HomeMy WebLinkAbout23-APRON C SWPPPConstruction Stormwater General Permit
Stormwater Pollution Prevention Plan
(SWPPP)
for
737 Max Flightline Utilities – Apron C
Prepared for:
The Washington State Department of Ecology
Northwest Region
Permittee / Owner Developer Operator /Contractor
Boeing Commercial Airplanes Boeing Commercial Airplanes GLY Construction
770 Perimeter Road West, Renton WA 98055
Certified Erosion and Sediment Control Lead (CESCL)
Name Organization Contact Phone Number
Glen Trowbridge GLY Construction 425-301-6198
SWPPP Prepared By
Name Organization Contact Phone Number
Tara L. Burton DOWL 425-869-2670
SWPPP Preparation Date
September 21, 2015
Project Construction Dates
Activity / Phase Start Date End Date
Site Construction 12/015/15 12/31/16
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Table of Contents
1 Project Information ...............................................................................................................4
1.1 Existing Conditions .......................................................................................................4
1.2 Proposed Construction Activities ...................................................................................5
2 Construction Stormwater Best Management Practices (BMPs) ............................................7
2.1 The 12 Elements ...........................................................................................................7
2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits .........................................7
2.1.2 Element 2: Establish Construction Access .............................................................8
2.1.3 Element 3: Control Flow Rates...............................................................................9
2.1.4 Element 4: Install Sediment Controls ...................................................................10
2.1.5 Element 5: Stabilize Soils.....................................................................................11
2.1.6 Element 6: Protect Slopes....................................................................................12
2.1.7 Element 7: Protect Drain Inlets.............................................................................13
2.1.8 Element 8: Stabilize Channels and Outlets ..........................................................14
2.1.9 Element 9: Control Pollutants ...............................................................................15
2.1.10 Element 10: Control Dewatering ..........................................................................18
2.1.11 Element 11: Maintain BMPs .................................................................................19
2.1.12 Element 12: Manage the Project ..........................................................................20
3 Pollution Prevention Team .................................................................................................22
4 Monitoring and Sampling Requirements ............................................................................23
4.1 Site Inspection ............................................................................................................23
4.2 Stormwater Quality Sampling ......................................................................................23
4.2.1 Turbidity Sampling ...............................................................................................23
4.2.2 pH Sampling ........................................................................................................25
5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies .........................26
5.1 303(d) Listed Waterbodies ..........................................................................................26
5.2 TMDL Waterbodies .....................................................................................................26
6 Reporting and Record Keeping ..........................................................................................27
6.1 Record Keeping ..........................................................................................................27
6.1.1 Site Log Book ......................................................................................................27
6.1.2 Records Retention ...............................................................................................27
6.1.3 Updating the SWPPP ...........................................................................................27
6.2 Reporting ....................................................................................................................28
6.2.1 Discharge Monitoring Reports ..............................................................................28
6.2.2 Notification of Noncompliance ..............................................................................28
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List of Tables
Table 1 – Summary of Site Pollutant Constituents .................................................................4
Table 2 – Pollutants ................................................................................................................15
Table 3 – pH-Modifying Sources ............................................................................................17
Table 4 – Dewatering BMPs ....................................................................................................18
Table 5 – Management ............................................................................................................20
Table 6 – BMP Implementation Schedule ..............................................................................21
Table 7 – Team Information ....................................................................................................22
Table 8 – Turbidity Sampling Method ....................................................................................23
Table 9 – pH Sampling Method ..............................................................................................25
List of Appendices
Appendix/Glossary
A. Site Map
B.BMP Detail
C.Correspondence
D. Site Inspection Form
E.Construction Stormwater General Permit (CSWGP)
F.303(d) List Waterbodies / TMDL Waterbodies Information
G.Contaminated Site Information
H. Engineering Calculations
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List of Acronyms and Abbreviations
Acronym / Abbreviation Explanation
303(d)Section of the Clean Water Act pertaining to Impaired Waterbodies
BFO Bellingham Field Office of the Department of Ecology
BMP(s)Best Management Practice(s)
CESCL Certified Erosion and Sediment Control Lead
CO2 Carbon Dioxide
CRO Central Regional Office of the Department of Ecology
CSWGP Construction Stormwater General Permit
CWA Clean Water Act
DMR Discharge Monitoring Report
DO Dissolved Oxygen
Ecology Washington State Department of Ecology
EPA United States Environmental Protection Agency
ERO Eastern Regional Office of the Department of Ecology
ERTS Environmental Report Tracking System
ESC Erosion and Sediment Control
GULD General Use Level Designation
NPDES National Pollutant Discharge Elimination System
NTU Nephelometric Turbidity Units
NWRO Northwest Regional Office of the Department of Ecology
pH Power of Hydrogen
RCW Revised Code of Washington
SPCC Spill Prevention, Control, and Countermeasure
su Standard Units
SWMMEW Stormwater Management Manual for Eastern Washington
SWMMWW Stormwater Management Manual for Western Washington
SWPPP Stormwater Pollution Prevention Plan
TESC Temporary Erosion and Sediment Control
SWRO Southwest Regional Office of the Department of Ecology
TMDL Total Maximum Daily Load
VFO Vancouver Field Office of the Department of Ecology
WAC Washington Administrative Code
WSDOT Washington Department of Transportation
WWHM Western Washington Hydrology Model
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1 Project Information
Project/Site Name: 737 Max Flightline Utilities Apron C
Street/Location: 770 Perimeter Road West
City: Renton State: WA Zip code: 98055
Subdivision:N/A
Receiving waterbody: Lake Washington
1.1 Existing Conditions
Total acreage (including support activities such as off-site equipment staging yards, material
storage areas, borrow areas).
Total acreage:4.52
Disturbed acreage:3.68
Existing structures:Yes – the site is fully developed for airport use
Landscape
topography:
Pavement, sloping between 0.5% - 5%
Drainage patterns:Both Apron C South and North are collected with existing drainage systems
that convey runoff to the existing box culvert in Perimeter Road West
Existing Vegetation: Some landscape areas around the perimeter
Critical Areas (wetlands, streams, high erosion
risk, steep or difficult to stabilize slopes):
None
List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the
receiving waterbody: No category 5 known impairments.
Bacteria Category 2
Total Phosphorus Category 1
Table 1 includes a list of suspected and/or known contaminants associated with the construction
activity.
List all known or suspected contaminants associated with this site in Table 1. Include
contaminants previously remediated.
Table 1 – Summary of Site Pollutant Constituents
Constituent
(Pollutant)Location Depth Concentration
Petroleum Unknown Unknown Unknown
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1.2 Proposed Construction Activities
Description of site development (example: subdivision):
Boeing is expanding its manufacturing operation for the new 737 Max aircraft. The increased
monthly production rate will require that aircraft be moved out of the assembly building and onto
apron parking spots for the final work and testing of the aircraft. Apron C is on the west side of
the airport and is owned by the City of Renton. Boeing has a long term lease on the south
portion (Apron C South) and a short term lease on the north portion (Apron C North). C North
and C South are separated by the Rainier Flight Service building. C South will have 5 stalls (C-
1 through C-5) and there is potential for a previously fueled aircraft on Apron C South. C North
will have two stalls (C-6 and C-7) and are for never fueled aircraft. Ancillary improvements such
as crew and production structures, parking and security fencing will be provided.
Description of construction activities (example: site preparation, demolition, excavation):
The site is bordered by an airplane taxiway to the east, perimeter road to the west, Apron A to
the south and an additional taxiway that is part or Renton Airport to the north. Earthwork for the
project will be limited to excavation necessary for foundations, Stormfilters, oil water separators
and additional utilities. The existing site is paved; the existing concrete and asphalt will remain
in place as long as possible. Both portions of the project will use commercial filtration tanks
during construction for stormwater runoff and dewatering. Due to high groundwater it is
anticipated that dewatering will be a significant challenge on this project and the dewatering
pump rate will drive the water treatment capacity. All water from dewatering will be routed
through the commercial filtration tanks.
Description of site drainage including flow from and onto adjacent properties. Must be consistent
with Site Map in Appendix A:
Two basins were established, C South and C North, to reflect the separate stormwater systems.
The apron pavement will be partially replaced with the intent of providing a cement concrete
surface suitable for heavy aircraft. Not all pavement will need to be replaced. The aprons
generally slope west to east and stormwater is collected via catch basins and slot drains. The
stormwater is conveyed to a flow splitter, a CPS oil water separator and a Stormfilter before
being released into the existing box culvert in Perimeter Road. C South will incorporate fuel spill
containment. C South will also pump the stormwater to the box culvert in Perimeter Road.
Description of final stabilization (example: extent of revegetation, paving, landscaping):
The site will be stabilized once the paving, landscaping, utilities, crew and production structures,
parking and security fencing are installed.
Contaminated Site Information:
Proposed activities regarding contaminated soils or groundwater (example: on-site treatment
system, authorized sanitary sewer discharge):
Page |6
Recognizing the potential for a fuel spill in C South, where there is the potential for fueled
aircraft to be located a spill valve vault will be installed. The vault will contain two solenoid
pneumatically actuated ball valves, a 14-inch valve on the storm sewer main and 12-inch valve
on the dead end containment. The 14-inch main line valve is normally open, the 12-inch
diversion valve normally closed. The containment volume is 10,000 gallons or 115% of the fuel
truck volume. The activation of the diversion is a manual panic button mounted on a panel at
each stall capable of holding a fueled aircraft.
There are diversion structures at each of the stalls to divert any Skydrol that might be spilled.
The aircraft hydraulic systems are filled and pressurized in the assembly building and leaks are
generally discovered and repaired prior to parking the aircraft on the apron. There will be a
Skydrol cart at each stall with a capacity of 80 gallons. The cart will be used to add fluid to the
system, and in some cases pressurize the system for testing purposes. The carts will be stored
beneath a cover with a depression holding a minimum of 115% of the cart capacity. Each stall
will have a catch basin with an aircraft rated lift assisted grate. The catch basin is connected to
the storm sewer main and to an adjacent dead end containment vault. There will be hand
actuated shear gates in the catch basin, the storm drain connection being normally open, and
the Skydrol containment normally closed. During Skydrol operations the storm drain line will be
closed and the containment line open. The containment vault will be a Utility Vault precast box
holding in excess of 400 gallons to the inlet invert, well in excess of the required volume.
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2 Construction Stormwater Best Management Practices (BMPs)
The SWPPP is a living document reflecting current conditions and changes throughout the life
of the project. These changes may be informal (i.e., hand-written notes and deletions). Update
the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design.
2.1 The 12 Elements
2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits
List and describe BMPs:
·High Visibility Plastic or Metal Safety Fence (King County D.3.1.1)
·Paint the edge of the concrete removal limits
The safety fence may be coincidental with the permanent site security fencing.
Installation Schedules: The fences will be installed at the start of construction. The concrete
removal and replacement limits will be spray painted just before concrete panel removal begins.
Inspection and Maintenance plan: If the fence has been damaged it shall be repaired, it shall be
inspected once a week or when other BMPs are inspected.
Responsible Staff: GLY Construction
Page |8
2.1.2 Element 2: Establish Construction Access
List and describe BMPs:
· City of Renton 215.00 – Wheel Wash and Paved Construction Entrance
· City of Renton 215.10 – Stabilized Construction Entrance
· King County D3.8 – Dust Control
Installation Schedules: The site is currently paved, the asphalt will remain in place
as long as possible. Once the driveway asphalt is removed a construction entrance per the City
of Renton standard detail 215.10 could be employed. Sequentially a construction entrance
might not be necessary. Wheel washing, street sweeping and street cleaning shall be employed
as necessary to prevent sediment from tracking onto the Perimeter Road.
Inspection and Maintenance plan: Periodic inspection and needed maintenance after each rain.
Roadways are to be inspected at the end of each work day. Any sediment tracked onto
pavement shall be removed by shoveling or street sweeping. The sediment collected by
sweeping shall be removed or stabilized onsite. The pavement shall not be cleaned by washing
down the street, except when high efficiency sweeping is ineffective and there is a threat to
public safety. If it is necessary to wash the streets, the construction of a small sump to contain
the wash water shall be considered. The sediment would then be washed into the sump where
it can be controlled.
Responsible Staff: GLY Construction
Page |9
2.1.3 Element 3: Control Flow Rates
Will you construct stormwater retention and/or detention facilities?
Yes No
Will you use permanent infiltration ponds or other low impact development (example: rain
gardens, bio-retention, porous pavement) to control flow during construction?
Yes No
List and describe BMPs: This project is located in a direct discharge area for Lake Washington
and no flow control will be provided.
Installation Schedules: N/A
Inspection and Maintenance plan: N/A
Responsible Staff: N/A
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2.1.4 Element 4: Install Sediment Controls
List and describe BMPs:
· King County D.3.3.4 Triangular Silt Dike
· City of Renton 216.30 Catch Basin Filter
· DOE BMP C251 Construction Stormwater Filtration
Installation Schedules: The triangular silt dikes, catch basin filters, and Construction Stormwater
Filtration will be installed at the beginning of the construction. As the catch basins are installed,
storm drain inlet protection shall also be installed.
Inspection and Maintenance plan: The triangular silt dikes and catch basin filters shall be
inspected once a week or after large rainfall events.
Responsible Staff: GLY Construction
Page |11
2.1.5 Element 5: Stabilize Soils
West of the Cascade Mountains Crest
Season Dates Number of Days Soils Can
be Left Exposed
During the Dry Season May 1 – September 30 7 days
During the Wet Season October 1 – April 30 2 days
Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on
the weather forecast.
Anticipated project dates: Start date: 03/09/2016 End date: 07/31/2016
Will you construct during the wet season?
Yes No
List and describe BMPs:
· City of Renton 213.30 Plastic Covering
Installation Schedules: As there are exposed or unworked soils plastic covering shall be
installed.
Inspection and Maintenance plan: All exposed soils shall be inspected every 2 days (during the
wet season) and after rainfall events.
Responsible Staff: GLY Construction
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2.1.6 Element 6: Protect Slopes
Will steep slopes be present at the site during construction?
Yes No
List and describe BMPs:
· City of Renton 213.30 Plastic Covering
· D.3.2.2 Mulching
· D.3.2.6 Temporary and Permanent Seeding
Installation Schedules: The steep slopes are located at the perimeter of the project from the
parking lot to Perimeter Road. The steep slopes are currently landscaped; once the
landscaping has been removed all exposed slopes will be covered until they are stabilized with
the new landscape.
Inspection and Maintenance plan: The steep slopes shall be inspected at least once a week or
after large rainfall events.
Responsible Staff: GLY Construction
Page |13
2.1.7 Element 7: Protect Drain Inlets
List and describe BMPs:
· City of Renton 216.30 Catch Basin Filter
Installation Schedules: Catch basin filters will be installed on all existing catch basins and
immediately downstream of the project areas at the start of the construction. The catch basin
filters will be added to new structures as they are installed.
Inspection and Maintenance plan: Catch basin filters will be cleaned (or removed and replaced),
when sediment has filled the device by one third (1/3) or as specified by the manufacturer.
Catch basins will be inspected weekly and daily during storm events.
Responsible Staff: GLY Construction
Page |14
2.1.8 Element 8: Stabilize Channels and Outlets
West of the Cascade Mountains Crest
On-site conveyance channels must handle the peak 10-minute flow rate from a Type 1A, 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. KCRTS was used for the following results:
Apron C South 10 Year 1 Hour: 1.84 cfs * 1.6 = 2.94 cfs
Apron C North 10 Year 1 Hour: 0.50 cfs * 1.6 = 0.80 cfs
Provide stabilization, including armoring material, adequate to prevent erosion of outlets,
adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all
conveyance systems.
· DOE BMP C251 Construction Stormwater Filtration
List and describe BMPs: The stormwater will be treated with commercial filtration before being
released into the existing box culvert.
Installation Schedules: The stormwater filtration will be installed at the start of construction.
Inspection and Maintenance plan: The stormwater filtration shall be inspected once a week or
after heavy rain.
Responsible Staff: GLY Construction
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2.1.9 Element 9: Control Pollutants
The following pollutants are anticipated to be present on-site:
(See the Spill Prevention, Control and Countermeasures Plan for additional information.)
Table 2 – Pollutants
Pollutant (List pollutants and source, if applicable)
Possible cement treatment
Fossil Fuels - Equipment
Motor Oil & Hydraulic Fluid - Equipment
Form oil, curing compounds, sealers – Concrete Work
Paints, coatings, solvents, - Painting and Coating
Detergents & Cleaners - Cleaning
Fertilizers and pesticide
List and describe BMPs: (from the Stormwater Management Manual for Western Washington,
DOE)
BMP C151: Concrete Handling
BMP C152: Saw cutting and Surfacing Pollution Prevention
BMP C153: Material Delivery, Storage and Containment
BMP C154: Concrete Washout Area
BMP C251: Construction Stormwater Filtration
BMP C252: High pH Neutralization
BMP C253: pH control for High pH Water
S406 Streets/Highways/Applicable BMP’s
S407 Dust Control for Disturbed Land Areas and Unpaved Parking Lots
S409 Fueling at Dedicated Stations
S411 Landscaping and Lawn/Vegetation Management
S417 Maintenance for Stormwater Drainage and Treatment Systems
S419 Mobile Fueling of Vehicles and Heavy Equipment
S424 Roof/Building Drains at Manufacturing and Commercial Buildings
S430 Urban Streets
Installation Schedules: As the chemicals or possible contaminants are being used the BMP that
relates to that chemical will be implemented.
Inspection and Maintenance plan: During times when concrete is being poured the pH level at
the monitoring points as well as the turbidity shall be checked once a day.
Responsible Staff: GLY Construction
Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site?
Yes No
All equipment fueling operations will utilize pumps and funnels and absorbent pads.
Page |16
Fueling will be restricted to designated fueling areas.
A spill kit will be located within 100 feet of any fueling operation.
Engine, transmission and hydraulic oil may be added as needed utilizing funnels and drop pans.
Absorbent pads will be placed to prevent fluid contact with soil.
No fresh or used engine fluids will be stored on the project site. All liquid products will be stored
under cover on durable, impervious surfaces and within a bermed area or other means of
secondary containment capable of containing 110% of the largest single container in the
storage area.
No vehicle maintenance other than emergency repair will be performed on the project site. If
emergency repairs are necessary plastic or absorbent pads shall be placed beneath the vehicle.
Drip pans and absorbent pads will be placed under all equipment that is unused for more than 4
hours, overnights, weekends and holidays.
List and describe BMPs:
· BMP C251 Construction stormwater Filtration
· S419 BMPs for Mobile Fueling of Vehicles and Heavy Equipment
Installation Schedules: As the fueling is done, the drip pans, funnels and absorbent pads will be
used.
Inspection and Maintenance plan: Conduct daily visual inspections of storage areas, equipment,
drip pans, and secondary containment devices. Remove any damaged or otherwise
compromised product containers from the site and dispose of properly. Solicit 3rd party
hazardous waste disposal company if deemed necessary by the volume of the material
requiring disposal. Equipment drip pans that have been repeatedly driven over and are no
longer adequate to contain spills should be removed and replaced immediately.
Responsible Staff: GLY Construction
Will wheel wash or tire bath system BMPs be used during construction?
Yes No
List and describe BMPs:
· City of Renton 215.00 Wheel Wash and Paved Construction Entrance
Installation Schedules: As the existing site is currently paved, it is hoped that a wheel wash will
not be required.
Inspection and Maintenance plan: The public roadways shall be inspected at the end of every
day. If the stabilized construction entrance is not adequate, then a wheel wash shall be
installed.
Page |17
Responsible Staff: GLY Construction
Will pH-modifying sources be present on-site?
Yes No If yes, check the source(s).
Table 3 – pH-Modifying Sources
None
Bulk cement
Cement kiln dust
Fly ash
Other cementitious materials
New concrete washing or curing waters
Waste streams generated from concrete grinding and sawing
Exposed aggregate processes
Dewatering concrete vaults
Concrete pumping and mixer washout waters
Recycled concrete
Other (i.e., calcium lignosulfate) [please describe: ]
List and describe BMPs:
· BMP C151 Concrete Handling
· BMP C154 Concrete Washout Area
· BMP C251 Construction Stormwater Filtration
· BMP C252 High pH Neutralization Using CO2
Installation Schedules: Applicable BMP’s will be utilized during concrete placement. The
underground storage vaults are pre-cast.
Inspection and Maintenance plan: pH monitoring will occur daily during concrete placement and
for a minimum of 3 weeks afterwards, or longer as necessary.
Adjust pH of stormwater if outside the range of 6.5 to 8.5 su.
Obtain written approval from Ecology before using chemical treatment with the exception of
CO2 or dry ice to modify pH.
Responsible Staff: GLY Construction
Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches,
streets, or streams. Excess concrete must not be dumped on-site, except in designated
concrete washout areas with appropriate BMPs installed.
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2.1.10 Element 10: Control Dewatering
The water from foundations, vaults, and trenches will be pumped to the filtration tanks, treated
and released into the downstream storm system. The dewatering flow is anticipated to be set to
the flowrate for the treatment system. The treated water will then be released into the existing
box culvert on Perimeter Road. The amount of dewatering required is unknown at this time. It
is anticipated to be a significant amount of water. The Contractor has contracted with Clear
Water Filter Systems for the treatment of the dewatering water.
Table 4 – Dewatering BMPs
Infiltration
Transport off-site in a vehicle (vacuum truck for legal disposal)
Ecology-approved on-site chemical treatment or other suitable treatment technologies
Sanitary or combined sewer discharge with local sewer district approval (last resort)
Use of sedimentation bag with discharge to ditch or swale (small volumes of localized
dewatering)
List and describe BMPs:
· BMP C251 Construction stormwater Filtration
Installation Schedules: The dewatering is anticipated to be required as soon as the project starts
to dig.
Inspection and Maintenance plan: The discharge water will be monitored weekly or after large
storm events.
Responsible Staff: GLY Construction
Page |19
2.1.11 Element 11: Maintain BMPs
All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained
and repaired as needed to ensure continued performance of their intended function.
Maintenance and repair shall be conducted in accordance with each particular BMP
specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW).
Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar
week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the
site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to
once every calendar month.
All temporary ESC BMPs shall be removed within 30 days after final site stabilization is
achieved or after the temporary BMPs are no longer needed.
Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal
of either BMPs or vegetation shall be permanently stabilized.
Additionally, protection must be provided for all BMPs installed for the permanent control of
stormwater from sediment and compaction. BMPs that are to remain in place following
completion of construction shall be examined and restored to full operating condition. If
sediment enters these BMPs during construction, the sediment shall be removed and the facility
shall be returned to conditions specified in the construction documents.
Page |20
2.1.12 Element 12: Manage the Project
The project will be managed based on the following principles:
· Projects will be phased to the maximum extent practicable and seasonal work limitations
will be taken into account.
· Inspection and monitoring:
o Inspection, maintenance and repair of all BMPs will occur as needed to ensure
performance of their intended function.
o Site inspections and monitoring will be conducted in accordance with Special
Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map.
Sampling station(s) are located in accordance with applicable requirements of
the CSWGP.
· Maintain an updated SWPPP.
o The SWPPP will be updated, maintained, and implemented in accordance with
Special Conditions S3, S4, and S9 of the CSWGP.
As site work progresses the SWPPP will be modified routinely to reflect changing site
conditions. The SWPPP will be reviewed monthly to ensure the content is current.
Check all the management BMPs that apply at your site:
Table 5 – Management
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
Other (please describe)
Page |21
Table 6 – BMP Implementation Schedule
Phase of Construction
Project Stormwater BMPs Date Wet/Dry
Season
Perimeter Fencing High Visibility Fence 12/15/2015 Wet
Triangular Filtration
Dikes
D.3.3.4 Triangular Silt Dike 12/15/2015 Wet
Install Sanitary Sewer
and Utilities
Dewatering – Stormwater
Filtration
12/16/2015 Wet
Install Storm Drain
System
Storm Drain Inlet Protection 12/16/2015 Wet
Install Oil Water
Separators, Pre-Cast
Vaults
Dewatering - Stormwater
Filtration
01/02/2015 Wet
Construct Buildings N/A 01/02/2015 Wet
Pave the parking lot N/A 07/01/2015 Dry
Pour concrete BMP C151 07/01/2015 Dry
Page |22
3 Pollution Prevention Team
Table 7 – Team Information
Title Name(s)Phone Number
Certified Erosion and
Sediment Control Lead
(CESCL)
Glen Trowbridge 206-276-1760
Resident Engineer Tara L. Burton 425-869-2670
Emergency Ecology
Contact
TBD TBD
Emergency Permittee/
Owner Contact
Glen Trowbridge 206-276-1760
Non-Emergency Owner
Contact
Mark Clement 206-617-2944
Monitoring Personnel Glen Trowbridge 206-276-1760
Ecology Regional Office Northwest Regional Office 425-469-7000
Page |23
4 Monitoring and Sampling Requirements
Monitoring includes visual inspection, sampling for water quality parameters of concern, and
documentation of the inspection and sampling findings in a site log book. A site log book will be
maintained for all on-site construction activities and will include:
· A record of the implementation of the SWPPP and other permit requirements
· Site inspections
· Stormwater sampling data
File a blank form under Appendix D.
The site log book must be maintained on-site within reasonable access to the site and be made
available upon request to Ecology or the local jurisdiction.
Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See
CSWGP Special Condition S8 and Section 5 of this template.
4.1 Site Inspection
Site inspections will be conducted at least once every calendar week and within 24 hours
following any discharge from the site. For sites that are temporarily stabilized and inactive, the
required frequency is reduced to once per calendar month.
The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with
the applicable requirements of the CSWGP.
4.2 Stormwater Quality Sampling
4.2.1 Turbidity Sampling
Requirements include calibrated turbidity meter or transparency tube to sample site discharges
for compliance with the CSWGP. Sampling will be conducted at all discharge points at least
once per calendar week.
Method for sampling turbidity:
Table 8 – Turbidity Sampling Method
Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size)
Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size)
The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency
less than 33 centimeters.
If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to
or greater than 6 cm, the following steps will be conducted:
1. Review the SWPPP for compliance with Special Condition S9. Make appropriate
revisions within 7 days of the date the discharge exceeded the benchmark.
Page |24
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10
days of the date the discharge exceeded the benchmark. If installation of necessary
treatment BMPs is not feasible within 10 days, Ecology may approve additional time
when the Permittee requests an extension within the initial 10-day response period.
3. Document BMP implementation and maintenance in the site log book.
If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following
steps will be conducted:
1. Telephone the applicable Ecology Region’s Environmental Report Tracking System
(ERTS) number within 24 hours.
·Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan,
Yakima): (509) 575-2490
·Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant,
Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400
·Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish,
Whatcom): (425) 649-7000
·Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis,
Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10
days of the date the discharge exceeded the benchmark. If installation of necessary
treatment BMPs is not feasible within 10 days, Ecology may approve additional time
when the Permittee requests an extension within the initial 10-day response period
3. Document BMP implementation and maintenance in the site log book.
4. Continue to sample discharges daily until one of the following is true:
· Turbidity is 25 NTU (or lower).
· Transparency is 33 cm (or greater).
· Compliance with the water quality limit for turbidity is achieved.
o 1 - 5 NTU over background turbidity, if background is less than 50 NTU
o 1% - 10% over background turbidity, if background is 50 NTU or greater
· The discharge stops or is eliminated.
Page |25
4.2.2 pH Sampling
pH monitoring is required for “Significant concrete work” (i.e., greater than 1000 cubic yards
poured or recycled concrete over the life of the project). The use of engineered soils (soil
amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust
[CKD] or fly ash) also requires pH monitoring.
For significant concrete work, pH sampling will start the first day concrete is poured and
continue until it is cured, typically three (3) weeks after the last pour.
For engineered soils, pH sampling begins when engineered soils are first exposed to
precipitation and continues until the area is fully stabilized.
If the measured pH is 8.5 or greater, the following measures will be taken:
1. Prevent high pH water from entering storm sewer systems or surface water.
2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate
technology such as carbon dioxide (CO2) sparging (liquid or dry ice).
3. Written approval will be obtained from Ecology prior to the use of chemical treatment
other than CO2 sparging or dry ice.
Method for sampling pH:
Table 9 – pH Sampling Method
pH meter
pH test kit
Wide range pH indicator paper
Page |26
5 Discharges to 303(d) or Total Maximum Daily Load (TMDL)
Waterbodies
5.1 303(d) Listed Waterbodies
Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH?
Yes No
List the impairment(s):
N/A
5.2 TMDL Waterbodies
Waste Load Allocation for CWSGP discharges:
N/A
Describe the method(s) for TMDL compliance:
List and describe BMPs:
Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point
of discharge.
The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water
Body form is included in Appendix F.
Page |27
6 Reporting and Record Keeping
6.1 Record Keeping
6.1.1 Site Log Book
A site log book will be maintained for all on-site construction activities and will include:
· A record of the implementation of the SWPPP and other permit requirements
· Site inspections
· Sample logs
6.1.2 Records Retention
Records will be retained during the life of the project and for a minimum of three (3) years
following the termination of permit coverage in accordance with Special Condition S5.C of the
CSWGP.
Permit documentation to be retained on-site:
· CSWGP
· Permit Coverage Letter
· SWPPP
· Site Log Book
Permit documentation will be provided within 14 days of receipt of a written request from
Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when
requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP.
6.1.3 Updating the SWPPP
The SWPPP will be modified if:
· Found ineffective in eliminating or significantly minimizing pollutants in stormwater
discharges from the site.
· There is a change in design, construction, operation, or maintenance at the construction
site that has, or could have, a significant effect on the discharge of pollutants to waters
of the State.
The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine
additional or modified BMPs are necessary for compliance. An updated timeline for BMP
implementation will be prepared.
Page |28
6.2 Reporting
6.2.1 Discharge Monitoring Reports
Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring
Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given
monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR
due date is fifteen (15) days following the end of each calendar month.
DMRs will be reported online through Ecology’s WQWebDMR System.
To sign up for WQWebDMR go to:
http://www.ecy.wa.gov/programs/wq/permits/paris/webdmr.html
6.2.2 Notification of Noncompliance
If any of the terms and conditions of the permit is not met, and the resulting noncompliance may
cause a threat to human health or the environment, the following actions will be taken:
1. Ecology will be immediately notified of the failure to comply by calling the applicable
Regional office ERTS phone number (Regional office numbers listed below).
2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or
correct the noncompliance. If applicable, sampling and analysis of any noncompliance
will be repeated immediately and the results submitted to Ecology within five (5) days of
becoming aware of the violation.
3. A detailed written report describing the noncompliance will be submitted to Ecology
within five (5) days, unless requested earlier by Ecology.
Specific information to be included in the noncompliance report is found in Special Condition
S5.F.3 of the CSWGP.
Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6
cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as
required by Special Condition S5.A of the CSWGP.
·Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat,
Okanogan, or Yakima County
·Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin,
Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman
County
·Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit,
Snohomish, or Whatcom County
·Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor,
Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum
Page |29
Include the following information:
1. Your name and / Phone number
2. Permit number
3. City / County of project
4. Sample results
5. Date / Time of call
6. Date / Time of sample
7. Project name
In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will
be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH
water.
Page |30
Appendix/Glossary
A. Site Map
SITE05-YDAPRONCVICINITYMAP425-869-26708420154thAvenueNERedmond,Washington98052770PERIMETERROADWEST,RENTONWA98055FIGURE2
LANDUSEPERMIT
LANDUSEPERMIT
Page |31
B. BMP Detail
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-7
D.3 ESC MEASURES
This section details the ESC measures that are required to minimize erosion and sediment transport off a
construction site. These ESC measures represent Best Management Practices (BMPs)6 for the control of
erosion and entrained sediment as well as other impacts related to construction such as increased runoff
due to land disturbing activities. The measures and practices are grouped into nine sections corresponding
to each of the nine categories of ESC measures in Core Requirement #5, Section 1.2.5 of the King County
Surface Water Design Manual. The introductory paragraphs at the beginning each section present the
basic requirement for that category of measures, the purpose of those measures, installation requirements
relative to construction activity, guidelines for the conditions of use, and other information relevant to all
measures in the section/category. Compliance with each of the nine categories of the ESC measures, to
the extent applicable and necessary to meet the performance criteria in Section D.4, and compliance with
the ESC implementation requirements in Section D.5, constitutes overall compliance with King County's
ESC Standards.Note: Additional measures shall be required by the County if the existing standards are
insufficient to protect adjacent properties, drainage facilities, or water resources.
The standards for each individual ESC measure are divided into four sections:
1. Purpose
2. Conditions of Use
3. Design and Installation Specifications
4. Maintenance Requirements.
A code and symbol for each measure have also been included for ease of use on ESC plans. Note that the
"Conditions of Use" always refers to site conditions. As site conditions change, ESC measures must be
changed to remain in compliance with the requirements of this appendix.
Whenever compliance with King County ESC Standards is required, all of the following categories of
ESC measures must be considered for application to the project site as detailed in the following sections:
1.Clearing Limits:Prior to any site clearing or grading, areas to remain undisturbed during project
construction shall be delineated on the project's ESC plan and physically marked on the project site.
2.Cover Measures:Temporary and permanent cover measures shall be provided when necessary to
protect disturbed areas. The intent of these measures is to prevent erosion by having as much area as
possible covered during any period of precipitation.
3.Perimeter Protection:Perimeter protection to filter sediment from sheet flow shall be provided
downstream of all disturbed areas prior to upslope grading.
4.Traffic Area Stabilization:Unsurfaced entrances, roads, and parking areas used by construction
traffic shall be stabilized to minimize erosion and tracking of sediment offsite.
5.Sediment Retention:Surface water collected from all disturbed areas of the site shall be routed
through a sediment pond or trap prior to release from the site, except those areas at the perimeter of
the site small enough to be treated solely with perimeter protection. Sediment retention facilities shall
be installed prior to grading any contributing area.
6.Surface Water Collection:Surface water collection measures (e.g., ditches, berms, etc.) shall be
installed to intercept all surface water from disturbed areas, convey it to a sediment pond or trap, and
discharge it downstream of any disturbed areas. Areas at the perimeter of the site, which are small
enough to be treated solely with perimeter protection, do not require surface water collection.
Significant sources of upstream surface water that drain onto disturbed areas shall be intercepted and
6 Best Management Practices (BMPs) means the best available and reasonable physical, structural, managerial, or behavioral
activities, that when singly or in combination, eliminate or reduce the contamination of surface and/or ground waters.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-8
conveyed to a stabilized discharge point downstream of the disturbed areas. Surface water collection
measures shall be installed concurrently with or immediately following rough grading and shall be
designed, constructed, and stabilized as needed to minimize erosion.
7.Dewatering Control: The water resulting from construction site de-watering activities must be
treated prior to discharge or disposed of as specified.
8.Dust Control:Preventative measures to minimize wind transport of soil shall be implemented when a
traffic hazard may be created or when sediment transported by wind is likely to be deposited in water
resources.
9.Flow Control: Surface water from disturbed areas must be routed through the project's onsite flow
control facility or other provisions must made to prevent increases in the existing site conditions 2-
year and 10-year runoff peaks discharging from the project site during construction.
D.3.1 CLEARING LIMITS
Prior to any site clearing or grading, those areas that are to remain undisturbed during project construction
shall be delineated. At a minimum, clearing limits shall be installed at the edges of all critical area buffers
and any other areas required to be left uncleared such as portions of the site subject to clearing limits
under KCC 16.82.150, areas around significant trees identified to be retained, and other areas identified to
be left undisturbed to protect sensitive features.
Purpose: The purpose of clearing limits is to prevent disturbance of those areas of the project site that are
not designated for clearing or grading. This is important because limiting site disturbance is the single
most effective method for reducing erosion. Clearing limits may also be used to control construction
traffic, thus reducing the disturbance of soil and limiting the amount of sediment tracked off site.
When to Install: Clearing limits shall be installed prior to the clearing and/or grading of the site.
Measures to Use: Marking clearing limits by delineating the site with a continuous length of brightly
colored survey tape is sometimes sufficient. The tape may be supported by vegetation or stakes, and it
shall be 3 to 6 feet high and highly visible. Critical areas and their buffers require more substantial
protection and shall be delineated with plastic or metal safety fences or stake and wire fences. Fencing
may be required at the County's discretion to control construction traffic or at any location where greater
protection is warranted. Permanent fencing may also be used if desired by the applicant. Silt fence, in
combination with survey flagging, is also an acceptable method of marking critical areas and their buffers.
D.3.1.1 PLASTIC OR METAL FENCE
Code: FE Symbol:
Purpose
Fencing is intended to (1) restrict clearing to approved limits; (2) prevent disturbance of critical 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:
1. At the boundary of critical areas, their buffers, and other areas required to be left uncleared.
2. As necessary to control vehicle access to and on the site (see Sections D.3.4.1 and D.3.4.2).
D.3.1 CLEARING LIMITS
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-9
Design and Installation Specifications
1. The fence shall be designed and installed according to the manufacturer's specifications.
2. The fence shall be at least 3 feet high and must be highly visible.
3. The fence shall not be wired or stapled to trees.
Maintenance Requirements
1. If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and
visibility restored.
2. Disturbance of a critical area, critical area buffer, native growth retention area, or any other area
required to be left undisturbed shall be reported to the County for resolution.
D.3.1.2 STAKE AND WIRE FENCE
Code: SWF Symbol:
Purpose
Fencing is intended to (1) restrict clearing to approved limits; (2) prevent disturbance of critical areas,
their buffers, and other areas required to be left undisturbed; (3) limit construction traffic 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 clearing limits, stake or wire fence may be used:
1. At the boundary of critical areas, their buffers, and other areas required to be left uncleared.
2. As necessary, to control vehicle access to and on the site (see Sections D.3.4.1 and D.3.4.2).
Design and Installation Specifications
See Figure D.3.1.A for details.
Maintenance Requirements
1. If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and
visibility restored.
2. Disturbance of a critical area, critical area buffer, native growth retention area, or other area required
to be left undisturbed shall be reported to the County for resolution.
3. The County may require more substantial fencing if the fence does not prevent encroachment into
those areas that are not to be disturbed.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-10
FIGURE D.3.1.A STAKE AND WIRE FENCE
D.3.2 COVER MEASURES
Temporary and permanent cover measures shall be provided to protect all disturbed areas, including the
faces of cut and fill slopes. Temporary cover shall be installed if an area is to remain unworked for more
than seven days during the dry season (May 1 to September 30) or for more than two consecutive working
days during the wet season (October 1 to April 30). These time limits may be relaxed if an area poses a
low risk of erosion due to soil type, slope gradient, anticipated weather conditions, or other factors.
Conversely, the County may reduce these time limits if site conditions warrant greater protection (e.g.,
adjacent to significant aquatic resources or highly erosive soils) or if significant precipitation (see Section
D.5.2) is expected. Any area to remain unworked for more than 30 days shall be seeded or sodded, unless
the County determines that winter weather makes vegetation establishment infeasible. During the wet
season, slopes and stockpiles at 3H:1V or steeper and with more than ten feet of vertical relief shall be
covered if they are to remain unworked for more than 12 hours. Also during the wet season, the material
necessary to cover all disturbed areas must be stockpiled on site. The intent of these cover requirements is
to have as much area as possible covered during any period of precipitation.
Purpose: The purpose of covering exposed soils is to prevent erosion, thus reducing reliance on less
effective methods that remove sediment after it is entrained in runoff. Cover is the only practical method
of reducing turbidity in runoff. Structural measures, such as silt fences and sediment ponds, are only
capable of removing coarse particles and in most circumstances have little to no effect on turbidity.
When to Install: Any exposed soils that will remain unworked for more than the time limit set above
shall be covered by the end of the working day. If the exposed area is to remain unworked for more than
30 days, the area shall be seeded with the temporary seed mix or an equivalent mix that will provide rapid
protection (see Section D.3.2.5). If the disturbed area is to remain unworked for a year or more or if the
area has reached final grade, permanent seed mix or an equivalent mix shall be applied.
Measures to Use: Cover methods include the use of surface roughening, mulch, erosion control nets and
blankets, plastic covering, seeding, and sodding. Mulch and plastic sheeting are primarily intended to
protect disturbed areas for a short period of time, typically days to a few months. Seeding and sodding are
measures for areas that are to remain unworked for months. Erosion nets and blankets are to be used in
conjunction with seeding steep slopes. The choice of measures is left to the designer; however, there are
restrictions on the use of these methods, which are listed in the "Conditions of Use" and the "Design and
Installation Specifications" sections for each measure.
D.3.2 COVER MEASURES
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-11
The methods listed are by no means exhaustive. Variations on the standards presented here are
encouraged if other cost-effective products or methods provide substantially equivalent or superior
performance. Also, the details of installation can, and should, vary with the site conditions. A useful
reference on the application of cover measures in the Puget Sound area is Horner, Guedrey, and Kortenhof
(1990).
D.3.2.1 SURFACE ROUGHENING
Purpose
The purpose of surface roughening is to aid in the establishment of vegetative cover and to reduce runoff
velocity, increase infiltration, and provide for sediment trapping through the provision of a rough soil
surface. The rough soil surface may be created by operating a tiller or other equipment on the contour to
form horizontal depressions or by leaving slopes in a roughened condition by not fine grading.
Conditions of Use
1. All slopes steeper than 3:1 and greater than 5 vertical feet require surface roughening.
2. Areas with grades steeper than 3:1 should be roughened to a depth of 2 to 4 inches prior to seeding.
3. Areas that will not be stabilized immediately may be roughened to reduce runoff velocity until
seeding takes place.
4. Slopes with a stable rock face do not require roughening.
5. Slopes where mowing is planned should not be excessively roughened.
Design and Installation Specifications
There are different methods for achieving a roughened soil surface on a slope, and the selection of an
appropriate method depends upon the type of slope. Roughening methods include stair-step grading,
grooving, contour furrows, and tracking. See Figure D.3.2.A for information on 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. Sole reliance on roughening for temporary erosion
control is of limited effectiveness in intense rainfall events. Stair-step grading may not be practical for
sandy, steep, or shallow soils.
1. Disturbed areas that will not require mowing may be stair-step graded, grooved, or left rough after
filling
2. 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. Stairs should be wide enough to work with standard earth moving equipment.
Stair steps must be on contour or gullies will form on the slope.
3. Areas that will be mowed (slopes less steep than 3:1) may have small furrows left by disking,
harrowing, raking, or seed-planting machinery operated on the contour.
4. Graded 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, leaving a pattern of cleat imprints parallel to slope contours.
5.Tracking is done by operating equipment up and down the slope to leave horizontal depressions in the
soil.
D.3.2 COVER MEASURES
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-13
D.3.2.2 MULCHING
Code: MU Symbol:
Purpose
The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also
enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and
moderating soil temperatures. There is an enormous variety of mulches that may be used. Only the most
common types are discussed in this section.
Conditions of Use
As a temporary cover measure, mulch should be used:
1. On disturbed areas that require cover measures for less than 30 days
2. As a cover for seed during the wet season and during the hot summer months
3. During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical relief.
Design and Installation Specifications
For mulch materials, application rates, and specifications, see Table D.3.2.A.Note: Thicknesses may be
increased for disturbed areas in or near critical areas or other areas highly susceptible to erosion.
Maintenance Standards
1. The thickness of the cover must be maintained.
2. Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the
erosion problem is drainage related, then the drainage problem shall be assessed and alternate
drainage such as interceptor swales may be needed to fix the problem and the eroded area remulched.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-14
TABLE D.3.2.A MULCH STANDARDS AND GUIDELINES
Mulch
Material
Quality Standards Application Rates Remarks
Straw Air-dried; free from
undesirable seed andcoarse material
2"-3" thick; 2-3
bales per 1000 sfor 2-3 tons per acre
Cost-effective protection when applied with adequate
thickness. Hand-application generally requiresgreater thickness than blown straw. Straw should be
crimped to avoid wind blow. The thickness of straw
may be reduced by half when used in conjunction
with seeding.
Wood Fiber
Cellulose
No growth inhibiting
factors
Approx. 25-30 lbs
per 1000 sf or
1000-1500 lbs per
acre
Shall be applied with hydromulcher. Shall not be
used without seed and tackifier unless the application
rate is at least doubled. Some wood fiber with very
long fibers can be effective at lower application rates
and without seed or tackifier.
Compost No visible water or
dust during handling.
Must be purchased
from supplier with
Solid Waste Handling
Permit.
2" thick min.;
approx. 100 tons
per acre (approx.
800 lbs per cubic
yard)
More effective control can be obtained by increasing
thickness to 3". Excellent mulch for protecting final
grades until landscaping because it can be directly
seeded or tilled into soil as an amendment. Sources
for compost are available from the King County
Commission for Marketing Recyclable Materials at
(206) 296-4439. Compost may not be used in
Sensitive Lake7 basins unless analysis of the
compost shows no phosphorous release.
Hydraulic
Matrices
(Bonded
Fiber Matrix)
This mulch category
includes hydraulic
slurries composed of
wood fiber, paper fiber
or a combination of
the two held together
by a binding system.
The BFM shall be a
mixture of long wood
fibers and various
bonding agents.
Apply at rates from
3,000 lbs per acre
to 4,000 lbs per
acre and based on
manufacturers
recommendations
The BFM shall not be applied immediately before,
during or immediately after rainfall so that the matrix
will have an opportunity to dry for 24 hours after
installation. Application rates beyond 2,500 pounds
may interfere with germination and are not usually
recommended for turf establishment. BFM is
generally a matrix where all fiber and binders are in
one bag, rather than having to mix components from
various manufacturers to create a matrix. BFMs can
be installed via helicopter in remote areas. They are
approximately $1,000 per acre cheaper to install.
Chipped Site
Vegetation
Average size shall be
several inches.
2" minimum
thickness
This is a cost-effective way to dispose of debris from
clearing and grubbing, and it eliminates the problems
associated with burning. Generally, it should not be
used on slopes above approx. 10% because of its
tendency to be transported by runoff. It is not
recommended within 200 feet of surface waters. If
seeding is expected shortly after mulch, the
decomposition of the chipped vegetation may tie up
nutrients important to grass establishment.
7 Sensitive lake means a lake that has proved to be particularly prone to eutrophication; the County gives this designation when
an active input plan has been adopted to limit the amount of phosphorous entering the lake.
D.3.2 COVER MEASURES
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-17
D.3.2.4 PLASTIC COVERING
Code: PC Symbol:
Purpose
Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas.
Conditions of Use
1. Plastic covering may be used on disturbed areas that require cover measures for less than 30 days.
2. 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 applications.
3. Clear plastic sheeting may be used over newly-seeded areas to create a greenhouse effect and
encourage grass growth. Clear plastic should not be used for this purpose during the summer months
because the resulting high temperatures can kill the grass.
4. 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.
Note: There have been many problems with plastic, usually attributable to poor installation and
maintenance. However, the material itself can cause problems, even when correctly installed and
maintained, because it generates high-velocity runoff and breaks down quickly due to ultraviolet
radiation. In addition, if the plastic is not completely removed, it can clog drainage system inlets and
outlets. It is highly recommended that alternatives to plastic sheeting be used whenever possible and that
its use be limited.
Design and Installation Specifications
1. See Figure D.3.2.D for details.
2. Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
3. 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.
FIGURE D.3.2.D PLASTIC COVERING
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-18
Maintenance Standards for Plastic Covering
1. Torn sheets must be replaced and open seams repaired.
2. If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and
replaced.
3. When the plastic is no longer needed, it shall be completely removed.
D.3.2.5 STRAW WATTLES
Code: SW Symbol:
Purpose
Wattles are erosion and sediment control barriers consisting of straw wrapped in biodegradable tubular
plastic or similar encasing material. Wattles may reduce the velocity and can spread the flow of rill and
sheet runoff, and can capture and retain sediment. Straw wattles are typically 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.
Conditions of Use
1. Install on disturbed areas that require immediate erosion protection.
2. Use on slopes requiring stabilization until permanent vegetation can be established.
3. Can be used along the perimeter of a project, as a check dam in unlined ditches and around temporary
stockpiles
4. Wattles can be staked to the ground using willow cuttings for added revegetation.
5. Rilling can occur beneath and between wattles if not properly entrenched, allowing water to pass
below and between wattles
Design and Installation Specifications
1. It is critical that wattles are installed perpendicular to the flow direction and parallel to the slope
contour.
2. 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 during high rainfall events, the
trenches should be dug to a depth of 5 to 7 inches, or ½ to 2/3 of the thickness of the wattle.
3. Start construction of trenches and installing wattles from the base of the slope and work uphill.
Excavated material should be spread evenly along the uphill slope and compacted using hand tamping
or other method. Construct trenches at contour intervals of 3 to 30 feet apart depending on the
steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches
should be constructed.
4. Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends.
5. Install stakes at each end of the wattle, and at 4 foot centers along the entire length of the wattle.
6. If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and
into the soil.
7. At a minimum, wooden stakes should be approximately ¾ x ¾ x 24 inches. Willow cuttings or 3/8
inch rebar can also be used for stakes.
D.3.2 COVER MEASURES
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-21
D.3.2.6 TEMPORARY AND PERMANENT SEEDING
Code: SE Symbol:
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
1. Seeding shall be used throughout the project on disturbed areas that have reached final grade or that
will remain unworked for more than 30 days.
2.Vegetation-lined channels shall be seeded. Channels that will be vegetated should be installed
before major earthwork and hydroseeded or covered with a Bonded Fiber Matrix (BFM).
3.Retention/detention ponds shall be seeded as required.
4. At the County's discretion, seeding without mulch during the dry season is allowed even though it
will take more than seven days to develop an effective cover. Mulch is, however, recommended at all
times because it protects seeds from heat, moisture loss, and transport due to runoff.
5. At the beginning of the wet season, all disturbed areas shall be reviewed to identify which ones can
be seeded in preparation for the winter rains (see Section D.5.2). Disturbed areas shall be seeded
within one week of the beginning of the wet season. A sketch map of those areas to be seeded and
those areas to remain uncovered shall be submitted to the DDES inspector. The DDES inspector may
require seeding of additional areas in order to protect surface waters, adjacent properties, or drainage
facilities.
6. At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and
mulched (see Section D.5.5).
Design and Installation Specifications
1. The best time to seed is April 1 through June 30, and September 1 through October 15. Areas may be
seeded between July 1 and August 31, but irrigation may be required in order to grow adequate cover.
Areas may also be seeded during the winter months, but it may take several months to develop a
dense groundcover due to cold temperatures. The application and maintenance of mulch is critical for
winter seeding.
2. To prevent seed from being washed away, confirm that all required surface water control measures
have been installed.
3. The seedbed should be firm but not compacted because soils that are well compacted will not
vegetate as quickly or thoroughly. Slopes steeper than 3H:1V shall be surface roughened.
Roughening can be accomplished in a variety of ways, but the typical method is track walking, or
driving a crawling tractor up and down the slope, leaving cleat imprints parallel to the slope contours.
4. In general, 10-20-20 N-P-K (nitrogen-phosphorus-potassium)fertilizer may be used at a rate of 90
pounds per acre. Slow-release fertilizers are preferred 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. Disturbed areas within 200 feet of water bodies and wetlands must use slow-
release low-phosphorus fertilizer (typical proportions 3-1-2 N-P-K).
5. The following requirements apply to mulching:
a) Mulch is always required for seeding slopes greater than 3H:1V (see Section D.4.2.1).
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-22
b) If seeding during the wet season, mulch is required.
c) The use of mulch may be required during the dry season at the County's discretion if grass growth
is expected to be slow, the soils are highly erodible due to soil type or gradient, there is a water
body close to the disturbed area, or significant precipitation (see Section D.5.2) is anticipated
before the grass will provide effective cover.
d) Mulch may be applied on top of the seed or simultaneously by hydroseeding.
6.Hydroseeding is allowed as long as tackifier is included. Hydroseeding with wood fiber mulch is
adequate during the dry season. During the wet season, the application rate shall be doubled because
the mulch and tackifier used in hydroseeding break down fairly rapidly. It may be necessary in some
applications to include straw with the wood fiber, but this can be detrimental to germination.
7. Areas to be permanently landscaped shall use soil amendments. Good quality topsoil shall be tilled
into the top six inches to reduce the need for fertilizer and improve the overall soil quality. Most
native soils will require the addition of four inches of well-rotted compost to be tilled into the soil to
provide a good quality topsoil. Compost used should meet Ecology publication 98-38 specifications
for Grade A quality compost.
8. 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 may be reduced if soil amendments or slow-release fertilizers are used. Local suppliers
should be consulted for their recommendations because the appropriate mix depends on a variety of
factors, including exposure, soil type, slope, and expected foot traffic. Alternative seed mixes
approved by the County may be used.
Table D.3.2.B presents the standard mix for those areas where just a temporary vegetative cover is
required.
TABLE D.3.2.BTEMPORARY EROSION CONTROL SEED MIX
% Weight % Purity % Germination
Chewings or red fescue
Festuca rubra var. commutata or
Festuca rubra
40 98 90
Annual or perennial rye
Lolium multiflorum or Lolium perenne
40 98 90
Redtop or colonial bentgrass
Agrostis alba or Agrostis tenuis
10 92 85
White dutch clover
Trifolium repens
10 98 90
D.3.2 COVER MEASURES
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-23
Table D.3.2.C provides just one recommended possibility for landscaping seed.
TABLE D.3.2.C LANDSCAPING SEED MIX
% Weight % Purity % Germination
Perennial rye blend
Lolium perenne
70 98 90
Chewings and red fescue blend
Festuca rubra var. commutata or
Festuca rubra
30 98 90
This turf seed mix in Table D.3.2.D is for dry situations where there is no need for much water. The
advantage is that this mix requires very little maintenance.
TABLE D.3.2.D LOW-GROWING TURF SEED MIX
% Weight % Purity % Germination
Dwarf tall fescue (several varieties)
Festuca arundinacea var.
45 98 90
Dwarf perennial rye (Barclay)
Lolium perenne var. barclay
30 98 90
Red fescue
Festuca rubra
20 98 90
Colonial bentgrass
Agrostis tenuis
5 98 90
Table D.3.2.E presents a mix recommended for bioswales and other intermittently wet areas. Sod shall
generally not be used for bioswales because the seed mix is inappropriate for this application. Sod may be
used for lining ditches to prevent erosion, but it will provide little water quality benefit during the wet
season.
TABLE D.3.2.E BIOSWALE SEED MIX*
% Weight % Purity % Germination
Tall or meadow fescue
Festuca arundinacea or
Festuca elatior
75-80 98 90
Seaside/Creeping bentgrass
Agrostis palustris
10-15 92 85
Redtop bentgrass
Agrostis alba or Agrostis gigantea
5-10 90 80
* Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-24
The seed mix shown in Table D.3.2.F is a recommended low-growing, relatively non-invasive seed mix
appropriate for very wet areas that are not regulated wetlands (if planting in wetland areas, see Section
6.3.1 of the Surface Water Design Manual). Other mixes may be appropriate, depending on the soil type
and hydrology of the area. Apply this mixture at a rate of 60 pounds per acre.
TABLE D.3.2.F WET AREA SEED MIX*
% Weight % Purity % Germination
Tall or meadow fescue
Festuca arundinacea or
Festuca elatior
60-70 98 90
Seaside/Creeping bentgrass
Agrostis palustris
10-15 98 85
Meadow foxtail
Alepocurus pratensis
10-15 90 80
Alsike clover
Trifolium hybridum
1-6 98 90
Redtop bentgrass
Agrostis alba
1-6 92 85
* Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
The meadow seed mix in Table D.3.2.G is recommended 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 mix 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.
TABLE D.3.2.G MEADOW SEED MIX
% Weight % Purity % Germination
Redtop or Oregon bentgrass
Agrostis alba or Agrostis oregonensis
40 92 85
Red fescue
Festuca rubra
40 98 90
White dutch clover
Trifolium repens
20 98 90
Maintenance Standards for Temporary and Permanent Seeding
1. Any seeded areas that fail to establish at least 80 percent cover within one month shall be reseeded. If
reseeding is ineffective, an alternate method, such as sodding or nets/blankets, shall be used. If winter
weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the County
when critical areas would otherwise be protected.
D.3.2 COVER MEASURES
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-25
2. After adequate cover is achieved, any areas that experience erosion shall be re-seeded and protected
by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area
re-seeded and protected by mulch.
3. Seeded areas shall be supplied with adequate moisture, but not watered to the extent that it causes
runoff.
D.3.2.7 SODDING
Code: SO Symbol:
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 of Use
Sodding may be used in the following areas:
1. Disturbed areas that require short-term or long-term cover
2. Disturbed areas that require immediate vegetative cover
3. All waterways that require vegetative lining (except biofiltration swales—the seed mix used in most
sod is not appropriate for biofiltration swales). Waterways may also be seeded rather than sodded,
and protected with a net or blanket (see Section D.3.2.3).
Design and Installation Specifications
Sod shall be free of weeds, of uniform thickness (approximately 1-inch thick), and shall have a dense root
mat for mechanical strength.
The following steps are recommended for sod installation:
1. Shape and smooth the surface to final grade in accordance with the approved grading plan.
2. Amend two inches (minimum) of well-rotted compost into the top six inches of the soil if the organic
content of the soil is less than ten percent. Compost used should meet Ecology publication 98-38
specifications for Grade A quality compost.
3. Fertilize according to the supplier's recommendations. Disturbed areas within 200 feet of water
bodies and wetlands must use non-phosphorus fertilizer.
4. Work lime and fertilizer 1 to 2 inches into the soil, and smooth the surface.
5. Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water
flow. Wedge strips securely into place. Square the ends of each strip to provide for a close, tight fit.
Stagger joints at least 12 inches. Staple on slopes steeper than 3H:1V.
6. Roll the sodded area and irrigate.
7. When sodding is carried out in alternating strips or other patterns, seed the areas between the sod
immediately after sodding.
Maintenance Standards
If the grass is unhealthy, the cause shall be determined and appropriate action taken to reestablish a
healthy groundcover. If it is impossible to establish a healthy groundcover due to frequent saturation,
instability, or some other cause, the sod shall be removed, the area seeded with an appropriate mix, and
protected with a net or blanket.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-30
D.3.3 PERIMETER PROTECTION
Perimeter protection to filter sediment from sheetwash shall be located downslope of all disturbed areas
and shall be installed prior to upslope grading. Perimeter protection includes the use of vegetated strips as
well as, constructed measures, such as silt fences, fiber rolls, sand/gravel barriers, brush or rock filters,
triangular silt dikes and other methods. During the wet season, 50 linear feet of silt fence (and the
necessary stakes) per acre of disturbed area must be stockpiled on site.
Purpose: The purpose of perimeter protection is to reduce the amount of sediment transported beyond the
disturbed areas of the construction site. Perimeter protection is primarily a backup means of sediment
control. Most, if not all, sediment-laden water is to be treated in a sediment trap or pond. The only
circumstances in which perimeter control is to be used as a primary means of sediment removal is when
the catchment is very small (see below).
When to Install: Perimeter protection is to be installed prior to any upslope clearing and grading.
Measures to Use: The above measures may be used interchangeably and are not the only perimeter
protection measures available. If surface water is collected by an interceptor dike or swale and routed to a
sediment pond or trap, there may be no need for the perimeter protection measures specified in this
section.
Criteria for Use as Primary Treatment: At the boundary of a site, perimeter protection may be used as
the sole form of treatment when the flowpath meets the criteria listed below. If these criteria are not met,
perimeter protection shall only be used as a backup to a sediment trap or pond.
Average Slope Slope Percent Flowpath Length
1.5H:1V or less 67% or less 100 feet
2H:1V 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
10H:1V or less 10% or less 250 feet
D.3.3.1 SILT FENCE
Code: SF Symbol:
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.
Conditions of Use
1. Silt fence may be used downslope of all disturbed areas.
2. 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
trap or pond. The only circumstance in which overland flow may be treated solely by a silt fence,
rather than by a sediment trap or pond, is when the area draining to the fence is small (see "Criteria
for Use as Primary Treatment" on page D-30).
Design and Installation Specifications
1. See Figure D.3.3.A and Figure D.3.3.B for details.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-34
D.3.3.3 VEGETATED STRIP
Code: VS Symbol:
Purpose
Vegetated strips 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
1. Vegetated strips may be used downslope of all disturbed areas.
2. 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 trap or pond. The only circumstance in which overland flow may be treated solely by a
strip, rather than by a sediment trap or pond, is when the area draining to the strip is small (see
"Criteria for Use as Primary Treatment" on page D-30).
Design and Installation Specifications
1. The vegetated strip shall consist of a 25-foot minimum width continuous strip of dense vegetation
with a permeable topsoil. Grass-covered, landscaped areas are generally not adequate because the
volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed
native growth with a well-developed soil that allows for infiltration of runoff.
2. The slope within the strip shall not exceed 4H:1V.
3. The uphill boundary of the vegetated strip shall be delineated with clearing limits as specified in
Section D.3.1 (p. D-8).
Maintenance Standards
1. Any areas damaged by erosion or construction activity shall be seeded immediately and protected by
mulch.
2. If more than 5 feet of the original vegetated strip width has had vegetation removed or is being
eroded, sod must be installed using the standards for installation found in Section D.4.2.5.
If there are indications that concentrated flows are traveling across the buffer, surface water controls must
be installed to reduce the flows entering the buffer, or additional perimeter protection must be installed.
D.3.3.4 TRIANGULAR SILT DIKE (GEOTEXTILE ENCASED CHECK DAM)
Code: TSD Symbol:
Purpose
Triangular silt dikes (TSDs) may be used as check dams, for perimeter protection, for temporary soil
stockpile protection, for drop inlet protection, or as a temporary interceptor dike. Silt dikes, if attached to
impervious surfaces with tack or other adhesive agent may also be used as temporary wheel wash areas, or
concrete washout collection areas.
Conditions of Use
1. May be used for temporary check dams in ditches.
D.3.3 PERIMETER PROTECTION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-35
2. May be used on soil or pavement with adhesive or staples.
3. TSDs have been used to build temporary sediment ponds, diversion ditches, concrete washout
facilities, curbing, water bars, level spreaders, and berms.
Design and Installation Specifications
1. TSDs must be made of urethane foam sewn into a woven geosynthetic fabric.
2. TSDs are triangular, 10 inches to 14 inches high in the center, with a 20-inch to 28-inch base. A 2-
foot apron extends 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
3. Install TSDs with ends curved up to prevent water from flowing around the ends
4. Attach the TSDs and their fabric flaps to the ground with wire staples. Wire staples must be No. 11
gauge wire or stronger and shall be 200 mm to 300 mm in length.
5. When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting
unit and be stapled.
6. TSDs must be located and installed as soon as construction will allow.
7. TSDs must be placed perpendicular to the flow of water.
8. When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot
and staples.
9. When used in grass-lined ditches and swales, the TSD 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 TSD check dams shall be seeded and mulched
immediately after dam removal.
Maintenance Standards
1. Triangular silt dikes shall be monitored for performance and sediment accumulation during and after
each runoff producing rainfall event. Sediment shall be removed when it reaches one half the height
of the silt dike.
2. Anticipate submergence and deposition above the triangular silt dike and erosion from high flows
around the edges of the dike/dam. Immediately repair any damage or any undercutting of the
dike/dam.
D.3.3.5 COMPOST BERMS
Code: COBE Symbol:
Purpose
Compost berms are an option to meet the requirements of perimeter protection. Compost berms may
reduce the transport of sediment from a construction site by providing a temporary physical barrier to
sediment and reducing the runoff velocities of overland flow. Compost berms trap sediment by filtering
water passing through the berm and allowing water to pond, creating a settling area for solids behind the
berm. Organic materials in the compost can also reduce concentrations of metals and petroleum
hydrocarbons from construction runoff. Due to the increase in phosphorous seen in the effluent data from
compost berms, they should be used with some cautions in areas that drain to phosphorus sensitive water
bodies, and should only be used in Sensitive Lake watersheds, such as Lake Sammamish, with the
approval from the County or the local jurisdiction.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-36
Conditions of Use
1. Compost berms may be used in most areas requiring sediment or erosion control where runoff is in
the form of sheet flow or in areas where silt fence is normally considered acceptable. Compost berms
may be used in areas where migration of aquatic life such as turtles and salamanders are impeded by
the use of silt fence.
2. Compost berms are not intended to treat concentrated flows, nor are they intended to treat substantial
amounts of overland flow. Any concentrated flows must be conveyed via a drainage system to a
sediment pond or trap.
3. For purposes of long-term sediment control objectives, berms may be seeded at the time of installation
to create an additional vegetated filtering component.
Design and Installation Specifications
1. Compost berms shall be applied using a pneumatic blower device or equivalent, to produce a uniform
cross-section and berm density.
2. Compost berms shall be triangular in cross-section. The ratio of base to height dimensions shall be
2:1.
3. The minimum size of a compost berm is a 2-foot base with a 1-foot height.
4. Compost berms shall be sized and spaced as indicated in the table below.
SLOPE SLOPE Maximum Slope Length or
Berm Spacing (linear feet)
Berm Size Required
(height x base width)
0% - 2% Flatter than 50:1 250 1 ft x 2 ft
2% - 10% 50:1 – 10:1 125 1 ft x 2 ft
10% - 20% 10:1 – 5:1 100 1 ft x 2 ft
20% - 33% 5:1 – 3:1 75 1 ft x 2 ft
33% - 50% 3:1 – 2:1 50 1.5 ft x 3 ft
5. Compost berms shall not be used on slopes greater than 2H:1V
6. Compost shall meet criteria in WAC 173-350-220 (10) for Designation of Composted Materials
7. Compost shall be obtained from a supplier meeting the requirements of WAC 173-350-220.
8. Compost particle size distribution shall be as follows: 99% passing a 1 inch sieve, 90% passing a ¾
inch sieve and a minimum of 70% greater than the 3/8 inch sieve. A total of 98% shall not exceed 3
inches in length.
9. Berms shall be placed on level contours to assist in dissipating flow into sheet flow rather than
concentrated flows. Berms shall not be constructed to concentrate runoff or channel water. Sheet flow
of water shall be perpendicular to the berm at impact. No concentrated flow shall be directed towards
compost berms.
10. Where possible, berms shall be placed 5 feet or more from the toe of slopes to allow space for
sediment deposition and collection.
11. In order to prevent water from flowing around the ends of the berms, the ends of the berm shall be
constructed pointing upslope so the ends are at a higher elevation than the rest of the berm.
12. A compost blanket extending 10 – 15 feet above the berm is recommended where the surface above
the berm is rutted or uneven, to reduce concentrated flow and promote sheet flow into the berm.
D.3.3 PERIMETER PROTECTION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-37
Maintenance Standards
1. Compost berms shall be regularly inspected to make sure they retain their shape and allow adequate
flow-through of stormwater.
2. When construction is completed on site, the berms shall be dispersed for incorporation into the soil or
left on top of the site for final seeding to occur.
3. Any damage to berms must be repaired immediately. Damage includes flattening, compacting, rills,
eroded areas due to overtopping.
4. If concentrated flows are evident uphill of the berm, the flows must be intercepted and conveyed to a
sediment trap or pond.
5. The uphill side of the berm shall be inspected for signs of the berm clogging and acting as a barrier to
flows and causing channelization of flows parallel to the berm. If this occurs, replace the berm or
remove the trapped sediment.
6. Sediment that collects behind the berm must be removed when the sediment is more than 6 inches
deep.
D.3.3.6 COMPOST SOCKS
Code: COSO Symbol:
Purpose
Compost socks reduce the transport of sediment from a construction site by providing a temporary
physical barrier to sediment-laden water and reducing the runoff velocities of overland flow. Compost
socks trap sediment by filtering water that passes through the sock and allows water to pond behind the
sock, creating a settling area for solids. Organic materials in the compost also may reduce metal and
petroleum hydrocarbon concentrations in construction runoff. Compost socks function similarly to
compost berms; however, because the compost is contained in a mesh tube, they are appropriate for both
concentrated flow and sheet flow. Compost socks may be used to channel concentrated flow on hard
surfaces.
Conditions of Use
1. Compost socks may be used in areas requiring sediment or erosion control where runoff is in the form
of sheet flow or in areas that silt fence is normally considered acceptable. Compost socks may also be
used in sensitive environmental areas where migration of aquatic life, including turtles, salamanders
and other aquatic life may be impeded by the used of silt fence.
2. Compost socks are not intended to treat substantial amounts of overland flow. However, compost
socks may be subjected to some ponding and concentrated flows. If intended primarily as a filtration
device, the socks should be sized and placed so that flows do not overtop the socks.
3. For purposes of long term sediment control objectives, compost socks may be seeded at the time of
installation to create an additional vegetated filtering component.
Design and Installation Specifications
1. Compost socks shall be produced using a pneumatic blower hose or equivalent to fill a mesh tube
with compost to create a uniform cross-section and berm density.
2. Socks shall be filled so they are firmly – packed yet flexible. Upon initial filling, the socks shall be
filled to have a round cross-section. Once placed on the ground, it is recommended to apply weight to
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-38
the sock to improve contact with the underlying surface. This may cause the sock to assume an oval
shape.
3. Compost socks shall be a minimum of 8 inches in diameter. Larger diameter socks are recommended
for areas where ponding is expected behind the sock.
4. Compost socks shall not be used on slopes greater than 2H:1V.
5. Compost shall meet criteria in WAC 173-350-220 (10) for Designation of Composted Materials.
6. Compost shall be obtained from a supplier meeting the requirements of WAC 173-350-220.
7. Compost particle size distribution shall be as follows: 99% passing a 1 inch sieve, 90% passing a ¾
inch sieve and a minimum of 70% greater than the 3/8 inch sieve. A total of 98% shall not exceed 3
inches in length.
8. In order to prevent water from flowing around the ends of compost socks, the ends must be pointed
upslope so the ends of the socks are at a higher elevation than the remainder of the sock.
Maintenance Standards
1. Compost socks shall be regularly inspected to make sure the mesh tube remains undamaged, the socks
retain their shape, and allow adequate flow through of surface water. If the mesh tube is torn, it shall
be repaired using twine, zip-ties, or wire. Large sections of damaged socks must be replaced. Any
damage must be repaired immediately upon discovery of damage.
2. When the sock is no longer needed, the socks shall be cut open and the compost dispersed to be
incorporated into the soil or left on top of the soil for final seeding to occur. The mesh material must
be disposed of properly as solid waste. If spills of oil, antifreeze, hydraulic fluid, or other equipment
fluids have occurred that have saturated the sock, the compost must be disposed of properly as a
waste.
3. Sediment must be removed when sediment accumulations are within 3 inches of the top of the sock.
D.3.4 TRAFFIC AREA STABILIZATION
Unsurfaced entrances, roads, and parking areas used by construction traffic shall be stabilized to minimize
erosion and tracking of sediment off site. Stabilized construction entrances shall be installed as the first
step in clearing and grading. At the County's discretion, road and parking area stabilization is not required
during the dry season (unless dust is a concern) or if the site is underlain by coarse-grained soils. Roads
and parking areas shall be stabilized immediately after initial grading.
Purpose: The purpose of traffic area stabilization is to reduce the amount of sediment transported off site
by construction vehicles and to reduce the erosion of areas disturbed by vehicle traffic. Sediment
transported off site onto paved streets is a significant problem because it is difficult to effectively remove,
and any sediment not removed ends up in the drainage system. Additionally, sediment on public right-of-
way can pose a serious traffic hazard. Construction road and parking area stabilization is important
because the combination of wet soil and heavy equipment traffic typically forms a slurry of easily erodible
mud. Finally, stabilization also is an excellent form of dust control in the summer months.
When to Install: The construction entrance is to be installed as the first step in clearing and grading.
Construction road stabilization shall occur immediately after initial grading of the construction roads and
parking areas.
Measures to Use: There are two types of traffic area stabilization: (1) a stabilized construction entrance
and (2) construction road/parking area stabilization. Both measures must be used as specified under
"Conditions of Use" for each measure.
D.3.4 TRAFFIC AREA STABILIZATION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-39
D.3.4.1 STABILIZED CONSTRUCTION ENTRANCE
Code: CE Symbol:
Purpose
Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by
motor vehicles or runoff 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. Access and exits shall be limited to one
route if possible, or two for linear projects such as roadway where more than one access/exit is necessary
for maneuvering large equipment.
Design and Installation Specifications
1. See Figure D.3.4.A for details.
2. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into
the rock pad. The geotextile shall meet the following standards:
Grab Tensile Strength (ASTM D4751) 200 psi min.
Grab Tensile Elongation (ASTM D4632) 30% max.
Mullen Burst Strength (ASTM D3786-80a) 400 psi min.
AOS (ASTM D4751) 20-45 (U.S. standard sieve size)
3. Hog fuel (wood based mulch) may be substituted for or combined with quarry spalls in areas that will
not be used for permanent roads. The effectiveness of hog fuel is highly variable, but it has been used
successfully on many sites. It generally requires more maintenance than quarry spalls. Hog fuel is
not recommended for entrance stabilization in urban areas. 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 difficulties with compaction.
4. Fencing (see Section D.3.1) shall be installed as necessary to restrict traffic to the construction
entrance.
5. Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can
substantially increase the effectiveness of the pad and reduce the need for maintenance.
Maintenance Standards
1. Quarry spalls (or hog fuel) shall be added if the pad is no longer in accordance with the specifications.
2. 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. If washing is used, it
shall be done on an area covered with crushed rock, and wash water shall drain to a sediment trap or
pond.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-40
3. Any sediment that is tracked onto pavement shall be removed immediately by 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, a small sump must be constructed. The sediment
would then be washed into the sump where it can be controlled. Wash water must be pumped back
onto the site and can not discharge to systems tributary to surface waters.
4. Any quarry spalls that are loosened from the pad and end up on the roadway shall be removed
immediately.
5. If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing
(see Section D.3.1) shall be installed to control traffic.
FIGURE D.3.4.A STABILIZED CONSTRUCTION ENTRANCE
!"
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-42
D.3.4.3 WHEEL WASH
Code: WW Symbol:
Purpose
Wheel wash systems reduce the amount of sediment transported onto paved roadways and into surface
water systems by construction vehicles.
Conditions of Use
When a stabilized construction entrance is not preventing sediment from being tracked onto pavement:
Wheel washing is generally an effective erosion and sediment control method and BMP when
installed with careful attention to topography. For example, a wheel wash can be detrimental if
installed at the top of a slope abutting a right-of-way where the water from the dripping truck wheels
and undercarriage can run unimpeded into the street.
Pressure washing combined with an adequately sized and properly surfaced wash pad with direct
drainage discharge to a large 10 foot x 10-foot sump can be very effective.
Design and Installation Specifications
A suggested detail is shown in Figure D.3.4.B.
1. A minimum of 6inches of asphalt treated base (ATB) over crushed base material or 8 inches over a
good subgrade is recommended to pave the wheel wash area.
2. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will
work well to test clearance.
3. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck
tongues with water.
4. Midpoint spray nozzles are only needed in very muddy conditions.
5. Wheel wash systems should be designed with a small grade change, 6 to 12 inches for a 10-foot wide
pond, to allow sediment to flow to the low side of the pond and to help prevent re-suspension of
sediment.
6. A drainpipe with a 2 to 3 foot riser should be installed on the low side of the wheel wash pond to
allow for easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation
in a closed-loop system.
7. Polyacrylamide (PAM) added to the wheel washwater at a rate of 0.25 – 0.5 pounds per 1,000 gallons
of water increases effectiveness and reduces cleanup time. If PAM is already being used for dust or
erosion control and is being applied by a water truck, the same truck may be used to change the
washwater.
Maintenance Standards
1. The wheel wash should start out each day with clean, fresh water.
2. The washwater should be changed a minimum of once per day. On large earthwork jobs where more
than 10-20 trucks per hour are expected, the washwater will need to be changed more often.
3. Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system, such as
a closed-loop recirculation system or land application, or to the sanitary sewer system with proper
local sewer district approval or permits.
D.3.4 TRAFFIC AREA STABILIZATION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-43
FIGURE D.3.4.B WHEEL WASH AND PAVED CONSTRUCTION ENTRANCE
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-44
D.3.5 SEDIMENT RETENTION
Surface water collected from disturbed areas of the site shall be routed through a sediment pond or trap
prior to release from the site. An exception is for areas at the perimeter of the site with drainage areas
small enough to be treated solely with perimeter protection (see Section D.3.3, p. D-30). Also, if the soils
and topography are such that no offsite discharge of surface water is anticipated up to and including the
developed 2-year runoff event, sediment ponds and traps are not required. A 10-year peak flow using
KCRTS with 15-minute time steps shall be used for sediment pond/trap sizing if the project size, expected
timing and duration of construction, or downstream conditions warrant a higher level of protection (see
below). At the County's discretion, sites may be worked during the dry season without sediment ponds
and traps if there is some other form of protection of surface waters, such as a 100-foot forested buffer
between the disturbed areas and adjacent surface waters. For small sites, use the criteria defined in
Section D.3.3, Perimeter Protection to determine minimum flow path length. If the site work has to be
extended into the wet season, a back-up plan must be identified in the CSWPPP and implemented.
Protection of catch basins is required for inlets that are likely to be impacted by sediment generated by the
project and that do not drain to an onsite sediment pond or trap. Sediment retention facilities shall be
installed prior to grading of any contributing area and shall be located so as to avoid interference with the
movement of juvenile salmonids attempting to enter off-channel areas or drainages.
Purpose: The purpose of sediment retention facilities is to remove sediment from runoff generated from
disturbed areas.
When to Install: The facilities shall be constructed as the first step in the clearing and grading of the site.
The surface water conveyances may then be connected to the facilities as site development proceeds.
Measures to Use: There are three sediment retention measures in this section. The first two, sediment
traps and ponds, serve the same function but for different size catchments. All runoff from disturbed areas
must be routed through a trap or pond except for very small areas at the perimeter of the site small enough
to be treated solely with perimeter protection (see Section D.3.3, p. D-30). The third measure is for catch
basin protection. It is only to be used in limited circumstances and is not a primary sediment treatment
facility. It is only intended as a backup in the event of failure of other onsite systems.
Use of Permanent Drainage Facilities: All projects that are constructing permanent facilities for runoff
quantity control are strongly encouraged to use the rough-graded or final-graded permanent facilities for
ponds and traps. This includes combined facilities and infiltration facilities. When permanent facilities
are used as temporary sedimentation facilities, the surface area requirements of sediment traps (for
drainages less than 3 acres) or sediment ponds (more than 3 acres) must be met. If the surface area
requirements are larger than the surface area of the permanent facility, then the pond shall be enlarged to
comply with the surface area requirement. The permanent pond shall also be divided into two cells as
required for sediment ponds. Either a permanent control structure or the temporary control structure
described in Section D.3.5.2 may be used. If a permanent control structure is used, it may be advisable to
partially restrict the lower orifice with gravel to increase residence time while still allowing dewatering of
the pond.
If infiltration facilities are to be used, the sides and bottom of the facility must only be rough excavated to
a minimum of three feet above final grade. Excavation should be done with a backhoe working at "arms
length" to minimize disturbance and compaction of the infiltration surface. Additionally, any required
pretreatment facilities shall be fully constructed prior to any release of sediment-laden water to the
facility. Pretreatment and shallow excavation are intended to prevent the clogging of soil with fines.
Final grading of the infiltration facility shall occur only when all contributing drainage areas are fully
stabilized (see Section D.5.5, p. D-76).
Selection of the Design Storm: In most circumstances, the developed condition 2-year peak flow using
KCRTS with 15-minute time steps is sufficient for calculating surface area for ponds and traps and for
determining exemptions from the sediment retention and surface water collection requirements (Sections
D.3.5 SEDIMENT RETENTION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-45
D.3.5 and D.3.6, respectively). In some circumstances, however, the 10-year KCRTS 15-minute peak
flow should be used. Examples of such circumstances include the following:
Sites that are within ¼ mile of salmonid streams, wetlands, and designated sensitive lakes such as
Lake Sammamish
Sites where significant clearing and grading is likely to occur during the wet season
Sites with downstream erosion or sedimentation problems.
Natural Vegetation: Whenever possible, sediment-laden water shall be discharged into onsite, relatively
level, vegetated areas. This is the only way to effectively remove fine particles from runoff. This can be
particularly useful after initial treatment in a sediment retention facility. The areas of release must be
evaluated on a site-by-site basis in order to determine appropriate locations for and methods of releasing
runoff. Vegetated wetlands shall not be used for this purpose. Frequently, it may be possible to pump
water from the collection point at the downhill end of the site to an upslope vegetated area. Pumping shall
only augment the treatment system, not replace it because of the possibility of pump failure or runoff
volume in excess of pump capacity.
D.3.5.1 SEDIMENT TRAP
Code: ST Symbol:
Purpose
Sediment traps remove sediment from runoff originating from disturbed areas of the site. Sediment traps
are typically designed to only remove sediment as small as medium silt (0.02 mm). As a consequence,
they usually only result in a small reduction in turbidity.
Conditions of Use
A sediment trap shall be used where the contributing drainage area is 3 acres or less.
Design and Installation Specifications
1. See Figure D.3.5.A for details.
2. If permanent runoff control facilities are part of the project, they should be used for sediment retention
(see "Use of Permanent Drainage Facilities" on page D-44).
3. To determine the trap geometry, first calculate the design surface area (SA) of the trap, measured at
the invert of the weir. Use the following equation:
SA =FS(Q2/Vs)
where Q2 = Design inflow (cfs) from the contributing drainage area based on the developed
condition 2-year peak discharge using KCRTS with 15-minute time steps as
computed in the hydrologic analysis. The 10-year KCRTS 15-minute peak flow
shall be used if the project size, expected timing and duration of construction, or
downstream conditions warrant a higher level of protection. If no hydrologic
analysis is required, the Rational Method may be used (Section 3.2.1 of the Surface
Water Design Manual).
Vs = The settling velocity (ft/sec) of the soil particle of interest. The 0.02 mm (medium
silt) particle with an assumed density of 2.65 g/cm3 has been selected as the particle
of interest and has a settling velocity (Vs) of 0.00096 ft/sec.
FS = A safety factor of 2 to account for non-ideal settling.
D.3.5 SEDIMENT RETENTION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-51
D.3.5.3 STORM DRAIN INLET PROTECTION
Code: FFP or CBI or CBP Symbol: or or
Purpose
Storm drain inlets are protected to prevent coarse sediment from entering storm drainage systems.
Temporary devices around storm drains assist in improving the quality of water discharged to inlets or
catch basins by ponding sediment-laden water. These devices are effective only for relatively small
drainage areas.
Conditions of Use
1. Protection shall be provided for all storm drain inlets downslope and within 500 feet of a disturbed or
construction area, unless the runoff that enters the catch basin will be conveyed to a sediment pond or
trap.
2. Inlet protection may be used anywhere at the applicant's discretion to protect the drainage system.
This will, however, require more maintenance, and it is highly likely that the drainage system will still
require some cleaning.
3. The contributing drainage area must not be larger than one acre.
Design and Installation Specifications
1. There are many options for protecting storm drain inlets. Two commonly used options are filter
fabric protection and catch basin inserts.Filter fabric protection (see Figure D.3.5.E) is filter fabric
(geotextile) placed over the grate. This method is generally very ineffective and requires intense
maintenance efforts.Catch basin inserts (see Figure D.3.5.F) are manufactured devices that nest
inside a catch basin. This method also requires a high frequency of maintenance to be effective. Both
options provide adequate protection, but filter fabric is likely to result in ponding of water above the
catch basin, while the insert will not. Thus, filter fabric is only allowed where ponding will not be a
traffic concern and where slope erosion will not result if the curb is overtopped by ponded water.
Trapping sediment in the catch basins is unlikely to improve the water quality of runoff if it is treated
in a pond or trap because the coarse particles that are trapped at the catch basin settle out very quickly
in the pond or trap.Catch basin protection normally only improves water quality where there is
no treatment facility downstream. In these circumstances, catch basin protection is an important
last line of defense. It is not, however, a substitute for preventing erosion.
The placement of filter fabric under grates is generally prohibited and the use of filter fabric over
grates is strictly limited and discouraged.
2. It is sometimes possible to construct a small sump around the catch basin before final surfacing of the
road. This is allowed because it can be a very effective method of sediment control.
3. Block and gravel filters, gravel and wire mesh filter barriers, and bag barriers filled with various
filtering media placed around catch basins can be effective when the drainage area is 1 acre or less
and flows do not exceed 0.5 cfs. It is necessary to allow for overtopping to prevent flooding. Many
manufacturers have various inlet protection filters that are very effective in keeping sediment-laden
water from entering the storm drainage system. The following are examples of a few common
methods.
a)Block and gravel filters (Figure D.3.5.G) are a barrier formed around an inlet with standard
concrete block and gravel, installed as follows:
Height is 1 to 2 feet above the inlet.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-52
Recess the first row of blocks 2 inches into the ground for stability.
Support subsequent rows by placing a 2x4 through the concrete block opening.
Do not use mortar.
Lay some blocks in the bottom row on their side for dewatering the pooled water.
Place cloth or mesh with ½ inch openings over all block openings.
Place gravel below the top of blocks on slopes of 2:1 or flatter.
An alternate design is a gravel donut.
b)Gravel and wire mesh filters consist of a gravel barrier placed over the top of an inlet. This
structure generally does not provide overflow. Install as follows:
Cloth or comparable wire mesh with ½ inch openings is placed over inlet.
Coarse aggregate covers the cloth or mesh.
Height/depth of gravel should be 1 foot or more, 18 inches wider than inlet on all sides.
c)Curb inlet protection with a wooden weir is a barrier formed around an inlet with a wooden
frame and gravel, installed as follows:
Construct a frame and attach wire mesh (½ inch openings) and filter fabric to the frame.
Pile coarse washed aggregate against the wire/fabric.
Place weight on frame anchors.
d)Curb and gutter sediment barriers (Figure D.3.5.H) consist of sandbags or rock berms (riprap
and aggregate) 3 feet high and 3 feet wide in a horseshoe shape, installed as follows:
Bags of either burlap or woven geotextile fabric, filled with a variety of media such as gravel,
wood chips, compost or sand stacked tightly allows water to pond and allows sediment to
separate from runoff.
Leave a "one bag gap" in the top row of the barrier to provide a spillway for overflow.
Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 x 3 and at
least 2 feet from the inlet.
Construct a horseshoe shaped sedimentation trap on the outside of the berm to sediment trap
standards for protecting a culvert inlet.
4.Excavated drop inlet sediment traps are appropriate where relatively heavy flows are expected and
overflow capability is needed. If emergency overflow is provided, additional end-of-pipe treatment
may be required. Excavated drop inlets consist of an excavated impoundment area around a storm
drain. Sediment settles out of the stormwater prior to enter the drain. Install according to the
following specifications:
a) The impoundment area should have a depth of 1 - 2 feet measured from the crest of the inlet
structure.
b) Side slopes of the excavated area must be no steeper than 2:1.
c) Minimum volume of the excavated area should be 35 cubic yards.
d) Install provisions for draining the area to prevent standing water problems.
e) Keep the area clear of debris.
f) Weep holes may be drilled into the side of the inlet.
g) Protect weep holes with wire mesh and washed aggregate.
D.3.5 SEDIMENT RETENTION
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-53
h) Weep holes must be sealed when removing and stabilizing excavated area.
i) A temporary dike may be necessary on the down slope side of the structure to prevent bypass
flow.
Maintenance Standards
1. Any accumulated sediment on or around inlet protection shall be removed immediately. Sediment
shall not be removed with water, and all sediment must be disposed of as fill on site or hauled off site.
2. Any sediment in the catch basin insert shall be removed when the sediment has filled one-third of the
available storage. The filter media for the insert shall be cleaned or replaced at least monthly.
3. Regular maintenance is critical for all forms of catch basin/inlet protection. Unlike many forms of
protection that fail gradually, catch basin protection will fail suddenly and completely if not maintained
properly.
FIGURE D.3.5.E FILTER FABRIC PROTECTION
FIGURE D.3.5.F CATCH BASIN INSERT
D.3.7 DEWATERING CONTROL
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-65
D.3.7 DEWATERING CONTROL
Any runoff generated by dewatering shall be treated through construction of a sediment trap (Section
D.3.5.1) when there is sufficient space or by releasing the water to a well vegetated, gently sloping area.
Since pumps are used for dewatering, it may be possible to pump the sediment-laden water well away
from the surface water so that vegetation can be more effectively utilized for treatment. Discharge of
sediment-laden water from dewatering activities to surface and storm waters is prohibited. If dewatering
occurs from areas where the water has come in contact with new concrete, such as tanks, vaults, or
foundations, the pH of the water must be monitored and must be neutralized prior to discharge. Clean
non-turbid dewatering water, such as well point ground water can be discharged to systems tributary to, or
directly to surface waters provided the flows are controlled so no erosion or flooding occurs. Clean water
must not be routed through a stormwater sediment pond. Highly turbid or contaminated dewatering water
must be handled separately from stormwater.
Purpose: To prevent the untreated discharge of sediment-laden water from dewatering of utilities,
excavated areas, foundations, etc.
When to Install: Dewatering control measures shall be used whenever there is a potential for runoff from
dewatering of utilities, excavations, foundations, etc.
Measures to install:
1. Foundation, vault, excavation, and trench dewatering water that has similar characteristics to
stormwater runoff at the site shall be discharged into a controlled conveyance system prior to
discharge to a sediment trap or sediment pond. Foundation and trench dewatering water, which has
similar characteristics to stormwater runoff at the site, must be disposed of through one of the
following options depending on site constraints:
a) Infiltration,
b) Transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that
does not pollute surface waters,
c) Discharge to the sanitary sewer discharge with local sewer district approval if there is no other
option, or
d) Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized
dewatering.
2. Clean, non-turbid dewatering water, such as well-point ground water, may be discharged via stable
conveyance to systems tributary to surface waters, provided the dewatering flow does not cause
erosion or flooding of receiving waters.
3. Highly turbid or contaminated dewatering water shall be handled separately from stormwater.
SECTION D.3 ESC MEASURES
1/9/2009 2009 Surface Water Design Manual – Appendix D D-66
D.3.8 DUST CONTROL
Preventative measures to minimize the wind transport of soil shall be taken when a traffic hazard may be
created or when sediment transported by wind is likely to be deposited in water resources or adjacent
properties.
Purpose: To prevent wind transport of dust from exposed soil surfaces onto roadways, drainage ways, and
surface waters.
When to Install: Dust control shall be implemented when exposed soils are dry to the point that wind
transport is possible and roadways, drainage ways, or surface waters are likely to be impacted. Dust
control measures may consist of chemical, structural, or mechanical methods.
Measures to Install: Water is the most common dust control (or palliative) used in the area. When using
water for dust control, the exposed soils shall be sprayed until wet, but runoff shall not be generated by
spraying. Calcium chloride, Magnesium chloride, Lignin derivatives, Tree Resin Emulsions, and
Synthetic Polymer Emulsions may also be used for dust control. Exposed areas shall be re-sprayed as
needed. Oil shall not be used for dust control. The following table lists many common dust control
measures. Some of the measures are not recommended for use in King County and must have prior
approval prior to use from the DDES inspector assigned to specific projects.
D.3.8 DUST CONTROL
2009 Surface Water Design Manual – Appendix D 1/9/2009 D-67
TABLE D.3.8.A DUST CONTROL MEASURES*
METHOD CONSIDERATIONS SITE PREPARATION RECOMMENDEDAPPLICATION RATE
Water -Most commonly used practice-Evaporates quickly-Lasts less than 1 day
For all liquid agents:-Blade a small surface-Crown or slope surface to avoidponding-Compact soils if needed-Uniformly pre-wet at0.03 – 0.3 gal/sq yd-Apply solution under pressure.Overlap solution 6 – 12 inches-Allow treated area to cure0 – 4 hours
-Compact area after curing-Apply second treatment before first
treatment becomes ineffective
0.125 gal/sq yd every20 to 30 minutes
SaltsCalciumChloride(CaCl)
-Restricts evaporation-Lasts 6-12 months-Can be corrosive-Less effective in low humidity-Can build up in soils and leach by rain
Apply 38% solution at1.21L/m2 (0.27 gal/yd2)or as loose dry granulesper manufacturer
MagnesiumChloride(MgCl)
-Restricts evaporation-Works at higher temperatures and lowerhumidity than CaCl-May be more costly than CaCl
Apply 26 – 32% solutionat 2.3 L/m2 (0.5gal/yd2)
Sodium
Chloride(NaCl)
-Effective over smaller range of
conditions-Less expensive
-Can be corrosive-Less effective in low humidity
Per Manufacturer
Silicates -Generally expensive
-Available in small quantities-Require Second application
Surfactants -High evaporation rates-Effective for short time periods-Must apply frequently
Copolymers -Forms semi-permeable transparentcrust-Resists ultraviolet radiation and moistureinduced breakdown-Last 1 to 2 years
750 – 940 L/ha (80 –100 gal/ac)
Petroleum
Products
-Used oil is prohibited as a dust control
method-Bind soil particles
-May hinder foliage growth-Environmental and aesthetic concerns
-Higher cost
Use 57 – 63% resins as
base. Apply at 750 –940 L/ha (80-100
gal/ac)
LigninSulfonate -Paper industry waste product-Acts as dispersing agent
-Best in dry climates-Can be slippery
-Will decrease Dissolved Oxygen inwaterways therefore cannot be used
adjacent to surface water systems
Loosen surface 25-50mm (1 – 2 inches) Need
4-8% fines
VegetableOils -Coat grains of soils, so limited bindingability-May become brittle-Limited availability
Per Manufacturer
Spray onAdhesives -Available as organic or synthetic-Effective on dry, hard soils-Forms a crust-Can last 3 to 4 years
Per Manufacturer
Volume II – Construction Stormwater Pollution Prevention - August 2012
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Use geotextile fabrics to increase the strength of new roads or roads
undergoing reconstruction.
Encourage the use of alternate, paved routes, if available.
Restrict use of paved roadways by tracked vehicles and heavy trucks
to prevent damage to road surface and base.
Apply chemical dust suppressants using the admix method, blending
the product with the top few inches of surface material. Suppressants
may also be applied as surface treatments.
Pave unpaved permanent roads and other trafficked areas.
Use vacuum street sweepers.
Remove mud and other dirt promptly so it does not dry and then turn
into dust.
Limit dust-causing work on windy days.
Contact your local Air Pollution Control Authority for guidance and
training on other dust control measures. Compliance with the local Air
Pollution Control Authority constitutes compliance with this BMP.
Maintenance
Standards
Respray area as necessary to keep dust to a minimum.
BMP C150: Materials on Hand
Purpose Keep quantities of erosion prevention and sediment control materials on
the project site at all times to be used for regular maintenance and
emergency situations such as unexpected heavy summer rains. Having
these materials on-site reduces the time needed to implement BMPs when
inspections indicate that existing BMPs are not meeting the Construction
SWPPP requirements. In addition, contractors can save money by buying
some materials in bulk and storing them at their office or yard.
Conditions of Use Construction projects of any size or type can benefit from having
materials on hand. A small commercial development project could
have a roll of plastic and some gravel available for immediate
protection of bare soil and temporary berm construction. A large
earthwork project, such as highway construction, might have several
tons of straw, several rolls of plastic, flexible pipe, sandbags,
geotextile fabric and steel “T” posts.
Materials are stockpiled and readily available before any site clearing,
grubbing, or earthwork begins. A large contractor or developer could
keep a stockpile of materials that are available for use on several
projects.
If storage space at the project site is at a premium, the contractor could
maintain the materials at their office or yard. The office or yard must
be less than an hour from the project site.
Volume II – Construction Stormwater Pollution Prevention - August 2012
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Design and
Installation
Specifications
Depending on project type, size, complexity, and length, materials and
quantities will vary. A good minimum list of items that will cover
numerous situations includes:
Material
Clear Plastic, 6 mil
Drainpipe, 6 or 8 inch diameter
Sandbags, filled
Straw Bales for mulching,
Quarry Spalls
Washed Gravel
Geotextile Fabric
Catch Basin Inserts
Steel “T” Posts
Silt fence material
Straw Wattles
Maintenance
Standards
All materials with the exception of the quarry spalls, steel “T” posts,
and gravel should be kept covered and out of both sun and rain.
Re-stock materials used as needed.
BMP C151: Concrete Handling
Purpose Concrete work can generate process water and slurry that contain fine
particles and high pH, both of which can violate water quality standards in
the receiving water. Concrete spillage or concrete discharge to surface
waters of the State is prohibited. Use this BMP to minimize and eliminate
concrete, concrete process water, and concrete slurry from entering waters
of the state.
Conditions of Use Any time concrete is used, utilize these management practices. Concrete
construction projects include, but are not limited to, the following:
Curbs
Sidewalks
Roads
Bridges
Foundations
Floors
Runways
Design and
Installation
Wash out concrete truck chutes, pumps, and internals into formed
areas only. Assure that washout of concrete trucks is performed off-
Volume II – Construction Stormwater Pollution Prevention - August 2012
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Specifications site or in designated concrete washout areas. Do not wash out concrete
trucks onto the ground, or into storm drains, open ditches, streets, or
streams. Refer to BMP C154 for information on concrete washout
areas.
Return unused concrete remaining in the truck and pump to the
originating batch plant for recycling. Do not dump excess concrete on
site, except in designated concrete washout areas.
Wash off hand tools including, but not limited to, screeds, shovels,
rakes, floats, and trowels into formed areas only.
Wash equipment difficult to move, such as concrete pavers in areas
that do not directly drain to natural or constructed stormwater
conveyances.
Do not allow washdown from areas, such as concrete aggregate
driveways, to drain directly to natural or constructed stormwater
conveyances.
Contain washwater and leftover product in a lined container when no
formed areas are available,. Dispose of contained concrete in a manner
that does not violate ground water or surface water quality standards.
Always use forms or solid barriers for concrete pours, such as pilings,
within 15-feet of surface waters.
Refer to BMPs C252 and C253 for pH adjustment requirements.
Refer to the Construction Stormwater General Permit for pH
monitoring requirements if the project involves one of the following
activities:
Significant concrete work (greater than 1,000 cubic yards poured
concrete or recycled concrete used over the life of a project).
The use of engineered soils amended with (but not limited to)
Portland cement-treated base, cement kiln dust or fly ash.
Discharging stormwater to segments of water bodies on the 303(d)
list (Category 5) for high pH.
Maintenance
Standards
Check containers for holes in the liner daily during concrete pours and
repair the same day.
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BMP C152: Sawcutting and Surfacing Pollution Prevention
Purpose Sawcutting and surfacing operations generate slurry and process water
that contains fine particles and high pH (concrete cutting), both of which
can violate the water quality standards in the receiving water. Concrete
spillage or concrete discharge to surface waters of the State is prohibited.
Use this BMP to minimize and eliminate process water and slurry created
through sawcutting or surfacing from entering waters of the State.
Conditions of Use Utilize these management practices anytime sawcutting or surfacing
operations take place. Sawcutting and surfacing operations include, but
are not limited to, the following:
Sawing
Coring
Grinding
Roughening
Hydro-demolition
Bridge and road surfacing
Design and
Installation
Specifications
Vacuum slurry and cuttings during cutting and surfacing operations.
Slurry and cuttings shall not remain on permanent concrete or asphalt
pavement overnight.
Slurry and cuttings shall not drain to any natural or constructed
drainage conveyance including stormwater systems. This may require
temporarily blocking catch basins.
Dispose of collected slurry and cuttings in a manner that does not
violate ground water or surface water quality standards.
Do not allow process water generated during hydro-demolition,
surface roughening or similar operations to drain to any natural or
constructed drainage conveyance including stormwater systems.
Dispose process water in a manner that does not violate ground water
or surface water quality standards.
Handle and dispose cleaning waste material and demolition debris in a
manner that does not cause contamination of water. Dispose of
sweeping material from a pick-up sweeper at an appropriate disposal
site.
Maintenance
Standards
Continually monitor operations to determine whether slurry, cuttings, or
process water could enter waters of the state. If inspections show that a
violation of water quality standards could occur, stop operations and
immediately implement preventive measures such as berms, barriers,
secondary containment, and vacuum trucks.
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BMP C153: Material Delivery, Storage and Containment
Purpose Prevent, reduce, or eliminate the discharge of pollutants to the
stormwater system or watercourses from material delivery and storage.
Minimize the storage of hazardous materials on-site, store materials in a
designated area, and install secondary containment.
Conditions of Use These procedures are suitable for use at all construction sites with
delivery and storage of the following materials:
Petroleum products such as fuel, oil and grease
Soil stabilizers and binders (e.g. Polyacrylamide)
Fertilizers, pesticides and herbicides
Detergents
Asphalt and concrete compounds
Hazardous chemicals such as acids, lime, adhesives, paints, solvents
and curing compounds
Any other material that may be detrimental if released to the
environment
Design and
Installation
Specifications
The following steps should be taken to minimize risk:
Temporary storage area should be located away from vehicular traffic,
near the construction entrance(s), and away from waterways or storm
drains.
Material Safety Data Sheets (MSDS) should be supplied for all
materials stored. Chemicals should be kept in their original labeled
containers.
Hazardous material storage on-site should be minimized.
Hazardous materials should be handled as infrequently as possible.
During the wet weather season (Oct 1 – April 30), consider storing
materials in a covered area.
Materials should be stored in secondary containments, such as earthen
dike, horse trough, or even a children’s wading pool for non-reactive
materials such as detergents, oil, grease, and paints. Small amounts of
material may be secondarily contained in “bus boy” trays or concrete
mixing trays.
Do not store chemicals, drums, or bagged materials directly on the
ground. Place these items on a pallet and, when possible, and within
secondary containment.
If drums must be kept uncovered, store them at a slight angle to reduce
ponding of rainwater on the lids to reduce corrosion. Domed plastic
covers are inexpensive and snap to the top of drums, preventing water
from collecting.
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Material Storage Areas and Secondary Containment Practices:
Liquids, petroleum products, and substances listed in 40 CFR Parts
110, 117, or 302 shall be stored in approved containers and drums and
shall not be overfilled. Containers and drums shall be stored in
temporary secondary containment facilities.
Temporary secondary containment facilities shall provide for a spill
containment volume able to contain 10% of the total enclosed
container volume of all containers, or 110% of the capacity of the
largest container within its boundary, whichever is greater.
Secondary containment facilities shall be impervious to the materials
stored therein for a minimum contact time of 72 hours.
Secondary containment facilities shall be maintained free of
accumulated rainwater and spills. In the event of spills or leaks,
accumulated rainwater and spills shall be collected and placed into
drums. These liquids shall be handled as hazardous waste unless
testing determines them to be non-hazardous.
Sufficient separation should be provided between stored containers to
allow for spill cleanup and emergency response access.
During the wet weather season (Oct 1 – April 30), each secondary
containment facility shall be covered during non-working days, prior
to and during rain events.
Keep material storage areas clean, organized and equipped with an
ample supply of appropriate spill clean-up material (spill kit).
The spill kit should include, at a minimum:
1-Water Resistant Nylon Bag
3-Oil Absorbent Socks 3”x 4’
2-Oil Absorbent Socks 3”x 10’
12-Oil Absorbent Pads 17”x19”
1-Pair Splash Resistant Goggles
3-Pair Nitrile Gloves
10-Disposable Bags with Ties
Instructions
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BMP C154: Concrete Washout Area
Purpose Prevent or reduce the discharge of pollutants to stormwater from concrete
waste by conducting washout off-site, or performing on-site washout in a
designated area to prevent pollutants from entering surface waters or
ground water.
Conditions of Use Concrete washout area best management practices are implemented on
construction projects where:
Concrete is used as a construction material
It is not possible to dispose of all concrete wastewater and washout
off-site (ready mix plant, etc.).
Concrete trucks, pumpers, or other concrete coated equipment are
washed on-site.
Note: If less than 10 concrete trucks or pumpers need to be washed out
on-site, the washwater may be disposed of in a formed area awaiting
concrete or an upland disposal site where it will not contaminate
surface or ground water. The upland disposal site shall be at least 50
feet from sensitive areas such as storm drains, open ditches, or water
bodies, including wetlands.
Design and
Installation
Specifications
Implementation
The following steps will help reduce stormwater pollution from concrete
wastes:
Perform washout of concrete trucks off-site or in designated concrete
washout areas only.
Do not wash out concrete trucks onto the ground, or into storm drains,
open ditches, streets, or streams.
Do not allow excess concrete to be dumped on-site, except in
designated concrete washout areas.
Concrete washout areas may be prefabricated concrete washout
containers, or self-installed structures (above-grade or below-grade).
Prefabricated containers are most resistant to damage and protect
against spills and leaks. Companies may offer delivery service and
provide regular maintenance and disposal of solid and liquid waste.
If self-installed concrete washout areas are used, below-grade
structures are preferred over above-grade structures because they are
less prone to spills and leaks.
Self-installed above-grade structures should only be used if excavation
is not practical.
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Education
Discuss the concrete management techniques described in this BMP
with the ready-mix concrete supplier before any deliveries are made.
Educate employees and subcontractors on the concrete waste
management techniques described in this BMP.
Arrange for contractor’s superintendent or Certified Erosion and
Sediment Control Lead (CESCL) to oversee and enforce concrete
waste management procedures.
A sign should be installed adjacent to each temporary concrete
washout facility to inform concrete equipment operators to utilize the
proper facilities.
Contracts
Incorporate requirements for concrete waste management into concrete
supplier and subcontractor agreements.
Location and Placement
Locate washout area at least 50 feet from sensitive areas such as storm
drains, open ditches, or water bodies, including wetlands.
Allow convenient access for concrete trucks, preferably near the area
where the concrete is being poured.
If trucks need to leave a paved area to access washout, prevent track-
out with a pad of rock or quarry spalls (see BMP C105). These areas
should be far enough away from other construction traffic to reduce
the likelihood of accidental damage and spills.
The number of facilities you install should depend on the expected
demand for storage capacity.
On large sites with extensive concrete work, washouts should be
placed in multiple locations for ease of use by concrete truck drivers.
On-site Temporary Concrete Washout Facility, Transit Truck
Washout Procedures:
Temporary concrete washout facilities shall be located a minimum of
50 ft from sensitive areas including storm drain inlets, open drainage
facilities, and watercourses. See Figures 4.1.7 and 4.1.8.
Concrete washout facilities shall be constructed and maintained in
sufficient quantity and size to contain all liquid and concrete waste
generated by washout operations.
Approximately 7 gallons of wash water are used to wash one truck
chute.
Approximately 50 gallons are used to wash out the hopper of a
concrete pump truck.
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Washout of concrete trucks shall be performed in designated areas
only.
Concrete washout from concrete pumper bins can be washed into
concrete pumper trucks and discharged into designated washout area
or properly disposed of off-site.
Once concrete wastes are washed into the designated area and allowed
to harden, the concrete should be broken up, removed, and disposed of
per applicable solid waste regulations. Dispose of hardened concrete
on a regular basis.
Temporary Above-Grade Concrete Washout Facility
Temporary concrete washout facility (type above grade) should be
constructed as shown on the details below, with a recommended
minimum length and minimum width of 10 ft, but with sufficient
quantity and volume to contain all liquid and concrete waste
generated by washout operations.
Plastic lining material should be a minimum of 10 mil
polyethylene sheeting and should be free of holes, tears, or other
defects that compromise the impermeability of the material.
Temporary Below-Grade Concrete Washout Facility
Temporary concrete washout facilities (type below grade) should
be constructed as shown on the details below, with a recommended
minimum length and minimum width of 10 ft. The quantity and
volume should be sufficient to contain all liquid and concrete
waste generated by washout operations.
Lath and flagging should be commercial type.
Plastic lining material shall be a minimum of 10 mil polyethylene
sheeting and should be free of holes, tears, or other defects that
compromise the impermeability of the material.
Liner seams shall be installed in accordance with manufacturers’
recommendations.
Soil base shall be prepared free of rocks or other debris that may
cause tears or holes in the plastic lining material.
Maintenance
Standards
Inspection and Maintenance
Inspect and verify that concrete washout BMPs are in place prior to the
commencement of concrete work.
During periods of concrete work, inspect daily to verify continued
performance.
Check overall condition and performance.
Check remaining capacity (% full).
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If using self-installed washout facilities, verify plastic liners are
intact and sidewalls are not damaged.
If using prefabricated containers, check for leaks.
Washout facilities shall be maintained to provide adequate holding
capacity with a minimum freeboard of 12 inches.
Washout facilities must be cleaned, or new facilities must be
constructed and ready for use once the washout is 75% full.
If the washout is nearing capacity, vacuum and dispose of the waste
material in an approved manner.
Do not discharge liquid or slurry to waterways, storm drains or
directly onto ground.
Do not use sanitary sewer without local approval.
Place a secure, non-collapsing, non-water collecting cover over the
concrete washout facility prior to predicted wet weather to prevent
accumulation and overflow of precipitation.
Remove and dispose of hardened concrete and return the structure
to a functional condition. Concrete may be reused on-site or hauled
away for disposal or recycling.
When you remove materials from the self-installed concrete washout,
build a new structure; or, if the previous structure is still intact, inspect
for signs of weakening or damage, and make any necessary repairs.
Re-line the structure with new plastic after each cleaning.
Removal of Temporary Concrete Washout Facilities
When temporary concrete washout facilities are no longer required for
the work, the hardened concrete, slurries and liquids shall be removed
and properly disposed of.
Materials used to construct temporary concrete washout facilities shall
be removed from the site of the work and disposed of or recycled.
Holes, depressions or other ground disturbance caused by the removal
of the temporary concrete washout facilities shall be backfilled,
repaired, and stabilized to prevent erosion.
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Figure 4.1.7a – Concrete Washout Area
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The Chemical Process:
When carbon dioxide (CO2) is added to water (H2O), carbonic acid
(H2CO3) is formed which can further dissociate into a proton (H+) and a
bicarbonate anion (HCO3-) as shown below:
CO2 + H2O H2CO3 H++ HCO3-
The free proton is a weak acid that can lower the pH. Water temperature
has an effect on the reaction as well. The colder the water temperature is
the slower the reaction occurs and the warmer the water temperature is the
quicker the reaction occurs. Most construction applications in Washington
State have water temperatures in the 50°F or higher range so the reaction
is almost simultaneous.
Design and
Installation
Specifications
Treatment Process:
High pH water may be treated using continuous treatment, continuous
discharge systems. These manufactured systems continuously monitor
influent and effluent pH to ensure that pH values are within an acceptable
range before being discharged. All systems must have fail safe automatic
shut off switches in the event that pH is not within the acceptable
discharge range. Only trained operators may operate manufactured
systems. System manufacturers often provide trained operators or training
on their devices.
The following procedure may be used when not using a continuous
discharge system:
1. Prior to treatment, the appropriate jurisdiction should be notified in
accordance with the regulations set by the jurisdiction.
2. Every effort should be made to isolate the potential high pH water in
order to treat it separately from other stormwater on-site.
3. Water should be stored in an acceptable storage facility, detention
pond, or containment cell prior to treatment.
4. Transfer water to be treated to the treatment structure. Ensure that
treatment structure size is sufficient to hold the amount of water that is
to be treated. Do not fill tank completely, allow at least 2 feet of
freeboard.
5. The operator samples the water for pH and notes the clarity of the
water. As a rule of thumb, less CO2 is necessary for clearer water. This
information should be recorded.
6. In the pH adjustment structure, add CO2 until the pH falls in the range
of 6.9-7.1. Remember that pH water quality standards apply so
adjusting pH to within 0.2 pH units of receiving water (background
pH) is recommended. It is unlikely that pH can be adjusted to within
0.2 pH units using dry ice. Compressed carbon dioxide gas should be
introduced to the water using a carbon dioxide diffuser located near
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the bottom of the tank, this will allow carbon dioxide to bubble up
through the water and diffuse more evenly.
7. Slowly discharge the water making sure water does not get stirred up
in the process. Release about 80% of the water from the structure
leaving any sludge behind.
8. Discharge treated water through a pond or drainage system.
9. Excess sludge needs to be disposed of properly as concrete waste. If
several batches of water are undergoing pH treatment, sludge can be
left in treatment structure for the next batch treatment. Dispose of
sludge when it fills 50% of tank volume.
Sites that must implement flow control for the developed site must also
control stormwater release rates during construction. All treated
stormwater must go through a flow control facility before being released
to surface waters which require flow control.
Maintenance
Standards
Safety and Materials Handling:
All equipment should be handled in accordance with OSHA rules and
regulations.
Follow manufacturer guidelines for materials handling.
Operator Records:
Each operator should provide:
A diagram of the monitoring and treatment equipment.
A description of the pumping rates and capacity the treatment
equipment is capable of treating.
Each operator should keep a written record of the following:
Client name and phone number.
Date of treatment.
Weather conditions.
Project name and location.
Volume of water treated.
pH of untreated water.
Amount of CO2 needed to adjust water to a pH range of 6.9-7.1.
pH of treated water.
Discharge point location and description.
A copy of this record should be given to the client/contractor who should
retain the record for three years.
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BMP C253: pH Control for High pH Water
Purpose When pH levels in stormwater rise above 8.5 it is necessary to lower the
pH levels to the acceptable range of 6.5 to 8.5, this process is called pH
neutralization. Stormwater with pH levels exceeding water quality
standards may be treated by infiltration, dispersion in vegetation or
compost, pumping to a sanitary sewer, disposal at a permitted concrete
batch plant with pH neutralization capabilities, or carbon dioxide sparging.
BMP C252 gives guidelines for carbon dioxide sparging.
Reason for pH Neutralization:
A pH level range of 6.5 to 8.5 is typical for most natural watercourses, and
this pH range is required for the survival of aquatic organisms. Should the
pH rise or drop out of this range, fish and other aquatic organisms may
become stressed and may die.
Conditions of Use Causes of High pH:
High pH levels at construction sites are most commonly caused by the
contact of stormwater with poured or recycled concrete, cement, mortars,
and other Portland cement or lime containing construction materials. (See
BMP C151: Concrete Handling for more information on concrete handling
procedures). The principal caustic agent in cement is calcium hydroxide
(free lime).
Design and
Installation
Specifications
Disposal Methods:
Infiltration
Infiltration is only allowed if soil type allows all water to infiltrate (no
surface runoff) without causing or contributing to a violation of
surface or ground water quality standards.
Infiltration techniques should be consistent with Volume V, Chapter 7
Dispersion
Use BMP T5.30 Full Dispersion
Sanitary Sewer Disposal
Local sewer authority approval is required prior to disposal via the
sanitary sewer.
Concrete Batch Plant Disposal
Only permitted facilities may accept high pH water.
Facility should be contacted before treatment to ensure they can accept
the high pH water.
Stormwater Discharge
Any pH treatment options that generate treated water that must be
discharged off site are subject to flow control requirements. Sites that
must implement flow control for the developed site must also control
VolumeII–ConstructionStormwaterPollutionPrevention-August20124-127stormwaterreleaseratesduringconstruction.Alltreatedstormwatermustgothroughaflowcontrolfacilitybeforebeingreleasedtosurfacewaterswhichrequireflowcontrol.
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S406 BMPs for Streets/ Highways
Applicable BMPs:
Select de and anti-icers that cause the least adverse environmental
impact. Apply only as needed using minimum quantities.
Where practicable use roadway deicers, such as calcium magnesium
acetate, potassium acetate, or similar materials, that cause less adverse
environmental impact than urea, and sodium chloride.
Store and transfer de and anti-icing materials on an impervious
containment pad in accordance with BMP Storage or Transfer
(Outside) of Solid Raw Materials, By-Products, or Finished Products
in this volume.
Sweep/clean up accumulated de and anti-icing materials and grit from
roads as soon as possible after the road surface clears.
Recommended Additional BMPs
Intensify roadway cleaning in early spring to help remove particulates
from road surfaces.
Include limits on toxic metals in the specifications for de/anti-icers.
S407 BMPs for Dust Control at Disturbed Land Areas and Unpaved Roadways
and Parking Lots
Description of Pollutant Sources:Dust can cause air and water pollution
problems particularly at demolition sites and in arid areas where reduced
rainfall exposes soil particles to transport by air.
Pollutant Control Approach:Minimize dust generation and apply
environmentally friendly and government approved dust suppressant
chemicals, if necessary.
Applicable Operational BMPs:
Sprinkle or wet down soil or dust with water as long as it does not
result in a wastewater discharge.
Use only local and/or state government approved dust suppressant
chemicals such as those listed in Ecology Publication #96-433,
Techniques for Dust Prevention and Suppression.
Avoid excessive and repeated applications of dust suppressant
chemicals. Time the application of dust suppressants to avoid or
minimize their wash-off by rainfall or human activity such as
irrigation.
Apply stormwater containment to prevent the conveyance of sediment
into storm drains or receiving waters.
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Ecology prohibits the use of motor oil for dust control. Take care when
using lignin derivatives and other high BOD chemicals in areas
susceptible to contaminating surface water or ground water.
Consult with Ecology and the local permitting authority on discharge
permit requirements if the dust suppression process results in a
wastewater discharge to the ground, ground water, storm drain, or
surface water.
Recommended Additional Operational BMPs for Roadways and
Other Trafficked Areas:
Consider limiting use of off-road recreational vehicles on dust
generating land.
Consider graveling or paving unpaved permanent roads and other
trafficked areas at municipal, commercial, and industrial areas.
Consider paving or stabilizing shoulders of paved roads with gravel,
vegetation, or local government approved chemicals.
Encourage use of alternate paved routes, if available.
Vacuum sweep fine dirt and skid control materials from paved roads
soon after winter weather ends or when needed.
Consider using pre-washed traction sand to reduce dust emissions.
Additional Recommended Operational BMPs for Dust Generating
Areas:
Prepare a dust control plan. Helpful references include: Control of
Open Fugitive Dust Sources (EPA-450/3-88-088), and Fugitive Dust
Background Document and Technical Information Document for Best
Available Control Measures (EPA-450/2-92-004).
Limit exposure of soil (dust source) as much as feasible.
Stabilize dust-generating soil by growing and maintaining vegetation,
mulching, topsoiling, and/or applying stone, sand, or gravel.
Apply windbreaks in the soil such as trees, board fences, tarp curtains,
bales of hay, etc.
S408 BMPs for Dust Control at Manufacturing Areas
Description of Pollutant Sources:Industrial material handling activities
can generate considerable amounts of dust that is typically removed using
exhaust systems. Mixing cement and concrete products and handling
powdered materials can also generate dust. Particulate materials that can
cause air pollution include grain dust, sawdust, coal, gravel, crushed rock,
cement, and boiler fly ash. Air emissions can contaminate stormwater. The
objective of this BMP is to reduce the stormwater pollutants caused by
dust generation and control.
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Pollutant Control Approach:Prevent dust generation and emissions
where feasible, regularly clean-up dust that can contaminate stormwater,
and convey dust contaminated stormwater to proper treatment.
Applicable BMPs:
Clean, as needed, powder material handling equipment and vehicles.
Regularly sweep dust accumulation areas that can contaminate
stormwater. Conduct sweeping using vacuum filter equipment to
minimize dust generation and to ensure optimal dust removal.
Recommended BMPs:
In manufacturing operations, train employees to handle powders
carefully to prevent generation of dust.
Use dust filtration/collection systems such as bag house filters, cyclone
separators, etc. to control vented dust emissions that could contaminate
stormwater. Control of zinc dusts in rubber production is one example.
Use water spray to flush dust accumulations to sanitary sewers where
allowed by the local sewer authority or to other appropriate treatment
system.
Use approved dust suppressants such as those listed in Ecology
Publication Techniques for Dust Prevention and Suppression, #96-433
(Ecology, 1996). Application of some products may not be appropriate
in close proximity to receiving waters or conveyances close to
receiving waters. For more information check with Ecology or the
local jurisdiction.
Recommended Treatment BMPs:Install sedimentation basins, wet
ponds, wet vaults, catch basin filters, vegetated filter strips, or equivalent
sediment removal BMPs.
S409 BMPs for Fueling At Dedicated Stations
Description of Pollutant Sources:A fueling station is a facility dedicated to
the transfer of fuels from a stationary pumping station to mobile vehicles or
equipment. It includes above or under-ground fuel storage facilities. In
addition to general service gas stations, fueling may also occur at 24-hour
convenience stores, construction sites, warehouses, car washes,
manufacturing establishments, port facilities, and businesses with fleet
vehicles. Typical causes of stormwater contamination at fueling stations
include leaks/spills of fuels, lube oils, radiator coolants, and vehicle
washwater.
Pollutant Control Approach:New or substantially remodeled* fueling
stations must be constructed on an impervious concrete pad under a roof to
keep out rainfall and stormwater run-on. The facility must use a treatment
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BMP for contaminated stormwater and wastewaters in the fueling
containment area.
*Substantial remodeling includes replacing the canopy, or relocating or
adding one or more fuel dispensers in such a way that modify the Portland
cement concrete (or equivalent) paving in the fueling area.
For new or substantially remodeled Fueling Stations:
Applicable Operational BMPs:
Prepare an emergency spill response and cleanup plan (per S426
BMPs for Spills of Oil and Hazardous Substances) and have
designated trained person(s) available either on site or on call at all
times to promptly and properly implement that plan and immediately
cleanup all spills. Keep suitable cleanup materials, such as dry
adsorbent materials, on site to allow prompt cleanup of a spill.
Train employees on the proper use of fuel dispensers. Post signs in
accordance with the Uniform Fire Code (UFC) or International Fire
Code (IFC). Post “No Topping Off” signs (topping off gas tanks
causes spillage and vents gas fumes to the air). Make sure that the
automatic shutoff on the fuel nozzle is functioning properly.
The person conducting the fuel transfer must be present at the fueling
pump during fuel transfer, particularly at unattended or self-serve
stations.
Keep drained oil filters in a suitable container or drum.
Applicable Structural Source Control BMPs:
Design the fueling island to control spills (dead-end sump or spill
control separator in compliance with the UFC or IFC), and to treat
collected stormwater and/or wastewater to required levels. Slope the
concrete containment pad around the fueling island toward drains;
either trench drains, catch basins and/or a dead-end sump. The slope of
the drains shall not be less than 1 percent (Section 7901.8 of the UFC,
Section 5703.6.8 of the IFC).
Drains to treatment facilities must have a normally closed shutoff
valve. The spill control sump must be sized in compliance with
Section 7901.8 of the UFC; or
Design the fueling island as a spill containment pad with a sill or berm
raised to a minimum of four inches (Section 7901.8 of the UFC) to
prevent the runoff of spilled liquids and to prevent run-on of
stormwater from the surrounding area. Raised sills are not required at
the open-grate trenches that connect to an approved drainage-control
system.
The fueling pad must be paved with Portland cement concrete, or
equivalent. Ecology does not consider asphalt an equivalent material.
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of the mixture. Stormwater could be conveyed to a sanitary sewer
system if it is determined not to be explosive.
Transfer the fuel from the delivery tank trucks to the fuel storage tank
in impervious contained areas and ensure that appropriate overflow
protection is used. Alternatively, cover nearby storm drains during the
filling process and use drip pans under all hose connections.
Additional BMP for Vehicles 10 feet in height or greater
A roof or canopy may not be feasible at fueling stations that regularly fuel
vehicles that are 10 feet in height or greater, particularly at industrial or
WSDOT sites. At those types of fueling facilities, the following BMPs
apply, as well as the applicable BMPs and fire prevention (UFC
requirements) of this BMP for fueling stations:
If a roof or canopy is impractical, the concrete fueling pad must be
equipped with emergency spill control including a shutoff valve for
drainage from the fueling area. Maintain the valve in the closed
position in the event of a spill. An electronically actuated valve is
preferred to minimize the time lapse between spill and containment.
Clean up spills and dispose of materials off-site in accordance with
S406 BMPs for Spills of Oil and Hazardous Substances.
The valve may be opened to convey contaminated stormwater to a
sanitary sewer, if approved by the sewer authority, or to oil removal
treatment such as an API or CP oil/water separator, catchbasin insert,
or equivalent treatment, and then to a basic treatment BMP.
Discharges from treatment systems to storm sewer or surface water or
to the ground must not display ongoing or recurring visible sheen and
must not contain greater than a significant amount of oil and grease.
S410 BMPs for Illicit Connections to Storm Drains
Description of Pollutant Sources:Illicit connections are unpermitted
sanitary or process wastewater discharges to a storm sewer or to surface
water, rather than to a sanitary sewer, industrial process wastewater, or
other appropriate treatment. They can also include swimming pool water,
filter backwash, cleaning solutions/washwaters, cooling water, etc.
Experience has shown that illicit connections are common, particularly in
older buildings.
Pollutant Control Approach:Identify and eliminate unpermitted
discharges or obtain an NPDES permit, where necessary, particularly at
industrial and commercial facilities.
Applicable Operational BMPs:
Eliminate unpermitted wastewater discharges to storm sewer, ground
water, or surface water.
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Convey unpermitted discharges to a sanitary sewer if allowed by the
local sewer authority, or to other approved treatment.
Obtain appropriate state and local permits for these discharges.
Recommended Additional Operational BMPs: At commercial and
industrial facilities, conduct a survey of wastewater discharge connections
to storm drains and to surface water as follows:
Conduct a field survey of buildings, particularly older buildings, and
other industrial areas to locate storm drains from buildings and paved
surfaces. Note where these join the public storm drain(s).
During non-stormwater conditions inspect each storm drain for non-
stormwater discharges. Record the locations of all non-stormwater
discharges. Include all permitted discharges.
If useful, prepare a map of each area. Show on the map the known
location of storm sewers, sanitary sewers, and permitted and
unpermitted discharges. Aerial photos may be useful. Check records
such as piping schematics to identify known side sewer connections
and show these on the map. Consider using smoke, dye, or chemical
analysis tests to detect connections between two conveyance systems
(e.g., process water and stormwater). If desirable, conduct TV
inspections of the storm drains and record the footage on videotape.
Compare the observed locations of connections with the information
on the map and revise the map accordingly. Note suspect connections
that are inconsistent with the field survey.
Identify all connections to storm sewers or to surface water and take
the actions specified above as applicable BMPs.
S411 BMPs for Landscaping and Lawn/ Vegetation Management
Description of Pollutant Sources:Landscaping can include grading, soil
transfer, vegetation removal, pesticide and fertilizer applications, and
watering. Stormwater contaminants include toxic organic compounds,
heavy metals, oils, total suspended solids, coliform bacteria, fertilizers,
and pesticides.
Lawn and vegetation management can include control of objectionable
weeds, insects, mold, bacteria, and other pests with pesticides. Examples
include weed control on golf course lawns, access roads, and utility
corridors and during landscaping; sap stain and insect control on lumber
and logs; rooftop moss removal; killing nuisance rodents; fungicide
application to patio decks, and residential lawn/plant care. It is possible to
release toxic pesticides such as pentachlorophenol, carbamates, and
organometallics to the environment by leaching and dripping from treated
parts, container leaks, product misuse, and outside storage of pesticide
contaminated materials and equipment. Poor management of the
Volume IV - Source Control BMPs – August 2012
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vegetation and poor application of pesticides or fertilizers can cause
appreciable stormwater contamination.
Pollutant Control Approach:Control of fertilizer and pesticide
applications, soil erosion, and site debris to prevent contamination of
stormwater.
Develop and implement an Integrated Pest Management Plan (IPM) and
use pesticides only as a last resort. Carefully apply pesticides/ herbicides,
in accordance with label instructions. Maintain appropriate vegetation,
with proper fertilizer application where practicable, to control erosion and
the discharge of stormwater pollutants. Where practicable grow plant
species appropriate for the site, or adjust the soil properties of the subject
site to grow desired plant species.
Applicable Operational BMPs for Landscaping:
Install engineered soil/landscape systems to improve the infiltration
and regulation of stormwater in landscaped areas.
Do not dispose of collected vegetation into waterways or storm sewer
systems.
Recommended Additional Operational BMPs for Landscaping:
Conduct mulch-mowing whenever practicable
Dispose of grass clippings, leaves, sticks, or other collected vegetation,
by composting, if feasible.
Use mulch or other erosion control measures on soils exposed for
more than one week during the dry season or two days during the rainy
season.
Store and maintain appropriate oil and chemical spill cleanup materials
in readily accessible locations when using oil or other chemicals.
Ensure that employees are familiar with proper spill cleanup
procedures.
Till fertilizers into the soil rather than dumping or broadcasting onto
the surface. Determine the proper fertilizer application rate for the
types of soil and vegetation encountered.
Till a topsoil mix or composted organic material into the soil to create
a well-mixed transition layer that encourages deeper root systems and
drought-resistant plants.
Use manual and/or mechanical methods of vegetation removal rather
than applying herbicides, where practical.
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Applicable Operational BMPs for the Use of Pesticides:
Develop and implement an IPM (See section on IPM in Applicable
Operational BMPs for Vegetation Management) and use pesticides
only as a last resort.
Implement a pesticide-use plan and include at a minimum: a list of
selected pesticides and their specific uses; brands, formulations,
application methods and quantities to be used; equipment use and
maintenance procedures; safety, storage, and disposal methods; and
monitoring, record keeping, and public notice procedures. All
procedures shall conform to the requirements of Chapter 17.21 RCW
and Chapter 16-228 WAC (Appendix IV-D R.7).
Choose the least toxic pesticide available that is capable of reducing
the infestation to acceptable levels. The pesticide should readily
degrade in the environment and/or have properties that strongly bind it
to the soil. Conduct any pest control activity at the life stage when the
pest is most vulnerable. For example, if it is necessary to use a
Bacillus thuringiens application to control tent caterpillars, apply it to
the material before the caterpillars cocoon or it will be ineffective. Any
method used should be site-specific and not used wholesale over a
wide area.
Apply the pesticide according to label directions. Do not apply
pesticides in quantities that exceed manufacturer’s instructions.
Mix the pesticides and clean the application equipment in an area
where accidental spills will not enter surface or ground waters, and
will not contaminate the soil.
Store pesticides in enclosed areas or in covered impervious
containment. Do not discharge pesticide contaminated stormwater or
spills/leaks of pesticides to storm sewers. Do not hose down the paved
areas to a storm sewer or conveyance ditch. Store and maintain
appropriate spill cleanup materials in a location known to all near the
storage area.
Clean up any spilled pesticides. Keep pesticide contaminated waste
materials in designated covered and contained areas.
The pesticide application equipment must be capable of immediate
shutoff in the event of an emergency.
Do not spray pesticides within 100 feet of open waters including
wetlands, ponds, and streams, sloughs and any drainage ditch or
channel that leads to open water except when following approval of
Ecology or the local jurisdiction. Flag all sensitive areas including
wells, creeks, and wetlands prior to spraying.
Post notices and delineate the spray area prior to the application, as
required by the local jurisdiction or by Ecology.
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Conduct spray applications during weather conditions as specified in
the label direction and applicable local and state regulations. Do not
apply during rain or immediately before expected rain.
Recommended Additional Operational BMPs for the use of pesticides:
Consider alternatives to the use of pesticides such as covering or
harvesting weeds, substitute vegetative growth, and manual weed
control/moss removal.
Consider the use of soil amendments, such as compost, thatare known
to control some common diseases in plants, such as Pythium root rot,
ashy stem blight, and parasitic nematodes. The following are three
possible mechanisms for disease control by compost addition (USEPA
Publication 530-F-9-044):
1. Successful competition for nutrients by antibiotic production;
2. Successful predation against pathogens by beneficial
microorganism; and
3. Activation of disease-resistant genes in plants by composts.
Installing an amended soil/landscape system can preserve both the plant
system and the soil system more effectively. This type of approach
provides a soil/landscape system with adequate depth, permeability, and
organic matter to sustain itself and continue working as an effective
stormwater infiltration system and a sustainable nutrient cycle.
Once a pesticide is applied, evaluate its effectiveness for possible
improvement. Records should be kept showing the effectiveness of the
pesticides considered.
Develop an annual evaluation procedure including a review of the
effectiveness of pesticide applications, impact on buffers and sensitive
areas (including potable wells), public concerns, and recent
toxicological information on pesticides used/proposed for use. If
individual or public potable wells are located in the proximity of
commercial pesticide applications, contact the regional Ecology
hydrogeologist to determine if additional pesticide application control
measures are necessary.
Rinseate from equipment cleaning and/or triple-rinsing of pesticide
containers should be used as product or recycled into product.
For more information, contact the Washington State University (WSU)
Extension Home-Assist Program, (253) 445-4556, or Bio-Integral
Resource Center (BIRC), P.O. Box 7414, Berkeley, CA.94707, or EPA to
obtain a publication entitled “Suspended, Canceled, and Restricted
Pesticides” which lists all restricted pesticides and the specific uses that
are allowed.
Volume IV - Source Control BMPs – August 2012
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Applicable Operational BMPs for Vegetation Management:
Use at least an eight-inch "topsoil" layer with at least 8 percent organic
matter to provide a sufficient vegetation-growing medium. Amending
existing landscapes and turf systems by increasing the percent organic
matter and depth of topsoil can substantially improve the permeability
of the soil, the disease and drought resistance of the vegetation, and
reduce fertilizer demand. This reduces the demand for fertilizers,
herbicides, and pesticides. Organic matter is the least water-soluble
form of nutrients that can be added to the soil. Composted organic
matter generally releases only between 2 and 10 percent of its total
nitrogen annually, and this release corresponds closely to the plant
growth cycle. Return natural plant debris and mulch to the soil, to
continue recycling nutrients indefinitely.
Select the appropriate turfgrass mixture for the climate and soil type.
Certain tall fescues and rye grasses resist insect attack because the
symbiotic endophytic fungi found naturally in their tissues repel or kill
common leaf and stem-eating lawn insects. However, they do not,
repel root-feeding lawn pests such as Crane Fly larvae, and are toxic to
ruminants such as cattle and sheep. The fungus causes no known
adverse effects to the host plant or to humans. Endophytic grasses are
commercially available; use them in areas such as parks or golf
courses where grazing does not occur. Local agricultural or gardening
resources such as Washington State University Extension office can
offer advice on which types of grass are best suited to the area and soil
type.
Use the following seeding and planting BMPs, or equivalent BMPs to
obtain information on grass mixtures, temporary and permanent
seeding procedures, maintenance of a recently planted area, and
fertilizer application rates:Temporary and Permanent Seeding,
Mulching,Plastic Covering, and Sodding as described in Volume II.
Adjusting the soil properties of the subject site can assist in selection
of desired plant species. For example, design a constructed wetland to
resist the invasion of reed canary grass by layering specific strata of
organic matters (e.g., composted forest product residuals) and creating
a mildly acidic pH and carbon-rich soil medium. Consult a soil
restoration specialist for site-specific conditions.
Aerate lawns regularly in areas of heavy use where the soil tends to
become compacted. Conduct aeration while the grasses in the lawn are
growing most vigorously. Remove layers of thatch greater than ¾-inch
deep.
Mowing is a stress-creating activity for turfgrass. Grass decreases its
productivity when mown too short and there is less growth of roots
and rhizomes. The turf becomes less tolerant of environmental
stresses, more disease prone and more reliant on outside means such as
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pesticides, fertilizers, and irrigation to remain healthy. Set the mowing
height at the highest acceptable level and mow at times and intervals
designed to minimize stress on the turf. Generally mowing only 1/3 of
the grass blade height will prevent stressing the turf.
Irrigation:
The depth from which a plant normally extracts water depends on the
rooting depth of the plant. Appropriately irrigated lawn grasses
normally root in the top 6 to 12 inches of soil; lawns irrigated on a
daily basis often root only in the top 1 inch of soil. Improper irrigation
can encourage pest problems, leach nutrients, and make a lawn
completely dependent on artificial watering. The amount of water
applied depends on the normal rooting depth of the turfgrass species
used, the available water holding capacity of the soil, and the
efficiency of the irrigation system. Consult with the local water utility,
Conservation District, or Cooperative Extension office to help
determine optimum irrigation practices.
Fertilizer Management:
Turfgrass is most responsive to nitrogen fertilization, followed by
potassium and phosphorus. Fertilization needs vary by site depending
on plant, soil, and climatic conditions. Evaluation of soil nutrient
levels through regular testing ensures the best possible efficiency and
economy of fertilization. For details on soils testing, contact the local
Conservation District, a soils testing professional, or a Washington
State University Extension office.
Apply fertilizers in amounts appropriate for the target vegetation and
at the time of year that minimizes losses to surface and ground waters.
Do not fertilize when the soil is dry. Alternatively, do not apply
fertilizers within three days prior to predicted rainfall. The longer the
period between fertilizer application and either rainfall or irrigation,
the less fertilizer runoff occurs.
Use slow release fertilizers such as methylene urea, IDBU, or resin
coated fertilizers when appropriate, generally in the spring. Use of
slow release fertilizers is especially important in areas with sandy or
gravelly soils.
Time the fertilizer application to periods of maximum plant uptake.
Ecology generally recommends application in the fall and spring,
although Washington State University turf specialists recommend four
fertilizer applications per year.
Properly trained persons should apply all fertilizers. Apply no fertilizer
at commercial and industrial facilities, to grass swales, filter strips, or
buffer areas that drain to sensitive water bodies unless approved by the
local jurisdiction.
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Integrated Pest Management
An IPM program might consist of the following steps:
Step 1: Correctly identify problem pests and understand their life cycle
Step 2: Establish tolerance thresholds for pests.
Step 3: Monitor to detect and prevent pest problems.
Step 4: Modify the maintenance program to promote healthy plants and
discourage pests.
Step 5: Use cultural, physical, mechanical or biological controls first if
pests exceed the tolerance thresholds.
Step 6: Evaluate and record the effectiveness of the control and modify
maintenance practices to support lawn or landscape recovery and prevent
recurrence.
For an elaboration of these steps, refer to Appendix IV-F.
S412 BMPs for Loading and Unloading Areas for Liquid or Solid Material
Description of Pollutant Sources:Operators typically conduct
loading/unloading of liquid and solid materials at industrial and
commercial facilities at shipping and receiving, outside storage, fueling
areas, etc. Materials transferred can include products, raw materials,
intermediate products, waste materials, fuels, scrap metals, etc. Leaks and
spills of fuels, oils, powders, organics, heavy metals, salts, acids, alkalis,
etc. during transfer may cause stormwater contamination. Spills from
hydraulic line breaks are a common problem at loading docks.
Pollutant Control Approach:Cover and contain the loading/unloading
area where necessary to prevent run-on of stormwater and runoff of
contaminated stormwater.
Applicable Operational BMPs:
At All Loading/ Unloading Areas:
A significant amount of debris can accumulate at outside, uncovered
loading/unloading areas. Sweep these surfaces frequently to remove
loose material that could contaminate stormwater. Sweep areas
temporarily covered after removal of the containers, logs, or other
material covering the ground.
Place drip pans, or other appropriate temporary containment device, at
locations where leaks or spills may occur such as hose connections,
hose reels and filler nozzles. Always use drip pans when making and
breaking connections (see Figure 2.2.2). Check loading/ unloading
equipment such as valves, pumps, flanges, and connections regularly
for leaks and repair as needed.
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Recommended Treatment BMPs:
Install biofiltration swales and filter strips – (See Chapter 9, Volume V) to
treat roadside runoff wherever practicable and use engineered topsoils
wherever necessary to maintain adequate vegetation. These systems can
improve infiltration and stormwater pollutant control upstream of roadside
ditches.
S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems
Description of Pollutant Sources:Facilities include roadside catch basins
on arterials and within residential areas, conveyance systems, detention
facilities such as ponds and vaults, oil/water separators, biofilters, settling
basins, infiltration systems, and all other types of stormwater treatment
systems presented in Volume V. Oil and grease, hydrocarbons, debris,
heavy metals, sediments and contaminated water are found in catch basins,
oil and water separators, settling basins, etc.
Pollutant Control Approach:Provide maintenance and cleaning of
debris, sediments, and oil from stormwater collection, conveyance, and
treatment systems to obtain proper operation.
Applicable Operational BMPs:
Maintain stormwater treatment facilities per the operations and
maintenance (O&M) procedures presented in Section 4.6 of Volume V in
addition to the following BMPs:
Inspect and clean treatment BMPs, conveyance systems, and catch
basins as needed, and determine necessary O&M improvements.
Promptly repair any deterioration threatening the structural integrity of
stormwater facilities. These include replacement of clean-out gates,
catch basin lids, and rock in emergency spillways.
Ensure adequacy of storm sewer capacities and prevent heavy
sediment discharges to the sewer system.
Regularly remove debris and sludge from BMPs used for peak-rate
control, treatment, etc. and discharge to a sanitary sewer if approved
by the sewer authority, or truck to an appropriate local or state
government approved disposal site.
Clean catch basins when the depth of deposits reaches 60 percent of
the sump depth as measured from the bottom of basin to the invert of
the lowest pipe into or out of the basin. However, in no case should
there be less than six inches clearance from the debris surface to the
invert of the lowest pipe. Some catch basins (for example, WSDOT
Type 1L basins) may have as little as 12 inches sediment storage
below the invert. These catch basins need frequent inspection and
cleaning to prevent scouring. Where these catch basins are part of a
stormwater collection and treatment system, the system
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owner/operator may choose to concentrate maintenance efforts on
downstream control devices as part of a systems approach.
Clean woody debris in a catch basin as frequently as needed to ensure
proper operation of the catchbasin.
Post warning signs; “Dump No Waste - Drains to Ground Water,”
“Streams,” “Lakes,” or emboss on or adjacent to all storm drain inlets
where possible.
Disposal of sediments and liquids from the catch basins must comply
with “Recommendations for Management of Street Wastes” described
in Appendix IV-G of this volume.
Additional Applicable BMPs:Select additional applicable BMPs from
this chapter depending on the pollutant sources and activities conducted at
the facility. Those BMPs include:
S425 BMPs for Soil Erosion and Sediment Control at Industrial Sites
S427 BMPs for Storage of Liquid, Food Waste, or Dangerous Waste
Containers
S406 BMPs for Spills of Oil and Hazardous Substances
S410 BMPs for Illicit Connections to Storm Drains
S430 BMPs for Urban Streets
S418 BMPs for Manufacturing Activities - Outside
Description of Pollutant Sources:Manufacturing pollutant sources
include outside process areas, stack emissions, and areas where
manufacturing activity has taken place in the past and significant exposed
pollutant materials remain.
Pollution Control Approach:Cover and contain outside manufacturing
and prevent stormwater run-on and contamination, where feasible.
Applicable Operational BMP:
Sweep paved areas regularly, as needed, to prevent contamination of
stormwater.
Alter the activity by eliminating or minimizing the contamination of
stormwater.
Applicable Structural Source Control BMPs:Enclose the activity
(see Figure 2.2.6): If possible, enclose the manufacturing activity in a
building.
Cover the activity and connect floor drains to a sanitary sewer, if
approved by the local sewer authority. Berm or slope the floor as
needed to prevent drainage of pollutants to outside areas. (Figure
2.2.7)
Volume IV - Source Control BMPs – August 2012
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Class II Combustible Liquid, whereas they categorize gasoline as a
Flammable Liquid.
Historically organizations conducted mobile fueling for off-road vehicles
operated for extended periods in remote areas. This includes construction
sites, logging operations, and farms. Some organizations conduct mobile
fueling of on-road vehicles commercially in the State of Washington.
Pollutant Control Approach:Operators typically need proper training of
the fueling operators, and the use of spill/drip control and reliable fuel
transfer equipment with backup shutoff valving.
Applicable Operational BMPs:
Organizations and individuals conducting mobile fueling operations must
implement the bulleted BMPs below. The operating procedures for the
driver/operator should be simple, clear, effective, and their
implementation verified by the organization liable for environmental and
third party damage.
Ensure that the local fire department approves all mobile fueling
operations. Comply with local and Washington State fire codes.
In fueling locations that are in close proximity to sensitive aquifers,
designated wetlands, wetland buffers, or other waters of the State,
approval by local jurisdictions is necessary to ensure compliance with
additional local requirements.
Ensure compliance with all 49 CFR 178 requirements for DOT 406
cargo tanker. Documentation from a Department of Transportation
(DOT) Registered Inspector provides proof of compliance.
Ensure the presence and the constant observation/monitoring of the
driver/operator at the fuel transfer location at all times during fuel
transfer and ensure implementation of the following procedures at the
fuel transfer locations:
Locate the point of fueling at least 25 feet from the nearest storm
sewer or inside an impervious containment with a volumetric
holding capacity equal to or greater than 110 percent of the fueling
tank volume, or covering the storm sewer to ensure no inflow of
spilled or leaked fuel. Covers are not required for storm sewers that
convey the inflow to a spill control separator approved by the local
jurisdiction and the fire department. Potential spill/leak
conveyance surfaces must be impervious and in good repair.
Place a drip pan, or an absorbent pad under each fueling location
prior to and during all dispensing operations. The pan (must be
liquid tight) and the absorbent pad must have a capacity of at least
5 gallons. There is no need to report spills retained in the drip pan
or the pad.
Note that some
local fire
departments may
have restrictions
on mobile fueling
practices.
Volume IV - Source Control BMPs – August 2012
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Manage the handling and operation of fuel transfer hoses and
nozzle, drip pan(s), and absorbent pads as needed to prevent
spills/leaks of fuel from reaching the ground, storm sewer, and
receiving waters.
Avoid extending the fueling hoses across a traffic lane without
fluorescent traffic cones, or equivalent devices, conspicuously
placed to block all traffic from crossing the fuel hose.
Remove the fill nozzle and cease filling the tank when the
automatic shut-off valve engages. Do not lock automatic shutoff
fueling nozzles in the open position.
Do not “top off” the fuel receiving equipment.
Provide the driver/operator of the fueling vehicle with:
Adequate flashlights or other mobile lighting to view fuel fill
openings with poor accessibility. Consult with local fire
department for additional lighting requirements.
Two-way communication with his/her home base.
Train the driver/operator annually in spill prevention and cleanup
measures and emergency procedures. Make all employees aware of the
significant liability associated with fuel spills.
The responsible manager shall properly sign and date the fueling
operating procedures. . Distribute procedures to the operators, retain
them in the organization files, and make them available in the event an
authorized government agency requests a review.
Immediately notify the local fire department (911) and the appropriate
regional office of the Department of Ecology in the event of any spill
entering surface or ground waters. Establish a “call down list” to
ensure the rapid and proper notification of management and
government officials should any significant amount of product be lost
off-site. Keep the list in a protected but readily accessible location in
the mobile fueling truck. The “call down list” should also pre-identify
spill response contractors available in the area to ensure the rapid
removal of significant product spillage into the environment.
Maintain a minimum of the following spill clean-up materials in all
fueling vehicles, that are readily available for use:
Non-water absorbents capable of absorbing at least15 gallons of
diesel fuel.
A storm drain plug or cover kit.
A non-water absorbent containment boom of a minimum 10 feet in
length with a 12-gallon minimum absorbent capacity.
A non-spark generating shovel (a steel shovels could generate a
spark and cause an explosion in the right environment around a
spill).
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Two, five-gallon buckets with lids.
Use automatic shutoff nozzles for dispensing the fuel. Replace
automatic shut-off nozzles as recommended by the manufacturer.
Maintain and replace equipment on fueling vehicles, particularly hoses
and nozzles, at established intervals to prevent failures.
Applicable Structural Source Control BMPs:Include the following fuel
transfer site components:
Automatic fuel transfer shut-off nozzles.
An adequate lighting system at the filling point.
S420 BMPs for Painting/ Finishing /Coating of Vehicles/Boats/ Buildings/
Equipment
Description of Pollutant Sources:Surface preparation and the
application of paints, finishes, and/or coatings to vehicles, boats,
buildings, and/or equipment outdoors can be sources of pollutants.
Potential pollutants include organic compounds, oils and greases, heavy
metals, and suspended solids.
Pollutant Control Approach:Cover and contain painting and sanding
operations and apply good housekeeping and preventive maintenance
practices to prevent the contamination of stormwater with painting over
sprays and grit from sanding.
Applicable Operational BMPs:
Train employees in the careful application of paints, finishes, and
coatings to reduce misuse and over spray. Use drop cloths underneath
outdoor painting, scraping, sandblasting work, and properly clean and
temporarily store collected debris daily.
Do not conduct spraying, blasting, or sanding activities over open
water or where wind may blow paint into water.
Wipe up spills with rags and other absorbent materials immediately.
Do not hose down the area to a storm sewer, receiving water, or
conveyance ditch.
On marine dock areas sweep rather than hose down debris. Collect any
hose water generated and convey to appropriate treatment and
disposal.
Use an effective runoff control device if dust, grit, washwater, or other
pollutants may escape the work area and enter a catch basin. The
containment device(s) must be in place at the beginning of the
workday. Collect contaminated runoff and solids and properly dispose
of such wastes before removing the containment device(s) at the end
of the workday.
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Discharge Elimination System (NPDES) Permit Requirements,
Washington Department of Ecology, March 2011,website:
http://www.ecy.wa.gov/biblio/94146.html. Apply the BMPs in that
guidance document to scrap material recycling facilities depending on the
pollutant sources existing at those facilities.
S424 BMPs for Roof/ Building Drains at Manufacturing and Commercial Buildings
Description of Pollutant Sources:Stormwater runoff from roofs and
sides of manufacturing and commercial buildings can be sources of
pollutants caused by leaching of roofing materials, building vents, and
other air emission sources. Research has identified vapors and entrained
liquid and solid droplets/particles as potential pollutants in roof/building
runoff. Metals, solvents, acidic/alkaline pH, BOD, and organics, are some
of the pollutant constituents identified.
Ecology has performed a study on zinc in industrial stormwater. The study
is presented in Ecology Publication 08-10-025 Suggested Practices to
reduce Zinc Concentrations in Industrial Stormwater Discharges, website:
http://www.ecy.wa.gov/biblio/0810025.html. The user should refer to this
document for more details on addressing zinc in stormwater.
Pollutant Control Approach: Evaluate the potential sources of
stormwater pollutants and apply source control BMPs where feasible.
Applicable Operational Source Control BMPs:
If leachates and/or emissions from buildings are suspected sources of
stormwater pollutants, then sample and analyze the stormwater
draining from the building.
Sweep the area routinely to remove any zinc residuals.
If a roof/building stormwater pollutant source is identified, implement
appropriate source control measures such as air pollution control
equipment, selection of materials, operational changes, material
recycle, process changes, etc.
Applicable Structural Source Control BMPs:
Paint/coat the galvanized surfaces as described in Ecology Publication
# 08-10-025.
Applicable Treatment BMPs:
Treat runoff from roofs to the appropriate level. The facility may use
enhanced treatment BMPs as described in Volume V of the SWMMWW.
Some facilities regulated by the Industrial Stormwater General Permit, or
local jurisdiction, may have requirements than cannot be achieved with
enhanced treatment BMPs. In these cases, additional treatment measures
may be required. A treatment method for meeting stringent requirements
such as Chitosan-Enhanced Sand Filtration may be appropriate.
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S425 BMPs for Soil Erosion and Sediment Control at Industrial Sites
Description of Pollutant Sources:Industrial activities on soil areas;
exposed and disturbed soils; steep grading; etc. can be sources of
sediments that can contaminate stormwater runoff.
Pollutant Control Approach:Limit the exposure of erodible soil,
stabilize, or cover erodible soil where necessary to prevent erosion, and/or
provide treatment for stormwater contaminated with TSS caused by
eroded soil.
Applicable BMPs:
Cover Practice Options:
Vegetative cover such as grass, trees, shrubs, on erodible soil areas.
Covering with mats such as clear plastic, jute, synthetic fiber.
Preservation of natural vegetation including grass, trees, shrubs, and
vines.
Structural Practice Options:
Vegetated swale
Dike
Silt fence
Check dam
Gravel filter berm
Sedimentation basin
Proper grading.
(For design information refer to Volume II, “Standards and Specifications
for BMPs”).
S426 BMPs for Spills of Oil and Hazardous Substances
Description of Pollutant Sources:Federal law requires owners or
operators of facilities engaged in drilling, producing, gathering, storing,
processing, transferring, distributing, refining, or consuming oil and/or oil
products to have a Spill Prevention and Emergency Cleanup Plan
(SPECP). The SPECP is required if the above ground storage capacity of
the facility, is 1,320 gallons or more of oil. Additionally, the SPECP is
required if any single container with a capacity in excess of 660 gallons
and which, due to their location, could reasonably be expected to
discharge oil in harmful quantities, as defined in 40 CFR Part 110, into or
upon the navigable waters of the United States or adjoining shorelines {40
CFR 112.1 (b)}. Onshore and offshore facilities, which, due to their
location, could not reasonably be expected to discharge oil into or upon
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the navigable waters of the United States or adjoining shorelines are
exempt from these regulations {40 CFR 112.1(1)(i)}. State Law requires
owners of businesses that produce dangerous wastes to have a SPECP.
These businesses should refer to Appendix IV-D R.6. The federal
definition of oil is oil of any kind or any form, including, but not limited to
petroleum, fuel oil, sludge, oil refuse, and oil mixed with wastes other than
dredged spoil.
Pollutant Control Approach:Maintain, update, and implement a Spill
Prevention and Emergency Cleanup Plan.
Applicable Operational BMPs:The businesses and public agencies
identified in Appendix IV-A required to prepare and implement a Spill
Prevention and Emergency Cleanup Plan shall implement the following:
Prepare a Spill Prevention and Emergency Cleanup Plan (SPECP),
which includes:
A description of the facility including the owner's name and
address.
The nature of the activity at the facility.
The general types of chemicals used or stored at the facility.
A site plan showing the location of storage areas for chemicals, the
locations of storm drains, the areas draining to them, and the
location and description of any devices to stop spills from leaving
the site such as positive control valves.
Cleanup procedures.
Notification procedures used in the event of a spill, such as
notifying key personnel. Agencies such as Ecology, local fire
department, Washington State Patrol, and the local Sewer
Authority, shall be notified.
The name of the designated person with overall spill cleanup and
notification responsibility.
Train key personnel in the implementation of the SPECP. Prepare a
summary of the plan and post it at appropriate points in the building,
identifying the spill cleanup coordinators, location of cleanup kits, and
phone numbers of regulatory agencies to contact in the event of a spill.
Update the SPECP regularly.
Immediately notify Ecology, the local jurisdiction, and the local Sewer
Authority if a spill may reach sanitary or storm sewers, ground water,
or surface water, in accordance with federal and Ecology spill
reporting requirements.
Volume IV - Source Control BMPs – August 2012
2-49
Immediately clean up spills. Do not use emulsifiers for cleanup unless
there is an appropriate disposal method for the resulting oily
wastewater. Do not wash absorbent material down a floor drain or into
a storm sewer.
Locate emergency spill containment and cleanup kit(s) in high-
potential spill areas. The contents of the kit shall be appropriate for the
type and quantities of chemical liquids stored at the facility.
Recommended Additional Operational BMP:Spill kits should include
appropriately lined drums, absorbent pads, and granular or powdered
materials for neutralizing acids or alkaline liquids where applicable. In
fueling areas: Package absorbent material in small bags for easy use and
make available small drums for storage of absorbent and/or used
absorbent. Deploy spill kits in a manner that allows rapid access and use
by employees.
S427 BMPs for Storage of Liquid, Food Waste, or Dangerous Waste Containers
Description of Pollutant Sources:Steel and plastic drums with
volumetric capacities of 55 gallons or less are typically used at industrial
facilities for container storage of liquids and powders. The BMPs
specified below apply to container(s) located outside a building. Use these
BMPs when temporarily storing accumulated food wastes, vegetable or
animal grease, used oil, liquid feedstock, cleaning chemicals, or
Dangerous Wastes (liquid or solid). These BMPs do not apply when
Ecology has permitted the business to store the wastes (Appendix IV-D
R.4). Leaks and spills of pollutant materials during handling and storage
are the primary sources of pollutants. Oil and grease, acid/alkali pH, BOD,
COD are potential pollutant constituents.
Pollutant Control Approach:Store containers in impervious
containment under a roof, or other appropriate cover, or in a building.
When collection trucks directly pick up roll-containers, ensure a filet is on
both sides of the curb to facilitate moving the dumpster. For storage areas
on-site for less than 30 days, consider using a portable temporary
secondary system like that shown in Figure 2.2.8 in lieu of a permanent
system as described above.
Volume IV - Source Control BMPs – August 2012
2-50
Figure 2.2.8 – Secondary Containment System
Applicable Operational BMPs:
Place tight-fitting lids on all containers.
Place drip pans beneath all mounted container taps and at all potential
drip and spill locations during filling and unloading of containers.
Inspect container storage areas regularly for corrosion, structural
failure, spills, leaks, overfills, and failure of piping systems. Check
containers daily for leaks/spills. Replace containers, and replace and
tighten bungs in drums as needed.
Businesses accumulating Dangerous Wastes that do not contain free
liquids need only to store these wastes in a sloped designated area with
the containers elevated or otherwise protected from storm water run-
on.
Secure drums when stored in an area where unauthorized persons may
gain access in a manner that prevents accidental spillage, pilferage, or
any unauthorized use (see Figure 2.2.9).
Figure 2.2.9 – Locking System for Drum Lid
Volume IV - Source Control BMPs – August 2012
2-51
If the material is a Dangerous Waste, the business owner must comply
with any additional Ecology requirements as specified in Appendix
IV-D R.3.
Storage of reactive, ignitable, or flammable liquids must comply with
the Uniform Fire Code (Appendix IV-D R.2).
Cover dumpsters, or keep them under cover such as a lean-to, to
prevent the entry of stormwater. Replace or repair leaking garbage
dumpsters.
Drain dumpsters and/or dumpster pads to sanitary sewer. Keep
dumpster lids closed. Install waterproof liners.
Applicable Structural Source Control BMPs:
Keep containers with Dangerous Waste, food waste, or other potential
pollutant liquids inside a building unless this is not feasible due to site
constraints or Uniform/International Fire Code requirements.
Store containers in a designated area, which is covered, bermed or
diked, paved and impervious in order to contain leaks and spills (see
Figure 2.2.10). Slope the secondary containment to drain into a dead-
end sump for the collection of leaks and small spills.
For liquid wastes, surround the containers with a dike as illustrated in
Figure 2.2.10. The dike must be of sufficient height to provide a
volume of either 10 percent of the total enclosed container volume or
110 percent of the volume contained in the largest container,
whichever is greater.
Figure 2.2.10 – Covered and Bermed Containment Area
Where material is temporarily stored in drums, use a containment
system as illustrated, in lieu of the above system (see Figure 2.2.8).
Volume IV - Source Control BMPs – August 2012
2-52
Place containers mounted for direct removal of a liquid chemical for
use by employees inside a containment area as described above. Use a
drip pan during liquid transfer (see Figure 2.2.11).
Figure 2.2.11 – Mounted Container - with drip pan
(note that the secondary containment is not shown in this figure)
Applicable Treatment BMP:
For contaminated stormwater in the containment area, connect the
sump outlet to a sanitary sewer, if approved by the local Sewer
Authority, or to appropriate treatment such as an API or CP oil/water
separator, catch basin filter or other appropriate system (see Volume
V). Equip the sump outlet with a normally closed valve to prevent the
release of spilled or leaked liquids, especially flammables (compliance
with Fire Codes), and dangerous liquids. Open this valve only for the
conveyance of contaminated stormwater to treatment.
Another option for discharge of contaminated stormwater is to pump it
from a dead-end sump or catchment to a tank truck or other
appropriate vehicle for off-site treatment and/or disposal.
S428 BMPs for Storage of Liquids in Permanent Aboveground Tanks
Description of Pollutant Sources:Aboveground tanks containing liquids
(excluding uncontaminated water) may be equipped with a valved drain,
vent, pump, and bottom hose connection. Aboveground tanks may be
heated with steam heat exchangers equipped with steam traps, if required.
Leaks and spills can occur at connections and during liquid transfer. Oil
and grease, organics, acids, alkalis, and heavy metals in tank water and
condensate drainage can also cause stormwater contamination at storage
tanks.
Pollutant Control Approach:Install secondary containment or a double-
walled tank. Slope the containment area to a drain with a sump. Operators
may need to discharge stormwater collected in the containment area to
Note this treatment
BMP for
contaminated
stormwater from
drum storage
areas.
Volume IV - Source Control BMPs – August 2012
2-57
Stock cleanup materials, such as brooms, dustpans, and vacuum
sweepers near the storage area.
S430 BMPs for Urban Streets
Description of Pollutant Sources:Urban streets can be the source of
vegetative debris, paper, fine dust, vehicle liquids, tire and brake wear
residues, heavy metals (lead and zinc), soil particles, ice control salts,
domestic wastes, lawn chemicals, and vehicle combustion products. Street
surface contaminants contain significant concentrations of particle sizes
less than 250 microns (Sartor and Boyd, 1972).
Pollutant Control Approach:Conduct efficient street sweeping where
and when appropriate to minimize the contamination of stormwater. Do
not wash street debris into storm drains.
Facilities not covered under the Industrial Stormwater General Permit may
consider a minimum amount of water washing of streets. All facilities
must comply with their local stormwater requirements for discharging to
storm sewers. Municipal NPDES permittees are required to limit street
wash water discharges and may have special conditions or treatment
requirements.
Recommended BMPs:
For maximum stormwater pollutant reductions on curbed streets and
high volume parking lots, use efficient vacuum sweepers (refer to
Volume V, Ch. 12, for information about high-efficiency vacuum
sweeper technology).
Note: High-efficiency street sweepers utilize strong vacuums and the
mechanical action of main and gutter brooms combined with an air
filtration system that only returns clean air to the atmosphere (i.e.,
filters very fine particulates). They sweep dry and use no water since
they do not emit any dust.
High-efficiency vacuum sweepers have the capability of removing, 80
percent or more of the accumulated street dirt particles whose
diameters are less than 250 microns (Sutherland, 1998). This assumes
pavements under good condition and reasonably expected
accumulation conditions.
For moderate stormwater pollutant reductions on curbed streets use
regenerative air sweepers or tandem sweeping operations.
Note:A tandem sweeping operation involves a single pass of a
mechanical sweeper followed immediately by a single pass of a
vacuum sweeper or regenerative air sweeper.
A regenerative air sweeper blows air down on the pavement to
entrain particles and uses a return vacuum to transport the
material to the hopper.
Volume IV - Source Control BMPs – August 2012
2-58
These operations usually use water to control dust. This reduces
their ability to pick up fine particulates.
These types of sweepers have the capability of removing
approximately 25 to 50 percent of the accumulated street dirt particles
whose diameters are less than 250 microns.(Sutherland, 1998). This
assumes pavements under good conditions and typical accumulation
conditions.
For minimal stormwater pollutant reductions on curbed streets use
mechanical sweepers.
Note: The industry refers to mechanical sweepers as broom
sweepers and uses the mechanical action of main and gutter
brooms to throw material on a conveyor belt that transports it to
the hopper.
These sweepers usually use water to control dust. This reduces
their ability to pick up fine particulates.
Mechanical sweepers have the capability of removing only 10 to 20
percent of the accumulated street dirt particles whose diameters are
less than 250 microns (Sutherland, 1998). This assumes pavements
under good condition and the most favorable accumulation conditions.
Conduct vacuum sweeping at optimal frequencies. Optimal
frequencies are those scheduled sweeping intervals that produce the
most cost-effective annual reduction of pollutants normally found in
stormwater and can vary depending on land use, traffic volume and
rainfall patterns.
Train operators in those factors that result in optimal pollutant
removal. These factors include sweeper speed, brush adjustment and
rotation rate, sweeping pattern, maneuvering around parked vehicles,
and interim storage and disposal methods.
Consider the use of periodic parking restrictions in low to medium
density single-family residential areas to ensure the sweeper’s ability
to sweep along the curb.
Establish programs for prompt vacuum sweeping, removal, and
disposal of debris from special events that will generate higher than
normal loadings.
Disposal of street sweeping solids must comply with
“Recommendations for Management of Street Wastes” described in
Appendix IV-G of this volume.
Inform citizens about eliminating yard debris, oil and other wastes in
street gutters to reduce street pollutant sources.
Page |32
C. Correspondence
Ecology
EPA
Local Government
Page |33
D. Site Inspection Form
Create your own or download Ecology’s template:
http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html
Construction Stormwater Site Inspection Form
Page 1
Project Name Permit # Inspection Date Time
Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre
Print Name:
Approximate rainfall amount since the last inspection (in inches):
Approximate rainfall amount in the last 24 hours (in inches):
Current Weather Clear Cloudy Mist Rain Wind Fog
A.Type of inspection:Weekly Post Storm Event Other
B. Phase of Active Construction (check all that apply):
Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads
Concrete pours Vertical Construction/buildings Utilities
Offsite improvements Site temporary stabilized Final stabilization
C. Questions:
1. Were all areas of construction and discharge points inspected?Yes No
2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No
3.Was a water quality sample taken during inspection?(refer to permit conditions S4 & S5)Yes No
4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?*Yes No
5. If yes to #4 was it reported to Ecology?Yes No
6.Is pH sampling required?pH range required is 6.5 to 8.5.Yes No
If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken,
and when.
*If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33
cm or greater.
Sampling Results:Date:
Parameter Method (circle one)Result Other/Note
NTU cm pH
Turbidity tube, meter, laboratory
pH Paper, kit, meter
Construction Stormwater Site Inspection Form
Page 2
D. Check the observed status of all items. Provide “Action Required “details and dates.
Element #Inspection BMPs
Inspected
BMP needs
maintenance
BMP
failed
Action
required
(describe in
section F)
yes no n/a
1
Clearing
Limits
Before beginning land disturbing
activities are all clearing limits,
natural resource areas (streams,
wetlands, buffers, trees) protected
with barriers or similar BMPs? (high
visibility recommended)
2
Construction
Access
Construction access is stabilized
with quarry spalls or equivalent
BMP to prevent sediment from
being tracked onto roads?
Sediment tracked onto the road
way was cleaned thoroughly at the
end of the day or more frequent as
necessary.
3
Control Flow
Rates
Are flow control measures installed
to control stormwater volumes and
velocity during construction and do
they protect downstream
properties and waterways from
erosion?
If permanent infiltration ponds are
used for flow control during
construction, are they protected
from siltation?
4
Sediment
Controls
All perimeter sediment controls
(e.g. silt fence, wattles, compost
socks, berms, etc.) installed, and
maintained in accordance with the
Stormwater Pollution Prevention
Plan (SWPPP).
Sediment control BMPs (sediment
ponds, traps, filters etc.) have been
constructed and functional as the
first step of grading.
Stormwater runoff from disturbed
areas is directed to sediment
removal BMP.
5
Stabilize
Soils
Have exposed un-worked soils
been stabilized with effective BMP
to prevent erosion and sediment
deposition?
Construction Stormwater Site Inspection Form
Page 3
Element #Inspection BMPs
Inspected
BMP needs
maintenance
BMP
failed
Action
required
(describe in
section F)
yes no n/a
5
Stabilize Soils
Cont.
Are stockpiles stabilized from erosion,
protected with sediment trapping
measures and located away from drain
inlet, waterways, and drainage
channels?
Have soils been stabilized at the end of
the shift, before a holiday or weekend
if needed based on the weather
forecast?
6
Protect
Slopes
Has stormwater and ground water
been diverted away from slopes and
disturbed areas with interceptor dikes,
pipes and or swales?
Is off-site storm water managed
separately from stormwater generated
on the site?
Is excavated material placed on uphill
side of trenches consistent with safety
and space considerations?
Have check dams been placed at
regular intervals within constructed
channels that are cut down a slope?
7
Drain Inlets
Storm drain inlets made operable
during construction are protected.
Are existing storm drains within the
influence of the project protected?
8
Stabilize
Channel and
Outlets
Have all on-site conveyance channels
been designed, constructed and
stabilized to prevent erosion from
expected peak flows?
Is stabilization, including armoring
material, adequate to prevent erosion
of outlets, adjacent stream banks,
slopes and downstream conveyance
systems?
9
Control
Pollutants
Are waste materials and demolition
debris handled and disposed of to
prevent contamination of stormwater?
Has cover been provided for all
chemicals, liquid products, petroleum
products, and other material?
Has secondary containment been
provided capable of containing 110%
of the volume?
Were contaminated surfaces cleaned
immediately after a spill incident?
Were BMPs used to prevent
contamination of stormwater by a pH
modifying sources?
Construction Stormwater Site Inspection Form
Page 4
Element #Inspection BMPs
Inspected
BMP needs
maintenance
BMP
failed
Action
required
(describe in
section F)
yes no n/a
9
Cont.
Wheel wash wastewater is handled
and disposed of properly.
10
Control
Dewatering
Concrete washout in designated areas.
No washout or excess concrete on the
ground.
Dewatering has been done to an
approved source and in compliance
with the SWPPP.
Were there any clean non turbid
dewatering discharges?
11
Maintain
BMP
Are all temporary and permanent
erosion and sediment control BMPs
maintained to perform as intended?
12
Manage the
Project
Has the project been phased to the
maximum degree practicable?
Has regular inspection, monitoring and
maintenance been performed as
required by the permit?
Has the SWPPP been updated,
implemented and records maintained?
E. Check all areas that have been inspected.
All in place BMPs All disturbed soils All concrete wash out area All material storage areas
All discharge locations All equipment storage areas All construction entrances/exits
F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number;
be specific on location and work needed. Document, initial, and date when the corrective action has been completed
and inspected.
Element
#
Description and Location Action Required Completion
Date
Initials
Attach additional page if needed
Sign the following certification:
“I certify that this report is true, accurate, and complete, to the best of my knowledge and belief”
Inspected by: (print)(Signature)Date:
Title/Qualification of Inspector:
Page |34
E. Construction Stormwater General Permit (CSWGP)
Construction Stormwater General Permit – December 1, 2010
Page 2
TABLE OF CONTENTS
LIST OF TABLES .......................................................................................................................... 3
SPECIAL CONDITIONS ............................................................................................................... 5
S1. PERMIT COVERAGE ........................................................................................................5
S2. APPLICATION REQUIREMENTS ...................................................................................8
S3. COMPLIANCE WITH STANDARDS .............................................................................11
S4. MONITORING REQUIREMENTS ..................................................................................12
S5. REPORTING AND RECORDKEEPING REQUIREMENTS .........................................19
S6. PERMIT FEES...................................................................................................................22
S7. SOLID AND LIQUID WASTE DISPOSAL ....................................................................22
S8. DISCHARGES TO 303(D) OR TMDL WATER BODIES ..............................................22
S9. STORMWATER POLLUTION PREVENTION PLAN...................................................26
S10. NOTICE OF TERMINATION ..........................................................................................34
GENERAL CONDITIONS .......................................................................................................... 36
G1. DISCHARGE VIOLATIONS ...........................................................................................36
G2. SIGNATORY REQUIREMENTS.....................................................................................36
G3. RIGHT OF INSPECTION AND ENTRY .........................................................................37
G4. GENERAL PERMIT MODIFICATION AND REVOCATION ......................................37
G5. REVOCATION OF COVERAGE UNDER THE PERMIT .............................................37
G6. REPORTING A CAUSE FOR MODIFICATION ............................................................38
G7. COMPLIANCE WITH OTHER LAWS AND STATUTES .............................................38
G8. DUTY TO REAPPLY .......................................................................................................38
G9. TRANSFER OF GENERAL PERMIT COVERAGE .......................................................39
G10. REMOVED SUBSTANCES .............................................................................................39
G11. DUTY TO PROVIDE INFORMATION ...........................................................................39
G12. OTHER REQUIREMENTS OF 40 CFR ...........................................................................39
G13. ADDITIONAL MONITORING ........................................................................................39
G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS .............................................40
G15. UPSET ...............................................................................................................................40
Construction Stormwater General Permit – December 1, 2010
Page 3
G16. PROPERTY RIGHTS ........................................................................................................40
G17. DUTY TO COMPLY ........................................................................................................40
G18. TOXIC POLLUTANTS.....................................................................................................41
G19. PENALTIES FOR TAMPERING .....................................................................................41
G20. REPORTING PLANNED CHANGES .............................................................................41
G21. REPORTING OTHER INFORMATION ..........................................................................42
G22. REPORTING ANTICIPATED NON-COMPLIANCE .....................................................42
G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT ..........42
G24. APPEALS ..........................................................................................................................42
G25. SEVERABILITY ...............................................................................................................43
G26. BYPASS PROHIBITED ....................................................................................................43
APPENDIX A – DEFINITIONS .................................................................................................. 46
APPENDIX B – ACRONYMS .................................................................................................... 54
LIST OF TABLES
Table 1. Summary of Permit Report Submittals ....................................................................... 4
Table 2. Summary of Required On-site Documentation........................................................... 4
Table 3. Summary of Primary Monitoring Requirements ...................................................... 12
Table 4. Monitoring and Reporting Requirements ................................................................. 16
Table 5. Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed ... 24
Table 6. pH Sampling and Limits for 303(d)-Listed Waters .................................................. 24
Construction Stormwater General Permit – December 1, 2010
Page 4
SUMMARY OF PERMIT REPORT SUBMITTALS
Refer to the Special and General Conditions within this permit for additional submittal
requirements. Appendix A provides a list of definitions. Appendix B provides a list of
acronyms.
Table 1. Summary of Permit Report Submittals
Permit
Section
Submittal Frequency First Submittal Date
S5.A and
S8
High Turbidity/Transparency Phone
Reporting
As Necessary Within 24 hours
S5.B Discharge Monitoring Report Monthly* Within 15 days of
applicable monitoring
period
S5.F and
S8
Noncompliance Notification As necessary Immediately
S5.F Noncompliance Notification –
Written Report
As necessary Within 5 Days of non-
compliance
G2. Notice of Change in Authorization As necessary
G6. Permit Application for Substantive
Changes to the Discharge
As necessary
G8. Application for Permit Renewal 1/permit cycle No later than 180 days
before expiration
G9. Notice of Permit Transfer As necessary
G20. Notice of Planned Changes As necessary
G22. Reporting Anticipated Non-
compliance
As necessary
SPECIAL NOTE: *Permittees must submit Discharge Monitoring Reports (DMRs) to the Washington
State Department of Ecology monthly, regardless of site discharge, for the full duration of permit
coverage. Refer to Section S5.B of this General Permit for more specific information regarding DMRs.
Table 2. Summary of Required On-site Documentation
Document Title
Permit Conditions
Permit Coverage Letter See Conditions S2, S5
Construction Stormwater General Permit See Conditions S2, S5
Site Log Book See Conditions S4, S5
Stormwater Pollution Prevention Plan (SWPPP) See Conditions S9, S5
Construction Stormwater General Permit – December 1, 2010
Page 5
SPECIAL CONDITIONS
S1. PERMIT COVERAGE
A. Permit Area
This Construction Stormwater General Permit (CSWGP) covers all areas of
Washington State, except for federal and Tribal lands as specified in Special Condition
S1.E.3.
B. Operators Required to Seek Coverage Under this General Permit:
1. Operators of the following construction activities are required to seek coverage
under this CSWGP:
a. Clearing, grading and/or excavation that 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 that 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 discharge
stormwater to surface waters of the State.
i. This includes forest practices (including, but not limited to, class IV
conversions) that are part of a construction activity that will result in the
disturbance of one or more acres, and discharge to surface waters of the
State (that is, forest practices that prepare a site for construction
activities); and
b. Any size construction activity discharging stormwater to waters of the State
that the Department of Ecology ( ―Ecology‖):
i. Determines to be a significant contributor of pollutants to waters of the
State of Washington.
ii. Reasonably expects to cause a violation of any water quality standard.
2. Operators of the following activities are not required to seek coverage under this
CSWGP (unless specifically required under Special Condition S1.B.1.b. above):
a. Construction activities that discharge all stormwater and non-stormwater to
ground water, sanitary sewer, or combined sewer, and have no point source
discharge to either surface water or a storm sewer system that drains to
surface waters of the State.
b. Construction activities covered under an Erosivity Waiver (Special Condition
S2.C).
c. Routine maintenance that is performed to maintain the original line and grade,
hydraulic capacity, or original purpose of a facility.
Construction Stormwater General Permit – December 1, 2010
Page 6
C. Authorized Discharges:
1. Stormwater Associated with Construction Activity. Subject to compliance with
the terms and conditions of this permit, Permittees are authorized to discharge
stormwater associated with construction activity to surface waters of the State or to
a storm sewer system that drains to surface waters of the State. (Note that ―surface
waters of the State‖ may exist on a construction site as well as off site; for
example, a creek running through a site.)
2. Stormwater Associated with Construction Support Activity. This permit also
authorizes stormwater discharge from support activities related to the permitted
construction site (for example, an on-site portable rock crusher, off-site equipment
staging yards, material storage areas, borrow areas, etc.) provided:
a. The support activity relates directly to the permitted construction site that is
required to have a NPDES permit; and
b. The support activity is not a commercial operation serving multiple unrelated
construction projects, and does not operate beyond the completion of the
construction activity; and
c. Appropriate controls and measures are identified in the Stormwater Pollution
Prevention Plan (SWPPP) for the discharges from the support activity areas.
3. Non-Stormwater Discharges. The categories and sources of non-stormwater
discharges identified below are authorized conditionally, 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.
d. Pipeline hydrostatic test water.
e. Uncontaminated air conditioning or compressor condensate.
f. Uncontaminated ground water or spring water.
g. Uncontaminated excavation dewatering water (in accordance with S9.D.10).
h. Uncontaminated discharges from foundation or footing drains.
i. Water used to control dust. Permittees must minimize the amount of dust
control water used.
j. Routine external building wash down that does not use detergents.
k. Landscape irrigation water.
The SWPPP must adequately address all authorized non-stormwater discharges,
except for discharges from fire-fighting activities, and must comply with Special
Construction Stormwater General Permit – December 1, 2010
Page 7
Condition S3. At a minimum, discharges from potable water (including water line
flushing), fire hydrant system flushing, and pipeline hydrostatic test water must
undergo the following: dechlorination to a concentration of 0.1 parts per million
(ppm) or less, and pH adjustment to within 6.5 – 8.5 standard units (su), if
necessary.
D. Prohibited Discharges:
The following discharges to waters of the State, including ground water, are prohibited.
1. Concrete wastewater.
2. Wastewater from washout and clean-up of stucco, paint, form release oils, curing
compounds and other construction materials.
3. Process wastewater as defined by 40 Code of Federal Regulations (CFR) 122.1
(see Appendix A of this permit).
4. Slurry materials and waste from shaft drilling.
5. Fuels, oils, or other pollutants used in vehicle and equipment operation and
maintenance.
6. Soaps or solvents used in vehicle and equipment washing.
7. Wheel wash wastewater, unless discharged according to Special Condition
S9.D.9.d.
8. Discharges from dewatering activities, including discharges from dewatering of
trenches and excavations, unless managed according to Special Condition S9.D.10.
E. Limits on Coverage
Ecology may require any discharger to apply for and obtain coverage under an
individual permit or another more specific general permit. Such alternative coverage
will be required when Ecology determines that this CSWGP does not provide adequate
assurance that water quality will be protected, or there is a reasonable potential for the
project to cause or contribute to a violation of water quality standards.
The following stormwater discharges are not covered by this permit:
1. Post-construction stormwater discharges that originate from the site after
completion of construction activities and the site has undergone final stabilization.
2. Non-point 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.
3. Stormwater from any federal project or project on federal land or land within an
Indian Reservation except for the Puyallup Reservation. Within the Puyallup
Construction Stormwater General Permit – December 1, 2010
Page 8
Reservation, any project that discharges to surface water on land held in trust by
the federal government may be covered by this permit.
4. Stormwater from any site covered under an existing NPDES individual permit in
which stormwater management and/or treatment requirements are included for all
stormwater discharges associated with construction activity.
5. Stormwater from a site where an applicable Total Maximum Daily Load (TMDL)
requirement specifically precludes or prohibits discharges from construction
activity.
S2. APPLICATION REQUIREMENTS
A. Permit Application Forms
1. Notice of Intent Form/Timeline
a. Operators of new or previously unpermitted construction activities must
submit a complete and accurate permit application (Notice of Intent, or NOI)
to Ecology.
b. The operator must submit the NOI at least 60 days before discharging
stormwater from construction activities and must submit it on or before the
date of the first public notice (see Special Condition S2.B below for details).
The 30-day public comment period required by WAC 173-226-130(5) begins
on the publication date of the second public notice. Unless Ecology responds
to the complete application in writing, based on public comments, or any other
relevant factors, coverage under the general permit will automatically
commence on the thirty-first day following receipt by Ecology of a completed
NOI, or the issuance date of this permit, whichever is later, unless Ecology
specifies a later date in writing.
c. Applicants who propose to discharge to a storm or sewer system operated by
Seattle, King County, Snohomish County, Tacoma, Pierce County, or Clark
County must also submit a copy of the NOI to the appropriate jurisdiction.
d. If an applicant intends to use a Best Management Practice (BMP) selected on
the basis of Special Condition S9.C.4 (―demonstrably equivalent‖ BMPs), the
applicant must notify Ecology of its selection as part of the NOI. In the event
the applicant selects BMPs after submission of the NOI, it must provide notice
of the selection of an equivalent BMP to Ecology at least 60 days before
intended use of the equivalent BMP.
e. Permittees must notify Ecology regarding any changes to the information
provided on the NOI by submitting an updated NOI. Examples of such
changes include, but are not limited to,
i. changes to the Permittee’s mailing address,
ii. changes to the on-site contact person information, and
Construction Stormwater General Permit – December 1, 2010
Page 9
iii. changes to the area/acreage affected by construction activity.
2. Transfer of Coverage Form
The Permittee can transfer current coverage under this permit to one or more new
operators, including operators of sites within a Common Plan of Development,
provided the Permittee submits a Transfer of Coverage Form in accordance with
General Condition G9. Transfers do not require public notice.
B. Public Notice
For new or previously unpermitted construction activities, the applicant must publish a
public notice at least one time each week for two consecutive weeks, at least 7 days
apart, in a newspaper with general circulation in the county where the construction is to
take place. The notice must contain:
1. A statement that ―The applicant is seeking coverage under the Washington State
Department of Ecology’s Construction Stormwater NPDES and State Waste
Discharge General Permit."
2. The name, address and location of the construction site.
3. The name and address of the applicant.
4. The type of construction activity that will result in a discharge (for example,
residential construction, commercial construction, etc.), and the number of acres to
be disturbed.
5. The name of the receiving water(s) (that is, the surface water(s) to which the site will
discharge), or, if the discharge is through a storm sewer system, the name of the
operator of the system.
6. The statement: "Any persons desiring to present their views to the Washington State
Department of Ecology regarding this application, or interested in Ecology’s action
on this application, may notify Ecology in writing no later than 30 days of the last
date of publication of this notice. Ecology reviews public comments and considers
whether discharges from this project would cause a measurable change in receiving
water quality, and, if so, whether the project is necessary and in the overriding public
interest according to Tier II antidegradation requirements under WAC 173-201A-320.
Comments can be submitted to: Department of Ecology, P.O. Box 47696, Olympia,
WA 98504-7696 Attn: Water Quality Program, Construction Stormwater.‖
Construction Stormwater General Permit – December 1, 2010
Page 10
C. Erosivity Waiver
Construction site operators may qualify for an erosivity waiver from the CSWGP if the
following conditions are met:
1. The site will result in the disturbance of fewer than 5 acres and the site is not a
portion of a common plan of development or sale that will disturb 5 acres or
greater.
2. Calculation of Erosivity ―R‖ Factor and Regional Timeframe:
a. The project’s rainfall erosivity factor (―R‖ Factor) must be less than 5 during
the period of construction activity, as calculated using either the Texas A&M
University online rainfall erosivity calculator at: http://ei.tamu.edu/ or EPA's
calculator at http://cfpub.epa.gov/npdes/stormwater/lew/lewcalculator.cfm.
The period of construction activity starts when the land is first disturbed and
ends with final stabilization. In addition:
b. The entire period of construction activity must fall within the following
timeframes:
i. For sites west of the Cascades Crest: June 15 – September 15.
ii. For sites east of the Cascades Crest, excluding the Central Basin: June 15
– October 15.
iii. For sites east of the Cascades Crest, within the Central Basin: no
additional timeframe restrictions apply. The Central Basin is defined as
the portions of Eastern Washington with mean annual precipitation of
less than 12 inches. For a map of the Central Basin (Region 2), refer to
http://www.ecy.wa.gov/pubs/ecy070202.pdf.
3. Construction site operators must submit a complete Erosivity Waiver certification
form at least one week before disturbing the land. Certification must include
statements that the operator will:
a. Comply with applicable local stormwater requirements; and
b. Implement appropriate erosion and sediment control BMPs to prevent
violations of water quality standards.
4. This waiver is not available for facilities declared significant contributors of
pollutants as defined in Special Condition S1.B.1.b.
5. This waiver does not apply to construction activities which include non-
stormwater discharges listed in Special Condition S1.C.3.
6. If construction activity extends beyond the certified waiver period for any reason,
the operator must either:
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
Construction Stormwater General Permit – December 1, 2010
Page 11
project falls within the applicable regional timeframe in Special Condition
S2.C.2.b, complete and submit an amended waiver certification form before
the original waiver expires; or
b. Submit a complete permit application to Ecology in accordance with Special
Condition S2.A and B before the end of the certified waiver period.
S3. COMPLIANCE WITH STANDARDS
A. Discharges must not cause or contribute to a violation of surface water quality
standards (Chapter 173-201A WAC), ground water quality standards (Chapter 173-200
WAC), sediment management standards (Chapter 173-204 WAC), and human health-
based criteria in the National Toxics Rule (40 CFR Part 131.36). Discharges not in
compliance with these standards are not authorized.
B. Prior to the discharge of stormwater and non-stormwater to waters of the State, the
Permittee must apply all known, available, and reasonable methods of prevention,
control, and treatment (AKART). This includes the preparation and implementation of
an adequate Stormwater Pollution Prevention Plan (SWPPP), with all appropriate
BMPs installed and maintained in accordance with the SWPPP and the terms and
conditions of this permit.
C. Ecology presumes that a Permittee complies with water quality standards 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 complies with the following conditions. The Permittee must fully:
1. Comply with all permit conditions, including planning, sampling, monitoring,
reporting, and recordkeeping conditions.
2. Implement stormwater BMPs contained in stormwater management manuals
published or approved by Ecology, or BMPs that are demonstrably equivalent to
BMPs contained in stormwater technical manuals published or approved by
Ecology, including the proper selection, implementation, and maintenance of all
applicable and appropriate BMPs for on-site pollution control. (For purposes of
this section, the stormwater manuals listed in Appendix 10 of the Phase I
Municipal Stormwater Permit are approved by Ecology.)
D. Where construction sites also discharge to ground water, the ground water discharges
must also meet the terms and conditions of this CSWGP. Permittees who discharge to
ground water through an injection well must also comply with any applicable
requirements of the Underground Injection Control (UIC) regulations, Chapter 173-218
WAC.
Construction Stormwater General Permit – December 1, 2010
Page 12
S4. MONITORING REQUIREMENTS, BENCHMARKS AND REPORTING
TRIGGERS
Table 3. Summary of Primary Monitoring Requirements
Size of Soil
Disturbance1
Weekly Site
Inspections
Weekly
Sampling w/
Turbidity
Meter
Weekly
Sampling w/
Transparency
Tube
Weekly pH
Sampling2
Requires
CESCL
Certification?
Sites that disturb
less than 1 acre, but
are part of a larger
Common Plan of
Development
Required Not Required Not Required Not Required No
Sites that disturb 1
acre or more, but
fewer than 5 acres
Required Sampling Required –
either method3
Required Yes
Sites that disturb 5
acres or more
Required Required Not Required4 Required Yes
A. Site Log Book
The Permittee must 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
The Permittee’s (operator’s) site inspections must include all areas disturbed by
construction activities, all BMPs, and all stormwater discharge points. (See Special
Conditions S4.B.3 and B.4 below for detailed requirements of the Permittee’s Certified
Erosion and Sediment Control Lead [CESCL]).
1 Soil disturbance is calculated by adding together all areas affected by construction activity. Construction activity
means clearing, grading, excavation, and any other activity that disturbs the surface of the land, including
ingress/egress from the site. 2 If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work (1,000
cubic yards of poured or recycled concrete over the life of a project) or the use of engineered soils (soil amendments
including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and
stormwater from the affected area drains to surface waters of the State or to a storm sewer stormwater collection
system that drains to other surface waters of the State, the Permittee must conduct pH monitoring sampling in
accordance with Special Condition S4.D. 3 Sites with one or more acres, but fewer than 5 acres of soil disturbance, must conduct turbidity or transparency
sampling in accordance with Special Condition S4.C. 4 Sites equal to or greater than 5 acres of soil disturbance must conduct turbidity sampling using a turbidity meter in
accordance with Special Condition S4.C.
Construction Stormwater General Permit – December 1, 2010
Page 13
Construction sites one acre or larger that discharge stormwater to surface waters of the
State must have site inspections conducted by a certified CESCL. Sites less than one
acre may have a person without CESCL certification conduct inspections; sampling is
not required on sites that disturb less than an acre.
1. The Permittee must examine stormwater visually for the presence of suspended
sediment, turbidity, discoloration, and oil sheen. The Permittee must evaluate the
effectiveness of BMPs and determine if it is necessary to install, maintain, or repair
BMPs to improve the quality of stormwater discharges.
Based on the results of the inspection, the Permittee must correct the problems
identified by:
a. Reviewing the SWPPP for compliance with Special Condition S9 and making
appropriate revisions within 7 days of the inspection.
b. Immediately beginning the process of fully implementing and maintaining
appropriate source control and/or treatment BMPs as soon as possible,
addressing the problems no later than within 10 days of the inspection. If
installation of necessary treatment BMPs is not feasible within 10 days,
Ecology may approve additional time when an extension is requested by a
Permittee within the initial 10-day response period.
c. Documenting BMP implementation and maintenance in the site log book.
2. The Permittee must inspect all areas disturbed by construction activities, all BMPs,
and all stormwater discharge points at least once every calendar week and within
24 hours of any discharge from the site. (For purposes of this condition, individual
discharge events that last more than one day do not require daily inspections. For
example, if a stormwater pond discharges continuously over the course of a week,
only one inspection is required that week.) The Permittee may reduce the
inspection frequency for temporarily stabilized, inactive sites to once every
calendar month.
3. The Permittee must have staff knowledgeable in the principles and practices of
erosion and sediment control. The CESCL (sites one acre or more) or inspector
(sites less than one acre) must have the skills to assess the:
a. Site conditions and construction activities that could impact the quality of
stormwater, and
b. Effectiveness of erosion and sediment control measures used to control the
quality of stormwater discharges.
4. The SWPPP must identify the CESCL or inspector, who must be present on site or
on-call at all times. The CESCL must obtain this certification through an approved
erosion and sediment control training program that meets the minimum training
standards established by Ecology (see BMP C160 in the manual referred to in
Special Condition S9.C.1 and 2).
Construction Stormwater General Permit – December 1, 2010
Page 14
5. The Permittee must summarize the results of each inspection in an inspection
report or checklist and enter the report/checklist into, or attach it to, the site log
book. At a minimum, each inspection report or checklist must include:
a. Inspection date and time.
b. Weather information, the general conditions during inspection and the
approximate amount of precipitation since the last inspection, and
precipitation within the last 24 hours.
c. A summary or list of all implemented BMPs, including observations of all
erosion/sediment control structures or practices.
d. A description of the locations:
i. Of BMPs inspected.
ii. Of BMPs that need maintenance and why.
iii. Of BMPs that failed to operate as designed or intended, and
iv. Where additional or different BMPs are needed, and why.
e. A description of stormwater discharged from the site. The Permittee must
note the presence of suspended sediment, turbidity, discoloration, and oil
sheen, as applicable.
f. Any water quality monitoring performed during inspection.
g. General comments and notes, including a brief description of any BMP
repairs, maintenance or installations made following the inspection.
h. A summary report and a schedule of implementation of the remedial actions
that the Permittee plans to take if the site inspection indicates that the site is
out of compliance. The remedial actions taken must meet the requirements of
the SWPPP and the permit.
i. The name, title, and signature of the person conducting the site inspection, a
phone number or other reliable method to reach this person, and the following
statement: ―I certify that this report is true, accurate, and complete to the best
of my knowledge and belief.‖
C. Turbidity/Transparency Sampling Requirements
1. Sampling Methods
a. If construction activity involves the disturbance of 5 acres or more, the
Permittee must conduct turbidity sampling per Special Condition S4.C.
b. If construction activity involves 1 acre or more but fewer than 5 acres of soil
disturbance, the Permittee must conduct either transparency sampling or
turbidity sampling per Special Condition S4.C.
Construction Stormwater General Permit – December 1, 2010
Page 15
2. Sampling Frequency
a. The Permittee must sample all discharge locations at least once every calendar
week when stormwater (or authorized non-stormwater) discharges from the
site or enters any on-site surface waters of the state (for example, a creek
running through a site).
b. Samples must be representative of the flow and characteristics of the
discharge.
c. Sampling is not required when there is no discharge during a calendar week.
d. Sampling is not required outside of normal working hours or during unsafe
conditions.
e. If the Permittee is unable to sample during a monitoring period, the Permittee
must include a brief explanation in the monthly Discharge Monitoring Report
(DMR).
f. Sampling is not required before construction activity begins.
3. Sampling Locations
a. Sampling is required at all points where stormwater associated with
construction activity (or authorized non-stormwater) is discharged off site,
including where it enters any on-site surface waters of the state (for example,
a creek running through a site).
b. The Permittee may discontinue sampling at discharge points that drain areas of
the project that are fully stabilized to prevent erosion.
c. The Permittee must identify all sampling point(s) on the SWPPP site map and
clearly mark these points in the field with a flag, tape, stake or other visible
marker.
d. Sampling is not required for discharge that is sent directly to sanitary or
combined sewer systems.
4. Sampling and Analysis Methods
a. The Permittee performs turbidity analysis with a calibrated turbidity meter
(turbidimeter) either on site or at an accredited lab. The Permittee must record
the results in the site log book in nephelometric turbidity units (NTU).
b. The Permittee performs transparency analysis on site with a 1¾-inch-
diameter, 60-centimeter (cm)-long transparency tube. The Permittee will
record the results in the site log book in centimeters (cm). Transparency tubes
are available from: http://watermonitoringequip.com/pages/stream.html.
Construction Stormwater General Permit – December 1, 2010
Page 16
Table 4. Monitoring and Reporting Requirements
Parameter Unit Analytical Method Sampling
Frequency
Benchmark
Value
Phone
Reporting
Trigger Value
Turbidity NTU SM2130 or EPA
180.1
Weekly, if
discharging
25 NTU 250 NTU
Transparency cm Manufacturer
instructions, or
Ecology guidance
Weekly, if
discharging
33 cm 6 cm
5. Turbidity/Transparency Benchmark Values and Reporting Triggers
The benchmark value for turbidity is 25 NTU or less. The benchmark value for
transparency is 33 centimeters (cm). Note: Benchmark values do not apply to
discharges to segments of water bodies on Washington State’s 303(d) list
(Category 5) for turbidity, fine sediment, or phosphorus; these discharges are
subject to a numeric effluent limit for turbidity. Refer to Special Condition S8 for
more information.
a. Turbidity 26 – 249 NTU, or Transparency 32 – 7 cm:
If the discharge turbidity is 26 to 249 NTU; or if discharge transparency is less
than 33 cm, but equal to or greater than 6 cm, the Permittee must:
i. Review the SWPPP for compliance with Special Condition S9 and make
appropriate revisions within 7 days of the date the discharge exceeded the
benchmark.
ii. Immediately begin the process to fully implement and maintain
appropriate source control and/or treatment BMPs as soon as possible,
addressing the problems within 10 days of the date the discharge
exceeded the benchmark. If installation of necessary treatment BMPs is
not feasible within 10 days, Ecology may approve additional time when
the Permittee requests an extension within the initial 10-day response
period.
iii. Document BMP implementation and maintenance in the site log book.
b. Turbidity 250 NTU or greater, or Transparency 6 cm or less:
If a discharge point’s turbidity is 250 NTU or greater, or if discharge
transparency is less than or equal to 6 cm, the Permittee must complete the
reporting and adaptive management process described below.
i. Telephone the applicable Ecology Region’s Environmental Report
Tracking System (ERTS) number within 24 hours, in accordance with
Special Condition S5.F.
Central Region (Okanogan, Chelan, Douglas, Kittitas, Yakima,
Klickitat, Benton): (509) 575-2490
Construction Stormwater General Permit – December 1, 2010
Page 17
Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield,
Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla,
Whitman): (509) 329-3400
Northwest Region (Kitsap, Snohomish, Island, King, San Juan,
Skagit, Whatcom): (425) 649-7000
Southwest Region (Grays Harbor, Lewis, Mason, Thurston, Pierce,
Clark, Cowlitz, Skamania, Wahkiakum, Clallam, Jefferson, Pacific):
(360) 407-6300
These numbers are also listed at the following web site:
http://www.ecy.wa.gov/programs/wq/stormwater/construction/permit.html
ii. Review the SWPPP for compliance with Special Condition S9 and make
appropriate revisions within 7 days of the date the discharge exceeded the
benchmark.
iii. Immediately begin the process to fully implement and maintain
appropriate source control and/or treatment BMPs as soon as possible,
addressing the problems within 10 days of the date the discharge
exceeded the benchmark. If installation of necessary treatment BMPs is
not feasible within 10 days, Ecology may approve additional time when
the Permittee requests an extension within the initial 10-day response
period.
iv. Document BMP implementation and maintenance in the site log book.
v. Continue to sample discharges daily until:
a) Turbidity is 25 NTU (or lower); or
b) Transparency is 33 cm (or greater); or
c) The Permittee has demonstrated compliance with the water quality
limit for turbidity:
1) No more than 5 NTU over background turbidity, if background
is less than 50 NTU, or
2) No more than 10% over background turbidity, if background is
50 NTU or greater; or
d) The discharge stops or is eliminated.
D. pH Sampling Requirements -- Significant Concrete Work or Engineered Soils
If construction activity results in the disturbance of 1 acre or more, and involves
significant concrete work (significant concrete work means greater than 1000 cubic
yards poured concrete or recycled concrete used over the life of a project ) or the use of
engineered soils (soil amendments including but not limited to Portland cement-treated
base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area
Construction Stormwater General Permit – December 1, 2010
Page 18
drains to surface waters of the State or to a storm sewer system that drains to surface
waters of the state, the Permittee must conduct pH monitoring as set forth below. Note:
In addition, discharges to segments of water bodies on Washington State’s 303(d) list
(Category 5) for high pH are subject to a numeric effluent limit for pH; refer to Special
Condition S8.
1. For sites with significant concrete work, the Permittee must begin the pH
monitoring period when the concrete is first poured and exposed to precipitation,
and continue weekly throughout and after the concrete pour and curing period,
until stormwater pH is in the range of 6.5 to 8.5 (su).
2. For sites with engineered soils, the Permittee must begin the pH monitoring period
when the soil amendments are first exposed to precipitation and must continue
until the area of engineered soils is fully stabilized.
3. During the applicable pH monitoring period defined above, the Permittee must
obtain a representative sample of stormwater and conduct pH analysis at least once
per week.
4. The Permittee must 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 before the stormwater discharges to surface waters.
5. The benchmark value for pH is 8.5 standard units. Anytime sampling indicates that
pH is 8.5 or greater, the Permittee must either:
a. Prevent the high pH water (8.5 or above) from entering storm sewer systems
or surface waters; or
b. If necessary, adjust or neutralize the high pH water until it is in the range of
pH 6.5 to 8.5 (su) using an appropriate treatment BMP such as carbon dioxide
(CO2) sparging or dry ice. The Permittee must obtain written approval from
Ecology before using any form of chemical treatment other than CO2 sparging
or dry ice.
6. The Permittee must perform pH analysis on site with a calibrated pH meter, pH
test kit, or wide range pH indicator paper. The Permittee must record pH
monitoring results in the site log book.
Construction Stormwater General Permit – December 1, 2010
Page 19
S5. REPORTING AND RECORDKEEPING REQUIREMENTS
A. High Turbidity Phone Reporting
Anytime sampling performed in accordance with Special Condition S4.C indicates
turbidity has reached the 250 NTU phone reporting level, the Permittee must call
Ecology's Regional office by phone within 24 hours of analysis. The web site is
http://www.ecy.wa.gov/programs/wq/stormwater/construction/permit.html. Also see
phone numbers in Special Condition S4.C.5.b.i.
B. Discharge Monitoring Reports
Permittees required to conduct water quality sampling in accordance with Special
Conditions S4.C (Turbidity/Transparency), S4.D (pH), S8 (303[d]/TMDL sampling),
and/or G13 (Additional Sampling) must submit the results to Ecology.
Permittees must submit monitoring data using Ecology's WebDMR program. To find
out more information and to sign up for WebDMR go to:
http://www.ecy.wa.gov/programs/wq/permits/paris/webdmr.html.
Permittees unable to submit electronically (for example, those who do not have an
internet connection) must contact Ecology to request a waiver and obtain instructions
on how to obtain a paper copy DMR at:
Mailing Address:
Department of Ecology
Water Quality Program
Attn: Stormwater Compliance Specialist
PO Box 47696
Olympia, WA 98504-7696
Permittees who obtain a waiver not to use WebDMR must use the forms provided to
them by Ecology; submittals must be mailed to the address above. Permittees shall
submit DMR forms to be received by Ecology within 15 days following the end of each
month.
If there was no discharge during a given monitoring period, all Permittees must submit
a DMR as required with ―no discharge" entered in place of the monitoring results. For
more information, contact Ecology staff using information provided at the following
web site: http://www.ecy.wa.gov/programs/spills/response/assistancesoil%20map.pdf
C. Records Retention
The Permittee must 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 for the
entire life of the construction project and for a minimum of three years following the
termination of permit coverage. Such information must include all calibration and
maintenance records, and records of all data used to complete the application for this
Construction Stormwater General Permit – December 1, 2010
Page 20
permit. This period of retention must be extended during the course of any unresolved
litigation regarding the discharge of pollutants by the Permittee or when requested by
Ecology.
D. Recording Results
For each measurement or sample taken, the Permittee must record the following
information:
1. Date, place, method, and time of sampling or measurement.
2. The first and last name of the individual who performed the sampling or
measurement.
3. The date(s) the analyses were performed.
4. The first and last name of the individual who performed the analyses.
5. The analytical techniques or methods used.
6. The results of all analyses.
E. Additional Monitoring by the Permittee
If the Permittee monitors any pollutant more frequently than required by this permit
using test procedures specified by Special Condition S4 of this permit, the results of
this monitoring must be included in the calculation and reporting of the data submitted
in the Permittee’s DMR.
F. Noncompliance Notification
In the event the Permittee is unable to comply with any part of the terms and conditions
of this permit, and the resulting noncompliance may cause a threat to human health or
the environment, the Permittee must:
1. Immediately notify Ecology of the failure to comply by calling the applicable
Regional office ERTS phone number (find at
http://www.ecy.wa.gov/programs/spills/response/assistancesoil%20map.pdf) or
refer to Special Condition S4.C.5.b.i.
2. Immediately take action to prevent the discharge/pollution, or otherwise stop or
correct the noncompliance, and, if applicable, repeat sampling and analysis of any
noncompliance immediately and submit the results to Ecology within five (5) days
of becoming aware of the violation.
3. Submit a detailed written report to Ecology within five (5) days, unless requested
earlier by Ecology. The report must 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.
Construction Stormwater General Permit – December 1, 2010
Page 21
The Permittee must report any unanticipated bypass and/or upset that exceeds any
effluent limit in the permit in accordance with the 24-hour reporting requirement
contained in 40 C.F.R. 122.41(l)(6)).
Compliance with these requirements does not relieve the Permittee from
responsibility to maintain continuous compliance with the terms and conditions of
this permit or the resulting liability for failure to comply. Refer to Section G14 of
this permit for specific information regarding non-compliance.
G. Access to Plans and Records
1. The Permittee must retain the following permit documentation (plans and records)
on site, or within reasonable access to the site, for use by the operator or for on-site
review by Ecology or the local jurisdiction:
a. General Permit.
b. Permit Coverage Letter.
c. Stormwater Pollution Prevention Plan (SWPPP).
d. Site Log Book.
2. The Permittee must address written requests for plans and records listed above
(Special Condition S5.G.1) as follows:
a. The Permittee must provide a copy of plans and records to Ecology within 14
days of receipt of a written request from Ecology.
b. The Permittee must provide a copy of plans and records to the public when
requested in writing. Upon receiving a written request from the public for the
Permittee’s plans and records, the Permittee must either:
i. Provide a copy of the plans and records to the requester within 14 days of
a receipt of the written request; or
ii. Notify the requester within 10 days of receipt of the written request of the
location and times within normal business hours when the plans and
records may be viewed; and provide access to the plans and records
within 14 days of receipt of the written request; or
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 requester at an Ecology office, or a mutually agreed
location. If plans and records are viewed and/or copied at a location
other than at an Ecology office, the Permittee will provide reasonable
access to copying services for which a reasonable fee may be charged.
The Permittee must notify the requester within 10 days of receipt of the
request where the plans and records may be viewed and/or copied.
Construction Stormwater General Permit – December 1, 2010
Page 22
S6. PERMIT FEES
The Permittee must pay permit fees assessed by Ecology. Fees for stormwater discharges
covered under this permit are established by Chapter 173-224 WAC. Ecology continues to
assess permit fees until the permit is terminated in accordance with Special Condition S10
or revoked in accordance with General Condition G5.
S7. SOLID AND LIQUID WASTE DISPOSAL
The Permittee must handle and dispose of 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, in accordance with:
A. Special Condition S3, Compliance with Standards.
B. WAC 173-216-110.
C. Other applicable regulations.
S8. DISCHARGES TO 303(D) OR TMDL WATER BODIES
A. Sampling and Numeric Effluent Limits For Certain Discharges to 303(d)-listed Water
Bodies
1. Permittees who discharge to segments of water bodies listed as impaired by the
State of Washington under Section 303(d) of the Clean Water Act for turbidity,
fine sediment, high pH, or phosphorus, must conduct water quality sampling
according to the requirements of this section, and Special Conditions S4.C.2.b-f
and S4.C.3.b-d, and must comply with the applicable numeric effluent limitations
in S8.C and S8.D.
2. All references and requirements associated with Section 303(d) of the Clean Water
Act mean the most current listing by Ecology of impaired waters (Category 5) that
exists on January 1, 2011, or the date when the operator’s complete permit
application is received by Ecology, whichever is later.
B. Limits on Coverage for New Discharges to TMDL or 303(d)-listed Waters
Operators of construction sites that discharge to a 303(d)-listed water body are not
eligible for coverage under this permit unless the operator:
1. Prevents exposing stormwater to pollutants for which the water body is impaired,
and retains documentation in the SWPPP that details procedures taken to prevent
exposure on site; or
2. Documents that the pollutants for which the water body is impaired are not present
at the site, and retains documentation of this finding within the SWPPP; or
Construction Stormwater General Permit – December 1, 2010
Page 23
3. Provides Ecology with data indicating the discharge is not expected to cause or
contribute to an exceedance of a water quality standard, and retains such data on
site with the SWPPP. The operator must provide data and other technical
information to Ecology that sufficiently demonstrate:
a. For discharges to waters without an EPA-approved or -established TMDL,
that the discharge of the pollutant for which the water is impaired will meet
in-stream water quality criteria at the point of discharge to the water body; or
b. For discharges to waters with an EPA-approved or -established TMDL, that
there is sufficient remaining wasteload allocation in the TMDL to allow
construction stormwater discharge and that existing dischargers to the water
body are subject to compliance schedules designed to bring the water body
into attainment with water quality standards.
Operators of construction sites are eligible for coverage under this permit if
Ecology issues permit coverage based upon an affirmative determination that the
discharge will not cause or contribute to the existing impairment.
C. Sampling and Numeric Effluent Limits for Discharges to Water Bodies on the 303(d)
List for Turbidity, Fine Sediment, or Phosphorus
1. Permittees who discharge to segments of water bodies on the 303(d) list (Category
5) for turbidity, fine sediment, or phosphorus must conduct turbidity sampling in
accordance with Special Condition S4.C.2 and comply with either of the numeric
effluent limits noted in Table 5 below.
2. As an alternative to the 25 NTU effluent limit noted in Table 5 below (applied at
the point where stormwater [or authorized non-stormwater] is discharged off-site),
permittees may choose to comply with the surface water quality standard for
turbidity. The standard is: no more than 5 NTU over background turbidity when
the background turbidity is 50 NTU or less, or no more than a 10% increase in
turbidity when the background turbidity is more than 50 NTU. In order to use the
water quality standard requirement, the sampling must take place at the following
locations:
a. Background turbidity in the 303(d)-listed receiving water immediately
upstream (upgradient) or outside the area of influence of the discharge.
b. Turbidity at the point of discharge into the 303(d)-listed receiving water,
inside the area of influence of the discharge.
3. Discharges that exceed the numeric effluent limit for turbidity constitute a
violation of this permit.
4. Permittees whose discharges exceed the numeric effluent limit shall sample
discharges daily until the violation is corrected and comply with the non-
compliance notification requirements in Special Condition S5.F.
Construction Stormwater General Permit – December 1, 2010
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Table 5. Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters
Parameter identified
in 303(d) listing
Parameter
Sampled
Unit Analytical
Method
Sampling
Frequency
Numeric Effluent
Limit1
Turbidity
Fine Sediment
Phosphorus
Turbidity NTU SM2130 or
EPA180.1
Weekly, if
discharging
25 NTU, at the point
where stormwater is
discharged from the
site; OR
In compliance with the
surface water quality
standard for turbidity
(S8.C.1.a)
1Permittees subject to a numeric effluent limit for turbidity may, at their discretion, choose either numeric effluent
limitation based on site-specific considerations including, but not limited to, safety, access and convenience.
D. Discharges to Water Bodies on the 303(d) List for High pH
1. Permittees who discharge to segments of water bodies on the 303(d) list (Category
5) for high pH must conduct pH sampling in accordance with the table below, and
comply with the numeric effluent limit of pH 6.5 to 8.5 su (Table 6).
Table 6. pH Sampling and Limits for 303(d)-Listed Waters
Parameter identified in
303(d) listing
Parameter
Sampled/Units
Analytical
Method
Sampling
Frequency
Numeric Effluent
Limit
High pH pH /Standard
Units
pH meter Weekly, if
discharging
In the range of 6.5 –
8.5
2. At the Permittee's discretion, compliance with the limit shall be assessed at one of
the following locations:
a. Directly in the 303(d)-listed water body segment, inside the immediate area of
influence of the discharge; or
b. Alternatively, the permittee may measure pH at the point where the discharge
leaves the construction site, rather than in the receiving water.
3. Discharges that exceed the numeric effluent limit for pH (outside the range of 6.5 –
8.5 su) constitute a violation of this permit.
4. Permittees whose discharges exceed the numeric effluent limit shall sample
discharges daily until the violation is corrected and comply with the non-
compliance notification requirements in Special Condition S5.F.
Construction Stormwater General Permit – December 1, 2010
Page 25
E. Sampling and Limits for Sites Discharging to Waters Covered by a TMDL or Another
Pollution Control Plan
1. Discharges to a water body that is subject to a Total Maximum Daily Load
(TMDL) for turbidity, fine sediment, high pH, or phosphorus must be consistent
with the TMDL. Refer to http://www.ecy.wa.gov/programs/wq/tmdl/index.html for
more information on TMDLs.
a. Where an applicable TMDL sets specific waste load allocations or
requirements for discharges covered by this permit, discharges must be
consistent with any specific waste load allocations or requirements established
by the applicable TMDL.
i. The Permittee must sample discharges weekly or as otherwise specified by
the TMDL to evaluate compliance with the specific waste load allocations
or requirements.
ii. Analytical methods used to meet the monitoring requirements must
conform to the latest revision of the Guidelines Establishing Test
Procedures for the Analysis of Pollutants contained in 40 CFR Part 136.
Turbidity and pH methods need not be accredited or registered unless
conducted at a laboratory which must otherwise be accredited or
registered.
b. Where an applicable TMDL has established a general waste load allocation
for construction stormwater discharges, but has not identified specific
requirements, compliance with Special Conditions S4 (Monitoring) and S9
(SWPPPs) will constitute compliance with the approved TMDL.
c. Where an applicable TMDL has not specified a waste load allocation for
construction stormwater discharges, but has not excluded these discharges,
compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will
constitute compliance with the approved TMDL.
d. Where an applicable TMDL specifically precludes or prohibits discharges
from construction activity, the operator is not eligible for coverage under this
permit.
2. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or
phosphorus that is completed and approved by EPA before January 1, 2011, or before
the date the operator’s complete permit application is received by Ecology, whichever
is later. TMDLs completed after the operator’s complete permit application is
received by Ecology become applicable to the Permittee only if they are imposed
through an administrative order by Ecology, or through a modification of permit
coverage.
Construction Stormwater General Permit – December 1, 2010
Page 26
S9. STORMWATER POLLUTION PREVENTION PLAN
The Permittee must prepare and properly implement an adequate Stormwater Pollution
Prevention Plan (SWPPP) for construction activity in accordance with the requirements of
this permit beginning with initial soil disturbance and until final stabilization.
A. The Permittee’s SWPPP must meet the following objectives:
1. To implement best management practices (BMPs) to prevent erosion and
sedimentation, and to identify, reduce, eliminate or prevent stormwater
contamination and water pollution from construction activity.
2. To prevent violations of surface water quality, ground water quality, or sediment
management standards.
3. To control peak volumetric flow rates and velocities of stormwater discharges.
B. General Requirements
1. The SWPPP must include a narrative and drawings. All BMPs must be clearly
referenced in the narrative and marked on the drawings. The SWPPP narrative
must include documentation to explain and justify the pollution prevention
decisions made for the project. Documentation must include:
a. Information about existing site conditions (topography, drainage, soils,
vegetation, etc.).
b. Potential erosion problem areas.
c. The 12 elements of a SWPPP in Special Condition 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—for
example, a contingency plan for additional treatment and/or storage of
stormwater that would violate the water quality standards if discharged.
f. Engineering calculations for ponds and any other designed structures.
2. The Permittee must 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 must then:
a. Review the SWPPP for compliance with Special Condition S9 and make
appropriate revisions within 7 days of the inspection or investigation.
b. Immediately begin the process to fully implement and maintain appropriate
source control and/or treatment BMPs as soon as possible, addressing the
problems no later than 10 days from the inspection or investigation. If
Construction Stormwater General Permit – December 1, 2010
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installation of necessary treatment BMPs is not feasible within 10 days,
Ecology may approve additional time when an extension is requested by a
Permittee within the initial 10-day response period,
c. Document BMP implementation and maintenance in the site log book.
The Permittee must modify the SWPPP whenever there is a change in design,
construction, operation, or maintenance at the construction site that has, or could
have, a significant effect on the discharge of pollutants to waters of the State.
C. Stormwater Best Management Practices (BMPs)
BMPs must be consistent with:
1. Stormwater Management Manual for Western Washington (most recent edition),
for sites west of the crest of the Cascade Mountains; or
2. Stormwater Management Manual for Eastern Washington (most recent edition),
for sites east of the crest of the Cascade Mountains; or
3. Revisions to the manuals listed in Special Condition S9.C.1. & 2., or other
stormwater management guidance documents or manuals which provide an
equivalent level of pollution prevention, that are approved by Ecology and
incorporated into this permit in accordance with the permit modification
requirements of WAC 173-226-230; or
4. Documentation in the SWPPP that the BMPs selected provide an equivalent level
of pollution prevention, compared to the applicable Stormwater Management
Manuals, including:
a. The technical basis for the selection of all stormwater BMPs (scientific,
technical studies, and/or modeling) that support the performance claims for
the BMPs being selected.
b. An assessment of how the selected BMP will satisfy AKART requirements
and the applicable federal technology-based treatment requirements under 40
CFR part 125.3.
D. SWPPP – Narrative Contents and Requirements
The Permittee must include each of the 12 elements below in Special Condition S9.D.1-
12 in the narrative of the SWPPP and implement them unless site conditions render the
element unnecessary and the exemption from that element is clearly justified in the
SWPPP.
1. Preserve Vegetation/Mark Clearing Limits
a. Before beginning land-disturbing activities, including clearing and grading,
clearly mark all clearing limits, sensitive areas and their buffers, and trees that
are to be preserved within the construction area.
Construction Stormwater General Permit – December 1, 2010
Page 28
b. Retain the duff layer, native top soil, and natural vegetation in an undisturbed
state to the maximum degree practicable.
2. Establish Construction Access
a. Limit construction vehicle access and exit to one route, if possible.
b. Stabilize access points with a pad of quarry spalls, crushed rock, or other
equivalent BMPs, to minimize tracking sediment onto roads.
c. Locate wheel wash or tire baths on site, if the stabilized construction entrance is
not effective in preventing tracking sediment onto roads.
d. If sediment is tracked off site, clean the affected roadway thoroughly at the end
of each day, or more frequently as necessary (for example, during wet weather).
Remove sediment from roads by shoveling, sweeping, or pickup and transport
of the sediment to a controlled sediment disposal area.
e. Conduct street washing only after sediment removal in accordance with Special
Condition S9.D.2.d. Control street wash wastewater by pumping back on site or
otherwise preventing it from discharging into systems tributary to waters of the
State.
3. Control Flow Rates
a. Protect properties and waterways downstream of development sites from
erosion and the associated discharge of turbid waters due to increases in the
velocity and peak volumetric flow rate of stormwater runoff from the project
site, as required by local plan approval authority.
b. Where necessary to comply with Special Condition S9.D.3.a, construct
stormwater retention or detention facilities as one of the first steps in grading.
Assure that detention facilities function properly before constructing site
improvements (for example, impervious surfaces).
c. If permanent infiltration ponds are used for flow control during construction,
protect these facilities from siltation during the construction phase.
4. Install Sediment Controls
The Permittee must design, install and maintain effective erosion controls and
sediment controls to minimize the discharge of pollutants. At a minimum, the
Permittee must design, install and maintain such controls to:
a. Construct sediment control BMPs (sediment ponds, traps, filters, etc.) as one of
the first steps in grading. These BMPs must be functional before other land
disturbing activities take place.
b. Minimize sediment discharges from the site. The design, installation and
maintenance of erosion and sediment controls must address factors such as the
amount, frequency, intensity and duration of precipitation, the nature of
Construction Stormwater General Permit – December 1, 2010
Page 29
resulting stormwater runoff, and soil characteristics, including the range of soil
particle sizes expected to be present on the site.
c. Direct stormwater runoff from disturbed areas through a sediment pond or other
appropriate sediment removal BMP, before the runoff leaves a construction site
or before discharge to an infiltration facility. Runoff from fully stabilized areas
may be discharged without a sediment removal BMP, but must meet the flow
control performance standard of Special Condition S9.D.3.a.
d. Locate BMPs intended to trap sediment on site in a manner to avoid
interference with the movement of juvenile salmonids attempting to enter off-
channel areas or drainages.
e. Provide and maintain natural buffers around surface waters, direct stormwater
to vegetated areas to increase sediment removal and maximize stormwater
infiltration, unless infeasible.
f. Where feasible, design outlet structures that withdraw impounded stormwater
from the surface to avoid discharging sediment that is still suspended lower in
the water column.
5. Stabilize Soils
a. The Permittee must stabilize exposed and unworked soils by application of
effective BMPs that prevent erosion. Applicable BMPs include, but are not
limited to: temporary and permanent seeding, sodding, mulching, plastic
covering, erosion control fabrics and matting, soil application of
polyacrylamide (PAM), the early application of gravel base on areas to be
paved, and dust control.
b. The Permittee must control stormwater volume and velocity within the site to
minimize soil erosion.
c. The Permittee must control stormwater discharges, including both peak flow
rates and total stormwater volume, to minimize erosion at outlets and to
minimize downstream channel and stream bank erosion.
d. Depending on the geographic location of the project, the Permittee must not
allow soils to remain exposed and unworked for more than the time periods set
forth below to prevent erosion:
West of the Cascade Mountains Crest
During the dry season (May 1 - Sept. 30): 7 days
During the wet season (October 1 - April 30): 2 days
East of the Cascade Mountains Crest, except for Central Basin*
During the dry season (July 1 - September 30): 10 days
During the wet season (October 1 - June 30): 5 days
The Central Basin*, East of the Cascade Mountains Crest
Construction Stormwater General Permit – December 1, 2010
Page 30
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.
e. The Permittee must stabilize soils at the end of the shift before a holiday or
weekend if needed based on the weather forecast.
f. The Permittee must stabilize soil stockpiles from erosion, protected with
sediment trapping measures, and where possible, be located away from storm
drain inlets, waterways, and drainage channels.
g. The Permittee must minimize the amount of soil exposed during construction
activity.
h. The Permittee must minimize the disturbance of steep slopes.
i. The Permittee must minimize soil compaction and, unless infeasible, preserve
topsoil.
6. Protect Slopes
a. The Permittee must design and construct cut-and-fill slopes in a manner to
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 (for example, track walking).
b. The Permittee must divert off-site stormwater (run-on) or ground water 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 must
handle the peak 10-minute velocity of flow from a Type 1A, 10-year, 24-
hour frequency storm for the developed condition. Alternatively, the 10-
year, 1-hour flow rate predicted by an approved continuous runoff model,
increased by a factor of 1.6, may be used. The hydrologic analysis must
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 must use the temporary or permanent project land cover
condition, whichever will produce the highest flow rates. If using the
Western Washington Hydrology Model (WWHM) to predict flows, bare
soil areas should be modeled as "landscaped area.‖
Construction Stormwater General Permit – December 1, 2010
Page 31
ii. East of the Cascade Mountains Crest: Temporary pipe slope drains must
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. Place excavated material on the uphill side of trenches, consistent with safety
and space considerations.
e. Place check dams at regular intervals within constructed channels that are cut
down a slope.
7. Protect Drain Inlets
a. Protect all storm drain inlets made operable during construction so that
stormwater runoff does not enter the conveyance system without first being
filtered or treated to remove sediment.
b. Clean or remove and replace inlet protection devices 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. Design, construct and stabilize all on-site conveyance channels to prevent
erosion from the following expected peak flows:
i. West of the Cascade Mountains Crest: Channels must handle the peak 10-
minute velocity of flow from a Type 1A, 10-year, 24-hour frequency storm
for the developed condition. Alternatively, the 10-year, 1-hour flow rate
indicated by an approved continuous runoff model, increased by a factor of
1.6, may be used. The hydrologic analysis must 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 must 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 must handle the expected
peak flow velocity from a 6-month, 3-hour storm for the developed
condition, referred to as the short duration storm.
b. Provide stabilization, including armoring material, adequate to prevent erosion
of outlets, adjacent stream banks, slopes, and downstream reaches at the outlets
of all conveyance systems.
9. Control Pollutants
Design, install, implement and maintain effective pollution prevention measures to
minimize the discharge of pollutants. The Permittee must:
Construction Stormwater General Permit – December 1, 2010
Page 32
a. Handle and dispose of all pollutants, including waste materials and demolition
debris that occur on site in a manner that does not cause contamination of
stormwater.
b. Provide cover, containment, and protection from vandalism 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 must
include secondary containment. Secondary containment means placing tanks
or containers within an impervious structure capable of containing 110% of the
volume contained in the largest tank within the containment structure. Double-
walled tanks do not require additional secondary containment.
c. Conduct maintenance, fueling, and repair of heavy equipment and vehicles
using spill prevention and control measures. Clean contaminated surfaces
immediately following any spill incident.
d. Discharge wheel wash or tire bath wastewater to a separate on-site treatment
system that prevents discharge to surface water, such as closed-loop
recirculation or upland land application, or to the sanitary sewer with local
sewer district approval.
e. Apply fertilizers and pesticides in a manner and at application rates that will not
result in loss of chemical to stormwater runoff. Follow manufacturers’ label
requirements for application rates and procedures.
f. Use BMPs to prevent contamination of stormwater runoff by pH-modifying
sources. The sources for this contamination include, but are not limited to: bulk
cement, cement kiln dust, fly ash, new concrete washing and curing waters,
waste streams generated from concrete grinding and sawing, exposed aggregate
processes, dewatering concrete vaults, concrete pumping and mixer washout
waters. (Also refer to the definition for "concrete wastewater" in Appendix A--
Definitions.)
g. Adjust the pH of stormwater if necessary to prevent violations of water quality
standards.
h. Assure that washout of concrete trucks is performed offsite or in designated
concrete washout areas only. Do not wash out concrete trucks onto the ground,
or into storm drains, open ditches, streets, or streams. Do not dump excess
concrete on site, except in designated concrete washout areas. Concrete
spillage or concrete discharge to surface waters of the State is prohibited.
i. Obtain written approval from Ecology before using chemical treatment other
than CO2 or dry ice to adjust pH.
10. Control Dewatering
a. Permittees must discharge foundation, vault, and trench dewatering water,
which have characteristics similar to stormwater runoff at the site, into a
Construction Stormwater General Permit – December 1, 2010
Page 33
controlled conveyance system before discharge to a sediment trap or sediment
pond.
b. Permittees may discharge clean, non-turbid dewatering water, such as well-
point ground water, to systems tributary to, or directly into surface waters of the
State, as specified in Special Condition S9.D.8, provided the dewatering flow
does not cause erosion or flooding of receiving waters. Do not route clean
dewatering water through stormwater sediment ponds. Note that ―surface
waters of the State‖ may exist on a construction site as well as off site; for
example, a creek running through a site.
c. Other treatment or disposal options may include:
i. Infiltration.
ii. Transport off site 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 or combined sewer discharge with local sewer district approval,
if there is no other option.
v. Use of a sedimentation bag with discharge to a ditch or swale for small
volumes of localized dewatering.
d. Permittees must handle highly turbid or contaminated dewatering water
separately from stormwater.
11. Maintain BMPs
a. Permittees must maintain and repair all temporary and permanent erosion and
sediment control BMPs as needed to assure continued performance of their
intended function in accordance with BMP specifications.
b. Permittees must remove all temporary erosion and sediment control BMPs
within 30 days after achieving final site stabilization or after the temporary
BMPs are no longer needed.
12. Manage the Project
a. Phase development projects to the maximum degree practicable and take into
account seasonal work limitations.
b. Inspection and monitoring -- Inspect, maintain and repair all BMPs as needed to
assure continued performance of their intended function. Conduct site
inspections and monitoring in accordance with Special Condition S4.
c. Maintaining an updated construction SWPPP -- Maintain, update, and
implement the SWPPP in accordance with Special Conditions S3, S4 and S9.
Construction Stormwater General Permit – December 1, 2010
Page 34
E. SWPPP – Map Contents and Requirements
The Permittee’s SWPPP must also include a vicinity map or general location map (for
example, a USGS quadrangle map, a portion of a county or city map, or other
appropriate map) with enough detail to identify the location of the construction site and
receiving waters within one mile of the site.
The SWPPP must also include a legible site map (or maps) showing the entire
construction site. The following features must be identified, unless not applicable due
to site conditions:
1. The direction of north, property lines, and existing structures and roads.
2. Cut and fill slopes indicating the top and bottom of slope catch lines.
3. Approximate slopes, contours, and direction of stormwater flow before and after
major grading activities.
4. Areas of soil disturbance and areas that will not be disturbed.
5. Locations of structural and nonstructural controls (BMPs) identified in the
SWPPP.
6. Locations of off-site material, stockpiles, waste storage, borrow areas, and
vehicle/equipment storage areas.
7. Locations of all surface water bodies, including wetlands.
8. Locations where stormwater or non-stormwater discharges off-site and/or to a
surface water body, including wetlands.
9. Location of water quality sampling station(s), if sampling is required by state or
local permitting authority.
10. Areas where final stabilization has been accomplished and no further construction-
phase permit requirements apply.
S10. NOTICE OF TERMINATION
A. The site is eligible for termination of coverage when it has met any of the following
conditions:
1. The site has undergone final stabilization, the Permittee has removed all temporary
BMPs (except biodegradable BMPs clearly manufactured with the intention for the
material to be left in place and not interfere with maintenance or land use), and all
stormwater discharges associated with construction activity have been eliminated;
or
2. All portions of the site that have not undergone final stabilization per Special
Condition S10.A.1 have been sold and/or transferred (per General Condition G9),
and the Permittee no longer has operational control of the construction activity; or
Construction Stormwater General Permit – December 1, 2010
Page 35
3. For residential construction only, the Permittee has completed temporary
stabilization and the homeowners have taken possession of the residences.
B. When the site is eligible for termination, the Permittee must submit a complete and
accurate Notice of Termination (NOT) form, signed in accordance with General
Condition G2, to:
Department of Ecology
Water Quality Program - Construction Stormwater
PO Box 47696
Olympia, Washington 98504-7696
The termination is effective on the date Ecology receives the NOT form, unless
Ecology notifies the Permittee within 30 days that termination request is denied
because the Permittee has not met the eligibility requirements in Special Condition
S10.A.
Permittees transferring the property to a new property owner or operator/permittee are
required to complete and submit the Notice of Transfer form to Ecology, but are not
required to submit a Notice of Termination form for this type of transaction.
Construction Stormwater General Permit – December 1, 2010
Page 36
GENERAL CONDITIONS
G1. DISCHARGE VIOLATIONS
All discharges and activities authorized by this general permit must 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 must
constitute a violation of the terms and conditions of this permit.
G2. SIGNATORY REQUIREMENTS
A. All permit applications must bear a certification of correctness to be signed:
1. In the case of corporations, by a responsible corporate officer of at least the level
of vice president of a corporation;
2. In the case of a partnership, by a general partner of a partnership;
3. In the case of sole proprietorship, by the proprietor; or
4. In the case of a municipal, state, or other public facility, by either a principal
executive officer or ranking elected official.
B. All reports required by this permit and other information requested by Ecology must be
signed by a person described above or by a duly authorized representative of that
person. A person is a duly authorized representative only if:
1. The authorization is made in writing by a person described above and submitted to
the Ecology.
2. The authorization specifies either an individual or a position having responsibility
for the overall operation of the regulated facility, such as the position of plant
manager, superintendent, position of equivalent responsibility, or an individual or
position having overall responsibility for environmental matters.
C. Changes to authorization. If an authorization under paragraph G2.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 G2.B.2 above must 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 must 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 the
information submitted. Based on my inquiry of the person or persons who
manage the system, or those persons directly responsible for gathering
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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 must 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 are 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. GENERAL PERMIT MODIFICATION AND REVOCATION
This permit may be modified, revoked and reissued, or terminated in accordance with the
provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance,
or termination include, but are not limited to, the following:
A. When a change occurs in the technology or practices for control or abatement of
pollutants applicable to the category of dischargers covered under this permit.
B. When effluent limitation guidelines or standards are promulgated pursuant to the CWA
or Chapter 90.48 RCW, for the category of dischargers covered under this permit.
C. When a water quality management plan containing requirements applicable to the
category of dischargers covered under this permit is approved, or
D. When information is obtained that indicates cumulative effects on the environment
from dischargers covered under this permit are unacceptable.
G5. REVOCATION OF COVERAGE UNDER THE PERMIT
Pursuant to Chapter 43.21B RCW and Chapter 173-226 WAC, the Director may terminate
coverage for any discharger under this permit for cause. Cases where coverage may be
terminated include, but are not limited to, the following:
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A. Violation of any term or condition of this permit.
B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully
all relevant facts.
C. A change in any condition that requires either a temporary or permanent reduction or
elimination of the permitted discharge.
D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090.
E. A determination that the permitted activity endangers human health or the environment,
or contributes to water quality standards violations.
F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and
Chapter 173-224 WAC.
G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226-
130(5), when applicable.
The Director may require any discharger under this permit to apply for and obtain
coverage under an individual permit or another more specific general permit.
Permittees who have their coverage revoked for cause according to WAC 173-226-240
may request temporary coverage under this permit during the time an individual permit
is being developed, provided the request is made within ninety (90) days from the time
of revocation and is submitted along with a complete individual permit application
form.
G6. REPORTING A CAUSE FOR MODIFICATION
The Permittee must 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
must be submitted at least sixty (60) days prior to any proposed changes. Filing a request
for a permit modification, revocation and reissuance, or termination, or a notification of
planned changes or anticipated noncompliance does not relieve the Permittee of the duty to
comply with the existing permit until it is modified or reissued.
G7. COMPLIANCE WITH OTHER LAWS AND STATUTES
Nothing in this permit will be construed as excusing the Permittee from compliance with
any applicable federal, state, or local statutes, ordinances, or regulations.
G8. DUTY TO REAPPLY
The Permittee must apply for permit renewal at least 180 days prior to the specified
expiration date of this permit.
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G9. TRANSFER OF GENERAL PERMIT COVERAGE
Coverage under this general permit is automatically transferred to a new discharger,
including operators of lots/parcels within a common plan of development or sale, if:
A. A written agreement (Transfer of Coverage Form) between the current discharger
(Permittee) and new discharger, signed by both parties and containing a specific date
for transfer of permit responsibility, coverage, and liability is submitted to the Director;
and
B. The Director does not notify the current discharger and new discharger of the Director’s
intent to revoke coverage under the general permit. If this notice is not given, the
transfer is effective on the date specified in the written agreement.
When a current discharger (Permittee) transfers a portion of a permitted site, the current
discharger must also submit an updated application form (NOI) to the Director
indicating the remaining permitted acreage after the transfer.
G10. REMOVED SUBSTANCES
The Permittee must not re-suspend or reintroduce collected screenings, grit, solids, sludges,
filter backwash, or other pollutants removed in the course of treatment or control of
stormwater to the final effluent stream for discharge to state waters.
G11. DUTY TO PROVIDE INFORMATION
The Permittee must submit to Ecology, within a reasonable time, all information that
Ecology may request to determine whether cause exists for modifying, revoking and
reissuing, or terminating this permit or to determine compliance with this permit. The
Permittee must also submit to Ecology, upon request, copies of records required to be kept
by this permit [40 CFR 122.41(h)].
G12. OTHER REQUIREMENTS OF 40 CFR
All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by
reference.
G13. ADDITIONAL MONITORING
Ecology may establish specific monitoring requirements in addition to those contained in
this permit by administrative order or permit modification.
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G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS
Any person who is found guilty of willfully violating the terms and conditions of this permit
shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of
up to ten thousand dollars ($10,000) and costs of prosecution, or by imprisonment in the
discretion of the court. Each day upon which a willful violation occurs may be deemed a
separate and additional violation.
Any person who violates the terms and conditions of a waste discharge permit shall incur, in
addition to any other penalty as provided by law, a civil penalty in the amount of up to ten
thousand dollars ($10,000) for every such violation. Each and every such violation shall be
a separate and distinct offense, and in case of a continuing violation, every day’s
continuance shall be deemed to be a separate and distinct violation.
G15. UPSET
Definition – ―Upset‖ means an exceptional incident in which there is unintentional and
temporary noncompliance with technology-based permit effluent limitations because of
factors beyond the reasonable control of the Permittee. An upset does not include
noncompliance to the extent caused by operational error, improperly designed treatment
facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or
improper operation.
An upset constitutes an affirmative defense to an action brought for noncompliance with
such technology-based permit effluent limitations if the requirements of the following
paragraph are met.
A Permittee who wishes to establish the affirmative defense of upset must 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 Special Condition S5.F, and; 4) the Permittee
complied with any remedial measures required under this permit.
In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset
has the burden of proof.
G16. PROPERTY RIGHTS
This permit does not convey any property rights of any sort, or any exclusive privilege.
G17. DUTY TO COMPLY
The Permittee must 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.
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G18. TOXIC POLLUTANTS
The Permittee must 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.
G19. PENALTIES FOR TAMPERING
The Clean Water Act provides that any person who falsifies, tampers with, or knowingly
renders inaccurate any monitoring device or method required to be maintained under this
permit shall, upon conviction, be punished by a fine of not more than $10,000 per violation,
or by imprisonment for not more than two years per violation, or by both. If a conviction of
a person is for a violation committed after a first conviction of such person under this
condition, punishment shall be a fine of not more than $20,000 per day of violation, or
imprisonment of not more than four (4) years, or both.
G20. REPORTING PLANNED CHANGES
The Permittee must, as soon as possible, give notice to Ecology of planned physical
alterations, modifications or additions to the permitted construction activity. The Permittee
should be aware that, depending on the nature and size of the changes to the original permit,
a new public notice and other permit process requirements may be required. Changes in
activities that require reporting to Ecology include those that 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% or greater increase in
acreage disturbed by construction activity.
C. A change in or addition of surface water(s) receiving stormwater or non-stormwater
from the construction activity.
D. A change in the construction plans and/or activity that affects the Permittee’s
monitoring requirements in Special Condition S4.
Following such notice, permit coverage may be modified, or revoked and reissued pursuant
to 40 CFR 122.62(a) to specify and limit any pollutants not previously limited. Until such
modification is effective, any new or increased discharge in excess of permit limits or not
specifically authorized by this permit constitutes a violation.
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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 must promptly submit such facts or information.
G22. REPORTING ANTICIPATED NON-COMPLIANCE
The Permittee must give advance notice to Ecology by submission of a new application or
supplement thereto at least forty-five (45) days prior to commencement of such discharges,
of any facility expansions, production increases, or other planned changes, such as process
modifications, in the permitted facility or activity which may result in noncompliance with
permit limits or conditions. Any maintenance of facilities, which might necessitate
unavoidable interruption of operation and degradation of effluent quality, must be scheduled
during non-critical water quality periods and carried out in a manner approved by Ecology.
G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT
Any discharger authorized by this permit may request to be excluded from coverage under
the general permit by applying for an individual permit. The discharger must submit to the
Director an application as described in WAC 173-220-040 or WAC 173-216-070,
whichever is applicable, with reasons supporting the request. These reasons will 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 will 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 permit, as they apply to an individual
discharger, are appealable in accordance with Chapter 43.21B RCW within 30 days of
the effective date of coverage of that discharger. Consideration of an appeal of general
permit coverage of an individual discharger is limited to the general permit’s
applicability or nonapplicability to that individual discharger.
C. The appeal of general permit coverage of an individual discharger does not affect any
other dischargers covered under this general permit. If the terms and conditions of this
general permit are found to be inapplicable to any individual discharger(s), the matter
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shall be remanded to Ecology for consideration of issuance of an individual permit or
permits.
G25. SEVERABILITY
The provisions of this permit are severable, and if any provision of this permit, or
application of any provision of this permit to any circumstance, is held invalid, the
application of such provision to other circumstances, and the remainder of this permit shall
not be affected thereby.
G26. BYPASS PROHIBITED
A. Bypass Procedures
Bypass, which is the intentional diversion of waste streams from any portion of a
treatment facility, is prohibited for stormwater events below the design criteria for
stormwater management. Ecology may take enforcement action against a Permittee for
bypass unless one of the following circumstances (1, 2, 3 or 4) is applicable.
1. Bypass of stormwater is consistent with the design criteria and part of an approved
management practice in the applicable stormwater management manual.
2. Bypass for essential maintenance without the potential to cause violation of permit
limits or conditions.
Bypass is authorized if it is for essential maintenance and does not have the
potential to cause violations of limitations or other conditions of this permit, or
adversely impact public health.
3. Bypass of stormwater is unavoidable, unanticipated, and results in noncompliance
of this permit.
This bypass is permitted only if:
a. Bypass is unavoidable to prevent loss of life, personal injury, or severe
property damage. ―Severe property damage‖ means substantial physical
damage to property, damage to the treatment facilities which would cause
them to become inoperable, or substantial and permanent loss of natural
resources which can reasonably be expected to occur in the absence of a
bypass.
b. There are no feasible alternatives to the bypass, such as the use of auxiliary
treatment facilities, retention of untreated wastes, maintenance during normal
periods of equipment downtime (but not if adequate backup equipment should
have been installed in the exercise of reasonable engineering judgment to
prevent a bypass which occurred during normal periods of equipment
downtime or preventative maintenance), or transport of untreated wastes to
another treatment facility.
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c. Ecology is properly notified of the bypass as required in Special Condition
S5.F of this permit.
4. A planned action that would cause bypass of stormwater and has the potential to
result in noncompliance of this permit during a storm event.
The Permittee must notify Ecology at least thirty (30) days before the planned date
of bypass. The notice must contain:
a. a description of the bypass and its cause
b. an analysis of all known alternatives which would eliminate, reduce, or
mitigate the need for bypassing.
c. a cost-effectiveness analysis of alternatives including comparative resource
damage assessment.
d. the minimum and maximum duration of bypass under each alternative.
e. a recommendation as to the preferred alternative for conducting the bypass.
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.
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 must be
considered during preparation of the Stormwater Pollution Prevention Plan
(SWPPP) and must 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 before 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.
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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 must be notified and given an opportunity to
comment on bypass incidents of significant duration, to the extent feasible.
Approval of a request to bypass will be by administrative order issued by Ecology
under RCW 90.48.120.
B. Duty to Mitigate
The Permittee is required to take all reasonable steps to minimize or prevent any
discharge or sludge use or disposal in violation of this permit that has a reasonable
likelihood of adversely affecting human health or the environment.
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APPENDIX A – DEFINITIONS
AKART is an acronym for ―all known, available, and reasonable methods of prevention, control,
and treatment.‖ AKART represents the most current methodology that can be reasonably
required for preventing, controlling, or abating the pollutants and controlling pollution associated
with a discharge.
Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus, which
was completed and approved by EPA before January 1, 2011, or before the date the operator’s
complete permit application is received by Ecology, whichever is later.
Applicant means an operator seeking coverage under this permit.
Best Management Practices (BMPs) means schedules of activities, prohibitions of practices,
maintenance procedures, and other physical, structural and/or managerial practices to prevent or
reduce the pollution of waters of the State. BMPs include treatment systems, operating
procedures, and practices to control: stormwater associated with construction activity, spillage
or leaks, sludge or waste disposal, or drainage from raw material storage.
Buffer means an area designated by a local jurisdiction that is contiguous to and intended to
protect a sensitive area.
Bypass means the intentional diversion of waste streams from any portion of a treatment facility.
Calendar Day A period of 24 consecutive hours starting at 12:00 midnight and ending the
following 12:00 midnight.
Calendar Week (same as Week) means a period of seven consecutive days starting at 12:01 a.m.
(0:01 hours) on Sunday.
Certified Erosion and Sediment Control Lead (CESCL) means a person who has current
certification through an approved erosion and sediment control training program that meets the
minimum training standards established by Ecology (see BMP C160 in the SWMM).
Clean Water Act (CWA) means the Federal Water Pollution Control Act enacted by Public Law
92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq.
Combined Sewer means a sewer which has been designed to serve as a sanitary sewer and a
storm sewer, and into which inflow is allowed by local ordinance.
Common Plan of Development or Sale means a site where multiple separate and distinct
construction activities may be taking place at different times on different schedules and/or by
different contractors, but still under a single plan. Examples include: 1) phased projects and
projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed
under separate contract or by separate owners (e.g., a development where lots are sold to separate
builders); 2) a development plan that may be phased over multiple years, but is still under a
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consistent plan for long-term development; 3) projects in a contiguous area that may be
unrelated but still under the same contract, such as construction of a building extension and a
new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If
the project is part of a common plan of development or sale, the disturbed area of the entire plan
must be used in determining permit requirements.
Composite Sample means a mixture of grab samples collected at the same sampling point at
different times, formed either by continuous sampling or by mixing discrete samples. May be
"time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as
a constant sample volume at time intervals proportional to stream flow, or collected by
increasing the volume of each aliquot as the flow increases while maintaining a constant time
interval between the aliquots.
Concrete wastewater means any water used in the production, pouring and/or clean-up of
concrete or concrete products, and any water used to cut, grind, wash, or otherwise modify
concrete or concrete products. Examples include water used for or resulting from concrete
truck/mixer/pumper/tool/chute rinsing or washing, concrete saw cutting and surfacing (sawing,
coring, grinding, roughening, hydro-demolition, bridge and road surfacing). When stormwater
comingles with concrete wastewater, the resulting water is considered concrete wastewater and
must be managed to prevent discharge to waters of the state, including ground water.
Construction Activity means land disturbing operations including clearing, grading or excavation
which disturbs the surface of the land. Such activities may include road construction,
construction of residential houses, office buildings, or industrial buildings, and demolition
activity.
Contaminant means any hazardous substance that does not occur naturally or occurs at greater
than natural background levels. See definition of ―hazardous substance‖ and WAC 173-340-200.
Demonstrably Equivalent means that the technical basis for the selection of all stormwater BMPs
is documented within a SWPPP, including:
1. The method and reasons for choosing the stormwater BMPs selected.
2. The pollutant removal performance expected from the BMPs selected.
3. The technical basis supporting the performance claims for the BMPs selected, including
any available data concerning field performance of the BMPs selected.
4. An assessment of how the selected BMPs will comply with state water quality standards.
5. An assessment of how the selected BMPs will satisfy both applicable federal technology-
based treatment requirements and state requirements to use all known, available, and
reasonable methods of prevention, control, and treatment (AKART).
Department means the Washington State Department of Ecology.
Detention means the temporary storage of stormwater to improve quality and/or to reduce the
mass flow rate of discharge.
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Dewatering means the act of pumping ground water or stormwater away from an active
construction site.
Director means the Director of the Washington Department of Ecology or his/her authorized
representative.
Discharger means an owner or operator of any facility or activity subject to regulation under
Chapter 90.48 RCW or the Federal Clean Water Act.
Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundry
wastes from residences, buildings, industrial establishments, or other places, together with such
ground water infiltration or surface waters as may be present.
Ecology means the Washington State Department of Ecology.
Engineered Soils means the use of soil amendments including, but not limited, to Portland
cement treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil
characteristics.
Equivalent BMPs means operational, source control, treatment, or innovative BMPs which result
in equal or better quality of stormwater discharge to surface water or to ground water than BMPs
selected from the SWMM.
Erosion means the wearing away of the land surface by running water, wind, ice, or other
geological agents, including such processes as gravitational creep.
Erosion and Sediment Control BMPs means BMPs intended to prevent erosion and
sedimentation, such as preserving natural vegetation, seeding, mulching and matting, plastic
covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are
synonymous with stabilization and structural BMPs.
Final Stabilization (same as fully stabilized or full stabilization) means the establishment of a
permanent vegetative cover, or equivalent permanent stabilization measures (such as riprap,
gabions or geotextiles) which prevents erosion.
Ground Water means water in a saturated zone or stratum beneath the land surface or a surface
water body.
Hazardous Substance means any dangerous or extremely hazardous waste as defined in RCW
70.105.010 (5) and (6), or any dangerous or extremely dangerous waste as designated by rule
under chapter 70.105 RCW; any hazardous sub-stance as defined in RCW 70.105.010(14) or any
hazardous substance as defined by rule under chapter 70.105 RCW; any substance that, on the
effective date of this section, is a hazardous substance under section 101(14) of the federal
cleanup law, 42 U.S.C., Sec. 9601(14); petroleum or petroleum products; and any substance or
category of substances, including solid waste decomposition products, determined by the director
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by rule to present a threat to human health or the environment if released into the environment.
The term hazardous substance does not include any of the following when contained in an
underground storage tank from which there is not a release: crude oil or any fraction thereof or
petroleum, if the tank is in compliance with all applicable federal, state, and local law.
Injection Well means a well that is used for the subsurface emplacement of fluids. (See Well.)
Jurisdiction means a political unit such as a city, town or county; incorporated for local self-
government.
National Pollutant Discharge Elimination System (NPDES) means the national program for
issuing, modifying, revoking and reissuing, terminating, monitoring, and enforcing permits, and
imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the
Federal Clean Water Act, for the discharge of pollutants to surface waters of the State from point
sources. These permits are referred to as NPDES permits and, in Washington State, are
administered by the Washington Department of Ecology.
Notice of Intent (NOI) means the application for, or a request for coverage under this general
permit pursuant to WAC 173-226-200.
Notice of Termination (NOT) means a request for termination of coverage under this general
permit as specified by Special Condition S10 of this permit.
Operator means any party associated with a construction project that meets either of the
following two criteria:
The party has operational control over construction plans and specifications, including
the ability to make modifications to those plans and specifications; or
The party has day-to-day operational control of those activities at a project that are
necessary to ensure compliance with a SWPPP for the site or other permit conditions
(e.g., they are authorized to direct workers at a site to carry out activities required by the
SWPPP or comply with other permit conditions).
Permittee means individual or entity that receives notice of coverage under this general permit.
pH means a liquid’s measure of acidity or alkalinity. A pH of 7 is defined as neutral. Large
variations above or below this value are considered harmful to most aquatic life.
pH monitoring period means the time period in which the pH of stormwater runoff from a site
must be tested a minimum of once every seven days to determine if stormwater pH is between
6.5 and 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.)
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Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage,
garbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials,
radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and
industrial, municipal, and agricultural waste. This term does not include sewage from vessels
within the meaning of section 312 of the CWA, nor does it include dredged or fill material
discharged in accordance with a permit issued under section 404 of the CWA.
Pollution means contamination or other alteration of the physical, chemical, or biological
properties of waters of the State; including change in temperature, taste, color, turbidity, or odor
of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into
any waters of the State as will or is likely to create a nuisance or render such waters harmful,
detrimental or injurious to the public health, safety or welfare; or to domestic, commercial,
industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild
animals, birds, fish or other aquatic life.
Process wastewater means any water which, during manufacturing or processing, comes into
direct contact with or results from the production or use of any raw material, intermediate
product, finished product, byproduct, or waste product (40 CFR 122.1).
Receiving water means the water body at the point of discharge. If the discharge is to a storm
sewer system, either surface or subsurface, the receiving water is the water body to which the
storm system discharges. Systems designed primarily for other purposes such as for ground
water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return
flows that coincidentally convey stormwater are considered the receiving water.
Representative means a stormwater or wastewater sample which represents the flow and
characteristics of the discharge. Representative samples may be a grab sample, a time-
proportionate composite sample, or a flow proportionate sample. Ecology’s Construction
Stormwater Monitoring Manual provides guidance on representative sampling.
Sanitary sewer means a sewer which is designed to convey domestic wastewater.
Sediment means the fragmented material that originates from the weathering and erosion of
rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water.
Sedimentation means the depositing or formation of sediment.
Sensitive area means a water body, wetland, stream, aquifer recharge area, or channel migration
zone.
SEPA (State Environmental Policy Act) means the Washington State Law, RCW 43.21C.020,
intended to prevent or eliminate damage to the environment.
Significant Amount means an amount of a pollutant in a discharge that is amenable to available
and reasonable methods of prevention or treatment; or an amount of a pollutant that has a
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reasonable potential to cause a violation of surface or ground water quality or sediment
management standards.
Significant concrete work means greater than 1000 cubic yards poured concrete or recycled
concrete over the life of a project.
Significant 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.
Source control BMPs means physical, structural or mechanical devices or facilities that are
intended to prevent pollutants from entering stormwater. A few examples of source control
BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over
storage and working areas, and directing wash water and similar discharges to the sanitary sewer
or a dead end sump.
Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as,
temporary and permanent seeding, vegetative covers, mulching and matting, plastic covering and
sodding. See also the definition of Erosion and Sediment Control BMPs.
Storm drain means any drain which drains directly into a storm sewer system, usually found
along roadways or in parking lots.
Storm sewer system means a means a conveyance, or system of conveyances (including roads
with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade
channels, or storm drains designed or used for collecting or conveying stormwater. This does
not include systems which are part of a combined sewer or Publicly Owned Treatment Works
(POTW) as defined at 40 CFR 122.2.
Stormwater means that portion of precipitation that does not naturally percolate into the ground
or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater
drainage system into a defined surface water body, or a constructed infiltration facility.
Stormwater Management Manual (SWMM) or Manual means the technical Manual published by
Ecology for use by local governments that contain descriptions of and design criteria for BMPs
to prevent, control, or treat pollutants in stormwater.
Stormwater Pollution Prevention Plan (SWPPP) means a documented plan to implement
measures to identify, prevent, and control the contamination of point source discharges of
stormwater.
Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and
all other surface waters and water courses within the jurisdiction of the state of Washington.
Construction Stormwater General Permit – December 1, 2010
Page 52
Temporary Stabilization means the exposed ground surface has been covered with appropriate
materials to provide temporary stabilization of the surface from water or wind erosion. Materials
include, but are not limited to, mulch, riprap, erosion control mats or blankets and temporary
cover crops. Seeding alone is not considered stabilization. Temporary stabilization is not a
substitute for the more permanent ―final stabilization.‖
Total Maximum Daily Load (TMDL) means a calculation of the maximum amount of a pollutant
that a water body can receive and still meet state water quality standards. Percentages of the
total maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of
the allowable loads of a single pollutant from all contributing point and nonpoint sources. The
TMDL calculations must include a "margin of safety" to ensure that the water body can be
protected in case there are unforeseen events or unknown sources of the pollutant. The
calculation must also account for seasonable variation in water quality.
Treatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few
examples of treatment BMPs are detention ponds, oil/water separators, biofiltration, and
constructed wetlands.
Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm
transparency tube. The transparency tube is used to estimate the relative clarity or transparency
of water by noting the depth at which a black and white Secchi disc becomes visible when water
is released from a value in the bottom of the tube. A transparency tube is sometimes referred to
as a ―turbidity tube.‖
Turbidity means the clarity of water expressed as nephelometric turbidity units (NTU) and
measured with a calibrated turbidimeter.
Uncontaminated means free from any contaminant, as defined in MTCA cleanup regulations.
See definition of ―contaminant‖ and WAC 173-340-200.
Waste Load Allocation (WLA) means the portion of a receiving water’s loading capacity that is
allocated to one of its existing or future point sources of pollution. WLAs constitute a type of
water quality based effluent limitation (40 CFR 130.2[h]).
Water quality means the chemical, physical, and biological characteristics of water, usually with
respect to its suitability for a particular purpose.
Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR
Subpart 122.2 within the geographic boundaries of Washington State and "waters of the State" as
defined in Chapter 90.48 RCW, which include lakes, rivers, ponds, streams, inland waters,
underground waters, salt waters, and all other surface waters and water courses within the
jurisdiction of the state of Washington.
Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the largest
surface dimension. (See Injection well.)
Construction Stormwater General Permit – December 1, 2010
Page 53
Wheel wash wastewater means any water used in, or resulting from the operation of, a tire bath
or wheel wash (BMP C106: Wheel Wash), or other structure or practice that uses water to
physically remove mud and debris from vehicles leaving a construction site and prevent track-
out onto roads. When stormwater comingles with wheel wash wastewater, the resulting water is
considered wheel wash wastewater and must be managed according to Special Condition S9.D.9.
Construction Stormwater General Permit – December 1, 2010
Page 54
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
FR Federal Register
NOI Notice of Intent
NOT Notice of Termination
NPDES National Pollutant Discharge Elimination System
NTU Nephelometric Turbidity Unit
RCW Revised Code of Washington
SEPA State Environmental Policy Act
SWMM Stormwater Management Manual
SWPPP Stormwater Pollution Prevention Plan
TMDL Total Maximum Daily Load
UIC Underground Injection Control
USC United States Code
USEPA United States Environmental Protection Agency
WAC Washington Administrative Code
WQ Water Quality
WWHM Western Washington Hydrology Model
Page |35
F. 303(d) List Waterbodies / TMDL Waterbodies Information
N/A
Page |36
G. Contaminated Site Information
Administrative Order
Sanitary Discharge Permit
Soil Management Plan
Soil and Groundwater Reports
Maps and Figures Depicting Contamination
Page |37
H. Engineering Calculations
KCRTS INPUT
KCRTS Program...File Directory:
C:\KC_SWDM\KC_DATA\
[C] CREATE a new Time Series
ST
0.00 0.00 0.000000 Till Forest
0.00 0.00 0.000000 Till Pasture
0.00 0.00 0.000000 Till Grass
0.00 0.00 0.000000 Outwash Forest
0.00 0.00 0.000000 Outwash Pasture
0.00 0.00 0.000000 Outwash Grass
0.00 0.00 0.000000 Wetland
2.84 0.00 0.000000 Impervious
CSouth1hR.tsf
T
1.00000
T
[T] Enter the Analysis TOOLS Module
[P] Compute PEAKS and Flow Frequencies
csouth1hR.tsf
CSouth1HR.pks
[R] RETURN to Previous Menu
[C] CREATE a new Time Series
ST
0.00 0.00 0.000000 Till Forest
0.00 0.00 0.000000 Till Pasture
0.00 0.00 0.000000 Till Grass
0.00 0.00 0.000000 Outwash Forest
0.00 0.00 0.000000 Outwash Pasture
0.00 0.00 0.000000 Outwash Grass
0.00 0.00 0.000000 Wetland
1.68 0.00 0.000000 Impervious
CNorth1HR.tsf
T
1.00000
T
[T] Enter the Analysis TOOLS Module
[P] Compute PEAKS and Flow Frequencies
cNorth1HR.tsf
CNorth1HR.pks
[R] RETURN to Previous Menu
SOUTH BASIN (1 HOUR)
Flow Frequency Analysis
Time Series File:csouth.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
1.35 6 8/27/01 18:00 3.35 1 100.00 0.990
0.944 8 9/17/02 17:45 2.56 2 25.00 0.960
2.56 2 12/08/02 17:15 1.84 3 10.00 0.900
1.09 7 8/23/04 14:30 1.51 4 5.00 0.800
1.43 5 10/28/04 16:00 1.43 5 3.00 0.667
1.51 4 10/27/05 10:45 1.35 6 2.00 0.500
1.84 3 10/25/06 22:45 1.09 7 1.30 0.231
3.35 1 1/09/08 6:30 0.944 8 1.10 0.091
Computed Peaks 3.08 50.00 0.980
NORTH BASIN (1 HOUR)
Flow Frequency Analysis
Time Series File:cnorth1hr.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) Period
0.407 7 2/09/01 2:00 0.794 1 100.00 0.990
0.359 8 1/05/02 16:00 0.610 2 25.00 0.960
0.497 3 12/08/02 18:00 0.497 3 10.00 0.900
0.419 6 8/26/04 2:00 0.497 4 5.00 0.800
0.497 4 10/28/04 16:00 0.436 5 3.00 0.667
0.436 5 1/18/06 16:00 0.419 6 2.00 0.500
0.610 2 10/26/06 0:00 0.407 7 1.30 0.231
0.794 1 1/09/08 6:00 0.359 8 1.10 0.091
Computed Peaks 0.732 50.00 0.980.00 0.980