextile or special '
mulch protection such as fiberglass roving or straw and netting provide
stability until the vegetation is fully esta.blished. See Figure 4.9.
• Check dams shall be removed when the grass has matured sufficiently
to protect the ditch or swale unless the slope of the swale is greater
than 4 percent. The area beneath the check dams shall be seeded and
mulched immediately after dam removal.
• If vegetation is established by sodding, the permissible velocity for
established vegetation may be used and no temporary liner is needed.
• Do not subject grass-lined channel to sedimentation from disturbed
areas. Use sediment-trappi.ng BMPs upstream of the chan.nel.
• V-shaped grass channels generally apply where the quantity of water
is small, such as in short reaches along roadsides. The V-shaped cross
section is least desirable because it is difficult to stabilize the bottom
where velocities may be high.
• Trapezoidal grass channels are used where runoff volumes are large
and slope is low so that velocities are nonerosive to vegetated linings.
(Note: it is difficult to construct small parabolic shaped channels.)
• Subsurface drai.nage, or riprap channel bottoms,may be necessary on
sites that are subject to prolonged wet conditions due to long duration
flows or a high water table.
• Provide outlet protection at culvert ends and at channel intersections.
• Grass channels, at a minimum, should carry peak runoff for temporary
construction drainage facilities from the 10-year,24-hour storm
without eroding. Where flood hazard exists, increase the capacity
according to the potential damage.
• Grassed channel side slopes generally are constructed 3:1 or flatter to
aid in the establishment of vegetation and for maintenance.
• Construct channels a minimum of 0.2 foot larger around the periphery
to allow for soil bulking during seedbed preparations and sod buildup.
Maintenance During the establishment period, check grass-lined cha�els after every
Standards rainfall.
• After grass is established,periodically check the channel; check it after
every heavy rainfall event� Immediately make repairs.
• It is particularly important to check the channel outlet and all road
crossi.ngs for bank stability and evidence of piping or scour holes.
• Remove all significant sediment accumulations to maintain the
designed carrying capacity. Keep the grass in a healthy,vigorous
condition at all times, since it is the primary erosion protection for the �
' channel.
4-60 Volum.e!I—Constructi�n S'torr:�tivater Poll;�tion Prevention FeSruary 2005
Typical V-Shaped Channel Cross-section
� -
'\i,,\� ,i, � � '\j�' ���;-'�,,��, ��.���\j,\,
����/� '�',�� v�J�� //\�/�\ / �,\
.\..\� ��. ! ���r� � ./\\.� '-
%\�/\��//j � � /��, �s"_s°
\ - ��
Fiiter_�\,�� ��\/�� �150-225mm)
Fabric� �i��' Key in Fabric
Grass-Lined With Rock Center
Typical Parabolic Channel Cross-Section
Vi/�/, h�l��� �Gi� �u.,1�\� '
�l�y�, i � �I� �� �
%�,��
/�\ .�` I, �V r� '��iL�,�h , i V� � �����1\���1��/i��/ �\��^. , G� � ��\'�\\�// ��
\ �4 I i� /�/ 6 -9 � /� I
����j/��j/�/���j.��- � (150-225mm) ���� %��Filter I�
i Key In Fabric / / /
� � ���� Fabric
With Channel Liner W�th Rock Center
for Base Flow
Typical Trapezoidal Channel Cross-Section
% �� � Desi n De th y a���"� U ���I,
/��������� ✓��/�/� 9 P � �/ //\���\\.
` '\/\ ,\\�� ,` � ���'
. � \/.
<� � " �i�vl� ,r l� ,�I � �I� ,� rv���„J6�n.�����` /.//�/
torallow bulk ng du�rn gm� �\��\�,�\�j�\�j` ���\��\�����
seedbed preparation �/���
and growth of vegetation. Filter� With Rock Center For Base Flow
Fabric
Figure 4.8—Typical Grass-Lined Channels
February 2005 Volume ll— Construction Sformwafer Po!lution Prevention 4-61
���'r,� Overlap 6" (150mm) minimum ��
�/ � "� y�v �
� � � �� Excavate Channel to Design �,� /
%� �// � ��%i Grade and Cross Section ����a'� /�///
•, ����//� ./��/i\
., ��i�,, ���
� ,� �r,,�� Design Depth
� ,
/,/ ��,�.
OVERCUTCHANNEL Longitudinal
2"(50mmJ TOALLOW �'-� �V�� anchor trench
BULK/N6 DUR/NG SEEDBED � ����� ���1, •�11 V� .16
PREPARAT/ON � /� // / /,
\/, �\//�
P
P s•�,�,,,,,,� TYP/CAL /NSTALLAT/ON
W/TH E/�OS/ON CONTROL ��/��/
�/�/� '. �� �/ / / BLANKETS OR TUHF \ \� \�
�\//�\� . "o / /�\j�\j RE/NFORCEMENTMATS �/%�/���/\ /�/%�/%�/
\/�\�/�\\ (1 SO6mm) �\/�\//�\� /�\\�\\�j�rJ��\�j\\�j/�
Intermittent Check Slot Longitudinal Anchor Trench
Shingle-lap spliced ends or begin new
roll in an intermittent check slot
� -v�L v�-
Prepare soil and apply seed before O �
installing blankets, mats or other � LL �
temporary channel liner system (� �
U ��
� � W� �
�r � � . .
� - - - - - - - � �
�
��\i\\�i\ _ � ;/� /
�\.. �� /��"
!� • !�� /�' �'•
\ �
"��//�//\�////,\�//�/
NOTES:
1. Design velocities exceeding 2 ft/sec(O.Sm/sec)require temporary blankets,mats or similar
liners to protect seed and soil until vegetation becomes established.
2. Grass-lined channels with design velocities exceeding 6 ftlsec(2m/sec)should include
turf reinforcement mats.
Figure 4.9—Temporary Channel Liners
�
4-62 Volum.P ll— Co.nstrL�cfion Stc�r.m..water Pe!l�rr;�n p.,oE.A�t�e� FghrG��r�?np�
� BMP C205: Subsurface Drains
Purpose To intercept, collect,and convey ground water to a satisfactory outlet,
using a perforated pipe or conduit below the ground surface. Subsurface
drains are also known as "french drains." The perforated pipe provides a
dewatering mechanism to drain excessively wet soils,provide a stable
base for construction,improve stability of structures with shallow
foundations, or to reduce hydrostatic pressure to improve slope stability.
Conditions of Use Use when excessive water must be removed from the soil. The soil
permeability, depth to water table and impervious layers are all factors
which may govem the use of subsurface drains.
Design and Relief drains are used either to lower the water table in large, relatively
Installation flat areas, improve the growth of vegetation,or to remove surface water.
Specifications
They are installed along a slope and drain in the direction of the slope.
They can be installed in a grid pattern, a herringbone pattern,or a random
pattern.
• Interceptor drains are used to remove excess ground water from a
slope, stabilize steep slopes, and lower the water table immediately
below a slope to prevent the soil from becoming saturated.
They are installed perpendicular to a slope and drain to the side of the
slope.
They usually consist of a single pipe or series of single pipes instead of a
patterned layout.
• Depth and spacing of interceptor drains--The depth of an
interceptor drain is determined primarily by the depth to which the
water table is to be lowered or the depth to a confining layer. For
practical reasons,the maximum depth is usua.11y limited to 6 feet,with
a minimum cover of 2 feet to protect the conduit.
• The soil should have depth and sufficient permeability to permit
installation of an effective draina.ge system at a depth of 2 to 6 feet.
• An adequate outlet for the drainage system must be available either by
gravity or by pwnping.
• The_quantity and quality of discharge needs to be accounted for in the
receiving stream(additional detention may be required).
• This sta.ndard does not apply to subsurface drains for buildi.ng
foundations or deep excavations.
• The capacity of an interceptor drain is determined by calculating the
maximum rate of ground water flow to be intercepted. Therefore, it is _
good practice to make complete subsurface investigations, including
4-70 Volume!I— Constrtrction St�rm.water Po!lution Prevention Fe!�.�x.fary 20Q5
hydraulic conductivity of the soil,before designing a subsurface
drainage system.
• Size of drain--Size subsurface drains to carry the required capacity
without pressure flow. Mini.mum diameter for a subsurface drain is 4
inches.
• The minimum velocity required to prevent silting is 1.4 ft./sec. The ,
line shall be graded to achieve this velocity at a minirnum. The �
maximum allowable velocity using a sand-gravel filter or envelope is 9
. ft/sec.
• Filter material and fabric shall be used around all drains for proper
bedding and filtration of fine materials. Envelopes and filters should
surround the drain to a minimum of 3-inch thickness.
• The outlet of the subsurface drain shall empty into a sediment pond
through a catch basin. If free of sediment, it can then empty into a
receiving channel, swale, or stable vegetated area adequately protected ,
from erosion and undermining.
• The trench shall be constructed on a continuous grade with no reverse !
grades or low spots.
• Soft or yielding soils under the drain shall be stabilized with gravel or
other suitable material.
• Backfilli.ng shall be done immediately after placement of the pipe. No
sections of pipe shall remain uncovered overnight or during a
rainstorm. Backfill material shall be placed in the trench in such a
, manner that the drai.n pipe is not displaced or damaged. ,
• Do not install permanent drains near trees to avoid the tree roots that I
tend to clog the line. Use solid pipe with watertight connections where
it is necessary to pass a subsurface drainage system through a stand of
trees.
• Outtet--Ensure that the outlet of a drain empties into a channel or
other watercourse above the normal water leveL
• Secure an animal guard to the outlet end of the pipe to keep out I
rodents.
• Use outlet pipe of corrugated metal, cast iron, or heavy-duty plastic
without perforations and at least 10 feet long. Do not use an envelope
or filter material arou.nd the outlet pipe, and bury at least two-tivrds of
the pipe length.
• When outlet velocities exceed those allowable for the receiving
stream, outlet protection must be provided.
February 2005 Volume !l— Construction Stormwater Pollution Prevention 4-71
Maintenance Subsurface drains shall be checked periodically to ensure that they are
Standards free-flowing and not clogged with sediment or roots. '
• The outlet shall be kept clean and free of debris.
• Surface inlets shall be kept open and free of sediment and other debris.
• Trees located too close to a subsurface drain often clog the system
with their roots. If a drain becomes clogged, relocate the drain or
remove the trees as a last resort. Drain placement should be planned to
minimize this problem.
• Where drains are crossed by heavy vehicles,the line shall be checked
to ensure that it is not crushed.
'
i
i
i
� � _
� � �i �
+_I
` �
,
'
% .
4-72 Volume!1-GonstructiQn Stormvvater Pollution Pre!�ention Febnra^f 2�05
BMP C2Q6: Level Spreader
Purpose To provide a temporary outlet for dikes and diversions consisting of an
excavated depression constructed at zero grade across a slope. To convert
concentrated runoff to sheet flow and release it onto areas stabilized by
existing vegetation or an engineered filter strip.
Conditions of Use Used when a concentrated flow of water needs to be dispersed over a large I
area with existing stable vegetation. ,
• Items to consider are: I,
l. What is the risk of erosion or damage if the flow may become
concentrated?
2. Is an easement required if discharged to adjoining property?
3. Most of the flow should be as ground water and not as surface
flow.
4. Is there an unstable area downstream that cannot accept additional
ground water?
• Use only where the slopes are gentle,the water volume is relatively
low, and the soil will adsorb most of the low flow events.
Design and Use above undisturbed areas that are stabilized by eaListing vegetation.
Installation If the level spreader has any low points, flow will concentrate, create
Specifications channels and may cause erosion.
• Discharge area below the outlet must be uniform with a slope of less
than SH:1V.
• Outlet to be constructed level in a stable, undisturbed soil profile (not
on fill}.
• The runofF shall not reconcentrate after release unless intercepted by
another downstream measure.
• The grade of the channel for the last 20 feet of the dike or interceptor
entering the level spreader shall be less than or equal to 1 percent. The
grade of the level spreader shall be 0 percent to ensure uniform
spreading of storm runoff.
• A 6-inch high gravel berm placed across the level lip shall consist of
washed crushed rock, 2-to 4-inch or 3/4-inch to 11/Z-inch size.
• The spreader length shall be detemuned by estimating the peak flow
expected from the 10-year, 24-hour design storm. The length of the
spreader shall be a minimum of 15 feet for 0.1 cfs and shall be 10 feet
for each 0.1 cfs there after to a ma�mum of 0.5 cfs per spreader. Use
multiple spreaders for higher flows.
' • The width of the spreader should be at least 6 feet.
February 2005 Volume I!— Construcfion Sformwater PoNution Prevenfion 4-73
• The depth of the spreader as measured from the lip should be at least 6
inches and it should be uniform across the entire length. '
• Level spreaders shall be setback from the property line unless there is
an easement for flow.
• Level spreaders,when installed every so often in grassy swales, keep
the flows from concentrating. Materials that can be used include sand
bags, lumber, logs,concrete, and pipe. To function properly,the
material needs to be installed level and on contour. Figures 4.11 and
4.12 provide a cross-section and a detail of a level spreader.
Mainlenance The spreader should be inspected after every runoff event to ensure that it
Standards is functioning conectly.
• The contractor should avoid the placement of any material on the
structure and should prevent construction traffic from crossing over
the structure.
• If the spreader is damaged by construction traffic,it shall be �
immediately repaired.
� Pressur�Treated 2"x10" � � �
Densely vegetated for a �
Min. of'100'and slope
less than 5:1 ,� I �
�� i1 �� �� I I �� I I "I I 1 I I I��t —,1'iin.
�I�„ �� =11 �� , _� y �
3' Min.—�
Figure 4.11 -Cross Section of Level Spreader
Treated 2"x10" may be abutted end to
Spreader must be level end for max. spreader length of 50'
6"min. 1"mi�
� �_I�� 6" min �—� � � �
=� �1-- - -- -- -- - - -- ---- - - - - -- - -- � � �_
��—��— --————--_—— �—���
��I I I���I I I���I i I �I I I���I I I���I I I���I I I���I I��I I I���I I I���I I I���I I I���I I I� � I I���I I I���I I I���
18"min. rebar supports
8'max. spacing
�
' Figure 4.12-Detail of Levef Spreader
4-74 �/�r,�mA r!- Cen.strwletien Sterm.�:�at�r!7�!l;,,f;�� Prevert;or Fgb;ua;�2005
BMP C207: Check Dams
Purpose Construction of small dams across a swale or ditch reduces the velocity of
concentrated flow and dissipates energy at the check dam.
Conditions of Use �ere temporary channels or permanent channels are not yet vegetated,
channel lining is i.nfeasible, and velocity checks are required.
• Check dams may not be placed in streams unless approved by the State I
Department of Fish and Wildlife. Check dams may not be placed in
wetlands without approval from a permitting agency. '
• Check dams shall not be placed below the expected backwater from
any salmonid bearing water between October 1 and May 31 to ensure
that there is no loss of high flow refuge habitat for overwintering
juvenile salmonids and emergent salmonid fiy.
Design and Whatever material is used,the dam should form a triangle when viewed
Installation from the side. This prevents u.ndercutting as water flows over the face of
Specifications the dam rather than falling directly onto the ditch bottom.
Check dams in association with sumps work more effectively at slowing
flow and retaining sediment than just a check dam alone. A deep sump
should be provided immediately upstream of the check dam.
• In some cases, if carefully located and designed, check dams can
remain-as permanent installations with very minor regrading. They
may be left as either spillways,in which case accumulated sediment
would be graded and seeded, or as check dams to prevent further
sediment from leaving the site.
• Check dams can be constructed of either rock or pea-gravel filled bags.
Numerous new products are also available for this purpose. They tend
to be re-usable, quick and easy to install,effective, and cost efFicient.
• Check dams should be placed perpendicular to the flow of water.
• The maximum spacing between the dams shall be such that the toe of
the upstream dam is at the same elevation as the top of the downstream
da.m.
• Keep the maximum height at 2 feet at the center of the dam.
• Keep the center of the check dam at least 12 inches lower than the
outer edges at natural ground elevation.
• Keep the side slopes of the check dam at 2:1 or flatter.
� • Key the stone into the ditch banks and extend it beyond the abutments
a minimum of 18 inches to avoid washouts from overIlow around the
dam.
'
February 2005 Volume !t— Construction Sformtvafer Pollution Prevenfion 4-75
• Use filter fabric foundation under a rock or sand bag check dam. If a
blanket ditch liner is used,this is not necessary. A piece of organic or
� synthetic blanket cut to fit will also work for this purpose.
• Rock check dams shall be constructed of appropriately sized rock.
The rock must be placed by hand or by mechanical means (no
dumping of rock to form dam)to achieve complete coverage of the
ditch or swale and to ensure that the center of the dam is lower than
the edges. The rock used must be large enough to stay in place given
the expected design flow through the channel.
• Tn the case of grass-lined ditches and swales,all check dams and
accumulated sediment shall be removed when the grass has matured
sufficiently to protect the ditch or swale - unless the slope of the swale
is greater than 4 percent. The area beneath the check dams shall be
seeded and mulched immediately after dam removal.
• Ensure that channel appurtenances, such as culvert entrances below
check dams, are not subject to damage or blockage from displaced
stones. Figure 4.13 depicts a typical rock check dam.
Maintenance Check dams shall be monitored for performance and sediment
Standards- - - accumuiation during and aftei-each-runoffproducing rainfall. Sedirrient
shall be removed when it reaches one half the sump depth.
• Anticipate submergence and deposition above the check da.m and
erosion from high flows around the edges of the dam. ' :
• If significant erosion occurs between dams,install a protective riprap
liner in that portion of the channel.
i '
(
4-76 Volume 11-Construction Stormwarer Po!lc.�tion PreYention February 2005
View Looking Upstream � 18� �o.5m�
A
12" (150mm)
�\ \ o� �,
°: d0. . o. a0.°� ' /� /.•�i�//.�//
�\//�\//�\/�j\/� �Q�o�o,a0 �°oio�-6`��0���.//�/ 24" (0.6m)
NOTE: �o� �o;�.ao � �
Key stone into channel banks and � / / / /.
extend it beyond the abutments a �'\� ��\��\�\�\
minimum of 18"(0.5mj to prevent A
flow around dam.
Section A - A
FLOW �
24" (0.6m) Q,o���
� O, •o po
/� 0
�i `bo �� � �pOpc•.
�, � � °�°0 0 flo�,
' Qj� ,
, �\�/%\// ' %�\ \\ �\��\��\���. d
� ,�\.�\��\/���/����\i��\�j�\�j �j��,/�
� ./��/ ���
8' (2.4m)
Spacing Between Check Dams -
'L'=the distance such that points'A'and
'B'are of equal elevation.
. ,L,
� °' � POINT'B'
, ' / �° '�°�° r-POINT'A' �
//\��%��/�\/�\/�\/�\/�/�/ (�
//\//\�/��/. �i.�/ �� /� /� � � � O• •° o '�Jp•.�o
\\,�\\/�\\�\\�\\�\\�\\�\ �\ � � .
�'`�����������\�/�\���\/������`/�'/��\�/\�\�\ \ �
.�,��j���j���j��
NOT TO SCALE
Figure 4.13-Check Dams
February 2005 Volume !1- Construction Stormwater Pollution Prevention 4-77
BMP C208: Triangular Silt Dike (Geotextile-Encased Check Dam)
;
Purpose Triangular silt dikes may be used as check dams, for perimeter protection,
for temporary soil stockpile protection, for drop inlet protection, or as a
temporary interceptor dike.
Conditions of use May be used in place of straw bales for temporary check dams in ditches
of any dimension.
• May be used on soil or pavement witlz adhesive or staples.
• TSDs have been used to build temporary:
1. sediment ponds;
2. diversion ditches;
3. concrete wash out facilities;
4. curbing;
5. water bars;
6. level spreaders; and,
7. berms.
Design and Made of urethane foam sewn into a woven geosynthetic fabric.
- Installation It is friangular, 10 inches to 14 inches high in the center,with a 20-inch to
Specifications 2g_inch base. A 2—foot apron e�rtends beyond both sides of the triangle
along its standard section of 7 feet. A sleeve at one end allows attachment
of additional sections as needed.
• Install with ends curved up to prevent water from flowing around the
ends.
• The fabric flaps and check da.m units are attached to the ground with
wire staples. Wire staples should be No. 11 gauge wire and should be
200 mm to 300 mm in length.
• When multiple units are i.nstalled,the sleeve of fabric at the end of the
unit shall overlap the abutting unit and be stapled.
• Check dams should be located and insta.11ed as soon as construction
will allow.
• Check dams should be placed perpendicular to the flow of water.
• When used as check dams,the leading edge must be secured with
rocks, sandbags, or a small key slot and staples.
• In the case of girass-lined ditches and swales, check dams and
accumulated sediment shall be removed when the grass has matured
suffciently to protect the ditch or swale unless the slope of the swale
is greater than 4 percent. The area beneath the check dams shall be
seeded and mulched immediately after dam removal.
Maintenance • Triangular silt dams shall be monitored for performance and sediment
Standards accumulation during and after each runoffproducing rainfalL �,
4-78 l�alul??B II— Gnn.ctrrir.tinn .�tn�m�,yatar Pnll�rtinn pro��gntipn Fgl,Y����2nn�
Sedi.ment shall be removed when it reaches one half the height of the
dam.
• Anticipate submergence and deposition above the triangular silt dam
and erosion from high flows around the edges of the dam.
Immediately repair any damage or any undercutting of the dam.
'
February 2005 Volume ll— Construction Stormwater Pollution Prevention 4-79
BMP C209: Outlet Protectio�
Purpose Outlet protection prevents scour at conveyance outlets and minimizes the
potential for downstream erosion by reducing the velocity of concentrated
stormwater flows.
Conditions of use Outlet protection is required at the outlets of all ponds,pipes, ditches, or
other conveyances, and where runoff is conveyed to a natural or manmade
drainage feature such as a stream,wetland, lake, or ditch.
Design and �e receiving channel at the outlet of a culvert shall be protected from
Installation erosion by rock lining a minimum of 6 feet downstream and extending up
Specifications �e channel sides a minimum of 1—foot above the ma�mum tailwater
elevation or 1-foot above the crown, whichever is higher. For large pipes
(more than 18 inches in diameter),the outlet protection lining of the
channel is lengthened to four times the diameter of the culvert.
• Standard wingwalls, and tapered outlets and paved channels should
also be considered when appropriate for permanent culvert outlet
protection. (See WSDOT Hydraulic Manual, available through
WSDOT Engineering Publications).
• Organic or synthetic erosion blankets,with or without vegetation, are
usually more effective than rock, cheaper, and easier to install. I
Materials can be chosen using manufacturer product specifications.
ASTM test results are available for most products and the designer can
choose the correct material for the expected flow.
• With low flows, vegetation(including sod) can be effective.
• The following guidelines shall be used for riprap outlet protection:
1. If the discharge velocity at the outlet is less than 5 fps (pipe slope
less than 1 percent),use 2-inch to 8-inch riprap. Mi.nimum
thickness is 1-foot.
2. For 5 to 10 fps discharge velocity at the outlet(pipe slope less than
3 percent),use 24-inch to 4-foot riprap. Minimum thickness is 2
feet.
3. For outlets at the base of steep slope pipes (pipe slope greater than
10 percent), an engineered energy dissipater shall be used.
• Filter fabric or erosion c�ntrol blankets should always be used under.
riprap to prevent scour and channel erosion.
• New pipe outfalls can provide an opportun.ity for low-cost fish habitat
improvements. For example, an alcove of low-velocity water can be
created by constructi.ng 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 j
and migrating adult salmonids may use the alcove as shelter during
4-80 Volume ll— Constnrctron Stc�r.mw2ter Po.►!!�tion Prevention February 2Q05
high flows. Bank stabilization, bioengineering, and habitat features
may be required for disturbed areas. See Volume V for more
information on outfall system design.
Maintenance . �spect and repair as needed.
Standards
� Add rock as needed to maintain the intended function.
• Clean energy dissipater if sediment builds up.
February 2005 Volume!I- Construction Stormwafer Pollution Prevention 4-81
Stormwater Po1(ution Prevention Plan
APPENDIX D - GENERAL PERMIT
�
�
II _
'�
�
I
�I
I
� �
I
�
�
�
I
I
Issuance Date: November 16,2005
Effective Date: Decemher 16, 2005
Expiration Date: December 16, 2010
CONSTRUCTION STORMWATER GENERAL PERMIT
National Pollutant Discharge Elimination System (NPDES) and State Waste
� Discharge General Permit for Stormwater Discharges Associated With
'� Construction Activity
I State of Washington
Department of Ecology
I Olympia, Washington 98504-7600
In compliance with the provisions of
The State of Washington Water Pollution Control Law
Chapter 90.48 Revised Code of Washington
and
The Federal Water Pollution Control Act
� � � (The Clean Water Act)
! Title 33 United States Code, Section 12�1 et seq.
�
Until this permit expires, is modified or revoked, Permittees that have properly obtained
coverage under this general permit are authorized to discharge in accordance with the special and
general conditions which follow.
� �
�
David C. Peeler,Manager
Water Quality Program
Washington State Department of Ecolo�-
'
Page 2 of 46
TABLE OF CONTENTS
SIJIVIlVIA.RY OF PERMIT REPORT SUBMITTALS........................•------------.---............................3
SLTNIlvIARY OF REQUIRED ON SITE DOCUMENTATION.....................................................3
5PECIAL CONDITIONS
S1. PERMIT COVERAGE.....................................................................�-------.....-------�---��-------�-�
S3. COMPLIANCE WITH STANDARDS...............................................................................9
S4. MONITORING REQUIREMENTS..................................................................................l 0
S5. REPORTING AND RECORDKEEPING REQiJIREMENTS.........................................I 5
S6. PERMIT FEES.............................................................................................................�--...18
S7. SOLID AND LIQUID WASTE DISPOSAL ....................................................................18
, S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES................................................18
S9. STORMWATER POLLUTION PREVENTION PLAN...................................................?1
S 10. NOTICE OF TERMINATION.............................................:............................................29
GENERALCONDITIONS ............................................................................................•--............30
G1. DISCHARGE VIOLATIONS .....................................................................................�--...30
G2. SIGNAT'ORY REQLTIREMENTS.....................................................•---....................---•----30
G3. RIGHT OF INSPECTION AND ENTRY.........................................................................31
G4. GENERAL PERMIT MODIFICATION AND REVOCATTON......................................3 l
G5. REVOCATION OF COVERAGE UNDER'I'HE PERMIT .............................................31
G6. REPORTING A CAUSE FOR MODIFICATION............................................................32
G7. COMPLIANCE WITH OTI-�ER LAWS AND STATUTES............................:................32
G8. DUTY TO REAPPLY...................................................................•-•---..............................32
G9. TRANSFER OF GENERAL PERMIT COVERAGE....................................•--•--.............32
G10. REMOVED SUBSTANCES.................................•--.........................................................33
G11. DUTY TO PROVIDE INFORMATION...........................................................................33
G12. OTHER REQUIREMENTS OF 40 CFR...........................................................................33
G13. ADDITIONAL MOI�IITORING........................................................................................33
G 14. PENALTIES FOR VIOLATING PERMIT CONDITIONS .............................................33
G15. UPSET...............................................................................................................................34
G16. PROPERTY RIGHTS........................................................................................................34
G17. DUTY TO COMPLY.....................................................•--................................................34
G18. TOXIC POLLUTANTS.....................................................................................................34
G 19. PENALTIES FOR TAMPERiNG.....................................................................................3�
G20. REPOR'I'ING PLANNED CHANGES..............................................................................3�
G2l. REPORTING OTHER 1NFORMATiON..........................................................................3�
'
Page 3 of 46
G22. REPORTII�'G ANTICIPATED NON-COMPLIANCE.....................................................35
G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT..........36
G24. APPEALS................�--�----.....................................................----..........-�----.........................36
G25. SEVER.ABILI'I'1'...............................................................................................................36
G26. BYPASS PROHIBITED..........-•.......................•---..........................--�----............................36
APPENDIX A—DEFINITIONS...................................................................................................39
APPENDIX B—ACRONYMS .....................................................................................................46
SUMMARY OF PERMIT REPORT SUBMITTALS
Refer to the Special and General Conditions for additional submittal requirements.
Permit Submittal Frequency First Submittal Date
Section
SS.A High Turbidity/Transparency Phone As Necessary Within 24 hours
Reporting
S�.B Discharge Monitoring Report Monthly Within 15 days after the
applicable monitoring
period
SS.F Noncompliance Notification As necessary Immediately
SS.F Noncompliance Notification—Written As necessary Within 5 Days of non-
Report compliance ,
G2. Notice of Change in Authorization As necessary
G6. Permit Application for Substantive As necessary
Changes to the Discharge
G8. Application for Permit Renewal 1/pertnit cycle No later than 180 days
before expiration
G9. Notice of Permit Transfer As necessary
G20. Notice of Planned Changes As necessary
G22. Reporting Anticipated Non-compliance As necessary
SUIVIlVIARY OF REQUIRED ON SITE DOCUMENTATION
� i
Permit Conditions Document Title
Conditions S2, SS Permit Covera e Letter
Conditions S2, SS Construction Stormwater General Permit
Conditions S4, SS Site Lo Book
Conditions S9, S� Stormwater Pollution Prevention Plan (SWPPP)
Page 4 of 46
SPECIAL CONDITIONS i
S1. PERMIT COVERA"GE
A. Permit Area
This general permit covers all areas of Washinaton State, except for federal and tribal
lands specified in S1.D.3.
B. Operators Required to Seek Covera�e Under this General Permit:
1. Operators of the following construction activities are required to seek coverage under
this permit:
�
a. Clearing, grading and/or excavation which results in the disturbance of one or
more acres, and discharges stormwater to surface waters of the state; and clearing,
grading and/or excavation on sites smaller than one acre which are part of a larger
common plan of development or sale, if the common plan of development or sale
will ultimately disturb one acre or more, and discharges storm«-ater to surface
waters of the state.
i. This includes forest practices that are part of a construction activity that will
result in the disturbance of one or more acres, and discharges to surface w�aters
ofthe state (i.e., forest practices which are preparing a site for construction
activities); and
b. Any size construction activity discharging stormwater to���aters of the state«-hich
the Department of Ecology(Ecology):
� i. Determines to be a significant contr�ibutor•of pollutants to���aters of the state of
Washington, or
ii. Reasonably expects to cause a violation of any water quality standard.
2. Operators ofthe following activities are not required to seek coverage under this
permit, unless specifically required under Condition S1.B.l.b. (Significant
Contributor):
a. Construction activities which discharge all stormwater and non-stormwater to
ground water, and have no point source discharge to surface water or a storm
sewer.st>stem that drains to surface ��aters of the state;
b. Construction activities covered under an Erosiviry Vvaiver (Condition S2.C);
c. Routine maintenance that is performed to maintain the original line and grade,
hydraulic capacity, or original purpose of a facility.
Page 5 of 46
C. Authorized Discharges:
1. Stormwater Associated with Construction Activitv. Subject to compliance with the
terms and conditions of this permit,Permittees are authorized to discharge
stormwater associated with construction activity to surface waters of the state or to a
storm sewer system that drains to surface waters of the state_
2. Stormwater Associated with Construction Support Activity. This permit also
authorizes stormwater discharges from support activities related to the permitted
construction site(e.g., off-site equipment staging yards, material storage areas,
borrow areas, etc.)provided:
a. The support activity is directly related to the permitted construction site that is
required to have an NPDES permit; and
b. The support activity is not a commercial operation serving multiple unrelated
construction projects, and does not operate beyond the completion of the
construction activity; and
c. Appropriate controls and measures are identified in the Stormwater Pollution
Prevention Plan(SWPPP)far the discharges from the support activity areas.
3. Non-Stormwater Dischar�es. The categories and sources of non-stormwater
discharges identified below are condifionally authorized, provided the discharge is
consistent with the terms and conditions of this permit:
a. Discharges from fire fighting activities;
b. Fire hydrant system flushing;
c. Potable water including uncontaminated water line flushing(de-chlorinated);
d. Pipeline hydrostatic test water; '
e. Uncontaminated air conditioning or compressor condensate; ,
f Uncontaminated ground water or spring water; II,
g. Uncontaminated excavation de-watering(in accordance with S9.D.10)
h. Uncontaminated discharges from foundation or footing drains;
i. Water used to control dust;
j. Routine external building wash down that does not use detergents; and I',
k. Landscape irrigation.
�
I
Page 6 of 46
All authorized non-stormwater discharges, except for discharges from fire fighting
activities, shall be adequately addressed in the SWPPP and comply with Special
Condition S3.
D. Limitations on Covera�e
T'he Director may require any discha�•ger to apply for and obtain coverage under an
individual permit or another more specific general permit. Such alternative coverage
will be required when Ecology determines that this general permit does not provide
adequate assurance that water quality vvill be protected; or there is a reasonable potential
for the project to cause or contribute to a violation of water quality standards.
T'he following stormwater dischaxges are not covered by this permit:
1. Post-construction stormwater discharges that originate from the site after construction
activities have been completed and the site has undergone final stabilization.
2. Nonpoint source silvicultural activities such as nursery operations, site preparation,
reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and
fire control,harvesting operations, surface drainage, or road construction and
maintenance from which there is natural runoff as excluded in 40 CFR Subpart
122.27.
3. Stormwater from any federal project or project on federal land or land within an
Indian Reservation except for�he Puyallup Reservation. Within the Puyallup
Reservation, any project that discharges to surface water on land held in trust by the
federal government may be covered by this permit.
4. Stormwater from any site covered undcr an existing NPDES individual permit in
which stormwater management and/or treatment requirements are included for all
stormwater discharges associated�vith construction activity.
5. Where an applicable Total Maximum Daily Load (TIvIDL) specifically precludes or
prohibits discharges from construction activity, the operator is not eligible for
coverage under this permit.
S2. APPLICATION REQUIREMENTS
A. Permit Application Porms
1. Notice of Intent Form/Timeline
a. Operators of new or previously unpermitted construction activities shall submit a
complete and accurate pertnit application form [Notice of Intent(NOI)] to
Ecology. Applicants are encouraged to use Ecology's internet-based electronic
NOI to apply for pertnit coverage.
b. The NOI shall be submitted on or before the date of the first public notice (see
Condition S?.B below) and at least 60 days prior to the discharge of storm���ater
'
' Page 7 of 46
from construction activities. The 30-day public comment period required by WAC
173-226-130(5)begins on the publication date of the second public notice. Unless
Ecology responds to the complete application in writing, based on public
comments, or any other relevant factors, coverage under the general permit will
automatically commence an the thirty-first day following receipt by Ecology of a
completed NOI, or the issuance date of this permit,whichever is later;unless a
later date is specified by Ecology in writing.
c. Applicants that discharge to a storm sewer system operated by Seattle, King
County, Snohomish County, Tacoma, Pierce County, or Clark County shall also
submit a copy of the NOI to the appropriate jurisdiction.
2_ Transfer of Coverage Form
Current coverage under this permit may be transferred to one or more new operators,
including operators of sites within a Common Plan of Development, by submitting
a Transfer of Coverage Form in accordance with Condition G9. Transfers do not
require public notice.
B. Public Notice
For new or previously unpermitted sites, the applicant shall publish a public notice at
least one time each week for two consecutive weeks,with a 7-day time span between
_ dates, in a newspaper that has general circulation in the county in which the construction
is to take place. The notice shall contain the following: "
1. A statement that"The applicant is seeking coverage under the Washington State
Department of Ecology's Construction Stormwater NPDES and State Waste Discharge I
General Permit";
2. The name, address and location of the construction site;
3. The name and address of the applicant;
4_ The type of construcrion activity that will result in a discharge, (e.g., residential
construction, commercial construction, etc.}and the number of acres to be disturbed;
5. The name of the receiving water(s) (i.e.,the surface water(s)that the site will discharge
to), or if the discharge is through a storm sewer system,the name of the operator of the
storm sewer; and
6. The statement: "Any person desiring to present their views to the Department of
Ec�logy regarding this application, or interested in the Department's action on this
application may notify the Department of Ecology in writing within 30 days of the last
date of publication of this notice. Comments can be submitted to: Department of
Ecology, P.O.Box 47696, Olympia, WA 98504-7696, Attn: Water Quality Program,
Construction Stormwater�'.
'
Page 8 of 46
C. Erosivity Waiver ,
Operators may qualify for a waiver from the permit if the following conditions are met:
1. The site will result in the disturbance of less than 5 acres; and the site is not a portion
of a common plan of development or sale that will disturb 5 acres or greater.
2. Calculation of Erosivity "R"Factor and Regional Timeframe:
a. The project's rainfall erosivity factor("R"Factor)must be less than � during the
period of construction activity, as calculated using the Texas A&M Universit}�
online rainfall erosivity calculator at:http://ei.tamu.edu/. The period of
construction activity begins at initial earth disturbance and ends with frnal
stabilization; and, in addition:
b. T�he entire period of construction activit��must fall within the follo���ing
� timeframes:
i. For sites west of the Cascades Crest: June 15—September ]5; or
ii. For sites east of the Cascades Crest, excluding the Central Basin: June l 5 —
October 15; or
iii. Far sites east of the Cascades Crest, within the Central Basin*: no additional
timeframe restrictions apply.
*Note: The Central Basin is defined as the portions of Eastern Washington
with mean annual precipitation of less than 12 inches.
3. Operators must submit a complete Erosivity Waiver Certification Form at least one
week prior to commencing land disturbing activities. Certification must include:
a. A statement that the operator will comply with applicable local stormwater
requirements; and
b. A statement that the operator will implement appropriate erosion and sediment
control BMPs to prevent violations of water quality standards.
4. This waiver is not available for facilities declared a significant contributor of
pollutants as defined in Condition S1.B.l.b.
5. This waiver does not apply to construction activity��hich includes non-stormwater
discharges listed in SI.C.�.
6. If construction activity extends be}�ond the certified waiver period for any reason, the
operator shall either:
Page 9 of 46 '
a. Recalculate the rainfall erosivity"R"factor using the original start date and a new
projected ending date and, if the "R"factor is still under 5 and the entire project
falls within the applicable regional timeframe in S2.C2.b, complete and submit
an amended waiver certification form before the original waiver expires; or
b. Submit a complete permit application to Ecology in accordance with Condition
S2.A and B before the end of the certified waiver period.
S3. COMPLIANCE WITH STANDARDS
A. Discharges shall not cause or contribute to a violation of surface water quality standards
(Chapter 173-201A WAC), ground water quality standards(Chapter 173-200 WAC),
sediment management standards(Chapter 173-204 WAC), and human health-based
criteria in the National Toxics Rule (40 CFR Part 13136). Discharges that are not in
compliance with these standards are not autharized.
B. Prior to the discharge of stormwater and non-stormwater to waters of the state,the
Permittee shall apply all known, available, and reasonable methods of prevention,
control, and treatment(AKAR7). This includes the preparation and implementation of an
adequate Stormwater Pollution Prevention Plan (SWPPP),with all appropriate best
management practices(BMPs) installed and maintained in accordance with the SWPPP
and the terms and conditions of this permit.
C. Compliance with water quality standards shall be presumed,unless discharge monitoring
data or other site specific information demonstrates that a discharge causes or contributes
to a violation of water quality standards,when the Permittee is:
L In full compliance��vith all permit conditions, including planning, sampling,
monitoring, reporting, and recordkeeping conditions; and
2. Fully implementing stormwater BMPs contained in stormwatef•management manuals
published�r approved by Ecology, or BMPs that are demonstrably equivalent to
BMPs contained in stormwater technical manuals published or approved by Ecology,
including the proper selection, implementation, and maintenance of all applicable and
appropriate BMPs for on-site pollution control.
D. For sites that discharae to both surface water and ground water, all ground water
discharges are also subject to the terms and conditions of this permit. Permittees who
discharge to ground water through an injection well shall comply with any applicable
requirements of the Underground Injection Control (UIC) regulations, Chapter 173-218
WAC.
�
Page 10 of 46
S4. MONITORING REQUIREMENTS
The primary monitoring requirements are summarized in Table 3 (below):
Table 3. Summary of Monitoring Requirementsl
Size of Soi1 Disturbance2 Weekly Weekly Weekly Weekly
Site Sampling w/ Sampling w/ pH
Inspections ' Turbidity Meter Transparency sampling3
' Tube
Sites which disturb less than 1 Required Not Required Not Required Not
acre Re uired
Sites which disturb 1 acre or Required Sampling Requir�d—either Required
more, but less than 5 acres method
Sites which disturb 5 acres or Required Required � Not Requireds Required
more
A. Site Log Book
The Permittee shall maintain a site log book that contains a record of the
implementation of the SWPPP and other permit requirements including the installation
and maintenance of BMPs, site inspections, and stormwater monitoring.
B. Site Inspections
1. Site inspections shall include all areas distui-bed by construction activities, all BMPs, �
and all stormwater discharge points. Stormwater shall be visually examined for the '
I Additional monitoring requirements may apply for: 1)discharges to 303(d)listed waterbodies and waterbodies ',
with applicable TMDLs for turbidity,fine sediment,high pH,or phosphorus-see Condition S8;and 2)sites
required to perform additional monitoring by Ecology order—see Condition G13. �I
2 Soil disturbance is calculated by adding together a11 areas affected by construction activiry.Construction Activity I
means clearing,grading,excavation,and any other activity which disturbs the surface of tt�e land,including !
ingress/egress from tl�e site. ,
3 Beginning October 1,2006,if construction activity involves significant concrete work or the use of engineered
soils,and stormwater from the affected area drains to a storma�ater collection system or other surface water,the
Permittee shall conduct pH sampling in accordance with Condition S4.D.
4 Beginning October 1,2008,sites with one or more acres,but less than 5 acres of soil disturbance,shall conduct
turbidity or transparency sampling in accordance with Condition S4.C.
5 Beginning October 1,2006,sites greater than or equal to 5 acres of soil disturbance shall conduct turbidity
sampling using a turbidity meter in accordance H�th Condition S4.C.
'
Page 11 of 46
presence of suspended sediment, turbidity, discoloration, and oil sheen. Inspectors
shall evaluate the effectiveness of BNIPs and deternline if it is necessary to install,
maintain, or repair BMPs to improve the quality of stormwater discharges.
Based on the results of the inspection, the Permittee shall correct the problems
identified as follows:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions��ithin 7 days of the inspection; and
b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible, but no later than 10 days of the inspection; and
c. Document BMP implementation and maintenance in the site log book.
2. The site inspections shall be conducted at least once every calendar week and within
24 hours of any discharge from the site. The inspection frequency for temporarily
stabilized, inactive sites may be reduced to once every calendar month.
3. Site inspections shall be conducted by a person who is knowledgeable in the
principles and practices of erosion and sediment control. The inspectar shall have the
skills to:
a. Assess the site conditions and construction activities that could impact the quality
of stormwater, and
- _- b. Assess the effectiveness of erosion and sediment control measures used to control .
the quality of stormwater discharges.
4. Beginning October 1,2006, construction sites one acre or larger that discharge
stormwater to surface waters of the state, shall have site inspections conducted by a
Certified Erosion and Sediment Control Lead(CESCL). The CESCL shall be
I identified in the SWPPP and shall be resent on-site or on-call at all times.
P
Certification shall be obtained through an approved erosion and sediment control
training program that meets the minimum training standards established by Ecology
(see BMP C 160 in the Ma�ual).
5. The inspector shall summarize the results of each inspection in an inspection report or
checklist and be entered into, or attached to, the site log book. At a minimum, each
inspection report or checklist shall include:
a. Inspection date and time. !
b. Weather information; general conditions during inspection and approximate '
amount of precipitation since the last inspection, and within the last 24 hours. ',
c. A summary or list of all BMPs which have been implemented, including I�
observations of all erosion/sediment control structures or practices.
d. The following shall be noted:
i. locations of BMPs inspected,
'
Page 12 of 46
ii. locations of BMPs that need maintenance,
iii. the reason maintenance is needed,
iv. locations of BMPs that failed to operate as designed or intended, and
v. locations where additional or different BMPs are needed, and the reason(s)why.
e. A description of stormwater discharged from the site. The inspector shall note the
presence of suspended sediment, turbid water, discoloration, and/or oil sheen, as
applicable.
f. Any water quality monitoring performed during inspection.
g. General comments and notes, including a brief description of any BMP repairs, I�
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 �I
site is either in compliance or out of compliance with the terms and conditions of �
the SWPPP and the permit. If the site inspection indicates that the site is out of
compliance,the inspection report shall include a summary of the remedial actions
required to bring the site back into compliance, as well as a schedule of
implementation. ,
i I
i. Name, title, and signature of the person conducting site inspection; and the
following statement: "I certify that this report is true, accurate, and complete, to
the best of my knowledge and belieP'.
C. Turbidity/Transparencv Samplin�Requirements
1. Sampling Methods/Effective Dates
a. Beginning October l, 2006, if construction activity will involve the disturbance
of 5 acres or more, the Permittee shall conduct turbidity sampling per Condition
S4.C.
b. Beginning October 1, 2008, if construction activity will involve greater than or
equal to 1 acre,but less than 5 acres of soil disturbance, the Permittee shall
conduct transparency sampling or turbidiry sampling per Condition S4.C.
� 2. Sam lin Fre uenc
P g 9 Y
a. Sampling shall be conducted at least once every calendar week, when there is a
discharge of stormwater(or authorized non-stormwater) from the site. Samples
shall be representative of the flow and characteristics of the discharge.
b. When there is no discharge during a calendar week, sampling is not required.
c. Sampling is not required outside of normal working hours or during unsafe
conditions. If a Permittee is unable to sample during a monitoring period, the
�'i Discharge Monitoring Report (DMR) shall include a brief explanation.
II
i
Page 13 of 46
3. Sampling Locations
a. Sampling is required at all discharge points��-here storm«�ater(or authorized non-
stormwater) is discharged off-site.
I
b. All sampling point(s) shall be identified on the SWPPP site map and be clearly
marked in the field with a flag, tape, stake or other visible marker.
' 4. Sampling and Analysis Methods
a. Turbidity analysis shall be performed with a calibrated turbidity meter
(turbidimeter), either on-site or at an accredited lab. The results shall be recorded
� in the site log book in Nephelometric Turbidiry Units (NTLJ).
Ib. Transparency analysis shall be performed on-site with a 1 3/4 inch diameter, 60
' centimeter(cm)long Transparency Tube. The results shall be recorded in the site
log book in centimeters (cm). Transparency Tubes are available from:
http://watermonitorin�quip.c�m!pa�eslstrealn.html
Analytical Sampling Benchmark
Parameter Units Method Fre uenc ' Value
Turbidity NTU SM2130 or Weekly, if 25 NTU
EPA 180.1 discharging
Transparency cm Manufacturer Weekly, if 31 cm
ins�ructions, or discharging
Ecology
Guidance
5. Turbidity/Transparency Benchmark Values
The benchmark value for turbidity is 25 NTL7(Nephelometric Turbidity Units); and
the benchmark value for transparency is 31 cm.
a. Turbidity 26—249 NTLJ, ar Transparency 30—7 cm:
If discharge turbidity is greater than 25 NTU, but less than 250 NTU; or if
discharge transparency is less than 31 cm, but greater than 6 cm, the CESCL
shall:
i. Reviev��the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the benchmark; and
ii. Fully implement and maintain appropriate source control and/or treatment
BMPs as soon as possible, but within 10 days of the discharge that
exceeded the benchmark; and
iii. Document BMP implementation and maintenance in the site log book.
b. Turbidity 250 NTU or �reater, or Transparency 6 cm or less:
Page 14 of 46
If discharge turbidity is greater than or equal to 250 NTU; or if discharge
transparency is less than or equal to 6 cm, the CESCL sha1L• '
i. Notify Ecology by phone in accordance with Condition SS.A.; and
ii. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the benchmark; and
iii. Fully implement and maintain appropriate source control and/or treatment
BMPs as soon as possible, but within 10 days of the discharge that
exceeded the benchmark;
iv. Document BMP implementation and maintenance in the site log book; and
v. Continue to sample discharges daily until:
1. turbidity is 25 NTU(or lower); or
2. transparency is 31 cm (or greater); or
3. the CESCL has demonstrated compliance«�ith the water quality
standard for turbidity:
a. no more than 5 NTU over background turbidity, if background is
less than 50 NTU, or
' b. no more than 10% over background turbidity, if background is �0
NTU or greater; or
4. the discharge stops or is eliminated.
D. pH Monitorin�: Sites with Si�nificant Concrete Work or En�ineered Soils
Beginning October 1, 2006, if construction activity will result in the disturbance of 1
acre or more, and involves significant concrete work or the use of engineered soils, and
stormwater from the affected area drains to surface waters of the state or to a storm
sewer system that drains to surface vvaters of the state, the Permittee shall conduct pH
monitoring as set forth below:
1. For sites with significant concrete��ork, the pH monitoring period shall commence
when the concrete is first exposed to precipitation and continue ���eekly until
stormwater pH is 8.5 or less.
a. "Significant concrete work"means greater than 1000 cubic yards poured concrete
or recycled concrete.
2. For sites with engineered soils,the pH monitoring period shall commence when the
soil amendments are first exposed to precipitation and shall continue until the area of
engineered soils is fully stabilized.
Page 15 of 46
a. "Engineered soils" means soil amendments including, but not limited,to Portland
cement treated base (CTB), cement kiln dust(CKD), or fly ash.
3. During the pH monitoring period, the Permittee shall obtain a representative sample
of stortnwater and conduct pH analysis at least once per week.
4. The Permittee shall monitor pH in the sediment trap/pond(s)or other locations that
receive stormwater runoff from the area of significant concrete work or engineered
soils prior to discharge to surface waters.
S. The benchmark value for pH is 8.5 standard units. Any time sampling indicates that
pH is 8.5 or geater, the Permittee shall:
a. Prevent the high pH water(8.5 or above)from entering storm sewer systems or
surface v�7aters; and
b. If necessary, adjust or neutralize the high pH water using an appropriate treatment
BMP such as COZ sparging or dry ice. The Permittee shall obtain written
approval from Ecology prior to using an57 form of chemical treatment other than
COZ sparging or dry ice.
6. The Permittee shall perform pH analysis on-site with a calibrated pH meter, pH test
kit, or wide range pH indicator paper. The Permittee shall record pH monitoring
results in the site log book.
S5. REPO1rTING AND RECORDKEEPING REQUIREMENTS =
A. Hi�h Turbiditv Phone Reporting
Any time sampling performed in accordance with Special Condition S4.0 indicates
turbidity is 250 NTU or greater(or transparency is 6 cm or less)the Permittee shall notify
the appropriate Ecology regional office by phone within 24 hours of analysis.
B. Discharge Monitoring Reports
1. Permittees required to conduct water quality sampling in accordance with Special
Conditions S.4.0 (Turbidity/Transparency), S4.D (pH) and/or S8 [303(d)/TMDL
sampling] shall submit the results to Ecology monthly on Discharge Monitoring
Report (DMR) forms provided by Ecology.
Permittees are authorized and encouraged to submit electronic DMRs using the "E-
DMR Form" on Ecology's Construction Stormwater web site:
http://www.ecv.wa.gov/pro�ram s/wq/stormvvater/construction/.
2. The Permittee shall submit DMR forms electronically or by mail to be received by
Ecology within 15 days following the end of each month. If there was no discharge
during a given monitoring period, the Permittee shall submit the form as required
with the w�rds "no discharge" entered in place of the monitoring results. If the
Permittee is unable to submit discharge monitoring reports electronically,the
Permittee may mail reports to thc address listed belo«:
'
Page 16 of 46
Department of Ecology
Water Quality Program - Construction Storm��ater
PO Box 47696
Olympia, «'ashington 98504-7696
C. Records Retention
The Permittee shall retain records of all monitoring information (site log book, sampling
results, inspection reports/checklists, etc.), Stormwater Pollution Prevention Plan, and
any other documentation of compliance with permit requirements during the life of the
construction project and for a minimum of three years following the termination of
permit coverage. Such information shall include all calibration and maintenance records,
and records of all data used to complete the application for this permit. This period of
retention shall be extended during the course of any unresolved litigation regarding the
discharge of pollutants by the Permittee or���hen requested by Ecology.
D. Recording of Results
For each measurement or sample taken, the Permittee shall record the follov�ing
information:
l. Date, place, method, and time of sampling or measurement;
2. The individual who performed the sampling or measurement;
� 3. The dates the analyses were performed;
��
� 4. The individual who performed the analyses;
I
5. The analytical techniques or methods used; and
6. The results of all analyses.
E. Additional Monitoring bv the Permittee
If the Permittee monitors any pollutant more frequently than required by this permit using
test procedures specified by Condition S4 of this permit, the results of this monitoring
shall be included in the calculation and reporting of the data submitted in the Permittee's
DMR.
F. Noncompliance Notification
In the event the Permittee is unable to comply«-ith any of the terms and conditions of
this permit which may cause a threat to human health or the environment, the Permittee
� shall:
� L Immediately notify Ecology of the failure to comply.
2. Immediately take action to prevent the discharge/pollution, or other�-ise stop or
correct the noncompliance, and, if applicable, repeat sampling and analysis of an}
noncompliance immediately and submit the results to Ecolow within five (�) days
after becoming aware of the violation.
. Page 17 of 46
3. Submit a detailed written report to Ecology vvithin five (5) days, unless requested
earlier by Ecology. The report shall contain a description of the noncompliance,
including exact dates and times, and if the noncompliance has not been corrected, the
anticipated time it is expected to continue; and the steps taken or planned to reduce,
eliminate, and prevent reoccurrence of the noncompliance.
Compliance with these requirements does not relieve the Permittee from
responsibiliry to maintain continuous compliance with the terms and conditions of
this permit or the resulting liability for failure to comply.
G. Access to Plans and Records
1. The Permittee shall retain the following permit documentation (plans and records) on-
site, or within reasonable access to the site, for use by the operator; or on-site review
by Ecology or the local jurisdiction:
a. General Permit;
b. Permit Coverage Letter;
c. Stormwater Pollution Prevention Plan (SWPPP);and
d. Site Log Book
2. The Permittee(s) shall addtess v��ritten requests for plans and records listed above
(Condition SS.G.1) as follows:
a. A copy of plans and records shall be provided to Ecology within 14 days of
receipt of a written request from Ecology.
b. A copy of plans and records shall be provided to the public when requested in
writing. Upon receiving a written request from the public for the Permittee's
plans and records,the Permittee shall either:
i. Provide a copy of the plans and records to the requestor within 14 days of a
receipt of the written request; or
ii. Notify the requestor within 10 days of receipt of the written request of the
location and times within normal business hours when the plans and rec�rds '
may be viewed, and provide access to the plans and records within 14 days of
receipt of the written request; or
iii. Within 14 days of receipt of the written request, the Permittee may submit a ,
copy of the plans and records to Ecology for viewing and/or copying by the ',
requestor at an Ecology office, or a mutually agreed upon location. If plans I
and records are viewed and/or copied at a location other than at an Ecology
office, the Permittee will provide reasonable access to copying services for
which a reasonable fee may be charged_ "I�e Permittee shall notify the
Page 18 of 46
requestor within 10 days of receipt of the request where the plans and records
may be viewed and/or copied.
S6. PERMIT FEES
The Permittee shall pay permit fees assessed by Ecology. Fees for stormwater discharges
covered under this permit shall be established by Chapter 173-224 WAC. Permit fees will
continue to be assessed until the permit is terminated in accordance with Special Condition
S 10 or revoked in accordance with General Condition G5.
S7. 50LID AND LIQUID WASTE DISPOSAL
Solid and liquid wastes generated by construction activity such as demolition debris,
construction materials, contaminated materials, and waste materials from maintenance
activities, including liquids and solids from cleaning catch basins and other stormwater
facilities, shall be handled and disposed of in accordance with:
1. Special Condition S3, Compliance with Standards, and
2. WAC 173-216-110, and other applicable regulations. ,
S8. DISCHARGES TO 303(D) OR TMDL WATERBODIES
A. Sampling and Numeric Effluent Limitations For Dischar�es to 303(d)-listed Waterbodies
1. l.Permittees that discharge to water bodies listed as impaired by the State of
Washington under Section 303(d) of the Clean YVater Act for turbidity, fine
sediment, high pH,or phosphorus, shall conduct water quality sampling according
to the requirements of this section.
2. All references and requirements associated with Section 303(d) ofthe Clean Water '
Act mean the most current listing by Ecology of impaired waters that exists on
November 16, 2005, or the date when the operator's complete permit application is �
received by Ecology, whichever is later. �I
B. Discharges to 303(d)-Listed Waterbodies (Turbidity,Fine Sediment, or Phosphorus� I�
1. Permittees which discharge to waterbodies on the 303(d) list for turbidity, fine
sediment, or phosphorus shall conduct turbidity sampling at the following locations i
to evaluate compliance with the water quality standard for turbidity: ,,
a. Background turbidiry shall be measured in the 303(d)-listed receiving water �
immediately upstream (upgradient) or outside the area of influence of the
discharge; and
b. Discharge turbiditj shall be measured at the point of discharge into the 303(d)
listed receiving waterbody, inside the area of influence of the discharge; or
'
Page 19 of 46
Alternatively, discharge turbidity may be measured at the point where the
discharge leaves the construction site,rather than in the receiving waterbody.
2. Based on sampling, if the discharge turbidity exceeds the water qualiry standard for �
turbidity (more than 5 NTU over background turbidity when the background
turbidity is 50 NTU or less, or more than a 10% increase in turbidity when the
background turbidity is more than 50 NT[J), all future discharges shall comply with
a numeric effluent limit which is equal to the water quality standard for turbidity.
3. If a future discharge exceeds the water quality standard for turbidity, the Permittee
shall:
a: Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the standard;
b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible, but within 10 days of the discharge that exceeded the
standard;
c. Document BMP implementation and maintenance in the site log book;
d. Notify the appropriate Ecology Regional Office by phone within 24 hours of
analysis;
• e: Continue to sample daily until discharge turbidity meets the water quality �
standard for turbidity.
C. Discharges to waterbodies on the 303(d) list for Hi�pH
1. Permittees which discharge to waterbodies on the 303(d) list for high pH shall
conduct sampling at one of the following locations to evaluate compliance with the
water quality standard for pH(in the range of 6.5—8.5):
a. pH shall be measured at the point of discharge into the 303(d) listed waterbody,
inside the area of influence of the discharge; or
b. Alternatively, pH may be measured at the point where the discharge leaves the '
construction site,rather than in the receiving water. �
2. Based on the sampling set forth above, if the pH exceeds the water quality standard
for pH (in the range of 6.5—8.5), all future discharges shall comply with a numeric
effluent limit which is equal to the water qualiry standard for pH.
3. If a future discharge exceeds the water quality standard for pH, the Permittee shall:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the discharge that exceeded the water qualit;� standard;
Page 20 of 46
b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible,but within 10 days of the discharge that exceeded the
standards;
c. Document BMP implementation and maintenance in the site log book;
d. Notify the appropriate Ecology Regional Office by phone within 24 hours of
analysis; and
e_ Continue to sample daily until discharge meets the water quality standard for pH
(in the range of 6.5—8.5)or the discharge stops ar is eliminated.
Parameter identified Parameter/LJnits Analytical Sampling Water Quality
in 303(d) listing Method Frequency Standard
Turbidiry Turbidity/NTIJ SM2130 or ��Veekly; if If background is 50
Fine Sediment EPA180.1 discharging NTU or less: 5 NTU
Phosphorus over background; or
If background is
more than 50 NTiJ:
10% over
background
Hi h H H/Standard H meter Weekl , if In the ran e of
g P P P Y g
Units discharging 6.5 —8.5
D. Samplin�and Limitations For Sites Discharging to Applicable TMDLs I
1. Discharges to a waterbodies subject to an applicable Total M�imum Daily Load
(TMDL) for turbidity, fine sediment, high pH, or phosphorus, shall be consistent with I
the assumptions and requirements of the TMDL. '
a. Where an applicable TMDL sets specific waste load allocations or requirements �I,
for discharges covered by this permit, discharges shall be consistent with any !
specific waste load allocations or requirements established by the applicable
TMDL.
ii.The Permittee shall sample discharges weekly, or as otherwise specified by the I
TNIDL, to evaluate compliance with the specific waste load allocations or
requirements.
iii.Analytical methods used to meet the monitoring requirements shall conform to
the latest revision of the Guidelines Establishing Test Procedures for the
Analysis ofPollutants contained in 40 CFR Part 136. Turbidity and pH methods
'
Page 21 of 46
need not be accredited or registered unless conducted at a laboratory which must
otherwise be accredited or registered_
b. Where an applicable TMI�L has established a general waste load allocation for
construction stormwater discharges, but no specific requirements have been
identified, compliance with Conditions S4 (Monitoring) and S9 (SWPPPs)will be
assumed to be consistent with the approved TMDL.
c. Where an applicable T1�IDL has not specified a waste load allocation for
construction stormwater discharges, but has not excluded these discharges,
compliance with Conditions S4 (Monitoring) and S9 (SWPPPs)will be assumed
to be consistent with the approved TMDL.
d. Where an applicable TIvIDL specifically precludes or prohibits discharges from
construction activity, the operator is not eligible for coverage under this permit.
2. Applicable TMDL means a TNIDL for turbidity, fine sediment, high pH, or
phosphorus, which has been completed and approved by EPA prior to November 16,
2005, or prior to the date the operator's complete permit application is received by
Ecology, whichever is later. TMDLs completed after the operator's complete permit
application is received by Ecology become applicable to the Permittee only ifthey are
imposed through an administrative order by Ecology, or through a modification of
permit coverage.
S9. STORMWATER POLLUTION P1aEVENTION PLAN
An adequate Stormwater Pollution Prevention Plan (SWPPP)for construction activity shall
be prepared and implemented in accordance with the requirements of this permit beginning
with initial soil disturbance and until final stabilization.
A. The SWPPP shall meet the following objectives: I
1. To implement Best Management Practices (BMPs)to prevent erosion and ,
sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination
and water pollution from construction activiry.
2. To prevent violations of surface water quality, ground water quality, or sediment
management standards.
3. To control peak volumetric flo«- rates and velocities of stormwater discharQes.
B. General Requirements
1. The SWPPP shall include a narrative and dra��ings. All BMPs shall be clearly
referenced in the narrative and marked on the drawings.
The SV��'PPP narrative shall include documentation to explain and justify the pollution
prevention decisions made for the project. Documentation shall include:
a. information about existing site conditions(topography, drainage; soils,
vegetation, etc.);
Page 22 of 46
b. Potential erosion problem areas;
c. The 12 elements ofa SWPPP in S9.D.1-12, including BMPs used to address each
element;
d. Construction phasing/sequence and general BMP implementation schedule;
e. The actions to be taken if BMP performance goals are not achieved; and
f. Engineering calculations for ponds and any other designed structures.
2. The Permittee shall modify the SWPPP if, during inspections or investigations
conducted by the owner/operator, or the applicable local or state regulatory authority,
it is determined that the SWPPP is, or would be, ineffective in eliminating or
significantly minimizing pollutants in stormwater discharges from the site. The
Permittee shall take the following actions:
a. Review the SWPPP for compliance with Condition S9 and make appropriate
revisions within 7 days of the inspection or investigation;
b. Fully implement and maintain appropriate source control and/or treatment BMPs
as soon as possible; but no later than ]0 days from the inspection or investigation;
and
c. .Do.cument BMP implementation and maintenance in the site log book. _.
3. The Permittee shall modify the SWPPP whenever there is a change in design,
consttuction, operation, or maintenance at the construction site that has, or could '
have, a significant effect on the discharge of pollutants to waters of the state.
C. Stormwater Best Mana�ement Practices (BMPs�
BMPs shall be consistent with:
�
1. Stormwater Management Manual for Western Washington (most recent edition), for
sites west of the crest of the Cascade Mountains;
2. Stormwater Management Manual for Eastern Washington (most recent edition), for
sites east af the crest of the Cascade Mountains; or
3. Other stormwater management guidance documents or manuals which pr�vide an
, equivalent level of pollution prevention and are approved by Ecology; or
4. Documentation in the SWPPP that the BMPs selected provides an equivalent level of
pollution prevention, compared to the applicable Stormwater Management Manuals,
including:
' I
Page 23 of 46
a. The technical basis for the selection of all stormwater BMPs (scientific,technical
studies, and/or modeling)which support the performance claims for the BMPs
being selected; and
b. An assessment of how the selected BMP will satisfy AKART requirements and
the applicable federal technology-based treatment requirements under 40 CFR
part 1253.
D. SWPPP—Narrative Contents and Requirements
T1�e Permittee shall include each ofthe 12 elements below in S9.D1-12 in the narrative
of the SWPPP and ensure that they are implemented unless site conditions render the
element unnecessary and the exemption from that element is clearl} justified in the
SWPPP.
1. Preserve Vegetation/Mark Clearing Limits
a. Prior to beginning land disturbing activities, including clearing and grading,
clearly mark all clearing limits,sensitive areas and their huffers, and trees that arc
to be preserved within the construction area.
' b. The duff layer,native top soil, and natural vegetation shall be retained in an
undisturbed state to the maximum de ree racticable.
� P
_. 2. Establish Construction Access
a. Construction vehicle access and exit shall be limited to one route, if possible.
b. Access points shall be stabilized with a pad of quarry spalls,crushed rock,or other
� equivalent BMP,to minimize the tracking of sediment onto public roads.
c. Wheel wash or tire baths shall be located on site, if the stabilized construction
entrance is not effective in preventing sediment from being tracked onto public
roads.
d. If sediment is tracked off site, public roads shall be cleaned thorouahly at the end of
each day, or more frequently during wet weather. Sediment shall be removed from
roads by shoveling or pickup sweeping and shall be transported to a control]ed
sediment disposal area.
e. Street washing is allowed only after sediment is removed in accordance���ith
S9.D.2.d. Street wash wastewater shall be controlled by pumping back on site or
otherwise be prevented from discharging into systems tributary to waters of the
state.
3. Control Flow Rates
a. Properties and waterways do���nstream from development sites shall be protected
from erosion due to increases in the velocity and peak volumetric flow rate of
stormwater runoff from the project site, as required by local plan appro��al
authoritv.
,
Page 24 of 46 �,
b. Where necessary to comply with S9.D3.a., stormwater retention or detention
facilities shall be constructed as one ofthe first steps in grading. Detention
facilities shall be functional prior to construction of site improvements(e.g.,
impervious surfaces).
c. If permanent infiltration ponds are used for flow control during construction,these
facilities shall be protected from siltation during the construction phase.
4. Install Sediment Controls
a_ Stormwater runoff from disturbed areas shall pass through a sediment pond or other
appropriate sediment removal BMP,prior to leaving a construction site or prior to
discharge to an infiltration facility. Runoff from fully stabilized areas may be ,
discharged without a sediment removal BMP, but shall meet the flow control
performance standard of S9.D.3.a_
b. Sediment control BMPs(sediment ponds,traps, filters, etc.)shall be constructed as
one ofthe first steps in grading. These BMPs shall be functional before other land
disturbing activities take place.
c. BMPs intended to trap sediment on site shall be located in a manner to avoid
interference with the movement of juvenile salmonids attempting to enter off-
channel areas or drainages.
5. Stabilize Soils
a. Exposed and unworked soils shall be stabilized by application of effective BMPs
that prevent erosion.Applicable BMPs include,but are not limited to: temporary
and permanent seeding, sodding,mulching,plastic covering, erosion control fabrics
and matting, soil application of polyacrylamide(PA1V�,the early application of
gravel base on areas to be paved, and dust control.
b. Depending on the geographic location ofthe project, no soils shall remain exposed
and unworked for more than the time periods set forth below to prevent erosion:
V��est of the Cascade Mountains Crest
During the dry season (May 1 - Sept. 30): 7 days
During the wet season (October 1 -April 30): 2 days
East of the Cascade Mountains Crest, except for Central Basin*
During the dry season (July 1 - September 30): 10 days
During the wet season (October 1 - June 30): 5 days
The Central Basin*, East of the Cascade Mountains Crest
During the dry Season (July 1 - September 30): 30 days
During the wet season (October 1 -June 30): 15 days
*Note: The Central Basin is defined as the portions of Eastern Washington
with mean annual precipitation of less than 12 inches.
1
Page 2� of 46 '
The time period may be adjusted by a local jurisdiction, if the jurisdiction ,
can show that local precipitation data justify a different standard.
c. Soils shall be stabilized at the end of the shift before a holiday or weekend if needed
based on the weather forecast.
d. Soil stockpiles shall be stabilized from erosion, protected with sediment trapping
measures, and v�fiere possible,be located away from storm drain inlets,waterways,
and drainage channels.
6. Protect Slopes
a. Design and construct cut and fill slopes in a manner that will minimize erosion_
Applicable practices include, but are not limited to,reducing continuous length of
slope with terracing and diversions,reducing slope steepness, and roughening slope
surfaces (e_g.,track walkmg).
b. Off-site stormwater(run-on)or groundwater shall be diverted away from slopes and
disturbed areas with interceptor dikes, pipes, and/or swales. Off-site stormwater
should be managed separately from stormwater generated on the site.
c. At the top of slopes,collect drainage in pipe slope drains or protected channels to
prevent erosion.
i. West of the Cascade Mountains Crest: Temporary pipe slope drains shall
handle the peak 10-minute velocity of flow from a Type lA, 10-year, 24-hour
frequency storm for the developed condition. Alternatively,the 10-year, 1-
hour flow rate predicted by an approved continuous runoff model, increased
by a factor of 1.6, may be used. The hydrologic analysis shall use the existing
land cover condition for predicting flow rates from tributary areas outside the
project limits. For tributary areas on the project site,the analysis shall use the
temporary or permanent project land cover condition, whichever will produce
the highest flow rates. If using the WWHM to predict flows, bare soil areas
should be modeled as "landscaped area."
ii. East of the Cascade Mountains Crest: Temporary pipe slope drains shall
handle the expected peak flow velocity from a 6-month, 3-hour storm for the
developed condition,referred to as the short duration storm.
d. Excavated material shall be placed on the uphill side of trenches, consistent with
safety and space considerations.
e. Check dams shall be placed at regular intervals within constructed channels that
are cut down a slope.
7. Protect Drain Inlets
a. All storm drain inlets made operable during construction shall be protected so that
stormwater runoff does not enter the conveyance system without first being filtered
or treated to remove sediment.
�— _ _
Page 26 of 46
b. Inlet protection devices shall be cleaned or removed and replaced when sediment
has filled one-third of the available storage (unless a different standard is specified
by the product manufacturer).
8. Stabilize Channels and Outlets
a. All temporary on-site conveyance channels shall be designed, constructed, and
stabilized to prevent erosion from the following expected peak flows:
i. West of the Cascade Mountains Gest: Channels shall handle the peak 10
minute velocity of flow from a Type lA, 10-year, 24-hour frequency storm for
the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated
by an approved continuous runoff model, increased by a factor of 1.6, may be
used. The hydrologic analysis shall use the existing land cover condition for
predicting flow rates from tributary areas outside the project limits. For
tributary areas on the project site,the analysis shall use the temporary or
permanent project land cover condition,whichever will produce the highest
flow rates. If using the WWHM to predict flows, bare soil areas should be
modeled as "landscaped area."
ii. East of the Cascade Mountains Crest: Channels shall handle the expected peak
flow velocity from a 6-month, 3-hour starm for the developed condition,
referred to as the short duration storm.
b. Stabilization, including armoring material, adequate to prevent erosion of outlets, __
adjacent stream banks, slopes, and downstream reaches shall be provided at the
outlets of all conveyance systems.
9. Control Pollutants
a. All pollutants, including waste materials and demolition debris, that occur onsite
shall be handled and disposed of in a manner that does not cause contamination of
stormwater.
b. Cover, containment, and protection from vandalism shall be provided for all
chemicals, liquid products, petroleum products, and other materials that have the
potential to pose a threat to human health or the environment. On-site fueling tanks
shall include secondary containment.
c. Maintenance, fueling, and repair of heavy equipment and vehicles shall be
conducted using spill prevention and control measures. Contaminated surfaces shall
be cleaned immediately following any spill incident.
d. Wheel wash or tire bath wastewater shall be discharged to a separate on-site
treatment system or to the sanitary sewer with local sevver district approval.
e. Application of fertilizers and pesticides, shall be conducted in a manner and at
application rates that will not result in loss of chemical to stormwater runoff.
Manufacturers' label requirements for application rates and procedures shall be
follo«�ed. '
Page 27 of 46
f. BMPs shall be used to prevent or treat contamination of stormwater runoffby pH
modifying sources. T1�ese sources include,but are not limited to: bulk cement,
cement kiln dust, fly ash, new concrete washing and curing waters,waste streams
generated from concrete grinding and sawing, exposed aggregate processes,
dewatering concrete vaults,concrete pwnping and mixer washout waters.
Permittees shall adjust the pH of stormwater if necessary to prevent violations of
water quality standards.
g. Permittees shall obta.in written approval from Ecology prior to usina chemical
treatment, other than COz or dry ice to adjust pH. �
10. Control De-Watering
a. Foundation,vault, and trench de-watering water,which have similar characteristics
to stormwater runoffat the site, shall be discharged into a controlled conveyance
system prior to discharge to a sediment trap or sediment pond.
b. Clean,non-turbid de-watering water, such as well-point ground water, can be
discharged to systems tributary to, or directly into surface waters of the state, as
specified in S9.D.8,provided the de-watering flow does not cause erosion or
flooding of receiving waters. Clean de-watering«ater should not be routed through
stormwater sediment ponds.
c. Other de-waterina disposal optians ma�� include:
i. infiltration
ii. transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in
a manner that does not pollute state waters,
iii. Ecology-approved on-site chemical treatment or other suitable treatment
technologies;
iv. sanitary sewer discharge with local se«er district approval, if there is no other
option, or
v. use of a sedimentation bag with outfall to a ditch or swale for small volumes of
localized de-watering.
d. Highly turbid or contaminated de«�aterin�water shall be handled separately from
stormwater.
11. Maintain BMPs
a. All temporary and permanent erosion and sediment control BMPs shall be
maintained and repaired as needed to assure continued performance of their
intended function in accordance with BMP specifications.
b. All temporary erosion and sediment control BMPs shall be removed within 30 days
after final site stabilization is achieved or after the temporary BMPs are no longer
needed.
,
'
1 Page 28 of 46
12. Manage the Project ,
fa. Development projects shall be phased to the maYimum degree practicable and shall I
take into account seasonal work limitations. I
, b. Inspection and Monitoring
� All BMPs shall be inspected, maintained, and repaired as needed to assure
continued performance of their intended function. Site inspections and monitoring
shall be conducted in accordance with S4.
� c. Maintaining an Updated Construction SWPPP
The SWPPP shall be maintained, updated, and implemented in accordance with
Conditions S3, S4 and S9.
fE. SWPPP—Map Contents and Requirements
� The SWPPP shall also include a vicinity map or general location map (e.g. USGS
Quadrangle map, a portion of a county or city map, or other appropriate map) with
enough detail to identify the location of the construction site and receivina v,-aters within
1 one mile of the site. �
The SWPPP shall also include a legible site map (or maps) showing the entire
� construction site. The following features shall be identified; unless not applicable due to
site conditions:
( L The direction of north, properry lines, and existing structures and roads;
2. Cut and fill slopes indicating the top and bottom of slope catch lines;
f3. Approximate slopes, contours, and direction of stormvvater flow before and after
major grading activities,
I4. Areas of soil disturbance and areas that will not be disturbed;
5. Locations of structural and nonstructural controls (B�VIPs) identified in the SWPPP
1 6. Locations of off-site material, stockpiles, waste storage,borrow areas, and
vehicle/equipment storage areas;
I 7. Locations of all surface water bodies, including��etlands;
� 8. Locations where stormwater or non-storm«�ater discharges off-site andlor to a surface
water body, including wetlands;
� 9. Location of water qualiry sampling station(s), if sampling is required by state or local
permitting authorit5�; and
I
Page 30 of 46 '
GENERAL CONDITIONS
G1. DISCHARGE VIOLATIONS
All discharges and activities authorized by this general permit shall be consistent with the
terms and conditions of this general permit. Any discharge of any pollutant more frequent
than or at a level in excess of that identified and authorized by the general permit shall
constitute a violation of the terms and conditions of this permit
G2. SIGNATORY REQUIREMENTS
A. All permit applications shall bear a certification of correctness to be signed:
l. In the case of corporations, by a responsible corporate officer of at least the level of
vice president of a corporation;
2. In the case of a partnership, by a general partner of a partnership;
3. In the case of sole praprietorship, by the proprietor; or
_ 4. In the case of a municipal, state; ar other public facility, by either a principal
executive officer or ranking elected official.
B. All reports required by this permit and other information requested by Ecology shall be
signed by a person described above or by a duly authorized representative of that person.
A person is a duly authorized representative only i£
L The authorization is made in writing by a person described above and submitted to
the Ecology.
2. The authorization s ecifies either an individual or a osition havin res onsibili for
P P g P tY
the overall operation of the regulated facility, such as the position of plant manager,
' superintendent,position of equivalent responsibility, or an individual or position
having overall responsibility for environmental matters.
�' C. Changes to authorization. If an authorization under paragraph G2.B.2 above is no longer
� accurate because a different individual or position has responsibility for the overall
operation of the facility, a new authorization satisfying the requirements of paragraph
'I ', G2.B.2 above shall be submitted to Ecology prior to or together with any reports,
information, or applications to be signed by an authorized representative.
D. Certification. Any person signing a document under this section shall make the following
certification: ���,
"I certify under penalty of law,that this document and all attachments were ,
' prepared under my direction or supervision in accordance with a system '�
designed to assure that qualified personnel properly gathered and evaluated II
li '��
� I
Page 31 of 46
the information submitted. Based on my inquiry of the person or persons who
manage the system, or those persons directly responsible for gathering
information, the information submitted is,to the best of my knowledge and
belief, true, accurate, and complete. I am aware that there are significant
penalties for submitting false information, including the possibility of fine and •
imprisonment for knowing violations."
G3. RIGHT OF INSPECTION AND ENTRY
The Permittee shall allow an authorized representative of Ecology, upon the presentation of
credentials and such other documents as may be required by law:
A. To enter upon the premises where a discharge is located or where any records shall be
kept under the terms and conditions of this permit.
B. To have access to and copy- at reasonable times and at reasonable cost- any records
required to be kept under the terms and conditions of this permit.
C. To inspect- at reasonable times- any facilities, equipment(including monitoring and
control equipment), practices, methods, or operations regulated or required under this
permit.
D. To sample or monitor- at reasonable times- any substances or parameters at any location
for purposes of assuring permit compliance or as otherwise authorized by the Clean �
Water Act.
G4. GE�TERAL PERMIT MODIFICATION AND REVOCATION
This permit may be modified, revoked and reissued, or terminated in accordance with the '
provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance,
or termination include, but are not limited to,the following:
A. When a change which occurs in the technology or practices for control or abatement of
pollutants applicable to the category of dischargers covered under this permit;
B. When effluent limitation guidelines or standards are promulgated pursuantto the CWA or
Chapter 90.48 RCW, for the category of dischargers covered under this permit;
C. When a water quality management plan containing requirements applicable to the
category of dischargers covered under this permit is approved; or
D. When information is obtained which indicates that cumulative effects on the environment
from dischargers covered under this permit are unacceptable.
G5. REVOCATION OF COVERAGE UNDER THE PERMIT
Pursuant with Chapter 43.21B RCW and Chapter 173-226 WAC, the Director may terminate
coverage for any discharger under this permit for cause. Cases where coverage may be
terminated include,but are not limited to, the following:
Page 32 of 46
A. Violation of any term or condition of this permit;
B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully all
relevant facts;
C. A change in any condition that requires either a temporary or permanent reduction or
elimination of the permitted discharge;
D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090;
E. A determination that the permitted activity endangers human health ar the environment,
or contributes to water quality standards violations;
F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and
Chapter 173-224 WAC; . �
G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226-
130(5),when applicable.
The Director may require any discharger under this permit to apply for and obtai❑ coverage
under an individual permit or another more specific general permit. Permittees who have
their coverage revoked for cause according to WAC 173-226-240 may request temporary
coverage under this permit during the time an individual permit is being developed,provided
the request is made within ninety (90) days from the time of revocation and is submitted
along with a complete individual permit application form. _
G6. REPORTING A CAUSE FOR MODIFICATION
The Permittee shal) submit a new application, or a supplement to the previous application,
whenever a material change to the construction activity or in the quantity or type of discharge
is anticipated which is not specifically authorized by this permit. This application shall be
submitted at least sixry (60)days prior to any proposed changes. The filing of a request by
the Permittee for a permit modification, revocation and reissuance, or termination, or a
notification of planned changes or anticipated noncompliance does not relieve the Permittee
of the duty to comply with the existing permit until it is modified or reissued.
G7. COMPLIANCE VVITH OTHER LAWS AND STATUTES
Nothing in this permit shall be construed as excusing the Permittee from compliance «�ith
any applicable federal, state, or local statutes, ordinances, or regulations.
G8. DUTY TO REAPPLY
The Permittee shall apply for permit renewal at least 180 days prior to the specified
expiration date of this permit.
G9. TRANSFER OF GENERAL PERMIT COVERAGE
Coverage under this general pertnit is automatically transferred to a new discharger,
including operators of lots/parcels within a common plan of development or sale, if:
'
Page 33 of 46
A. A w�ritten, signed agreement(Transfer of Coverage Form) between the current discharger
(Permittee) and new discharger containing a specific date for transfer of permit
responsibility, coverage, and liability is submitted to the Director; and
B. The Director does not notify the current discharger and new discharger of the Director's
intent to revoke coverage under the general permit. If this notice is not given, the transfer
is effective on the date specified in the written agreement.
When a current discharger(Permittee)transfers�ortion of a permitted site, the current
discharger shall also submit an updated application form (NOI)to the Director indicating the
remaining permitted acreage after the transfer. When a cunent discharger(Permittee)
transfers all portions of a permitted site to one or more new dischargers,the current
discharger shall also submit a notice of termination (NO� form to the Director.
G10.REMOVED 5UBSTANCES
Collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in the
course of treatment or control of stormwater shall not be resuspended or reintroduced to the
final effluent stream for discharge to state waters.
G11.DUTY TO PROVIDE INFORMATION
The Permittee shall submit to Ecology, within a reasonable time, all information which
Ecology may request to determine whether cause e�sts for modifying, revoking and
reissuing, or terminating this permit or to determine compliance with this permit. The
Permittee shall also submit to Ecology upon request, copies of records required to be kept by I
this permit [40 CFR 122.41(h)].
G12.OTHER REQUIREMENTS OF 40 CFR
All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by
reference.
G13.ADDITIONAL MO1vITORING ��,
Ecology may establish specific monitoring requirements in addition to those contained in this
permit by administrative order or permit modification.
G14.PENALTIES FOR VIOLATING PERMIT CONDITIONS
Any person who is found guilty of willfully violating the terms and conditions of this permit
shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of
up to ten thousand dollars($10,000)and costs of prosecution, or by imprisonment in the ,
discretion of the court. Each day upon which a willful violation occurs may be deemed a '
separate and additional violation. ',
.4ny person who violates the terms and conditions of a waste discharge permit shall incur, in '�
addition to any other penalty as provided by law, a ci��il penalty in the amount of up to ten
Page 34 of 46
thousand dollars ($10,000) for every•such violation. Each and every such violation shall be a
separate and distinct offense, and in case of a continuing violation, every day's continuance
shall be deemed to be a separate and distinct violation.
G15.UPSET
Defmition—"Upset"means an exceptional incident in which there is unintentional and
temporary noncompliance with technology-based permit effluent limitations because of
factors beyond the reasonable control of the Permittee. An upset does not include
noncompliance to the extent caused by operational error, improperly designed treatment
facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or
improper operation.
An upset constitutes an affirmative defense to an action brought for noncompliance with such
technology-based permit effluent limitations if the requirements of the following paragraph
are met.
A Permittee who wishes to establish the affirmative defense of upset shall demonstrate,
through properly signed, contemporaneous operating logs or other relevant evidence that: 1)
an upset occurred and that the Permittee can identify the cause(s) of the upset; 2) the
permitted facility was being properly operated at the time of the upset; 3)the Permittee
submitted notice of the upset as required in condition SS.F; and 4)the Permittee complied ,
with any remedial measures required under this permit.
In any enforcement proceeding,the Permittee seeking to establish the occurrence of an upset
has the burden of proof.
G16.PROPERTY RIGHTS I
This permit does not convey any property rights of any sort, or any exclusive privilege.
G17.DUTY TO COMPLY
The Permittee shall comply with all conditions of this permit. Any permit noncompliance
constitutes a violation of the Clean Water Act and is grounds for enforcement action; for
permit termination,revocation and reissuance, or modification; or denial of a permit renewal
application.
G18.TOXIC POLLUTANTS .
The Permittee shall comply with effluent standards or prohibitions established under Section
307(a)of the Clean Water Act for toxic pollutants within the time provided in the regulations ,
that establish those standards or prohibitions, even if this permit has not yet been modified to
incorporate the requirement.
Page 35 of 46
G19.PENALTIES FOR TAMPERING
The Clean Water Act provides that any person who falsifies, tampers with, or knowingly
renders inaccurate any monitoring device or method required to be maintained under this
permit shall, upon conviction, be punished by a fine ofnot more than $10,000 per violation,
or by imprisonment for not more than two years per violation, or by both. If a conviction of
a person is for a violation committed after a first conviction of such person under this
Condition, punishment shall be a fine of not more than $20,000 per day of violation; or
imprisonment of not more than four(4)years, or both.
G20.REPORTING PLANNED CI3ANGES
The Permittee shall, as soon as possible, give notice to Ecology of planned physical
alterations, modifications or additions to the permitted construction activity, vvhich will result
in:
A. The permitted facility being determined to be a new source pursuant to 40 CFR
122.29(b);
B. A significant change in the nature or an increase in quantity of pollutants discharged,
including but not limited to: for sites 5 acres or larger, a 20°/o or greater increase in
acreage disturbed by construction activity;
C. A change in or addition of surface water(s) receiving stormwater or nan-storm��,rater from
the construction activity; or
D. A change in the construction plans and/or activity that affects the Permittee's monitaring
requirements in Special Condition S4.
Following such notice, permit coverage may be modified, or revoked and reissued pursuant
to 40 CFR 122.62(a)to specify and limit any pollutants not previously limited. Until such
modification is effective, any new or increased discharge in excess of permit limits or not
specifically authorized by this permit constitutes a violation.
G21.REPORTING OTHER INFORMATION
Where the Permittee becomes aware that it failed to submit any relevant facts in a permit
application, or submitted incorrect information in a permit application or in any report to
Ecology, it shall promptly submit such facts or information.
G22.REPORTING ANTICIPATED NON-COMPLIANCE
The Permittee shall give advance notice to Ecology by submission of a new application ar
supplement thereto at least forty-five (45) days prior to commencement of such discharges,
of any facility expansions, production increases, or other planned changes, such as process
modifications, in the permitted facility or activity�rhich may result in noncompliance with
permit limits ar conditions. Any maintenance of facilities,which might necessitate ��
Page 36 of 46
unavoidable interruption of operation and degradation of effluent quality, shall be scheduled
during non-critical water quality periods and carried out in a manner approved by Ecology.
G23.REQUESTS TO BE EXCLUDED FROM COVERAGE iJNDER THE PERNIIT
Any discharger authorized by this permit may request to be excluded from coverage under
the general permit by applying for an individual permit. The discharger shall submit to the
Director an application as described in WAC 173-220-040 or WAC 173-216-070, ��vhichever
is applicable,with reasons supporting the request. These reasons shall fully document how an
individual permit will apply to the applicant in a way that the general permit cannot. Ecology
may make specific requests for information to support the request. The Director shall either
issue an individual permit or deny the request with a statement explaining the reason for the
denial. When an individual permit is issued to a discharger otherwise subject to the
construction stormwater general permit,the applicability of the construction stormwater
general permit to that Permittee is automatically terminated on the effective date of the
individual permit.
G24.APPEALS
A. The terms and conditions of this general permit, as they apply to the appropriate class of
dischargers, are subject to appeal by any person within 30 days of issuance of this general
permit, in accordance with Chapter 43.21B RCW,and Chapter 173-226 WAC.
B. The terms and conditions of this general p�rtnit, as th�y apply to an individual discharger,
are appealable in accordance with Chapter 43.21B RCW within 30 days of the effective
date of coverage of that discharger. Consideration of an appeal of general permit
coverage of an individual discharger is limited to the general permit's applicabiliry or
nonapplicability to that individual discharger.
C. The appeal of general permit coverage of an individual discharger does not affect any ,
other dischargers covered under this general permit. If the terms and conditions of this I
general permit are found to be inapplicable to any individual discharger(s), the matter ��i
shall be remanded to Ecology for consideration of issuance of an individual permit or I
permits. '�
G25.SEVERABILITY
The provisions of this permit are severable, and if any provision of this permit, ar application
of any provision of this permit to any circumstance, is held invalid, the application of such
provision to other circumstances, and the remainder of this permit shall not be affected
thereby.
G2b.BYPASS PROHIBITED
A. Bvpass Procedures
Bypass, which is the intentional diversion of waste streams from any portion of a
treatment facility, is prohibited for storm«�ater events below the design criteria far
Page 37 of 46
stot-�nwater management. Ecology may take enforcement action against a Permittee for
bypass unless one ofthe following circumstances (1,2, 3 or 4) is applicable.
1. Bypass of stormwater is consistent with the design criteria and part of an approved
management practice in the applicable stormwater management manual.
2. Bypass for essential maintenance without the potential to cause violation of permit
limits or conditions.
Bypass is authorized if it is for essential maintenance and does not have the potential
to cause violations of limitations or other conditions of this permit, or adversely
impact public health.
3. Bypass of stormwater is unavoidable, unanticipated, and results in noncompliance of
this permit.
This bypass is permitted only if:
a. Bypass is unavoidable to prevent loss of life, personal injury, or severe property
damage_ "Severe property damage"means substantial physical damage to
properly, damage to the treatment facilities which would cause them to become
inoperable, or substantial and permanent loss of natural resources which can
reasonably be expected to occur in the absence of a bypass;
b. There are no feasible alternatives to the bypass, such as the use of auxiliary
treatmerif�`acilifies;retention of untreated wastes, maintenance during normal
periods of equipment downtime (but not if adequate backup equipment should
have been installed in the exercise of reasonable engineering judgment to prevent
a bypass which occurred during normal periods of equipment downtime or
preventative maintenance), or transport of untreated wastes to another treatment
facility; and
c. Ecology is properly notified of the bypass as required in Special Condition SS.F
of this permit.
4. A planned action that would cause bypass of stormwater and has the potential to
result in noncompliance of this permit during a storm event.
The Permittee shall notify Ecology at least thirty(30)days before the planned date of
bypass. The notice shall contain:
a. a description of the bypass and its cause;
b. an analysis of all known alternatives which would eliminate,reduce, or mitigate
� the need for bypassing;
c. a cost-effectiveness analysis of alternatives including comparative resource
damage assessment;
d. the minimum and ma�cimum duration of bypass under each alternative;
e. a recommendation as to the preferred altemative for conducting the bypass;
Page 38 of 46
f. the projected date of bypass initiation;
g. a statement of compliance with SEPA;
h. a request for modification of water quality standards as provided for in WAC 173-
201A-110, if an exceedance of any water quality standard is anticipated; and
i. steps taken or planned to reduce, eliminate, and prevent reoccurrence of the
bypass.
5. For probable construction bypasses,the need to bypass is to be identified as early in
the planning process as possible. The analysis required above shall be considered
during preparation of the Stormwater Pollution Prevention Plan (SWPPP) and shall
be included to the extent practical_ In cases where the probable need to bypass is
determined early, continued analysis is necessary up to and including the construction
period in an effort to minimize or eliminate the bypass.
Ecology will consider the following prior to issuing an administrative order for this
type bypass: �
a. If the bypass is necessary to perform construction or maintenance-related
activities essential to meet the requirements of this permit.
b. If there are feasible alternatives to bypass, such as the use of auxiliary treatment
facilities, retention of untreated wastes, stopping production, maintenance during ,
- �- normal periods of equipment down time, or transport of untreated wastes to • -
another treatment facility.
c. If the bypass is planned and scheduled to minimize adverse effects on the public
and the environment. j
After consideration of the above and the adverse effects of the proposed bypass and
any other relevant factors, Ecology will approve, conditionally approve, or deny the
request. The public shall be notified and given an opportunity to comment on bypass
, incidents of significant duration, to the e�ent feasible.Approval of a request to
bypass will be by administrative order issued by Ecology under RCW 90.48.120.
B. Duty to Miti ate
The Permittee is required to take all reasonable steps to minimize or prevent any
discharge or sludge use or disposal in violation of this permit that has a reasonable
likelihood of adversely affecting human health or the environment.
! I
Paae 39 of-�6
APPENDIX A—DEFIIVITIONS
AKART is an acronym for"all known, available, and reasonable methods of prevention, control,
and treatment."AKART represents the most current methodology that can be reasonably
required for preventing, controlling, or abating the pollutants and controlling pollution associated
with a discharge.
Applicable T.'IIDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus, which
has been completed and approved by EPA prior to November 16, 2005, or prior to the date the
operator's complete permit application is received by Ecology, whichever is later.
�plicant means an operator seeking coverage under this permit.
Best Management Practices(BMPs)means schedules of activities, prohibitions of practices,
maintenance procedures, and other physical, structw-al andlor managerial practices to prevent or
reduce the pollution of waters of the state. BMPs include treatment systems, operating
procedures, and practices to control: stormwater associated with construction activity, spillage
or leaks, sludge or waste disposal, or drainage from raw material storaae.
Bu er means an area designated by a local jurisdiction that is contiguous to and intended to
protect a sensitive area
Bvpass means the intentional diversion of waste streams from any portion of a treatment facilit}�.
Calendar Week(same as Week)means a period of seven consecutive days starting on Sunday.
Cert�ed Erosion and Sediment Control Lead(CESCL) means a person who has current
certification through an approved erosion and sediment control training program that meets the
minimum training standards established by Ecology(see BMP C160 in the SWMM).
Clean Water Act(CWA)means the Federal Water Pollution Control Act enacted by Public La���
92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq.
Combined Sewer means a sewer which has been designed to serve as a sanitac-y se«-er and a
storm sewer, and into which inflow is allowed by local ordinance.
Common plan of develo�menl or sale means a site where multiple separate and distinct
construction activities may be taking place at different times on different schedules, but still
under a single plan. Examples include: 1)phased projects and projects vvith multiple filings or
lots, even if the separate phases or filings/lots will be constructed under separate contract or by
separate owners (e.g., a development where lots are sold to separate builders); 2)a development
plan that may be phased over multiple years, but is still under a consistent plan for long-term
development; and 3)projects in a contiguous area that may be unrelated but still under the same
contract, such as construction of a building extension and a new parking lot at the same faciliri�.
Page 40 of 46
If the project is part of a common plan of development or sale,the disturbed area of the entire
plan shall be used in determining permit requirements.
Composite Sample A mixture of grab samples collected at the same sampling point at different
times, formed either by continuous sampling or by mixing discrete samples. May be "time-
composite" (collected at constant time intervals) or "flow-proportional" (collected either as a
constant sample volume at time intervals proportional to stream flow, or collected by increasing
the volume of each aliquot as the flow� increases «hile maintainin� a constant time inten�al
between the aliquots.
ConstructionActivitv means land disturbing operations including clearing, grading or excavation
which disturbs the surface of the land. Such activities may include road construction,
construction of residential houses, office buildings, or industrial buildinas, and demolition
activity. y
Demonstrably Eguivalent means that the technical basis for the selection of all stormwater BMPs
is documented within a SWPPP, including:
1. The method and reasons for choosing the stormwater BMPs selected;
2. The pollutant removal performance expected from the BMPs selected;
3. The technical basis supporting the performance claims for the BMPs selected,
including any available data concerning field performance of the BMPs selected;
4. An assessment of how the selected BMPs will comply with state water qualin
standards; and
5. An assessment of how the selected BMPs will satisfy both applicable federal
technology-based treatment requirements and state requirements to use all known,
available, and reasonable methods of prevention, control, and treatment(AKART�.
Department means the Washington State Department of Ecolog}�.
Detenlion means the temporary storage of storm«�ater to improve quality and.�or to reduce thc
mass flow rate of discharge.
De-waterin,�means the act of pumping ground��ater or storm��ater a«ay from an active
construction site.
Directo�-means the Director of the Washington Department of Fcology or his�'her authorized
representative.
Discharger means an ov��ner or operator of any facility or acti�ity subject to reQulation under
Chapter 90.48 RCW or the Federal Clean Water Act.
Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundn�
wastes from residences, buildings, industrial establishments, or other places, to�ether«�ith such
ground �ater infiltration or surface«�aters as may be present.
Page 41 of 46
En,gineered soils The use of soil amendments including, but not limited, to Portland cement
treated base (CTB), cement kiln dust(CKD), or fl}�ash to achieve certain desirable soil
characteristics.
E�uivalent Bl�s means operational, source control,treatment, or innovative BMPs which result
in equal or better quality of stormwater discharge to surface water or to ground water than BMPs
selected from the SWMM.
Erosion means the wearing away of the land surface by running water,wind, ice, or other
geological agents, including such processes as gravitational creep.
Erosion and Sediment Control BMPs means BMPs that are intended to prevent erosion and
sedimentation, such as preserving natural vegetation, seeding, mulching and matting, plastic
covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are
synonymous with stabilization and structural BMPs.
Final Stabilization(same as.�ly stabilized or,fzcll stabilization) means the establishment of a
permanent vegetative cover, or equivalent permanent stabilization measures(such as riprap,
gabions or geotextiles)which prevents erosion.
Ground Water means water in a saturated zone or stratum beneath the land surface or a surface
water body.
Injection well means a"well"that is used for the subsurface emplacement of fluids. (see d3'el�
� Jurisdiction means a political unit such as a city, town or county; incorporated for local self-
government.
IVational Pollutant Discharge Elimination System (NPDES) means the national program for
issuing, modifying, revoking and reissuing, terminating, monitoring, and enforcing permits, and
imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the
Federal Clean Water Act, for the discharge of pollutants to surface waters of the state from point
sources. These permits are refened to as NPDES permits and, in V�'ashington State, are
administered by the Washington Department of Ecology.
Notice o Intent (NOI) means the application for, or a request for coverage under this general
permit pursuant to WAC 173-226-200.
Notice of Termination (NOT) means a request for termination of coverage under this aeneral
pertnit as specified by Special Condition S 10 of this permit.
O erator means any party associated with a construction project that meets either of the
following two criteria:
1. The party has operational control over construction plans and specifications, including the
ability.to make modifications to those plans and specifications; or
�
Page 42 of 46
2. T'he party has day-to-day operational control of those activities at a project which are I
necessary to ensure compliance with a SWPPP for the site or other permit conditions (e.g., they .
are authorized to direct workers at a site to carry out activities required by the SWPPP or comply
with other permit conditions}.
Ou all means the location where stormwater leaves the site. It also includes the location where
stormwater is discharged to a surface waterbody within a site, but does not include discharges to
on-site stormwater treatmentlinfiltration devices or storm sewer systems.
Permittee means individual or entiry that receives notice of coverage under this general permit.
�means a liquid's acidiry or alkalinity. A pH of 7 is defined as neutral. Large variations above
or below this value are considered harmful to most aquatic life.
pHMonitoring Period means the time period in which the pH of stormwater runoff from a site
shall be tested a minimum of once every seven days to detertnine if stormwater is above pH 8.5.
Point Source means any discernible, confined, and discrete conveyance, including but not �'
limited to, any pipe, ditch, channel, tunnel, conduit,well, discrete fissure; and container from
which pollutants are or may be discharged to surface waters of the state. This term does not
include return flows from irrigated agriculture. (See Fact Sheet for further explanation.)
Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage,
garbage, d�mestic sewage sludge (biosolids), munitions, chemical wastes, biological materials, -- a
radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and '
industrial, municipal, and agricultural waste. This term does not include sewage from vessels �I
within the meaning of section 312 of the CWA, nor does it include dredged or fill material I
discharged in accordance with a permit issued under section 404 of the CWA.
Pollution means contamination or other alteration of the physical, chemical, or biological i
properties of waters of the state; including change in temperature,taste, color, turbidity, or odor �I
of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into i
any waters of the state as will or is likely to create a nuisance or render such waters harmful,
detrimental or injurious to the public health, safety or welfare; or to domestic, commercial,
industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild .
animals, birds, fish or other aquatic life. ,
Receiving Water means the waterbody at the point of discharge. If the discharge is to a storm
sewer system, either surface or subsurface, the receiving water is the waterbody that the storm
sewer system discharges to. Systems designed primarily for other purposes such as for ground
water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return ,
flows that coincidentally convey stormwater are considered the receiving water. �
Representative means a stormwater or wastewater sample which represents the flow and
characteristics of the discharge. Representative samples may be a grab sample, a time-
proportionate composite sample, or a flow proportionate sample. Ecology's Construction
Storm«�ater Monitoring Manual provides widance on representative sampling.
Page 43 of 46
Sanitary Sewer means a sewer which is designed to convey domestic wastewatef-.
Sediment means the fragmented material that originates from the weathering and erosion of rocks
or unconsolidated deposits, and is transported by, suspended in, or deposited by water. 'i
Sedimentation means the depositing or formation of sediment. I
Sensitive area means a waterbody,wetland, stream, aquifer recharge area, or channel migration
zone.
SEPA (State Environmental Policy Act)means the Washington State Law, RCW 43.21C.020,
intended to prevent or eliminate damage to the environment.
Si�ificantAmount means an amount of a pollutant in a discharge that is amenable to available
and reasonable methods of prevention or treatment; or an amount of a pollutant that has a
reasonable potential to cause a violation of surface or ground water quality or sediment
management standards.
Si.�nificant Concrete Work means greater than 1000 cubic yards poured concrete or recycled
concrete.
Si�nificant Contributor of Pollutants means a facility determined by Ecology to be a contributor
of a�significant amount(s)of a pollutant(s)to waters of the state of Washington. �
Site means the land or water area where any "facility or activity" is physically located or
conducted.
Sour•ce Control B11IPs means physical, structural or mechanical devices or facilities that are
intended to prevent pollutants from entering stormwater. A few examples of source control
BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over
storage and working areas, and directing v��ash water and similar discharges to the sanitary sewer
or a dead end sump.
Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as,
temporary and permanent seeding,vegetative covers, mulching and matting, plastic covering and
sodding. See also the definition of Erosion and Sediment Control BMPs.
Storm Drain means any drain which drains directly into a storm sewer stem, usuall}� found
along roadways or in parking lots.
Storm Sewer Svstem means a means a conveyance, or system of conveyances (including roads
with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade
channels, or storm drains designed or used for collecting or conveying stormwater. This does
not include systems which are part of a combined sewer or Publicly Owned Treatment Works
(POTW) as defined at 40 CFR 122.2.
Page 44 of 46
Stormwater means that portion of precipitation that does not naturally percolate into the ground
or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater
drainage system into a defined surface water body, or a constructed infiltration faciliry.
, Stormwater Management Manua11SW1l�LA�1) or Manual means the technical manual published by
Ecology for use by local governments that contain descriptions of and design criteria for BMPs
to prevent, control, or treat pollutants in stormwater.
Stormwater Pollution Prevention Plan (SWPPP�means a documented plan to implement
measures to identify,prevent, and control the contamination of point source discharges of
stormwater.
Surface Waters ofthe State includes lakes, rivers, ponds, streams, inland waters, salt waters, and
all other surface waters and water courses within the jurisdiction of the state of Washington.
Total Maximum Daily Load(TMDL) means a calculation of the m�imum amount of a pollutant
that a waterbody can receive and still meet state water quality standards. Percentages of the total
maximum daily load are allocated to the various pollutant sources. A TZvIDL is the sum of the
allowable loads of a single pollutant from all contributing point and nonpoint sources. The
"I'MDL calculations shall include a "margin of safety" to ensure that the waterbody can be
protected in case there are unforeseen events or unknown sources of the pollutant. The
calculati�n shall also account for seasonable variation in water quality.
�'reatment BMPs means BMPs that are intended to remove pollutants from stormwater_ A few
examples of treatment BMPs are detention ponds, oiUwater separa.tors, biofiltration, and
constructed wetlands.
Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm.
transparency tube. The transparency tube is used to estimate the relative clarity or transparency
of water by noting the depth at which a black and��vhite Secchi disc becomes visible when water
is released from a value in the bottom of the tube. A transparency tube is sometimes referred to
as a"turbidity tube".
Turbidi The clarity of water expressed as nephelometric turbidity units(NT'U) and measured
��ith a ca(ibrated turbidimeter.
T�G"aste Load Allocation (T�LA) means the portion of a receivin�vvater's loadin� capacity that is
allocated to one of its existing or future point sources of pollution. WLAs constitute a type of
water quality based effluent limitation (40 CFR 130.2(h)).
Water Quality means the chemical, physical, and biological characteristics of water, usually with
respect to its suitability for a particular purpose.
Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR
Subpart 122.2 within the geographic boundaries of Washington State and "waters of the sta.te" as
Page 45 of 46
defined in Chapter 90.48 RCW which include lakes,rivers, ponds, streams, inland waters,
underground waters, salt waters, and all other surface waters and water courses within the
jurisdiction of the state of Washington.
�ell means a bored, drilled or driven shaft, or dug hole whose depth is greater than the
largest surface dimension. (see Injection Wel�
�-,
,�_ � �
�
� i
_
i '; - _- �._s.
i
i '
'
Page 46 of 46
APPENDIX B—ACRONYMS
AKART All Known,Available, and Reasonable Methods of Prevention, Control, and
Treatment
BMP Best Management Practice
CESCL Certified Erosion and Sediment Control Lead
CFR Code of Federal Regulations
CKD Cement Kiln Dust
cm Centimeters
CTB Cement Treated Base
CWA Clean Water Act
DMR Discharge Monitoring Report
EPA Environmental Protection Agency
ESC Erosion and Sediment Control
NOI Notice of Intent
NOT Notice of Termination
NPDES National Pollutant Discharge Elimination System
NT[J Nephelometric Turbidity Unit � -
RCW Revised Code of Washington
SEPA State Environmental Policy Act
SWMM Stormwater Management Manual
SWPPP Stormwater Pollution Prevention Plan
TMDL Total M�imum Daily Load
UIC Underground Injection Control
USC United States Code
USEPA United States Environmental Protection Agency
I WAC Washington Administrative Code
WQ Water Quality
i WVV��IIVI Western Washington Hydrology Model
Stormwater Pollution Prevention Plan
APPENDIX E — SITE INSPECTION FORMS (AND SITE LOG)
The results of each inspection shall be summarized in an inspection report or checklist
that is entered into or attached to the site logbook. 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.
I C. A summary or list of all BMPs that have been implemented, including
observations of all erosion/sediment control structures or practices.
D. The following shall be noted:
1. locations of BMPs inspected,
2. locations of BMPs that need maintenance,
3. the reason maintenance is needed,
4. locations of BMPs that failed to operate as designed or intended,
and
5. locations where additional or different BMPs are needed, and the
reason(s) why
E. A description of stormwater discharged from the site. The presence of
' suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted,
i as applicable.
F. A description of any water quality monitoring performed during inspection, and
the results of that monitoring. �
i G. General comments and notes, including a brief description of any BMP repairs,
maintenance or installations made as a result of the inspection.
I
I
� _
Storm��✓ater Pcllution Prevention Plan
H. A statement that, in the judgment of the person conducting the site inspection,
the site is either in compliance or out of compliance with the terms and conditions
of the SWPPP and the NPDES permit. If the site inspection indicates that the
site is out of compliance, the inspection report shall include a summary of the
remedial actions required to bring the site back into compliance, as well as a
schedule of implementation.
I. Name, title, and signature of person conducting the site inspection; and the
following statement: "I certify under penalty of law that this report is true,
accurate, and complete, to the best of my knowledge and belief".
When the site inspection indicates that the site is not in compliance with any terms and
conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop,
contain, and clean up the unauthorized discharges, or otherwise stop the
noncompliance; correct the problem(s); implement appropriate Best Management
Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve
compliance with all applicable standards and permit conditions. In addition, if the
noncompliance causes a threat to human health or the environment, the Permittee shall
comply with the Noncompliance Notification requirements in Special Condition SS.F of
the permit.
Stormwafer Pollution Prevention Plan
Site Inspection Form
' Generallnformation
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
Gonditions:
Inspection of BMPs
Element 1: Mark Clearing Limits
BMP:
' Inspected Functionin ' ,
Location ' g Problem/Corrective Action
, ' Y � Y � NIP '
BMP:
'Inspected Functionin '
Location ' g ' P�oblem/Corrective'Action
Y �, ,Y ►� ' N1P '
Element 2: Esfablish Construction Access
BMP: �
' lnspected Functionin
Location g , Problem/Corrective Action
Y � ' Y � NIP
Stormwater Pollution Prevention Plan
I
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
� r _;
E/emenf 3: Control Flow Rates
BMP:
lnspected Functionin
Location Problem/Corrective Action
Y � Y � NIP
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
� I
Element 4: Instal/ Sediment Controls
BMP:
Inspected Func#ionin
Location Problem/Corrective Action
Y I� ' Y � NIP
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
BMP: '
Inspected Functionin
Location Problem/Corrective Action
Y � Y � NIP
Stormwater Pol/ution Prevention Plan
BMP:
Inspected Functionin
Location Problem/Corrective Action
Y � Y � NIP
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
Element 5: Stabilize Soils
BMP:
Inspected Functionin
Location Problem/Corrective Action
Y � Y ' � NIP
I �
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
� � ',
BMP: ' '
Inspected Functionin
Location Problem/Corrective Action
Y � Y � � ' NIP
� � i
BMP: �I
Inspected Functionin �'
Location Problem/Corrective Action
Y � Y f� NIP
,
I ' '
Stormwater Pollution Prevenfion Plan
Element 6: Protect S/opes ' ,
BMP: I
Inspected Functionin '
Location Problem/Corrective Action
� Y � Y � NIP
: �
BMP: ' �
lnspected Functionin
Location g Problem/Corrective Action '
Y � Y � NIP ,
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
;
EJement 7: Protect Drain Inlets
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
'
BMP: ,
lnspected Functionin
Location g Problem/Corrective Action
I _
Y � Y . � NIP
� ' '
Storm�vater Pollution Prevention P/an
BMP:
Inspected Functionin
Location Problem/Corrective Action
,_ I ,
Y � Y I� NIP
Element 8: Stabilize Channels and Dutlets
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
BMP:
Inspected Functionin
Location g ProblemlCorrective Action
Y � Y � NIP
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y ' � NIP
'
, �
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y P� NIP
;I
'I Stormwater Pollutron Prevention Plan
I
�
Element 9: Control Poltutants
BMP: ,
Inspected Functionin
Locatian Problem/Corrective Action
Y � Y ' � NIP '�
BMP: : I
' Inspected Functionin
Location Problem/Corrective Action
' , Y � Y � N1P ' '
Element 10: Control Dewatering ,
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y 1� NIP
BMP:
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � � NIP ,
'
BMP: , , , ,
Inspected Functionin
Location g Problem/Corrective Action
Y � Y � NIP
�-
Stormwater Pol/ution Prevention Plan
Stormwater Dischar es From the Site
Observed? Problem/Corrective Action
Y �
Location
' Turbidity
Discoloration
� Sheen
I' Location
Turbidity
! Discoloration �
' Sheen
Water Quality Monitorin
Was any water quality monitoring ❑ Yes ❑ No
conducted?
If water quality monitoring was conducted, record results here:
If water quality monitoring indicated turbidity 250 NTU or greater; or !
transparency 6 cm or less, was Ecology notified by phone within 24 hrs? '
❑ Yes � No �
If Ecology was notified, indicate the date, time, contact name and phone i
number below: �
I Date:
Time: �
' Contact
Name:
Phone #:
General Comments and Notes
� Include BMP repairs, maintenance, or installations made as a result of the
; inspection.
; Were Photos Taken? � Yes ❑ No
! If photos taken, describe photos below: '
Stormwater Pollution Prevention Plan �i
APPENDIX F - ENGINEERING CALCULATIONS ',
'
i
� Dewaterinq Orifice
Ao =AS(2h)°5/0.6x3600Tgo.5
� where: Ao = orifice area
AS = pond surface area (sf)
� h = head of water above orifice (height of riser in ft) 3.5 ft
T = dewatering time {24hours)
g =gravity(32.2 ft/s2}
� Ao = 0.094848 sf
Convert to required diameter=
D = 13.54 x P,o0�5
� I D = 4.17 in ,
Ii
Round to nearest 1/16" —► 4.1875 in �,
� 1l16" 0.0625 �
1/8" 0.125 ';
3116" 0.1875 I
' 1/4" 0.25
5J16" 0.3125
6116" 0.375
� 7116" 0.4375
1/2" 0.5
9/16" 0.5625
' 10116" 0.625
11/16" 0.6875
314" 0.75
13/16" 0.8125
� 7/8" 0.875
15/16" 0.9375
� ;Sediment Pond Summary � � �� ;
�Top of Pond Length = 162 ft �
;Top of Pond Width = 82 ft ;
� IBottom of Pond Length = 120 ft I
�Bottom of Pond = 40 ft �
�Pond depth = 7 ft �
�Riser Diamter= 15 in � �`
1 �Emergency Spillway Length = 24 ft � '
�Dewatering Orifice Diameter = 4.1875 in � ,
,Drainage Tubing Diameter= 6.187� in . ,
1 � Min 2" larger than dewatering orifice � �
� --� Use 8" dia tubing �
�-------------------- ---------� !
' '
f '
�
� i
;
�
Dev Event Summary
Sediment Pond sized based on developed condirions for Ph 1 and 2
Event Peak Q (cfs) Peak T (hrs) Hyd Vol (acft) Area (ac)�Method Rainty�pe
6mo `; 2.1695 � 8.00 0.7181 � 7.8 OS 0 SCS ',TYPEIA
�2 year ''� 3.2069 8.00 �0700 � 7.8500 SCS ,TY lEP A
5 year 4.1380 8.00 1.3884 � 7.8500 � SCS !TYPEIA
10 year ',; 5.0702 8.00 1.7088 7.8500 SCS jT A
25 year ; 6.0020 �8.00 2.0322 7.8500 SCS jTYPEIA
100 year 6.9329 8.00 2.3555 '; 7. 058 0 i CS S�TYPEIA ;
Record Id: Dev
!Design Method SCS jRainfall type i TYPElA
'';H,yd Intv 10.00 min !Peaking Factor ' 484.00
�Abstraction Coeff j 0.20
�Pervious Area (AMC 2) 1.57 ac ;DCIA i 6
Pervious CN 90.00 I;DC CN 98.00
iPervious TC 6.30 min �DC TC 6.30 min
; Pervious CN Calc
Description ; SubArea Sub cn
Landscaping ' 1.57 ac ', 90.00 �.
Pervious Composited CN(AMC 2) �90.00 i
Pervious TC Calc i
- - ;
� Type Description Length j Slope �I Coeff � M si c TT j
'Fixed �:6.30 min
�i Pervious TC ; 6.30 min
Directly Connected CN Calc
Description j SubArea Sub cn
Impervious 6.28 ac � 98.00
DC Composited CN (AMC 2) 98.00
' DirectlSr Connected TC Calc �
, Type ' Description j Length ; Slope � C eo f Misc TT
��i Fixed � 6.30 min
���� Directly Connected TC , 6.30min
�- -