SWPPP+11.8.2022_2.07.58_PM+3209838RECEIVED
Nov 16 2022
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
Construction Stormwater General Permit (CSWGP)
BLD2022-0989
Stormwater Pollution Prevention Plan
(SWPPP)
for
SUGAR HOUSE
Prepared for:
Department of Ecology
Northwest Region
Permittee / Owner
Developer
Operator / Contractor
NORTH STAR VISIONS,
LLC
NORTH STAR VISIONS,
LLC
(to be determined)
Project Location:
10234 242"d PI SW
Edmonds, WA
Certified Erosion and Sediment Control Lead (CESCL)
Name
Organization
Contact Phone Number
To Be Determined
To Be Determined
To Be Determined
SWPPP Prepared By
Name
Organization
Contact Phone Number
Tara Beitler, PE
PACE Engineers
(425) 486-6533
SWPPP Preparation Date
September 16, 2022
Project Construction Dates
Activity / Phase
Start Date
End Date
Site Construction
October 2022
October 2024
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
COz
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
GUILD
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
Project Information (1.0)
Project/Site Name: Sugar House
Street/Location:
Receiving waterbody: N/A Regional Infiltration
Existing Conditions (1.1)
Total acreage (including support activities such as off -site equipment staging yards, material
storage areas, borrow areas).
Total acreage:
Disturbed acreage:
Existing structures:
Landscape topography:
Drainage patterns:
0.22 ac
0.22ac
None, undeveloped property
Slopes to the north
Sheet flows to the north
Existing Vegetation: Trees, shrubs, blackberries
Critical Areas: None
List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the
receiving waterbody:
There does not appear to be a 303(d) listed or TMDL water body within the'/4-mile
downstream analysis area.
Table 1 includes a list of suspected and/or known contaminants associated with the construction
activity.
Table 1 — Summary of Site Pollutant Constituents
Constituent
(Pollutant)
Location
Depth
Concentration
None Known
N/A
N/A
N/A
Proposed Construction Activities (1.2)
Description of site development (example: subdivision):
Single family lot with new house, driveway and porch.
Description of construction activities (example: site preparation, demolition, excavation):
The project is expected to involve clearing of the property to install a house and
driveway.
Description of site drainage including flow from and onto adjacent properties. Must be consistent
with Site Map in Appendix A:
There is a small amount of flow that sheet flows onto the property from the south, and
then it sheet flows to the north onto the adjacent property and into the Right -Of -Way on
242"d PI SW, where it is collected in an existing stormwater conveyance system.
Description of final stabilization (example: extent of revegetation, paving, landscaping):
Installation of the house, driveway and rain garden
Contaminated Site Information:
Proposed activities regarding contaminated soils or groundwater (example: on -site treatment
system, authorized sanitary sewer discharge):
No contaminated soils or groundwater have been identified at the site.
Construction Stormwater Best Management Practices (BMPs) (2.0)
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.
The 12 Elements (2.1)
Element 1: Preserve Vegetation / Mark Clearing Limits (2.1.1)
The clearing limits are expected to be located by orang barrier fencing and silt fence
List and describe BMPs
Installation Schedules:
BMP C233: Silt Fence
Prior to clearing activity
Inspection and Maintenance plan: Project CESCL
Responsible Staff: Project CESCL
Element 2: Establish Construction Access (2.1.2)
The proposed driveway will be used for construction access.
List and describe BMPs: BMP C105: Stabilized Construction Entrance/Exit
Installation Schedules: Prior to clearing activity
Inspection and Maintenance plan: Project CESCL
Responsible Staff: Project CESCL
Element 3: Control Flow Rates (2.1.3)
The rain garden can be used to control flow rates.
Will you construct stormwater retention and/or detention facilities?
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, the soil for the rain garden will not be installed until the house is constructed and
the site is stabilized.
List and describe BMPs
Installation Schedules:
Inspection and Maintenance plan
Responsible Staff:
None
As site clearing occurs
Project CESCL
Project CESCL
Element 4: Install Sediment Controls (2.1.4)
The project is proposing to use the rain garden until the property is stabilized. While
construction activity is underway, and then the rain garden will be cleaned and then the
soil will be added after the site is stabilized.
List and describe BMPs
Installation Schedules:
Inspection and Maintenance plan
BMP C233: Silt Fence
As site clearing occurs
Project CESCL
Responsible Staff: Project CESCL
Element 5: Stabilize Soils (2.1.5)
The project intends to strip and stockpile the existing topsoil on -site under plastic
covering. At the conclusion of construction, the project is expected to spread the
stockpiled topsoil over the landscaped areas. These areas are expected to be
hydroseeded or sodded for stabilization at the conclusion of construction.
Topsoiling/composting may be performed if the stockpiled topsoil does not meet the
requirements of BMPT5.13. Seeding and mulching may be used on a temporary basis for
areas that will be left unworked for a significant period of time.
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: Approximate Start date: October, 2022
Approximate End date: August, 2024
Will you construct during the wet season?
Yes
List and describe BMPs: BMP C120: Temporary & Permanent Seeding
BMP C121: Mulching
BMP C124: Sodding
BMP C125: Topsoiling/Composting
BMP C140: Dust Control
Installation Schedules: As site clearing occurs
Inspection and Maintenance plan: Project CESCL
Responsible Staff: Project CESCL
Element 6: Protect Slopes (2.1.6)
The steep slopes on the southwest side of the site are outside of the clearing limits and
will not be disturbed during construction.
Will steep slopes be present at the site during construction?
Yes
List and describe BMPs: N/A
Installation Schedules: Not applicable
Inspection and Maintenance plan: N/A
Responsible Staff: N/A
Element 7: Protect Drain Inlets (2.1.7)
Storm drain inlet protection devices will be installed at the existing nearby catch basins
prior to construction of the site.
List and describe BMPs: BMP C220: Storm Drain Inlet Protection
Installation Schedules: Prior to clearing
Inspection and Maintenance plan: Per project CESCL
Responsible Staff: Per project CESCL
Element 8: Stabilize Channels and Outlets (2.1.8)
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.
The project does not propose any free outlets that need to be stabilized.
List and describe BMPs: N/A
Installation Schedules: N/A
Inspection and Maintenance plan: Per project CESCL
Responsible Staff: Per project CESCL
Element 9: Control Pollutants (2.1.9)
The following pollutants are anticipated to be present on -site:
Table 2 — Pollutants
Pollutant (and source, if applicable)
Demolition materials
Sawcutting debris & concrete wash water
Construction vehicle fuel/oil/lubricants
All demolition materials shall be disposed of at an appropriate off -site location.
Construction vehicle fueling/service shall be performed off -site to the greatest practical
extent. In the event of a fuel/oil spill, the contaminated area should be isolated and
cleaned immediately. Sawcutting debris should be vacuumed at the conclusion of
sawcutting activity. A concrete washout area shall be constructed on -site, and excess
concrete shall be returned to the mix plant for recycling, when possible.
List and describe BMPs: BMP C151: Concrete Handling
BMP C152: Sawcut & Surface Pollution Pevention
BMP C153: Material Delivery, Storage & Containment
BMP C154: Concrete Washout Area
Installation Schedules: As needed
Inspection and Maintenance plan: Per project CESCL
Responsible Staff: Per project CESCL
Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on -site?
No
Will wheel wash or tire bath system BMPs be used during construction?
No
Will pH -modifying sources be present on -site?
Yes If yes, check the source(s).
Table 3 — pH -Modifying Sources
None
X
Bulk cement
X
Cement kiln dust
X
Fly ash
Other cementitious materials
X
New concrete washing or curing waters
X
Waste streams generated from concrete grinding and sawing
X
Exposed aggregate processes
Dewatering concrete vaults
X
Concrete pumping and mixer washout waters
X
Recycled concrete
Other (i.e. calcium lignosulfate) [please describe]
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.
Element 10: Control Dewatering (2.1.10)
No significant dewatering activity is anticipated.
List and describe BMPs: None Anticipated
Installation Schedules: As needed
Inspection and Maintenance plan: Per project CESCL
Responsible Staff: Per project CESCL
Element 11: Maintain BMPs (2.1.11)
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 11 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.
Element 12: Manage the Project (2.1.12)
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.
Table 5 — Management
X
Design the project to fit the existing topography, soils, and drainage patterns
X
Emphasize erosion control rather than sediment control
X
Minimize the extent and duration of the area exposed
X
Keep runoff velocities low
X
Retain sediment on -site
X
Thoroughly monitor site and maintain all ESC measures
X
Schedule major earthwork during the dry season
Other (please describe)
Element 13: Protect Low Impact Development (LID) BMPs
This site consists of a rain garden that will overflow into the existing stormwater system.
The raingarden will not have the soil added until after the site has been stabilized.
The permeable layers for the driveway will not be added until after the house is
constructed.
Pollution Prevention Team (3.0)
Table 7 — Team Information
Title
Names
Phone Number
Certified Erosion and
Sediment Control Lead
To Be Determined (TBD)
TBD
(CESCL)
Resident Engineer
Tara L. Beitler, PE
(425) 486-6533
Emergency Ecology
Contact
Northwest Region
(425) 649-7000
Emergency Permittee/
Owner Contact
TBD
TBD
Non -Emergency Owner
Contact
TBD
TBD
Monitoring Personnel
TBD
TBD
Ecology Regional Office
Northwest Region
(425) 778-4111
Monitoring and Sampling Requirements (4.0)
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
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.
Complete the following paragraph for sites that discharge to impaired waterbodies for fine
sediment, turbidity, phosphorus, or pH:
Site Inspection (4.1)
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.
Stormwater Quality Sampling (4.2)
Turbidity Sampling (4.2.1)
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
X
Turbidity Meter/Turbid imeter (required for disturbances 5 acres or greater in size)
X
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.
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:
Telephone or submit an electronic report to the applicable Ecology Region's
Environmental Report Tracking System (ERTS) within 24 hours.
https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue
• 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).
0 Transparency is 33 cm (or greater).
• Compliance with the water quality limit for turbidity is achieved.
0 1 - 5 NTU over background turbidity, if background is less than 50 NTU
0 1 % - 10% over background turbidity, if background is 50 NTU or greater
• The discharge stops or is eliminated.
pH Sampling (4.2.2)
pH monitoring is required for "Significant concrete work" (i.e. greater than 1000 cubic yards
poured concrete 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 and recycled concrete, pH sampling begins when engineered soils or
recycled concrete 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 8 — pH Sampling Method
X
pH meter
X
pH test kit
X
Wide range pH indicator paper
Discharges to 303(d) or Total Maximum Daily Load (TMDL)
Waterbodies (5.0)
303(d) Listed Waterbodies (5.1)
Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH?
No
List the impairment(s):
TMDL Waterbodies (5.2)
The project does not appear to be directly tributary to a TMDL water body
Reporting and Record Keeping (6.0)
Record Keeping (6.1)
Site Log Book (6.1.1)
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
Records Retention (6.1.2)
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 S5.0 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.
Updating the SWPPP (6.1.3)
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.
Reporting (6.2)
Discharge Monitoring Reports (6.2.1)
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.
https://www.ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Water-quality-
permits-guidance/WQWebPortal-guidance
Notification of Noncompliance (6.2.2)
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 notified within 24-hours 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.
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
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.
APPENDIX A
Site Map
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FILL: 18 CY S\0 ®,• ® ; • ° r \ I 1 HEIGHT CALCD' ern, �2 �2 C� 0
NET: 287 CY (CUT) �G g 41 q \ RECTANGLE �< O � ,
UP FLOOR >. I I OVERFLOW % 2� a
�� °' PROPOSED STANDPIPE
NOTES: CANTIjVER SILT FEN \ _
,,gi�pp
1. ROOF RUN OFF WILL BE CONNECTED TO DOWNSPOUT 0
\ o < 0
� � � �� >s - - PER C 3" WOOD MUL H, I �� �'' �� �
CLEANOUTS AND FOOTING DRAIN, TO TIGHTLINED TO THE I \------ N DIET E1.1 3:1 MAX LI' d. k,
40q, o AGGREGATE, SO o
GARDEN ON PARALLEL OF 184TH ST. v 9 D b (TYP) o ',_0
2. FINE GRADING AROUND THE PROPOSED STRUCTURESE \\ 45.49' o - TOP EL. 388.5 12" FREEBOARD o
PERFORMED TO ENSURE SLOPES ARE AWAY FROM THE PRt�P.o,� 1 MAX WS EL. 388.0 6" LIVE STORAGE
DWELLING. o �/ BOT EL. 387.0 3' rn�pcE CO EX. FIRE
3. CATCH BASIN INLET PROTECTION SHALL BE ADDED TO ANY 4.6 5' CH INLI ON L-'L"-fN. R S RICTIVE LAYER 18" BIORETENTION e OSA HYDRANT
CATCHBASIN DIRECTLY DOWNSTREAM AND ADJACENT TO THIS SITE. $ 50 WOOD FENCE A RAIN GARDEN SECTION / W
4. TEMPORARY STOCKPILE AREA SHALL BE COVERED WITHIN 24 �' ��0 POSED 0 �E o
HOURS. BA ING, (TYP) - N.T.S.
5. ALL DISTURBED SOILS WILL BE COMPOST AMENDED PER BMP FOOTING DRAIN NOTE: LOT COVERAGE:
T5.13.
6. INSTALL AND MAINTAIN ALL TESC MEASURES ACCORDING TO FOOTING DRAINS SHALL BE SEPERATE LOT COVERAGE: 2,257 SF
APPROVED PLANS, CITY OF EDMONDS STANDARD DETAILS, AND ALL R 2.5' 10' DRIVE AISLE 2,5' R FROM ROOF DRAIN PIPING AND TIED LOT AREA: 9,534 SF IMPERVIOUS AREA:
OTHER MEASURES THAT MAY BE REQUIRED DURING CONSTRUCTION. DIRECTLY INTO ... % OF LOT COVERAGE: 23.7 % EXISTING IMPERVIOUS AREA: 0 SF
7. PROPOSED STRUCTURE WILL BE REQUIRED TO PROVIDE NFPA 1-2% HEIGHT CALCS: (MAXIMUM COVERAGE IS 35%)
13D RESIDENTIAL FIRE SPRINKLER SYSTEM REGARDLESS OF BUILDING 1-�% f-
SQUARE FOOTAGE. AVERAGE EXISTING GRADE: 401.40 NOTE: LOT COVERAGE IS MEASURED PROP. HOUSE
q 8. INSTALL 14 GA. VINYL COATED TRACER WIRE (TAPED TO PLASTIC PROPOSED ELEVATIONS- BY EXTERNAL WALLS AND (W/ROOF OVERHANG): 2,526 SF
PROPOSED WALKWAY/PATIO: 50 SF
PIPE EVERY 10') TO BE GROUNDED AT METER AND PROPOSED GEOTEXTILE A: 399.66 SUPPORTING MEMBERS, INCLUDING PROPOSED PERVIOUS D/W: 1072 SF
o HOME. 6" POROUS ASPHALT FABRIC B: 398.18 UPPER CANTILEVERED AREAS, PROPOSED CONC. DRIVEWAY: 744 SF
9. MINIMUM HORIZONTAL SEPARATION BETWEEN WATER AND SEWER TOP COURSE C: 402.00 COVERED & UNCOVERED PATIO TOTAL IMPERVIOUS AREA: 4,393 SF
IS 10'. D: 401.81 AREAS, EXCLUDES ROOF OVERHANG.
10. MINIMUM HORIZONTAL SEPARATION BETWEEN WATER AND STORM 2" CHOKER COURSE AVERAGE GRADE= 400.41
9 LINES IS 5'. 10" RESERVOIR COURSE PROPOSED BUILDING HEIGHT (25'-0")= 425.41 5% OF ROOF= 126 SF TO BIORETENTION
11. ALL FINAL RESTORATION SHALL BE COMPLETED BY THE 18" (MIN) TREATMENT MAXIMUM HEIGHT ALLOWED (25')= 426.41
- CONTRACTOR NOT THE CITY OF EDMONDS. COURSE ACR
"- 12. MIN. 3' SEPERATION IS REQUIRED BETWEEN DRY UTILITIES
Desi
(POWER, GAS, PHONE, CABLE, ECT) AND WET UTILITIES (STORM, NATIVE MATERIAL OR KDSgn 3501 Colby Ave Suite 101 SUGAR HOUSE Design Change
u SEWER, WATER). ALL UTILITIES INSTALLED PER ECDG 18.05. ADDITIONAL TREATMENT Everett, WA 98201
u Drawn p. 425.486.6533
13. MIN. 2' COVER IS REQUIRED FOR ALL PIPES LOCATED UNDER COURSE TO SUBGRADE 9/8/22 Sheet Affected
DRIVABLE SURFACE AND 1' MIN. COVER UNDER LANDSCAPE AREAS. Date Civil I Structural I Planning I Survey LOT 2
A PERVIOUS DRIVEWAY SECTION An Engineenng Services Company www. paceengrs.com
14. THE 6" SSCO AT THE PROPERTY LINE SHALL HAVE A 12" CAST 362-025-22 BUILDING SITE PLAN
IRON LAMPHOLE COVER WITH" HEXBOLTS. - N.T.S. Project No. Sheets Affected
'rojects\362 (KLN Construction)\025-22 (Sugar House)\Dwg\sheets\SH-Site Plan.dwg 36x24
APPENDIX B
BMP Detail
BMP C103: High Visibility Fence
Purpose
Fencing is intended to:
I. Restrict clearing to approved limits.
2. Prevent disturbance of sensitive areas, their buffers, and other areas
required to be left undisturbed.
3. Limit construction traffic to designated construction entrances, exits,
or internal roads.
4. Protect areas where marking with survey tape may not provide
adequate protection.
Conditions of Use
To establish clearing limits plastic, fabric, or metal fence may be used:
• At the boundary of sensitive areas, their buffers, and other areas
required to be left uncleared.
• As necessary to control vehicle access to and on the site.
Design and
High visibility plastic fence shall be composed of a high -density
Installation
polyethylene material and shall be at least four feet in height. Posts for
Specifications
the fencing shall be steel or wood and placed every 6 feet on center
(maximum) or as needed to ensure rigidity. The fencing shall be fastened
to the post every six inches with a polyethylene tie. On long continuous
lengths of fencing, a tension wire or rope shall be used as a top stringer to
prevent sagging between posts. The fence color shall be high visibility
orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM
D4595 testing method.
If appropriate install fabric silt fence in accordance with BMP C233 to
act as high visibility fence. Silt fence shall be at least 3 feet high and
must be highly visible to meet the requirements of this BMP.
Metal fences shall be designed and installed according to the
manufacturer's specifications.
Metal fences shall be at least 3 feet high and must be highly visible.
Fences shall not be wired or stapled to trees.
Maintenance
If the fence has been damaged or visibility reduced, it shall be repaired or
Standards
replaced immediately and visibility restored.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-6
BMP C105: Stabilized Construction Entrance / Exit
Purpose Stabilized Construction entrances are established to reduce the amount of
sediment transported onto paved roads by vehicles or equipment. This is
done by constructing a stabilized pad of quarry spalls at entrances and
exits for construction sites.
Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering
or leaving a construction site if paved roads or other paved areas are
within 1,000 feet of the site.
For residential construction provide stabilized construction entrances for
each residence, rather than only at the main subdivision entrance.
Stabilized surfaces shall be of sufficient length/width to provide vehicle
access/parking, based on lot size/configuration.
On large commercial, highway, and road projects, the designer should
include enough extra materials in the contract to allow for additional
stabilized entrances not shown in the initial Construction SWPPP. It is
difficult to determine exactly where access to these projects will take
place; additional materials will enable the contractor to install them where
needed.
Design and See Figure 4.1.1 for details. Note: the 100' minimum length of the
Installation entrance shall be reduced to the maximum practicable size when the size
Specifications or configuration of the site does not allow the full length (100').
Construct stabilized construction entrances with a 12-inch thick pad of 4-
inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base
(ATB), or use existing pavement. Do not use crushed concrete, cement,
or calcium chloride for construction entrance stabilization because these
products raise pH levels in stormwater and concrete discharge to surface
waters of the State is prohibited.
A separation geotextile shall be placed under the spalls to prevent fine
sediment from pumping up into the rock pad. The geotextile shall meet
the following standards:
Grab Tensile Strength (ASTM D4751)
200 psi min.
Grab Tensile Elongation (ASTM
30% max.
D4632)
Mullen Burst Strength (ASTM
400 psi min.
D3786-80a)
AOS (ASTM D4751)
20-45 (U.S. standard sieve
size)
• Consider early installation of the first lift of asphalt in areas that will
paved; this can be used as a stabilized entrance. Also consider the
installation of excess concrete as a stabilized entrance. During large
concrete pours, excess concrete is often available for this purpose.
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-7
• Fencing (see BMP C103) shall be installed as necessary to restrict
traffic to the construction entrance.
• Whenever possible, the entrance shall be constructed on a firm,
compacted subgrade. This can substantially increase the effectiveness
of the pad and reduce the need for maintenance.
Construction entrances should avoid crossing existing sidewalks and
back of walk drains if at all possible. If a construction entrance must
cross a sidewalk or back of walk drain, the full length of the sidewalk
and back of walk drain must be covered and protected from sediment
leaving the site.
Maintenance Quarry spalls shall be added if the pad is no longer in accordance with
Standards the specifications.
If the entrance is not preventing sediment from being tracked onto
pavement, then alternative measures to keep the streets free of
sediment shall be used. This may include replacement/cleaning of the
existing quarry spalls, street sweeping, an increase in the dimensions
of the entrance, or the installation of a wheel wash.
Any sediment that is tracked onto pavement shall be removed by
shoveling or street sweeping. The sediment collected by sweeping
shall be removed or stabilized on site. The pavement shall not be
cleaned by washing down the street, except when high efficiency
sweeping is ineffective and there is a threat to public safety. If it is
necessary to wash the streets, the construction of a small sump to
contain the wash water shall be considered. The sediment would then
be washed into the sump where it can be controlled.
• Perform street sweeping by hand or with a high efficiency sweeper. Do
not use a non -high efficiency mechanical sweeper because this creates
dust and throws soils into storm systems or conveyance ditches.
• Any quarry spalls that are loosened from the pad, which end up on the
roadway shall be removed immediately.
• If vehicles are entering or exiting the site at points other than the
construction entrance(s), fencing (see BMP C103) shall be installed to
control traffic.
• Upon project completion and site stabilization, all construction
accesses intended as permanent access for maintenance shall be
permanently stabilized.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-8
Driveway shall meet the
requirements of the
permitting agency
It is recommended that the
entrance be crowned so that
runoff drains off the pad
ire \
Install driveway culvert if there
is a roadside ditch present 1
4' — 8" ouarry soalls �f
Geotextile
12" min. thickness
Provide full width of
inqress/eqress area
Figure 4.1.1 — Stabilized Construction Entrance
Approved as Ecology has approved products as able to meet the requirements of BMP
Equivalent C 105. The products did not pass through the Technology Assessment
Protocol — Ecology (TAPE) process. Local jurisdictions may choose not
to accept this product approved as equivalent, or may require additional
testing prior to consideration for local use. The products are available for
review on Ecology's website at
http://www.ecy.wa. gov/pro,grams/wq/stormwater/newtech/equivalent.html
BMP C106: Wheel Wash
Purpose Wheel washes reduce the amount of sediment transported onto paved
roads by motor vehicles.
Conditions of Use When a stabilized construction entrance (see BMP C105) is not preventing
sediment from being tracked onto pavement.
Wheel washing is generally an effective BMP when installed with
careful attention to topography. For example, a wheel wash can be
detrimental if installed at the top of a slope abutting a right-of-way
where the water from the dripping truck can run unimpeded into the
street.
Volume H— Construction Stormwater Pollution Prevention - December 2014
4-9
stable driving surface and to stabilize any areas that have eroded.
Following construction, these areas shall be restored to pre -construction
condition or better to prevent future erosion.
Perform street cleaning at the end of each day or more often if necessary.
BMP C120: Temporary and Permanent Seeding
Purpose
Seeding reduces erosion by stabilizing exposed soils. A well -established
vegetative cover is one of the most effective methods of reducing erosion.
Conditions of Use
Use seeding throughout the project on disturbed areas that have reached
final grade or that will remain unworked for more than 30 days.
The optimum seeding windows for western Washington are April 1
through June 30 and September I through October 1.
Between July 1 and August 30 seeding requires irrigation until 75 percent
grass cover is established.
Between October 1 and March 30 seeding requires a cover of mulch with
straw or an erosion control blanket until 75 percent grass cover is
established.
Review all disturbed areas in late August to early September and complete
all seeding by the end of September. Otherwise, vegetation will not
establish itself enough to provide more than average protection.
• Mulch is required at all times for seeding because it protects seeds
from heat, moisture loss, and transport due to runoff. Mulch can be
applied on top of the seed or simultaneously by hydroseeding. See
BMP C121: Mulching for specifications.
• Seed and mulch, all disturbed areas not otherwise vegetated at final
site stabilization. Final stabilization means the completion of all soil
disturbing activities at the site and the establishment of a permanent
vegetative cover, or equivalent permanent stabilization measures (such
as pavement, riprap, gabions, or geotextiles) which will prevent
erosion.
Design and
Seed retention/detention ponds as required.
Installation
Install channels intended for vegetation before starting major
Specifications
earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated
channels that will have high flows, install erosion control blankets
over hydroseed. Before allowing water to flow in vegetated
channels, establish 75 percent vegetation cover. If vegetated
channels cannot be established by seed before water flow; install sod
in the channel bottom —over hydromulch and erosion control
blankets.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-13
• Confirm the installation of all required surface water control measures
to prevent seed from washing away.
• Hydroseed applications shall include a minimum of 1,500 pounds per
acre of mulch with 3 percent tackifier. See BMP C121: Mulching for
specifications.
• Areas that will have seeding only and not landscaping may need
compost or meal -based mulch included in the hydroseed in order to
establish vegetation. Re -install native topsoil on the disturbed soil
surface before application.
• When installing seed via hydroseeding operations, only about 1/3 of
the seed actually ends up in contact with the soil surface. This reduces
the ability to establish a good stand of grass quickly. To overcome this,
consider increasing seed quantities by up to 50 percent.
• Enhance vegetation establishment by dividing the hydromulch
operation into two phases:
1. Phase 1- Install all seed and fertilizer with 25-30 percent mulch
and tackifier onto soil in the first lift.
2. Phase 2- Install the rest of the mulch and tackifier over the first lift.
Or, enhance vegetation by:
1. Installing the mulch, seed, fertilizer, and tackifier in one lift.
2. Spread or blow straw over the top of the hydromulch at a rate of
800-1000 pounds per acre.
3. Hold straw in place with a standard tackifier.
Both of these approaches will increase cost moderately but will greatly
improve and enhance vegetative establishment. The increased cost
may be offset by the reduced need for:
• Irrigation.
• Reapplication of mulch.
• Repair of failed slope surfaces.
This technique works with standard hydromulch (1,500 pounds per
acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum).
• Seed may be installed by hand i£
• Temporary and covered by straw, mulch, or topsoil.
• Permanent in small areas (usually less than 1 acre) and covered
with mulch, topsoil, or erosion blankets.
• The seed mixes listed in the tables below include recommended
mixes for both temporary and permanent seeding.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-14
Apply these mixes, with the exception of the wetland mix, at a rate
of 120 pounds per acre. This rate can be reduced if soil
amendments or slow -release fertilizers are used.
Consult the local suppliers or the local conservation district for
their recommendations because the appropriate mix depends on a
variety of factors, including location, exposure, soil type, slope,
and expected foot traffic. Alternative seed mixes approved by the
local authority may be used.
Other mixes may be appropriate, depending on the soil type and
hydrology of the area.
Table 4.1.2 lists the standard mix for areas requiring a temporary
vegetative cover.
Table 4.1.2
Temporary Erosion Control Seed Mix
% Weight
% Purity
% Germination
Chewings or annual blue grass 40
98
90
Festuca rubra var. commutata or
Poa anna
Perennial rye - 50
98
90
Lolium perenne
Redtop or colonial bentgrass 5
92
85
Agrostis alba or Agrostis tenuis
White dutch clover 5
98
90
Trifolium repens
Table 4.1.3 lists a recommended mix for landscaping seed.
Table 4.1.3
Landscaping Seed Mix
% Weight % Purity % Germination
Perennial rye blend 70 98 90
Lolium perenne
Chewings and red fescue blend 30 98 90
Festuca rubra var. commutata
or Festuca rubra
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-15
• Table 4.1.4 lists a turf seed mix for dry situations where there is no
need for watering. This mix requires very little maintenance.
Table 4.1.4
Low -Growing Turf Seed Mix
% Wei ht
% Purit
% Germination
Dwarf tall fescue (several varieties)
45
98
90
Festuca arundinacea var.
Dwarf perennial rye (Barclay)
30
98
90
Lolium perenne var. Barclay
Red fescue
20
98
90
Festuca rubra
Colonial bentgrass
5
98
90
Agrostis tenuis
• Table 4.1.5 lists a mix for bioswales and other intermittently wet areas.
Table 4.1.5
Bioswale Seed Mix*
% Wei ht
% Purit
% Germination
Tall or meadow fescue 75-80
98
90
Festuca arundinacea or Festuca
elation
Seaside/Creeping bentgrass 10-15
92
85
Agrostis palustris
Redtop bentgrass 5-10
90
80
Agrostis alba or Agrostis gigantea
* Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
Volume II— Construction Stormwater Pollution Prevention - December 2014
4-16
• Table 4.1.6 lists a low -growing, relatively non-invasive seed mix
appropriate for very wet areas that are not regulated wetlands. Apply
this mixture at a rate of 60 pounds per acre. Consult Hydraulic Permit
Authority (HPA) for seed mixes if applicable.
Table 4.1.6
Wet Area Seed Mix*
% Wei ht
% Purit
% Germination
Tall or meadow fescue
60-70
98
90
Festuca arundinacea or
Festuca elation
Seaside/Creeping bentgrass
10-15
98
85
Agrostis palustris
Meadow foxtail
10-15
90
80
Alepocurus pratensis
Alsike clover
1-6
98
90
Trifolium hybridum
Redtop bentgrass
1-6
92
85
Agrostis alba
* Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
• Table 4.1.7 lists a recommended meadow seed mix for infrequently
maintained areas or non -maintained areas where colonization by native
plants is desirable. Likely applications include rural road and utility
right-of-way. Seeding should take place in September or very early
October in order to obtain adequate establishment prior to the winter
months. Consider the appropriateness of clover, a fairly invasive
species, in the mix. Amending the soil can reduce the need for clover.
Table 4.1.7
Meadow Seed Mix
% Wei ht
% Purit
% Germination
Redtop or Oregon bentgrass
20
92
85
Agrostis alba or Agrostis
oregonensis
Red fescue
70
98
90
Festuca rubra
White dutch clover
10
98
90
Trifolium repens
Volume II— Construction Stormwater Pollution Prevention -December 2014
4-17
Roughening and Rototilling:
• The seedbed should be firm and rough. Roughen all soil no matter
what the slope. Track walk slopes before seeding if engineering
purposes require compaction. Backblading or smoothing of slopes
greater than 4H:1 V is not allowed if they are to be seeded.
Restoration -based landscape practices require deeper incorporation
than that provided by a simple single -pass rototilling treatment.
Wherever practical, initially rip the subgrade to improve long-term
permeability, infiltration, and water inflow qualities. At a
minimum, permanent areas shall use soil amendments to achieve
organic matter and permeability performance defined in
engineered soil/landscape systems. For systems that are deeper
than 8 inches complete the rototilling process in multiple lifts, or
prepare the engineered soil system per specifications and place to
achieve the specified depth.
• Fertilizers:
Conducting soil tests to determine the exact type and quantity of
fertilizer is recommended. This will prevent the over -application
of fertilizer.
Organic matter is the most appropriate form of fertilizer because it
provides nutrients (including nitrogen, phosphorus, and potassium)
in the least water-soluble form.
In general, use 10-4-6 N-P-K (nitrogen -phosphorus -potassium)
fertilizer at a rate of 90 pounds per acre. Always use slow -release
fertilizers because they are more efficient and have fewer
environmental impacts. Do not add fertilizer to the hydromulch
machine, or agitate, more than 20 minutes before use. Too much
agitation destroys the slow -release coating.
• There are numerous products available that take the place of
chemical fertilizers. These include several with seaweed extracts
that are beneficial to soil microbes and organisms. If 100 percent
cottonseed meal is used as the mulch in hydroseed, chemical
fertilizer may not be necessary. Cottonseed meal provides a good
source of long-term, slow -release, available nitrogen.
Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix:
On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically
Bonded Fiber Matrix (MBFM) products. Apply BFM/MBFM
products at a minimum rate of 3,000 pounds per acre of mulch
with approximately 10 percent tackifier. Achieve a minimum of 95
percent soil coverage during application. Numerous products are
available commercially. Installed products per manufacturer's
instructions. Most products require 24-36 hours to cure before
rainfall and cannot be installed on wet or saturated soils.
Volume 11— Construction Stormwater Pollution Prevention - December 2014
4-18
Generally, products come in 40-50 pound bags and include all
necessary ingredients except for seed and fertilizer.
• BFMs and MBFMs provide good alternatives to blankets in most
areas requiring vegetation establishment. Advantages over
blankets include:
• BFM and MBFMs do not require surface preparation.
• Helicopters can assist in installing BFM and MBFMs in remote
areas.
• On slopes steeper than 2.5H:1V, blanket installers may require
ropes and harnesses for safety.
• Installing BFM and MBFMs can save at least $1,000 per acre
compared to blankets.
Maintenance Reseed any seeded areas that fail to establish at least 80 percent cover
Standards (100 percent cover for areas that receive sheet or concentrated flows). If
reseeding is ineffective, use an alternate method such as sodding,
mulching, or nets/blankets. If winter weather prevents adequate grass
growth, this time limit may be relaxed at the discretion of the local
authority when sensitive areas would otherwise be protected.
• Reseed and protect by mulch any areas that experience erosion after
achieving adequate cover. Reseed and protect by mulch any eroded
area.
• Supply seeded areas with adequate moisture, but do not water to the
extent that it causes runoff.
Approved as Ecology has approved products as able to meet the requirements of BMP
Equivalent C120. The products did not pass through the Technology Assessment
Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to
accept this product approved as equivalent, or may require additional testing
prior to consideration for local use. The products are available for review on
Ecology's website at
http://www. ecy.wa. goy/programs/wq/stonnwater/newtech/equivalent.html.
BMP C121: Mulching
Purpose Mulching soils provides immediate temporary protection from erosion.
Mulch also enhances plant establishment by conserving moisture, holding
fertilizer, seed, and topsoil in place, and moderating soil temperatures.
There is an enormous variety of mulches that can be used. This section
discusses only the most common types of mulch.
Conditions of Use As a temporary cover measure, mulch should be used:
• For less than 30 days on disturbed areas that require cover.
• At all times for seeded areas, especially during the wet season and
during the hot summer months.
Volume 11 — Construction Stormwater Pollution Prevention - December 2014
4-19
• During the wet season on slopes steeper than 3H:1V with more than
10 feet of vertical relief.
Mulch may be applied at any time of the year and must be refreshed
periodically.
For seeded areas mulch may be made up of 100 percent: cottonseed
meal; fibers made of wood, recycled cellulose, hemp, kenaf; compost;
or blends of these. Tackifier shall be plant -based, such as guar or alpha
plantago, or chemical -based such as polyacrylamide or polymers. Any
mulch or tackifier product used shall be installed per manufacturer's
instructions. Generally, mulches come in 40-50 pound bags. Seed and
fertilizer are added at time of application.
Design and For mulch materials, application rates, and specifications, see Table 4.1.8.
Installation Always use a 2-inch minimum mulch thickness; increase the thickness
Specifications until the ground is 95% covered (i.e. not visible under the mulch layer).
Note: Thickness may be increased for disturbed areas in or near sensitive
areas or other areas highly susceptible to erosion.
Where the option of "Compost" is selected, it should be a coarse compost
that meets the following size gradations when tested in accordance with
the U.S. Composting Council "Test Methods for the Examination of
Compost and Composting" (TMECC) Test Method 02.02-B.
Coarse Compost
Minimum Percent passing 3" sieve openings 100%
Minimum Percent passing 1" sieve openings 90%
Minimum Percent passing 3/4" sieve openings 70%
Minimum Percent passing'/4" sieve openings 40%
Mulch used within the ordinary high-water mark of surface waters should
be selected to minimize potential flotation of organic matter. Composted
organic materials have higher specific gravities (densities) than straw,
wood, or chipped material. Consult Hydraulic Permit Authority (HPA) for
mulch mixes if applicable.
Maintenance • The thickness of the cover must be maintained.
Standards • 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 problem shall be fixed and the eroded area remulched.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-20
Table 4.1.8
Mulch Standards and Guidelines
Application
Mulch Material
Quality Standards
Rates
Remarks
Straw
Air-dried; free from
2"-3" thick; 5
Cost-effective protection when applied with adequate thickness.
undesirable seed and
bales per 1,000
Hand -application generally requires greater thickness than
coarse material.
sf or 2-3 tons per
blown straw. The thickness of straw may be reduced by half
acre
when used in conjunction with seeding. In windy areas straw
must be held in place by crimping, using a tackifier, or covering
with netting. Blown straw always has to be held in place with a
tackifier as even light winds will blow it away. Straw, however,
has several deficiencies that should be considered when
selecting mulch materials. It often introduces and/or encourages
the propagation of weed species and it has no significant long-
term benefits. It should also not be used within the ordinary
high-water elevation of surface waters (due to flotation).
Hydromulch
No growth
Approx. 25-30
Shall be applied with hydromulcher. Shall not be used without
inhibiting factors.
lbs per 1,000 sf
seed and tackifier unless the application rate is at least doubled.
or 1,500 - 2,000
Fibers longer than about 3/4-1 inch clog hydromulch equipment.
lbs per acre
Fibers should be kept to less than3/4 inch.
Compost
No visible water or
2" thick min.;
More effective control can be obtained by increasing thickness
dust during
approx. 100 tons
to 3". Excellent mulch for protecting final grades until
handling. Must be
per acre (approx.
landscaping because it can be directly seeded or tilled into soil
produced per WAC
800 lbs per yard)
as an amendment. Compost used for mulch has a coarser size
173-350, Solid
gradation than compost used for BMP C 125 or BMP T5.13 (see
Waste Handling
Chapter 5 of Volume V of this manual) It is more stable and
Standards, but may
practical to use in wet areas and during rainy weather
have up to 35%
conditions. Do not use near wetlands or near phosphorous
biosolids.
impaired water bodies.
Chipped Site
Average size shall
2" thick min.;
This is a cost-effective way to dispose of debris from clearing
Vegetation
be several inches.
and grabbing, and it eliminates the problems associated with
Gradations from
burning. Generally, it should not be used on slopes above
fines to 6 inches in
approx. 10% because of its tendency to be transported by
length for texture,
runoff. It is not recommended within 200 feet of surface waters.
variation, and
If seeding is expected shortly after mulch, the decomposition of
interlocking
the chipped vegetation may tie up nutrients important to grass
properties.
establishment.
Wood -based
No visible water or
2" thick min.;
This material is often called "hog or hogged fuel." The use of
Mulch or Wood
dust during
approx. 100 tons
mulch ultimately improves the organic matter in the soil.
Straw
handling. Must be
per acre (approx.
Special caution is advised regarding the source and composition
purchased from a
800 lbs. per
of wood -based mulches. Its preparation typically does not
supplier with a Solid
cubic yard)
provide any weed seed control, so evidence of residual
Waste Handling
vegetation in its composition or known inclusion of weed plants
Permit or one
or seeds should be monitored and prevented (or minimized).
exempt from solid
waste regulations.
Wood Strand
A blend of loose,
2" thick min.
Cost-effective protection when applied with adequate thickness.
Mulch
long, thin wood
A minimum of 95-percent of the wood strand shall have lengths
pieces derived from
between 2 and 10-inches, with a width and thickness between
native conifer or
l/16 and %-inches. The mulch shall not contain resin, tannin, or
deciduous trees with
other compounds in quantities that would be detrimental to plant
high length -to -width
life. Sawdust or wood shavings shall not be used as mulch.
ratio.
(WSDOT specification (9-14.4(4))
Volume H— Construction Stormwater Pollution Prevention - December 2014
4-21
BMP C123: Plastic Covering
Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
Conditions of Plastic covering may be used on disturbed areas that require cover
U.se measures for less than 30 days, except as stated below.
• Plastic is particularly useful for protecting cut and fill slopes and
stockpiles. Note: The relatively rapid breakdown of most polyethylene
sheeting makes it unsuitable for long-term (greater than six months)
applications.
• Due to rapid runoff caused by plastic covering, do not use this method
upslope of areas that might be adversely impacted by concentrated
runoff. Such areas include steep and/or unstable slopes.
• Plastic sheeting may result in increased runoff volumes and velocities,
requiring additional on -site measures to counteract the increases.
Creating a trough with wattles or other material can convey clean
water away from these areas.
• To prevent undercutting, trench and backfill rolled plastic covering
products.
• While plastic is inexpensive to purchase, the added cost of
installation, maintenance, removal, and disposal make this an
expensive material, up to $1.50-2.00 per square yard.
• Whenever plastic is used to protect slopes install water collection
measures at the base of the slope. These measures include plastic -
covered berms, channels, and pipes used to covey clean rainwater
away from bare soil and disturbed areas. Do not mix clean runoff from
a plastic covered slope with dirty runoff from a project.
• Other uses for plastic include:
1. Temporary ditch liner.
2. Pond liner in temporary sediment pond.
3. Liner for bermed temporary fuel storage area if plastic is not
reactive to the type of fuel being stored.
4. Emergency slope protection during heavy rains.
5. Temporary drainpipe ("elephant trunk") used to direct water.
Design and Plastic slope cover must be installed as follows:
Installation 1. Run plastic up and down slope, not across slope.
Specifications
2. Plastic may be installed perpendicular to a slope if the slope length
is less than 10 feet.
3. Minimum of 8-inch overlap at seams.
Volume II — Construction Stormwater Pollution Prevention - December 2014
Cb�l
4. On long or wide slopes, or slopes subject to wind, tape all seams.
5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench
at the top of the slope and backfill with soil to keep water from
flowing underneath.
6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and tie them together with twine to hold them in place.
7. Inspect plastic for rips, tears, and open seams regularly and repair
immediately. This prevents high velocity runoff from contacting
bare soil which causes extreme erosion.
8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
• Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
If erosion at the toe of a slope is likely, a gravel berm, riprap, or other
suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
Maintenance • Torn sheets must be replaced and open seams repaired.
Standards • Completely remove and replace the plastic if it begins to deteriorate
due to ultraviolet radiation.
• Completely remove plastic when no longer needed.
• Dispose of old tires used to weight down plastic sheeting
appropriately.
Approved as Ecology has approved products as able to meet the requirements of BMP
Equivalent C 123. The products did not pass through the Technology Assessment
Protocol — Ecology (TAPE) process. Local jurisdictions may choose not
to accept this product approved as equivalent, or may require additional
testing prior to consideration for local use. The products are available for
review on Ecology's website at
http://www. ecy. wa. goy/pro grams/wq/stormwater/newtech/equivalent.html
BMP C124: Sodding
Purpose The purpose of sodding is to establish permanent turf for immediate
erosion protection and to stabilize drainage ways where concentrated
overland flow will occur.
Conditions of Use Sodding may be used in the following areas:
Disturbed areas that require short-term or long-term cover.
Disturbed areas that require immediate vegetative cover.
• All waterways that require vegetative lining. Waterways may also be
seeded rather than sodded, and protected with a net or blanket.
Volume H— Construction Stormwater Pollution Prevention -December 2014
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Design and Sod shall be free of weeds, of uniform thickness (approximately 1-inch
Installation thick), and shall have a dense root mat for mechanical strength.
Specifications The following steps are recommended for sod installation:
• Shape and smooth the surface to final grade in accordance with the
approved grading plan. The swale needs to be overexcavated 4 to 6
inches below design elevation to allow room for placing soil
amendment and sod.
• Amend 4 inches (minimum) of compost into the top 8 inches of the
soil if the organic content of the soil is less than ten percent or the
permeability is less than 0.6 inches per hour. See
httn://www.ecv.wa.izov/nroizrams/swfa/orizanics/soil.html for further
information.
Fertilize according to the supplier's recommendations.
• Work lime and fertilizer 1 to 2 inches into the soil, and smooth the
surface.
• Lay strips of sod beginning at the lowest area to be sodded and
perpendicular to the direction of water flow. Wedge strips securely
into place. Square the ends of each strip to provide for a close, tight fit.
Stagger joints at least 12 inches. Staple on slopes steeper than 3H:1V.
Staple the upstream edge of each sod strip.
Roll the sodded area and irrigate.
• When sodding is carried out in alternating strips or other patterns, seed
the areas between the sod immediately after sodding.
Maintenance If the grass is unhealthy, the cause shall be determined and appropriate
Standards action taken to reestablish a healthy groundcover. If it is impossible to
establish a healthy groundcover due to frequent saturation, instability, or
some other cause, the sod shall be removed, the area seeded with an
appropriate mix, and protected with a net or blanket.
BMP C125: Topsoiling / Composting
Purpose Topsoiling and composting provide a suitable growth medium for final
site stabilization with vegetation. While not a permanent cover practice in
itself, topsoiling and composting are an integral component of providing
permanent cover in those areas where there is an unsuitable soil surface
for plant growth. Use this BMP in conjunction with other BMPs such as
seeding, mulching, or sodding. Note that this BMP is functionally the
same as BMP T5.13 (see Chapter 5 of Volume V of this manual) which is
required for all disturbed areas that will be developed as lawn or
landscaped areas at the completed project site.
Native soils and disturbed soils that have been organically amended not
only retain much more stormwater, but they also serve as effective
Volume H — Construction Stormwater Pollution Prevention - December 2014
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BMP C140: Dust Control
Purpose
Dust control prevents wind transport of dust from disturbed soil surfaces
onto roadways, drainage ways, and surface waters.
Conditions of Use
• In areas (including roadways) subject to surface and air movement of
dust where on -site and off -site impacts to roadways, drainage ways, or
surface waters are likely.
Design and
• Vegetate or mulch areas that will not receive vehicle traffic. In areas
Installation
where planting, mulching, or paving is impractical, apply gravel or
Specifications
landscaping rock.
Limit dust generation by clearing only those areas where immediate
activity will take place, leaving the remaining area(s) in the original
condition. Maintain the original ground cover as long as practical.
• Construct natural or artificial windbreaks or windscreens. These may
be designed as enclosures for small dust sources.
• Sprinkle the site with water until surface is wet. Repeat as needed. To
prevent carryout of mud onto street, refer to Stabilized Construction
Entrance (BMP C 105).
Irrigation water can be used for dust control. Irrigation systems should
be installed as a first step on sites where dust control is a concern.
• Spray exposed soil areas with a dust palliative, following the
manufacturer's instructions and cautions regarding handling and
application. Used oil is prohibited from use as a dust suppressant.
Local governments may approve other dust palliatives such as calcium
chloride or PAM.
• PAM (BMP C126) added to water at a rate of 0.5 lbs. per 1,000
gallons of water per acre and applied from a water truck is more
effective than water alone. This is due to increased infiltration of water
into the soil and reduced evaporation. In addition, small soil particles
are bonded together and are not as easily transported by wind. Adding
PAM may actually reduce the quantity of water needed for dust
control. Use of PAM could be a cost-effective dust control method.
Techniques that can be used for unpaved roads and lots include:
Lower speed limits. High vehicle speed increases the amount of dust
stirred up from unpaved roads and lots.
• Upgrade the road surface strength by improving particle size, shape,
and mineral types that make up the surface and base materials.
Add surface gravel to reduce the source of dust emission. Limit the
amount of fine particles (those smaller than .075 mm) to 10 to 20
percent.
Volume H— Construction Stormwater Pollution Prevention -December 2014
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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 Respray area as necessary to keep dust to a minimum.
Standards
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 11— Construction Stormwater Pollution Prevention - December 2014
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Design and
Installation
Specifications
Maintenance
Standards
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
• 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 • Assure that washout of concrete trucks, chutes, pumps, and internals is
Installation performed at an approved off -site location or in designated concrete
Volume H— Construction Stormwater Pollution Prevention -December 2014
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Specifications washout areas. Do not wash out concrete trucks onto the ground, or
into storm drains, open ditches, streets, or streams. Refer to BMP
C 154 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 Check containers for holes in the liner daily during concrete pours and
Standards 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
• Vacuum slurry and cuttings during cutting and surfacing operations.
Installation
Slurry and cuttings shall not remain on permanent concrete or asphalt
Specifications
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
Continually monitor operations to determine whether slurry, cuttings, or
Standards
process water could enter waters of the state. If inspections show that a
violation of water quality standards could occur, stop operations and
immediately implement preventive measures such as berms, barriers,
secondary containment, and vacuum trucks.
Volume H— Construction Stormwater Pollution Prevention -December 2014
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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 Implementation
Installation The following steps will help reduce stormwater pollution from concrete
Specifications wastes:
• Perform washout of concrete trucks at an approved off -site location 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.
Volume H— Construction Stormwater Pollution Prevention -December 2014
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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 C 105). 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.
• Washout of concrete trucks shall be performed in designated areas
only.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-48
• 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 FacilitX
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 FacilitX
• 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 Inspection and Maintenance
Standards
• Inspect and verify that concrete washout BMPs are in place prior to the
commencement of concrete work.
• Duringperiods of concrete work, inspect daily to verify continued
performance.
• Check overall condition and performance.
• Check remaining capacity (% full).
If using self -installed washout facilities, verify plastic liners are
intact and sidewalls are not damaged.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-49
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.
Volume H— Construction Stormwater Pollution Prevention -December 2014
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SANDBAG
10 mil PLASTIC LINING
1 m
BERM
SECTIOK
LATH AND NOT TO SCALE
FLAGGING ON
3 SIDES
3m MINIMUM
Q O O
VAPoES I Q
10 mil PLASTIC LINING
WOOD FRAME SECURELY
FASTENED AROUND
ENTIRE PERIMETER
WITH TWO STAKES
30211211�
NOT TO SCALE
Q TWO -STACKED 1_ .... �,. 2
202 ROLr •_ ••�••
WOOD FRA
Q
Q
❑ ❑ Q
SANDBAG 10 ml F.......... .........
am
10 mil PLASTIC LINING NOT TO SCALE BERM
TYPE 'BE= GRADE
ROTES
1. ACTUAL LAYOUT DETERMINED IN THE FIELD.
2. THE CONCRETE WASHOUT SIGN (SEE PAGE 6) SHALL
BE INSTALLED WITHIN 10 m OF THE TEMPORARY
CONCRETE WASHOUT FACILITY.
Figure 4.1.7a — Concrete Washout Area
JILM
NOT TO SCALE
TYPE "ABOVE GRADE'
WITH WOOD PLANKS
Volume 11— Construction Stormwater Pollution Prevention - December 2014
4-51
STAKF
(IYP.)
STRAW BALE
STAPLES
BINDING WIRE -7
(2 PER BALE)
10 mil PLASTIC LINING
WOOD OR METAL
NATIVE MATERIAL
STAKES (2 PER BALE)
_
(OPTIONAL)
SECTION 11-IY
NOT TO SCALE
I
1� 3m MINIMUM
STAKE
B
VARIES
STRAW BALE
10 mil PLASTIC LINING am(TYP,)
NOT TO SCALE
TYPE 'ABOVE GRADE'
WITH STRAW BALES
NOTES:
1. ACTUAL LAYOUT DETERMINED IN THE FIELD.
2. THE CONCRETE WASHOUT SIGN (SEE FIG. 4-15)
SHALL BE INSTALLED WITHIN 10 m OF THE
TEMPORARY CONCRETE WASHOUT FACILITIY.
CtiMOXS/M1 14.DK SAC 8-14-02
PLYWOOD
1200 mm x 610 mm
PAINTED WHITE
CONCRETE i i
BLACK LETTERS
i WASHOUT I 1
_
150 mm HEIGHT
I.I
LAG SCREWS
(12.5 mm)
915 mm
WOOD POST
915 mm
(89 mm x 89 mm x 2.4 m)
CONCRETE WASHOUT
SIGN DETAIL
(OR EQUIVALENT)
50 mm
200 (w STEE mm DIA
}T STEEL WIRE
I
STAPLE DETAIL
Figure 4.1.7b — Concrete Washout Area
Figure 4.1.8 — Prefabricated Concrete Washout Container w/Ramp
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-52
Treated 2"xl0" may be abutted end to
Spreader must be level end for max. spreader length of 50'
6" min. 1" min.
777
6" min I I !
IIII I —ICI
i it l li i it l li i it l li it l li i it l li i it l li i it l li i it l mil l li i it l li i it l li i it l li i it l li i I li i it I li i II I li i
18" min. rebar supports
8' max. spacing
Figure 4.2.6 — Detail of Level Spreader
BMP C207: Check Dams
Purpose Construction of small dams across a swale or ditch reduces the velocity of
concentrated flow and dissipates energy at the check dam.
Conditions of Use Where temporary channels or permanent channels are not yet vegetated,
channel lining is infeasible, and/or velocity checks are required.
• Check dams may not be placed in streams unless approved by the State
Department of Fish and Wildlife. Check dams may not be placed in
wetlands without approval from a permitting agency.
Do not place check dams below the expected backwater from any
salmonid bearing water between October 1 and May 31 to ensure that
there is no loss of high flow refuge habitat for overwintering juvenile
salmonids and emergent salmonid fry.
Construct rock check dams from appropriately sized rock. The rock
used must be large enough to stay in place given the expected design
flow through the channel. The rock must be placed by hand or by
mechanical means (no dumping of rock to form dam) to achieve
complete coverage of the ditch or swale and to ensure that the center
of the dam is lower than the edges.
Check dams may also be constructed of either rock or pea -gravel filled
bags. Numerous new products are also available for this purpose. They
tend to be re -usable, quick and easy to install, effective, and cost
efficient.
Place check dams perpendicular to the flow of water.
• The dam should form a triangle when viewed from the side. This
prevents undercutting as water flows over the face of the dam rather
than falling directly onto the ditch bottom.
Volume II— Construction Stormwater Pollution Prevention -December 2014
4- 74
• Before installing check dams impound and bypass upstream water
flow away from the work area. Options for bypassing include pumps,
siphons, or temporary channels.
• Check dams in association with sumps work more effectively at
slowing flow and retaining sediment than just a check dam alone. A
deep sump should be provided immediately upstream of the check
dam.
• In some cases, if carefully located and designed, check dams can
remain as permanent installations with very minor regrading. They
may be left as either spillways, in which case accumulated sediment
would be graded and seeded, or as check dams to prevent further
sediment from leaving the site.
• The maximum spacing between the dams shall be such that the toe of
the upstream dam is at the same elevation as the top of the downstream
dam.
• Keep the maximum height at 2 feet at the center of the dam.
• Keep the center of the check dam at least 12 inches lower than the
outer edges at natural ground elevation.
• Keep the side slopes of the check dam at 2H: IV or flatter.
• Key the stone into the ditch banks and extend it beyond the abutments
a minimum of 18 inches to avoid washouts from overflow around the
dam.
• Use filter fabric foundation under a rock or sand bag check dam. If a
blanket ditch liner is used, filter fabric is not necessary. A piece of
organic or synthetic blanket cut to fit will also work for this purpose.
• In the case of grass -lined ditches and swales, all check dams and
accumulated sediment shall be removed when the grass has matured
sufficiently to protect the ditch or swale - unless the slope of the swale
is greater than 4 percent. The area beneath the check dams shall be
seeded and mulched immediately after dam removal.
• Ensure that channel appurtenances, such as culvert entrances below
check dams, are not subject to damage or blockage from displaced
stones. Figure 4.2.7 depicts a typical rock check dam.
Maintenance Check dams shall be monitored for performance and sediment
Standards accumulation during and after each runoff producing rainfall. Sediment
shall be removed when it reaches one half the sump depth.
• Anticipate submergence and deposition above the check dam and
erosion from high flows around the edges of the dam.
• If significant erosion occurs between dams, install a protective riprap
liner in that portion of the channel.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-75
Approved as Ecology has approved products as able to meet the requirements of BMP
Equivalent C207. The products did not pass through the Technology Assessment
Protocol — Ecology (TAPE) process. Local jurisdictions may choose not
to accept this product approved as equivalent, or may require additional
testing prior to consideration for local use. The products are available for
review on Ecology's website at
http://www. ecy.wa. goy/programs/wq/stonnwater/newtech/equivalent.httnl
Volume II— Construction Stormwater Pollution Prevention -December 2014
4-76
View Looking Upstream
flow around dam.
Section A - A
R OIAi
Spacing Between Check Dams
!l
'L' = the distance such that points 'A' and
'B' are of equal elevation.
L'
POINT'A' - POINT 'B'
NOT TO SCALE
Figure 4.2.7 — Rock Check Dam
Volume II — Construction Stormwater Pollution Prevention - December 2014
4- 77
New pipe outfalls can provide an opportunity for low-cost fish habitat
improvements. For example, an alcove of low -velocity water can be
created by constructing the pipe outfall and associated energy
dissipater back from the stream edge and digging a channel, over -
widened to the upstream side, from the outfall. Overwintering juvenile
and migrating adult salmonids may use the alcove as shelter during
high flows. Bank stabilization, bioengineering, and habitat features
may be required for disturbed areas. This work may require a HPA.
See Volume V for more information on outfall system design.
Maintenance • Inspect and repair as needed.
Standards . Add rock as needed to maintain the intended function.
• Clean energy dissipater if sediment builds up.
BMP C220: Storm Drain Inlet Protection
Purpose Storm drain inlet protection prevents coarse sediment from entering
drainage systems prior to permanent stabilization of the disturbed area.
Conditions of Use Use storm drain inlet protection at inlets that are operational before
permanent stabilization of the disturbed drainage area. Provide protection
for all storm drain inlets downslope and within 500 feet of a disturbed or
construction area, unless conveying runoff entering catch basins to a
sediment pond or trap.
Also consider inlet protection for lawn and yard drains on new home
construction. These small and numerous drains coupled with lack of
gutters in new home construction can add significant amounts of sediment
into the roof drain system. If possible delay installing lawn and yard drains
until just before landscaping or cap these drains to prevent sediment from
entering the system until completion of landscaping. Provide 18-inches of
sod around each finished lawn and yard drain.
Table 4.2.2 lists several options for inlet protection. All of the methods for
storm drain inlet protection tend to plug and require a high frequency of
maintenance. Limit drainage areas to one acre or less. Possibly provide
emergency overflows with additional end -of -pipe treatment where
stormwater ponding would cause a hazard.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-80
Table 4.2.2
Storm Drain Inlet Protection
Applicable for
Type of Inlet
Emergency
Paved/ Earthen
Protection
Overflow
Surfaces
Conditions of Use
Drop Inlet Protection
Excavated drop inlet
Yes,
Earthen
Applicablefor heavy flows. Easy
protection
temporary
to maintain. Large area
flooding will
Requirement: 30' X 30'/acre
occu r
Block and gravel drop
Yes
Paved or Earthen
Applicablefor heavy concentrated
inlet protection
flows. Will not pond.
Gravel and wire drop
No
Applicablefor heavy concentrated
inlet protection
flows. Will pond. Can withstand
traffic.
Catch basin filters
Yes
Paved or Earthen
Frequent maintenance required.
Curb Inlet Protection
Curb inlet protection
Small capacity
Paved
Used for sturdy, more compact
with a wooden weir
overflow
installation.
Block and gravel curb
Yes
Paved
Sturdy, but limited filtration.
inlet protection
Culvert Inlet Protection
Culvert inlet sediment
18 month expected life.
trap
Design and Excavated Drop Inlet Protection - An excavated impoundment around the
Installation storm drain. Sediment settles out of the stormwater prior to entering the
Specifications storm drain.
• Provide a depth of 1-2 ft as measured from the crest of the inlet
structure.
• Slope sides of excavation no steeper than 2H:IV.
• Minimum volume of excavation 35 cubic yards.
• Shape basin to fit site with longest dimension oriented toward the
longest inflow area.
• Install provisions for draining to prevent standing water problems.
• Clear the area of all debris.
• Grade the approach to the inlet uniformly.
• Drill weep holes into the side of the inlet.
• Protect weep holes with screen wire and washed aggregate.
• Seal weep holes when removing structure and stabilizing area.
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-81
• Build a temporary dike, if necessary, to the down slope side of the
structure to prevent bypass flow.
Block and Gravel Filter - A barrier formed around the storm drain inlet
with standard concrete blocks and gravel. See Figure 4.2.8.
• Provide a height of 1 to 2 feet above inlet.
• Recess the first row 2-inches into the ground for stability.
• Support subsequent courses by placing a 2x4 through the block
opening.
• Do not use mortar.
• Lay some blocks in the bottom row on their side for dewatering the
pool.
• Place hardware cloth or comparable wire mesh with V2-inch openings
over all block openings.
• Place gravel just below the top of blocks on slopes of 2H:1 V or flatter.
• An alternative design is a gravel donut.
• Provide an inlet slope of 3H:IV.
• Provide an outlet slope of 2H:IV.
• Provide al -foot wide level stone area between the structure and the
inlet.
• Use inlet slope stones 3 inches in diameter or larger.
• Use gravel'/2- to 3/4-inch at a minimum thickness of 1-foot for the
outlet slope.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-82
Plan View A
Drain
Grate
p 0���poo oOoa000°°
°�o
O e2-C —0
o°O 0
ao0a o0 0 Z. Q 9 o Concrete
°tea Block
o�o.0
�_ Gravel
� -C °a .O Backfill
°oo°oo
l000000 ° oo D�oQO oo°°��
�a�o 06 �Q��Qloo O
In °
r
y55�c��oQ� A
Section A - A Concrete Block Wire screen or
Filter Fabric
Gravel Backfill � Overflow
Water Ponding Height
o po0 c
ooC ��oO water �°�00 .0oo
�i\\jam\j\\j\\j\\j\\j\,>.
Drop Inlet \\\
Notes:
1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%)
2. Excavate a basin of sufficient size adjacent to the drop inlet.
3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent
runoff from bypassing the inlet. A temporary dike may be necessary on the downslope side of the structure.
Figure 4.2.8 — Block and Gravel Filter
Gravel and Wire Mesh Filter - A gravel barrier placed over the top of the
inlet. This structure does not provide an overflow.
• Use a hardware cloth or comparable wire mesh with %2-inch openings.
• Use coarse aggregate.
• Provide a height 1-foot or more, 18-inches wider than inlet on all
sides.
• Place wire mesh over the drop inlet so that the wire extends a
minimum of 1-foot beyond each side of the inlet structure.
• Overlap the strips if more than one strip of mesh is necessary.
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-83
• Place coarse aggregate over the wire mesh.
• Provide at least a 12-inch depth of gravel over the entire inlet opening
and extend at least 18-inches on all sides.
Catchbasin Filters — Use inserts designed by manufacturers for
construction sites. The limited sediment storage capacity increases the
amount of inspection and maintenance required, which may be daily for
heavy sediment loads. To reduce maintenance requirements combine a
catchbasin filter with another type of inlet protection. This type of inlet
protection provides flow bypass without overflow and therefore may be a
better method for inlets located along active rights -of -way.
• Provides 5 cubic feet of storage.
• Requires dewatering provisions.
• Provides a high -flow bypass that will not clog under normal use at a
construction site.
• Insert the catchbasin filter in the catchbasin just below the grating.
Curb Inlet Protection with Wooden Weir — Barrier formed around a curb
inlet with a wooden frame and gravel.
• Use wire mesh with 1/2-inch openings.
• Use extra strength filter cloth.
• Construct a frame.
• Attach the wire and filter fabric to the frame.
• Pile coarse washed aggregate against wire/fabric.
• Place weight on frame anchors.
Block and Gravel Curb Inlet Protection — Barrier formed around a curb
inlet with concrete blocks and gravel. See Figure 4.2.9.
• Use wire mesh with 1/2-inch openings.
• Place two concrete blocks on their sides abutting the curb at either side
of the inlet opening. These are spacer blocks.
• Place a 2x4 stud through the outer holes of each spacer block to align
the front blocks.
• Place blocks on their sides across the front of the inlet and abutting the
spacer blocks.
• Place wire mesh over the outside vertical face.
• Pile coarse aggregate against the wire to the top of the barrier.
Curb and Gutter Sediment Barrier — Sandbag or rock berm (riprap and
aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure
4.2.10.
Volume II — Construction Stormwater Pollution Prevention -December 2014
4-84
• Construct a horseshoe shaped berm, faced with coarse aggregate if
using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet.
• Construct a horseshoe shaped sedimentation trap on the outside of the
berm sized to sediment trap standards for protecting a culvert inlet.
Maintenance
• Inspect catch basin filters frequently, especially after storm events.
Standards
Clean and replace clogged inserts. For systems with clogged stone
filters: pull away the stones from the inlet and clean or replace. An
alternative approach would be to use the clogged stone as fill and put
fresh stone around the inlet.
• Do not wash sediment into storm drains while cleaning. Spread all
excavated material evenly over the surrounding land area or stockpile
and stabilize as appropriate.
Approved as
Ecology has approved products as able to meet the requirements of BMP
Equivalent
C220. The products did not pass through the Technology Assessment
Protocol — Ecology (TAPE) process. Local jurisdictions may choose not
to accept this product approved as equivalent, or may require additional
testing prior to consideration for local use. The products are available for
review on Ecology's website at
http://www.ecy.wa. goy/programs/wq/stonnwater/newtech/equivalent.httnl
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-85
Plan View
Back of Sidewalk A Catch Basin
2x4 Wood Stud
Back of Curb Concrete Block
Curb Inlet
2ob
oo• oo• o° o� o°o• o• �°o• ° o°off o oo° a}� °8°0°
.0�8 � d o°a �d " �d�� do°o °i `� �• ° °o�. 'o o �S •o O�:o �
o d�R Oa°°.=. d:° Q °�d.bJQ ° d�Cp�oU�•p �a o 0
Wire Screen or A Filter Fabric Concrete Block
Section A - A 3/4' Drain Gravel
(20mm)
3/4' Drain Gravel
(20mm)
Ponding Height
Concrete Block
Overflow
a \\/,
Curb Inlet
\
Wire Screen or
Filter Fabric
4 Wood Stud \\� Catch Basin
(100x50 Timber Stud) \ j'
NOTES:
1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment,
where water can pond and allow sediment to separate from runoff.
2. Barrier shall allow for overflow from severe storm event.
3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed
from the traveled way immediately.
Figure 4.2.9 — Block and Gravel Curb Inlet Protection
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-86
Plan View
Back of Sidewalk
Burlap Sacks to Catch Basin
Overlap onto Curb
Curb Inlet
Back of Curb
I
RUNOFF
RUNOFF SPILLWAY
Gravel Filled Sandbags
Stacked Tightly
NOTES:
1. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow
sediment to separate from runoff.
2. Sandbags of either burlap or woven 'geotextile' fabric, are filled with gravel, layered and packed tightly.
3. Leave a one sandbag gap in the top row to provide a spillway for overflow.
4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from
the traveled way immediately.
Figure 4.2.10 — Curb and Gutter Barrier
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-87
BMP C232: Gravel Filter Berm
Purpose
A gravel filter berm is constructed on rights -of -way or traffic areas within
a construction site to retain sediment by using a filter berm of gravel or
crushed rock.
Conditions of Use
Where a temporary measure is needed to retain sediment from rights -of -
way or in traffic areas on construction sites.
Design and
• Berm material shall be 3/4 to 3 inches in size, washed well -grade gravel
Installation
or crushed rock with less than 5 percent fines.
Specifications
Spacing of berms:
— Every 300 feet on slopes less than 5 percent
— Every 200 feet on slopes between 5 percent and 10 percent
— Every 100 feet on slopes greater than 10 percent
• Berm dimensions:
— 1 foot high with 3H:1V side slopes
— 8 linear feet per 1 cfs runoff based on the 10-year, 24-hour design
storm
Maintenance
• Regular inspection is required. Sediment shall be removed and filter
Standards
material replaced as needed.
BMP C233: Silt Fence
Purpose Use of a silt fence reduces the transport of coarse sediment from a
construction site by providing a temporary physical barrier to sediment
and reducing the runoff velocities of overland flow. See Figure 4.2.12 for
details on silt fence construction.
Conditions of Use Silt fence may be used downslope of all disturbed areas.
• Silt fence shall prevent soil carried by runoff water from going
beneath, through, or over the top of the silt fence, but shall allow the
water to pass through the fence.
• Silt fence is not intended to treat concentrated flows, nor is it intended
to treat substantial amounts of overland flow. Convey any
concentrated flows through the drainage system to a sediment pond.
• Do not construct silt fences in streams or use in V-shaped ditches. Silt
fences do not provide an adequate method of silt control for anything
deeper than sheet or overland flow.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-89
Joints in filter fabric shall be spliced at
posts. Use staples, wire rings or
equivalent to attach fabric to posts
max
Post spacing may be increased
to 8' if wire backing is used
2"x2" by 14 Ga. wire or
equivalent. if standard
strength fabric used
Filter fabric
c
CV
11I-1I�
_ - c
Minimum 4"x4" trench _- Ali E
CV
Backfill trench with native soil
or 3/4"-1.5" washed gravel
2"x2" wood posts, steel fence
posts, or equivalent
Figure 4.2.12 — Silt Fence
Design and • Use in combination with sediment basins or other BMPs.
Installation Maximum slope steepness (normal (perpendicular) to fence line)
Specifications 1 H:1 V.
Maximum sheet or overland flow path length to the fence of 100 feet.
• Do not allow flows greater than 0.5 cfs.
• The geotextile used shall meet the following standards. All geotextile
properties listed below are minimum average roll values (i.e., the test
result for any sampled roll in a lot shall meet or exceed the values
shown in Table 4.2.3):
Table 4.2.3
Geotextile Standards
Polymeric Mesh AOS
0.60 min maximum for slit film woven (#30 sieve). 0.30
(ASTM D4751)
mm maximum for all other geotextile types (#50 sieve).
0.15 mm minimum for all fabric types (#100 sieve).
Water Permittivity
0.02 sec-1 minimum
(ASTM D4491)
Grab Tensile Strength
180 lbs. Minimum for extra strength fabric.
(ASTM D4632)
100 lbs minimum for standard strength fabric.
Grab Tensile Strength
30% maximum
(ASTM D4632)
Ultraviolet Resistance
70% minimum
(ASTM D4355)
Support standard strength fabrics with wire mesh, chicken wire, 2-inch
x 2-inch wire, safety fence, or jute mesh to increase the strength of the
fabric. Silt fence materials are available that have synthetic mesh
backing attached.
Volume I — Construction Stormwater Pollution Prevention - December 2014
4-90
• Filter fabric material shall contain ultraviolet ray inhibitors and
stabilizers to provide a minimum of six months of expected usable
construction life at a temperature range of 0°F. to 120°F.
• One -hundred percent biodegradable silt fence is available that is
strong, long lasting, and can be left in place after the project is
completed, if permitted by local regulations.
• Refer to Figure 4.2.12 for standard silt fence details. Include the
following standard Notes for silt fence on construction plans and
specifications:
The contractor shall install and maintain temporary silt fences at
the locations shown in the Plans.
2. Construct silt fences in areas of clearing, grading, or drainage prior
to starting those activities.
3. The silt fence shall have a 2-feet min. and a 21/2-feet max. height
above the original ground surface.
4. The filter fabric shall be sewn together at the point of manufacture
to form filter fabric lengths as required. Locate all sewn seams at
support posts. Alternatively, two sections of silt fence can be
overlapped, provided the Contractor can demonstrate, to the
satisfaction of the Engineer, that the overlap is long enough and
that the adjacent fence sections are close enough together to
prevent silt laden water from escaping through the fence at the
overlap.
5. Attach the filter fabric on the up -slope side of the posts and secure
with staples, wire, or in accordance with the manufacturer's
recommendations. Attach the filter fabric to the posts in a manner
that reduces the potential for tearing.
6. Support the filter fabric with wire or plastic mesh, dependent on
the properties of the geotextile selected for use. If wire or plastic
mesh is used, fasten the mesh securely to the up -slope side of the
posts with the filter fabric up -slope of the mesh.
7. Mesh support, if used, shall consist of steel wire with a maximum
mesh spacing of 2-inches, or a prefabricated polymeric mesh. The
strength of the wire or polymeric mesh shall be equivalent to or
greater than 180 lbs. grab tensile strength. The polymeric mesh
must be as resistant to the same level of ultraviolet radiation as the
filter fabric it supports.
8. Bury the bottom of the filter fabric 4-inches min. below the ground
surface. Backfill and tamp soil in place over the buried portion of
the filter fabric, so that no flow can pass beneath the fence and
scouring cannot occur. When wire or polymeric back-up support
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-91
mesh is used, the wire or polymeric mesh shall extend into the
ground 3-inches min.
9. Drive or place the fence posts into the ground 18-inches min. A
12—inch min. depth is allowed if topsoil or other soft subgrade soil
is not present and 18-inches cannot be reached. Increase fence post
min. depths by 6 inches if the fence is located on slopes of 3H:1 V
or steeper and the slope is perpendicular to the fence. If required
post depths cannot be obtained, the posts shall be adequately
secured by bracing or guying to prevent overturning of the fence
due to sediment loading.
10. Use wood, steel or equivalent posts. The spacing of the support
posts shall be a maximum of 6-feet. Posts shall consist of either:
• Wood with dimensions of 2-inches by 2-inches wide min. and
a 3-feet min. length. Wood posts shall be free of defects such
as knots, splits, or gouges.
• No. 6 steel rebar or larger.
• ASTM A 120 steel pipe with a minimum diameter of 1-inch.
• U, T, L, or C shape steel posts with a minimum weight of 1.35
lbs./ft.
• Other steel posts having equivalent strength and bending
resistance to the post sizes listed above.
11. Locate silt fences on contour as much as possible, except at the
ends of the fence, where the fence shall be turned uphill such that
the silt fence captures the runoff water and prevents water from
flowing around the end of the fence.
12. If the fence must cross contours, with the exception of the ends of
the fence, place gravel check dams perpendicular to the back of the
fence to minimize concentrated flow and erosion. The slope of the
fence line where contours must be crossed shall not be steeper than
3H:1 V.
Gravel check dams shall be approximately 1-foot deep at the
back of the fence. Gravel check dams shall be continued
perpendicular to the fence at the same elevation until the top of
the check dam intercepts the ground surface behind the fence.
Gravel check dams shall consist of crushed surfacing base
course, gravel backfill for walls, or shoulder ballast. Gravel
check dams shall be located every 10 feet along the fence
where the fence must cross contours.
• Refer to Figure 4.2.13 for slicing method details. Silt fence installation
using the slicing method specifications:
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-92
1. The base of both end posts must be at least 2- to 4-inches above the
top of the filter fabric on the middle posts for ditch checks to drain
properly. Use a hand level or string level, if necessary, to mark
base points before installation.
2. Install posts 3- to 4-feet apart in critical retention areas and 6- to 7-
feet apart in standard applications.
3. Install posts 24-inches deep on the downstream side of the silt
fence, and as close as possible to the filter fabric, enabling posts to
support the filter fabric from upstream water pressure.
4. Install posts with the nipples facing away from the filter fabric.
5. Attach the filter fabric to each post with three ties, all spaced
within the top 8-inches of the filter fabric. Attach each tie
diagonally 45 degrees through the filter fabric, with each puncture
at least 1-inch vertically apart. Each tie should be positioned to
hang on a post nipple when tightening to prevent sagging.
6. Wrap approximately 6-inches of fabric around the end posts and
secure with 3 ties.
7. No more than 24-inches of a 36-inch filter fabric is allowed above
ground level.
Compact the soil immediately next to the filter fabric with the front
wheel of the tractor, skid steer, or roller exerting at least 60 pounds
per square inch. Compact the upstream side first and then each side
twice for a total of four trips. Check and correct the silt fence
installation for any deviation before compaction. Use a flat -bladed
shovel to tuck fabric deeper into the ground if necessary.
Volume H— Construction Stormwater Pollution Prevention -December 2014
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Ponding height POST SPACING:
max. 24- 7' max. on open runs
4' max. on pooling areas
Attach fsbdc to Belt
upstream slde of post [Op e•
FLOW
Drive over each side of POST DEPTH.
silt fence 2 to 4 times As much below ground
with device exerting as fabric above ground
60 p.s.l. or greater
onal
100% compactlo?t 1W%compaction Diagubless engLh. t
doubles sYength.
/ ATTACHMENT DETAILS:
i�\ a Gather fabric at posts, if needed.
l% Z/%�/� // i �//\�//\\\ a ()tilize three esper post, all within top 8" of fabric.
3 \ \ \ \
mineach imum of 1Positione aPdiagonally, puncturing holes vertically
ai
e Hang each tie on a post nipple and tighten securely.
No more than 24" of a 36" fabric Use cable ties (50lbs) or soft wire.
is allowed above ground.
Roll of silt fence
Post
installed
after
compaction
Silt Fence
1
Gomm
1
Horizontal chisel point Slicing blade
(76 mm width) (1 S mm width)
Vibratory plow is not acceptable because of horizontal compaction
Figure 4.2.13 — Silt Fence Installation by Slicing Method
Maintenance • Repair any damage immediately.
Standards • Intercept and convey all evident concentrated flows uphill of the silt
fence to a sediment pond.
• Check the uphill side of the fence for signs of the fence clogging and
acting as a barrier to flow and then causing channelization of flows
parallel to the fence. If this occurs, replace the fence or remove the
trapped sediment.
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-94
BMP C240: Sediment Trap
Purpose A sediment trap is a small temporary ponding area with a gravel outlet
used to collect and store sediment from sites cleared and/or graded during
construction. Sediment traps, along with other perimeter controls, shall be
installed before any land disturbance takes place in the drainage area.
Conditions of Use Prior to leaving a construction site, stormwater runoff must pass through a
sediment pond or trap or other appropriate sediment removal best
management practice. Non -engineered sediment traps may be used on -site
prior to an engineered sediment trap or sediment pond to provide
additional sediment removal capacity.
It is intended for use on sites where the tributary drainage area is less than
3 acres, with no unusual drainage features, and a projected build -out time
of six months or less. The sediment trap is a temporary measure (with a
design life of approximately 6 months) and shall be maintained until the
site area is permanently protected against erosion by vegetation and/or
structures.
Sediment traps and ponds are only effective in removing sediment down
to about the medium silt size fraction. Runoff with sediment of finer
grades (fine silt and clay) will pass through untreated, emphasizing the
need to control erosion to the maximum extent first.
Whenever possible, sediment -laden water shall be discharged into on -site,
relatively level, vegetated areas (see BMP C234 — Vegetated Strip). This
is the only way to effectively remove fine particles from runoff unless
chemical treatment or filtration is used. This can be particularly useful
after initial treatment in a sediment trap or pond. The areas of release must
be evaluated on a site -by -site basis in order to determine appropriate
locations for and methods of releasing runoff. Vegetated wetlands shall
not be used for this purpose. Frequently, it may be possible to pump water
from the collection point at the downhill end of the site to an upslope
vegetated area. Pumping shall only augment the treatment system, not
replace it, because of the possibility of pump failure or runoff volume in
excess of pump capacity.
All projects that are constructing permanent facilities for runoff quantity
control should use the rough -graded or final -graded permanent facilities
for traps and ponds. This includes combined facilities and infiltration
facilities. When permanent facilities are used as temporary sedimentation
facilities, the surface area requirement of a sediment trap or pond must be
met. If the surface area requirements are larger than the surface area of the
permanent facility, then the trap or pond shall be enlarged to comply with
the surface area requirement. The permanent pond shall also be divided
into two cells as required for sediment ponds.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-102
Either a permanent control structure or the temporary control structure
(described in BMP C241, Temporary Sediment Pond) can be used. If a
permanent control structure is used, it may be advisable to partially restrict
the lower orifice with gravel to increase residence time while still allowing
dewatering of the pond. A shut-off valve may be added to the control
structure to allow complete retention of stormwater in emergency
situations. In this case, an emergency overflow weir must be added.
A skimmer may be used for the sediment trap outlet if approved by the
Local Permitting Authority.
Design and • See Figures 4.2.16 and 4.2.17 for details.
Installation . If permanent runoff control facilities are part of the project, they
Specifications
should be used for sediment retention.
To determine the sediment trap geometry, first calculate the design
surface area (SA) of the trap, measured at the invert of the weir. Use
the following equation:
SA = FS(Q2/Vs)
where
Q2 = Design inflow based on the peak discharge from the
developed 2-year runoff event from the contributing
drainage area as computed in the hydrologic analysis. The
10-year peak flow shall be used if the project size, expected
timing and duration of construction, or downstream
conditions warrant a higher level of protection. If no
hydrologic analysis is required, the Rational Method may
be used.
Vs = The settling velocity of the soil particle of interest. The
0.02 min (medium silt) particle with an assumed density of
2.65 g/cm3 has been selected as the particle of interest and
has a settling velocity (Vs) of 0.00096 ft/sec.
FS = A safety factor of 2 to account for non -ideal settling.
Therefore, the equation for computing surface area becomes:
SA = 2 x Q2/0.00096 or
2080 square feet per cfs of inflow
Note: Even if permanent facilities are used, they must still have a
surface area that is at least as large as that derived from the above
formula. If they do not, the pond must be enlarged.
• To aid in determining sediment depth, all sediment traps shall have a
staff gauge with a prominent mark 1-foot above the bottom of the trap.
Volume H— Construction Stormwater Pollution Prevention -December 2014
4-103
• Sediment traps may not be feasible on utility projects due to the
limited work space or the short-term nature of the work. Portable tanks
may be used in place of sediment traps for utility projects.
Maintenance • Sediment shall be removed from the trap when it reaches 1-foot in
Standards depth.
• Any damage to the pond embankments or slopes shall be repaired.
Surface area determined
at top of weir
L
1' Min.
IN
3.5'-5'
1 Flat Bottom
3/4 " - 1.5"
Washed gravel
Note: Trap may be formed by berm or by
partial or complete excavation
4' Min.
II'Min. Overflow
D 1
\ 2"-4" Rock RipRap
Geotextile
Discharge to stabilized
conveyance, outlet, or
level spreader
Figure 4.2.16 — Cross Section of Sediment Trap
I
Native soil or
compacted backfill
Geotextile
{� 6' Min.
1' Min. depth overflow spillway
Figure 4.2.17 — Sediment Trap Outlet
'Min. 1' depth
2"-4"' rock
Min. 1' depth 3/4"-1.5"
washed gravel
Volume II — Construction Stormwater Pollution Prevention - December 2014
4-104
APPENDIX C
Correspondence
(to be added as needed)
APPENDIX D
Site Inspection Form
Construction Stormwater Site Inspection Form
Project Name
Permit #
Inspection Date
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
Concrete pours
Offsite improvements
C. Questions:
Time
Clearing/Demo/Grading Infrastructure/storm/roads
Vertical Utilities
Construction/buildings
Site temporary stabilized Final stabilization
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
Page 1
Construction Stormwater Site Inspection Form
D. Check the observed status of all items. Provide "Action Required "details and dates.
Element #
Inspection
BMPs
BMP needs
BMP
Action
Inspected
maintenance
failed
required
(describe in
yes
no
n/a
section F)
1
Before beginning land disturbing
Clearing
activities are all clearing limits,
Limits
natural resource areas (streams,
wetlands, buffers, trees) protected
with barriers or similar BMPs? (high
visibility recommended)
2
Construction access is stabilized
Construction
with quarry spalls or equivalent
Access
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
Are flow control measures installed
Control Flow
to control stormwater volumes and
Rates
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
All perimeter sediment controls
Sediment
(e.g. silt fence, wattles, compost
Controls
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
Have exposed un-worked soils
Stabilize
been stabilized with effective BMP
Soils
to prevent erosion and sediment
deposition?
Page 2
Construction Stormwater Site Inspection Form
Element #
Inspection
BMPs
BMP needs
BMP
Action
Inspected
maintenance
failed
required
yes
no
n/a
(describe in
section F)
5
Are stockpiles stabilized from erosion,
Stabilize Soils
protected with sediment trapping
Cont.
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?
Has stormwater and ground water
6
been diverted away from slopes and
Protect
disturbed areas with interceptor dikes,
Slopes
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
Storm drain inlets made operable
Drain Inlets
during construction are protected.
Are existing storm drains within the
influence of the project protected?
8
Have all on -site conveyance channels
Stabilize
been designed, constructed and
Channel and
stabilized to prevent erosion from
Outlets
expected peak flows?
Is stabilization, including armoring
material, adequate to prevent erosion
of outlets, adjacent stream banks,
slopes and downstream conveyance
systems?
9
Are waste materials and demolition
Control
debris handled and disposed of to
Pollutants
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?
Page 3
Construction Stormwater Site Inspection Form
Element #
Inspection
BMPs
BMP needs
BMP
Action
Inspected
maintenance
failed
required
(describe in
yes
no
n/a
section F)
9
Wheel wash wastewater is handled
Cont.
and disposed of properly.
10
Concrete washout in designated areas.
Control
No washout or excess concrete on the
Dewatering
ground.
Dewatering has been done to an
approved source and in compliance
with the SWPPP.
Were there any clean non turbid
dewatering discharges?
11
Are all temporary and permanent
Maintain
erosion and sediment control BMPs
BMP
maintained to perform as intended?
12
Has the project been phased to the
Manage the
maximum degree practicable?
Project
Has regular inspection, monitoring and
maintenance been performed as
required by the permit?
Has the SWPPP been updated,
implemented and records maintained?
13
Is all Bioretention and Rain Garden
Protect LID
Facilities protected from
sedimentation with appropriate BMPs?
Is the Bioretention and Rain Garden
protected against over compaction of
construction equipment and foot
traffic to retain its infiltration
capabilities?
Permeable pavements are clean and
free of sediment and sediment laden -
water runoff. Muddy construction
equipment has not been on the base
material or pavement.
Have soiled permeable pavements
been cleaned of sediments and pass
infiltration test as required by
stormwater manual methodology?
Heavy equipment has been kept off
existing soils under LID facilities to
retain infiltration rate.
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 ❑
Page 4
Construction Stormwater Site Inspection Form
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 5
APPENDIX E
Construction Stormwater General Permit (CSWGP)
(to be added once it is obtained)
APPENDIX F
303(d) List Waterbodies / TMDL Waterbodies Information
(no 303d or TMDL waterbodies for this project)
APPENDIX G
Contaminated Site Information
(no known contaminants onsite)
APPENDIX H
Sediment Pond
Design Calculations
(Not Applicable)