Yelm Fields CSWPPP - 2200807 (2)
Civil Engineers ● Structural Engineers ● Landscape Architects ● Community Planners ● Land Surveyors
Construction Stormwater
Pollution Prevention Plan
PREPARED FOR:
Yelm Community Schools
107 1st Street N
Yelm, WA 98597
PROJECT:
Yelm School District Field Upgrades -
Ridgeline Middle School and Yelm High
School
909 Mill Road SE and 1315 Yelm Ave W
Yelm, WA 98597
2200807.10
PREPARED BY:
Charles Stout, PE
Project Engineer
REVIEWED BY:
Todd Sawin, PE, DBIA, LEED AP
Principal
DATE:
March 2021
Construction Stormwater
Pollution Prevention Plan
PREPARED FOR:
Yelm Community Schools
107 1st Street N
Yelm, WA 98597
PROJECT:
Yelm School District Field Upgrades -
Ridgeline Middle School and Yelm High
School
909 Mill Road SE and 1315 Yelm Ave W
Yelm, WA 98597
2200807.10
PREPARED BY:
Charles Stout, PE
Project Engineer
REVIEWED BY:
Todd Sawin, PE, DBIA, LEED AP
Principal
(253) 383-2422
tsawin@ahbl.com
DATE:
March 2021
I hereby state that this Construction
Stormwater Pollution Prevention Plan for
the Yelm School District Field Upgrades
project has been prepared by me or under
my supervision, and meets the standard
of care and expertise that is usual and
customary in this community for
professional engineers. I understand that
City of Yelm does not and will not assume
liability for the sufficiency, suitability, or
performance of drainage facilities
prepared by me.
Construction Stormwater Pollution Prevention Plan
Yelm Middle School
2200807.10
Table of Contents
Section Page
1.0 Introduction .................................................................................................................................... 1
2.0 Project Description ........................................................................................................................ 2
3.0 Existing Site Conditions ................................................................................................................ 2
4.0 Adjacent Areas and Drainage ....................................................................................................... 2
5.0 Critical Areas .................................................................................................................................. 3
6.0 Soils ................................................................................................................................................. 3
7.0 Potential Erosion Problems .............................................................. Error! Bookmark not defined.
8.0 Construction Stormwater Pollution Prevention Elements ......................................................... 3
8.1 Mark Clearing Limits ........................................................................................................... 3
8.2 Establish Construction Access ............................................................................................ 3
8.3 Control Flow Rates.............................................................................................................. 4
8.4 Install Sediment Controls .................................................................................................... 4
8.5 Stabilize Soils ...................................................................................................................... 4
8.6 Protect Slopes ..................................................................................................................... 4
8.7 Protect Drain Inlets.............................................................................................................. 5
8.8 Stabilize Channels and Outlets ........................................................................................... 5
8.9 Control Pollutants ................................................................................................................ 5
8.10 Control Dewatering ............................................................................................................. 7
8.11 Maintain BMPs .................................................................................................................... 7
8.12 Manage the Project ............................................................................................................. 9
8.13 Protect LID BMPs ................................................................................................................ 9
LID BMPs will be maintained and protected throughout the construction process. ........................ 9
9.0 Construction Sequence and Phasing .......................................................................................... 9
10.0 Construction Schedule ................................................................................................................ 10
11.0 Financial/Ownership Responsibilities ....................................................................................... 10
12.0 Engineering Calculations .................................................................. Error! Bookmark not defined.
13.0 Certified Erosion and Sediment Control Lead (CESCL) .......................................................... 10
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Exhibits
Exhibit 1
Vicinity Map
Exhibit 2
Erosion Control Plans (11X17)
Exhibit 3
Sediment Trap Calculations
Exhibit 4
Inspection Logs
Exhibit 5
Best Management Practices (BMPs)
BMP C101 ........ Preserving Natural Vegetation
BMP C102 ....... Buffer Zones
BMP C103 ........ High Visibility Plastic or Metal Fence
BMP C105 ........ Stabilized Construction Entrance
BMP C106 ........ Wheel Wash
BMP C107 ........ Construction Road / Parking Area Stabilization
BMP C120 ........ Temporary and Permanent Seeding
BMP C121 ........ Mulching
BMP C123 ........ Plastic Covering
BMP C125 ........ Topsoiling / Composting
BMP C140 ........ Dust Control
BMP C150 ........ Materials on Hand
BMP C151 ........ Concrete Handling
BMP C152 ........ Sawcutting and Surface Pollution Prevention
BMP C153 ........ Material Delivery, Containment & Storage
BMP C154 ........ Concrete Washout Area
BMP C160 ........ Certified Erosion and Sediment Control Lead
BMP C162 ........ Scheduling
BMP C200 ........ Interceptor Dike and Swale
BMP C201 ........ Grass-Lined Channels
BMP C207 ........ Check Dams
BMP C220 ........ Inlet Protection
BMP C233 ........ Silt Fence
BMP C240 ........ Sediment Trap
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1.0 Introduction
In 1972, Congress passed the Federal Water Pollution Control Act (FWPCA), also known as the
Clean Water Act (CWA), to restore and maintain the quality of the nation's waterways. The
ultimate goal was to make sure that rivers and streams were fishable, swimmable, and drinkable.
In 1987, the Water Quality Act (WQA) added provisions to the CWA that allowed the
Environmental Protection Agency to govern stormwater discharges from construction sites. The
National Pollutant Discharge Elimination System (NPDES) General Permit includes provisions for
development of a Stormwater Pollution Prevention Plan (SWPPP) to maximize the potential
benefits of pollution prevention and sediment and erosion control measures at construction sites.
Development, implementation, and maintenance of the Construction SWPPP (CSWPPP) will
provide the selected General Contractor with the framework for reducing soil erosion and
minimizing pollutants in stormwater during construction of the proposed improvements.
This CSWPPP will:
· Define the characteristics of the site and the type of construction that will occur.
· Describe the existing site conditions, including existing land use, soil types at the site, and
the location of surface waters that are located on or next to the site.
· Identify the body or bodies of water that will receive runoff from the construction site,
including the ultimate body of water that receives the stormwater.
· Identify the drainage areas and potential stormwater contaminants.
· Describe the stormwater management controls and various Best Management Practices
(BMPs) necessary to reduce erosion, sediment, and pollutants in stormwater discharge.
· Create an implementation schedule to ensure that the practices described in this CSWPPP
are in fact implemented, and to evaluate the plan's effectiveness in reducing erosion,
sediment, and pollutant levels in stormwater discharged from the site.
· Identify the Certified Erosion and Sedimentation Control Lead (CESCL) with a description
of this person's duties.
· Identify the Stormwater Pollution Prevention Team (SWPP Team) that will assist in
implementation of the CSWPPP during construction.
· Describe the facility monitoring plan and how controls will be coordinated with construction
activities.
· Describe the implementation schedule and provisions for amendment of the plan.
· Describe the final stabilization/termination design to minimize erosion and prevent
stormwater impacts after construction is complete.
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2.0 Project Description
The Yelm School District Field Upgrades project proposes maintenance improvements to both
the Ridgeline Middle School existing track and field and the Yelm High School existing baseball
and softball fields.
The Ridgeline Middle School (RMS) track and field maintenance improvements are located on
the west side of Tax Parcel 21725140100. Maintenance improvements include replacing the
existing underdrained grass field with an underdrained artificial turf field, replacing the existing
track with a new rubberized track over asphalt, new field event facilities within the track and field
area, hose connections to the onsite irrigation system, and minor grading improvements to the
concrete pedestrian areas on the east side of the track and field area. The site is located in a
portion of Section 25, Township 17 North, Range 01 East, in the City of Yelm, Thurston County,
Washington. The project parcel totals 29.99 acres and houses both Ridgeline Middle School and
Mill Pond Intermediate School; maintenance improvements are located in the northwest corner of
the site and will cover approximately 3.35 acres.
The Yelm High School (YHS) baseball and softball field maintenance improvements are located
near the southwest corner of Tax Parcel 21724210500. Maintenance improvements include
replacing the existing underdrained grass fields and associated batting cages and bullpen areas
with underdrained artificial turf fields. The site is located in a portion of Section 24, Township 27
North, Range 01 East, in the City of Yelm, Thurston County, Washington. The project parcel
totals 36.60 acres and houses Yelm High School; maintenance improvements are located near
the southwest corner of the site and will cover approximately 4.02 acres.
Stormwater management is to comply with the July 2019 Amended Edition of the Department of
Ecology (DOE) Stormwater Management Manual for Western Washington (SMMWW), as
adopted by the City of Yelm.
General drainage patterns of the sites will be maintained during the construction activities. The
sites will remain relatively flat, and temporary erosion control facilities will be constructed to
prevent sediment-laden runoff from leaving the site boundaries or the existing RMS onsite
infiltration pond.
3.0 Existing Site Conditions
The RMS site consists of an underdrained natural grass field with a gravel track and bleacher and
pedestrian access areas on the east side of the improvements. The existing track and field
discharge to the existing underdrain system and the surrounding areas discharge to existing
catch basins located outside of the track and field area; all stormwater generated in the
immediate vicinity of the project site discharges to the existing infiltration trench located north of
the proposed track and field maintenance improvements for onsite infiltration.
The YHS site consists of an underdrained baseball field and an underdrained softball field with
associated batting cages and bullpen areas. The existing ball fields discharge to the existing
underdrain systems and discharges runoff on the west side of the property where it disperses
through the neighboring property and eventually disperses into Thompsons Creek.
4.0 Adjacent Areas and Drainage
The proposed RMS track and field maintenance improvements are part of a larger existing onsite
drainage basin that discharges to the existing infiltration trench located north of the proposed
track and field maintenance improvements. The existing concrete bleacher pads, stairs,
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pedestrian ramps, and level landings on the east side of the track and field area discharge onto
the project site. Landscape and vegetated areas surrounding the track and field area discharge to
existing catch basins that surround the track and field area and do not discharge runoff onto the
project site.
The proposed YHS baseball and softball field maintenance improvements are part of their own
subbasin with little flows from the surrounding portions of the YHS site discharging into the ball
field area.
5.0 Critical Areas
The project sites are both located within an extreme aquifer recharge area.
6.0 Soils
Landau Associates, Inc. prepared a Summary of Geotechnical Engineering Services, dated
February 5, 2021, which is included as an attachment to the Stormwater Requirements Memo
prepared for both RMS and YHS.
The Ridgeline Middle School portion of the investigation, test pits 1-4, found that subsurface
conditions mainly consist of glacial outwash consisting of gravel with variable sand, silt, and
cobble content in a medium dense to very dense, moist to wet condition. Groundwater was
observed at depth ranging from 6.9 to 7.9 feet below existing ground surface at this site.
The Yelm High School portion of the investigation, test pits 5-9, found that the subsurface
conditions mainly consist of fill, consisting of gravel with variable silt, sand, and cobble content or
of sand with silt and gravel, over glacial outwash similar to the glacial outwash soils found at the
RMS site. This fill soil was found at a medium dense to dense, moist condition and extended 1.1
to 5.3 feet below existing ground surface. No true groundwater table was observed at this site.
7.0 Construction Stormwater Pollution Prevention Elements
The purpose of this section is to describe how each of the 13 Construction Stormwater Pollution
Prevention Elements has been addressed and to identify the type and location of BMPs used to
satisfy the required element. If an element is not applicable to the project, a reason is provided.
7.1 Mark Clearing Limits
Prior to beginning land-disturbing activities, clearing limits will be marked with high visibility fence
(BMP C103: High Visibility Fence). The only vegetation located within the construction limits is
grass, no trees or shrubs will be disturbed as part of the proposed maintenance improvements.
7.2 Establish Construction Access
Both the RMS and YHS sites have existing stabilized access roads that will be protected as part
of the proposed maintenance improvements. These stabilized access roads will be utilized as
stabilized construction entrances for these two sites. If sediment is transported onto the Ridgeline
Middle School or Yelm High School onsite parking or site access areas, or offsite road surfaces,
the road shall be cleaned each day by shoveling or sweeping prior to washing. If sediment is
tracked from the site, the City may require stabilization of internal roads and car parking areas to
contain the sediment or require the installation of a wheel wash basin.
Dump trucks hauling material to and from the site will be covered by a tarp.
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7.3 Control Flow Rates
Proposed field improvements at both the RMS and YHS site have limited earthwork activities and
final stabilization of the exposed soils will occur quickly. Proposed improvements are scheduled
to occur during the dry season and will be completed prior to the wet season. Disturbed areas not
ready for final stabilization will be hydroseeded.
7.4 Install Sediment Controls
Structural control measures will be used to reduce erosion and retain sediment on the
construction site. The control measures are selected to fit specific site and seasonal conditions.
The temporary erosion and sediment control (TESC) plans include the following structural
measures:
1. Stabilized construction entrance to prevent transport of sediment onto existing asphalt
pavement.
2. Filter fabric fencing around portions of the perimeter of the site to prevent sediment-laden
stormwater from being transported offsite.
3. Catch basin inlet protection to prevent sedimentation of stormwater conveyance systems.
7.5 Stabilize Soils
Since source control is the most important form of erosion control, construction practices must
adhere to stringent cover requirements.
More specifically, during the period of May 1 through September 30, the Contractor will not be
allowed to leave soils unprotected for more than 15 days, and immediate seeding will be required
for areas brought to finish grade with no further work planned for the next 30 days. Areas to be
paved may be armored with crushed rock subbase in place of other stabilizing measures. The
area of clearing will be limited to the amount that can be stabilized by September 30 of that year.
During the period of October 1 through April 30, all disturbed soil areas will be covered or
stabilized within 5 days or 24 hours when a major storm event is predicted. Cover measures may
include mulching, netting, plastic sheeting, erosion control blankets, or free draining material.
The extent of clearing shall be limited to the amount of land that can be covered or stabilized
within 24 hours. No construction activities are expected to occur during this time period.
Soil stockpiles shall be stabilized by plastic covering (BMP 123) or surrounded by filter fabric
fence. The stockpiles shall be a minimum of 50 feet from critical areas, including wetland buffers
and drainage swales.
Dust control (BMP C140) will be provided by sprinkling the site with water.
Permanent erosion control measures will include site paving and seeding of exposed soils.
7.6 Protect Slopes
Slopes on the site will be protected to minimize erosion. Temporary and permanent seeding and
plastic sheeting will be used to reduce erosion of exposed soils on slopes. Runoff shall be
directed away from slopes by grading.
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7.7 Protect Drain Inlets
Storm drain inlets within construction limits shall be protected so surface water runoff does not
enter the conveyance system without first being filtered. Inlets shall be inspected weekly, at a
minimum, and daily during storm events. Storm Drain Inlet Protection (BMP C220) will be
provided.
7.8 Stabilize Channels and Outlets
No temporary construction outlets are proposed onsite. Interceptor swales (BMP C200), may be
used to convey construction runoff to outfall locations if found necessary onsite. These interceptor
swales must be hydroseeded with gravel check dams (BMP C207) located along the length of
these swales to control runoff velocity.
7.9 Control Pollutants
The Contractor shall be responsible for controlling pollutants at the work site. Key elements, such
as centralized areas for equipment and concrete truck washing and temporary storage of debris
and other stockpiled materials, are the responsibility of the Contractor.
All pollutants, including waste materials and demolition debris, that occur onsite shall be handled
and disposed of in a manner that does not cause contamination of stormwater. Woody debris
may be chopped and spread onsite.
Cover, containment, and protection from vandalism shall be provided for all chemicals, liquid
products, petroleum products, and non-inert wastes present on the site (see Chapter 173-304
WAC for the definition of inert waste). Onsite fueling tanks shall include secondary containment.
Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system
drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and
other activities which may result in discharge or spillage of pollutants to the ground or into
stormwater runoff must be conducted using spill prevention measures, such as drip pans.
Contaminated surfaces shall be cleaned immediately following any discharge or spill incident.
Emergency repairs may be performed onsite using temporary plastic placed beneath and, if
raining, over the vehicle.
Wheel wash or tire bath wastewater shall be discharged to a separate onsite treatment system or
to the sanitary sewer.
Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a
manner and at application rates that will not result in loss of chemical to stormwater runoff.
Manufacturers’ recommendations for application rates and procedures shall be followed.
BMPs shall be used to prevent or treat contamination of stormwater runoff by pH modifying
sources. These sources include, but are not limited to, bulk cement, cement kiln dust, fly ash,
new concrete washing and curing waters, waste streams generated from concrete grinding and
sawing, exposed aggregate processes, and concrete pumping and mixer washout waters.
Stormwater discharges shall not cause or contribute to a violation of the water quality standard for
pH in the receiving water.
Construction sites with significant concrete work shall adjust the pH of stormwater if necessary to
prevent violations of water quality standards.
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Table 1 below lists several pollutants that are commonly found on construction sites that have the
potential to contaminate storm runoff. These pollutants will be present, mainly in areas of building
and pavement construction. The Contractor and the CESCL will be responsible for identifying
areas where these pollutants are being used and monitor runoff coming from these areas.
Pollutant sources will be covered with plastic if contaminated runoff is observed from these areas.
If contaminated runoff is found in the sediment trap or soils, the CESCL will direct the Contractor
to remove the polluted water/soil and dispose of it in an approved area offsite.
Table 1 – Potential Construction Site Stormwater Pollutants
Trade Name Material Chemical/Physical
Description(1)
Stormwater Pollutants(1)
Pesticides (insecticides,
fungicides, herbicide,
rodenticides)
Various colored to colorless
liquid, powder, pellets, or
grains
Chlorinated hydrocarbons,
organophosphates, carbamates,
arsenic
Fertilizer Liquid or solid grains Nitrogen, phosphorous
Plaster White granules or powder Calcium sulphate, calcium
carbonate, sulfuric acid
Cleaning solvents Colorless, blue, or yellow-
green liquid
Perchloroethylene, methylene
chloride, trichloroethylene,
petroleum distillates
Asphalt Black solid Oil, petroleum distillates
Concrete White solid Limestone, sand
Glue, adhesives White or yellow liquid Polymers, epoxies
Paints Various colored liquid Metal oxides, Stoddard solvent, talc,
calcium carbonate, arsenic
Curing compounds Creamy white liquid Naphtha
Wastewater from construction
equipment washing
Water Soil, oil & grease, solids
Wood preservatives Clear amber or dark brown
liquid
Stoddard solvent, petroleum
distillates, arsenic, copper,
chromium
Hydraulic oil/fluids Brown oily petroleum
hydrocarbon
Mineral oil
Gasoline Colorless, pale brown or pink
petroleum hydrocarbon
Benzene, ethyl benzene, toluene,
xylene, MTBE
Diesel fuel Clear, blue-green to yellow
liquid
Petroleum distillate, oil & grease,
naphthalene, xylenes
Kerosene Pale yellow liquid petroleum
hydrocarbon
Coal oil, petroleum distillates
Antifreeze/coolant Clear green/yellow liquid Ethylene glycol, propylene glycol,
heavy metals (copper, lead, zinc)
Erosion Solid Particles Soil, Sediment
(1) Data obtained from MSDS when available
7.9.1 Required BMPs
The following BMPs or equivalent measures are required of all businesses and agencies during
concrete pouring and asphalt application at temporary sites:
· Employees must be educated on the pollution hazards of concrete and asphalt application
and cutting.
· Loose aggregate chunks and dust must be swept or shoveled and collected (not hosed
down a storm drain) for recycling or proper disposal at the end of each work day, especially
at work sites such as streets, driveways, parking lots, sidewalks, curbs, and gutters where
rain can readily pick up the loose material and carry it to the nearest stormwater
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conveyance. Small amounts of excess concrete, grout, and mortar can be disposed of in
the trash.
· Storm drain covers or similarly effective containment devices must be placed over all
nearby drains at the beginning of each day. Shovel or vacuum slurry and remove from the
site. All accumulated runoff and solids must be collected and properly disposed at the end
of each workday, or more often if necessary.
· If directed to a drain, a catch basin filter insert must be used to remove the solids. This is
especially useful if the activity must proceed on rainy days.
· Cleaning of concrete application and mixing equipment or concrete vehicles on the work
site must be done in a designated area where the rinse water is controlled. The rinse water
must either be collected for proper disposal or put into a hole in the ground where the water
can percolate away and the solids later covered with soil or recovered and disposed or
recycled.
The use of any treatment BMP must not result in the violation of groundwater, surface water, or
drinking water quality standards.
7.10 Control Dewatering
Dewatering is not expected to be required during construction of the proposed RMS and YHS
maintenance improvements because construction is scheduled for the summer months. If
dewatering is required during construction, dewatering discharge shall be directed to a sediment
trap for onsite infiltration.
7.11 Maintain BMPs
In order for the ESC facilities to function properly, they must be maintained and sediment
removed on a regular basis. Inspection and sediment removal shall be performed on all ESC
facilities, as described in the following inspection schedule.
Erosion control facilities shall not be allowed to fall into disrepair. All ESC facilities shall be
inspected, at a minimum, according to the following schedule.
· Dry Season: Once a week.
· Wet Season: Daily and after every storm event that produces runoff.
Needed repairs shall be made within 24 hours or immediately, if possible.
The following inspection/maintenance schedules shall be utilized to ensure the ESC facilities are
functioning as designed:
Construction Entrance
· The construction entrance shall be inspected once a week during the dry season and after
every rainfall event during the wet season. If the entrance is not preventing sediment from
being tracked onto adjacent pavement, then alternate measures to keep the pavement free
of sediment shall be used. This may include street sweeping, an increase in the dimension
of the entrance, or the installation of a wheel wash.
· If vehicles are entering or exiting the site at points other than the approved entrance,
temporary fencing shall be installed to control traffic.
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Temporary and Permanent Seeding
· Seeding may be used throughout the project on disturbed areas. During the dry season,
areas that have reached final grade, or are not being actively worked, shall be seeding
within 15 days. Seeded areas shall be supplied with adequate moisture, but not watered to
the extent that it causes runoff.
· During the wet season, all disturbed areas not being actively worked shall be seeded or
stabilized with mulch or plastic sheeting.
· During the wet season, no more area shall be exposed than can be controlled and
effectively stabilized by the end of each working day.
· To prevent seed from being washed away, confirm that all other approved
erosion/sedimentation control facilities have been installed and are functioning properly.
· Any seeded areas that fail to establish 80 percent cover (100 percent cover for areas that
receive sheet or concentrated flows) shall be reseeded. If reseeding is ineffective, an
alternate method shall be used.
· Seeded areas shall be inspected after every rainfall event during the wet season. Any
areas that experience erosion shall be reseeded and protected by mulch. If the erosion
problem is drainage related, the problem shall be fixed and the eroded area reseeded and
protected by mulch.
· Seeding shall not be used in areas subject to heavy vehicular traffic.
Mulching
· Mulching shall be inspected once a week during the dry season and after every rainfall
event during the wet season.
· Mulch shall be inspected to verify that the proper thickness is being maintained if
applicable.
· Any areas that experience erosion shall be re-mulched and/or protected with a net or
blanket. If the erosion problem is drainage related, the problem shall be fixed and the
eroded area re-mulched.
Plastic Covering
· Plastic sheeting shall be inspected once a week during both the wet and dry season.
· Torn sheets must be replaced and open seams repaired.
· If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely
removed and replaced.
· When the plastic is no longer needed, it shall be completely removed.
· If tires are used to weight down the plastic sheeting, they must be disposed of properly.
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Silt Fence
· Any damage shall be repaired immediately.
· Check the uphill side of the fence for signs of the fence clogging and acting as a barrier to
flow and causing channelization of flows parallel to the fence. If this occurs, replace the
fence or remove the trapped sediment.
· Sediment deposits shall be removed when the deposit reaches approximately one-third the
height of the silt fence, or a second silt fence shall be installed.
· If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be
replaced.
The maintenance inspection report will be made after each inspection. Copies of the report forms
to be completed by the CESCL are attached as Exhibit 4 of this CSWPPP. Completed forms will
be provided to the City Inspector and will also be maintained onsite during the entire construction
project. If construction activities or design modifications are made to the site plan that could
impact stormwater, or if AHBL or the City determines that the measures are not adequate to
prevent erosion and the discharge of sediment from the site (based on turbidity measurements),
this CSWPPP will be amended appropriately. The amended CSWPPP will have a description of
the new activities that contribute to the increased pollutant loading and the planned source control
activities.
7.12 Manage the Project
The following practices will be required during construction to properly manage activities:
· Comply with seasonal work limitations.
· Inspect, maintain, and repair BMPs.
· Identify a Certified Erosion and Sediment Control Lead (CESCL).
· Maintain the CSWPPP onsite at all times, including narrative and plans.
7.13 Protect LID BMPs
LID BMPs will be maintained and protected throughout the construction process.
· All areas proposed to be used for infiltration will be protected from sedimentation using
BMPs such as silt fencing.
· Compaction will be prevented in infiltration areas by excluding construction activities from
these areas as much as possible. Heavy equipment will not be allowed in these areas.
8.0 Construction Sequence and Phasing
Project improvements are proposed in a single phase at each site.
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9.0 Construction Schedule
Construction is planned to begin during the summer of 2021 and be completed during the
summer of 2021.
10.0 Financial/Ownership Responsibilities
Yelm Community Schools is the party responsible for initiation of bonds and other financial
securities. The project must comply with City of Yelm financial liability requirements.
11.0 Certified Erosion and Sediment Control Lead (CESCL)
The General Contractor shall be required to provide a CESCL prior to construction. Once this
individual is identified, the City Inspector will be notified.
The contractor will designate their CESCL here:
Name: _____________________________________________
Address: _____________________________________________
Phone: _____________________________________________
Fax Number: _____________________________________________
The CESCL is required to meet DOE certification requirements. The City Inspector will be
provided with CESCL information.
The duties of the CESCL include:
· Implement the CSWPPP/TESC plan with the aid of the SWPP Team.
· Oversee maintenance practices identified as BMPs in the CSWPPP.
· Conduct or provide for inspection and monitoring activities.
· Sample stormwater for turbidity using a turbidity meter.
· Identify other potential pollutant sources and make sure they are added to the plan.
· Identify any deficiencies in the CSWPPP and make sure they are corrected.
· Ensure that any changes in construction plans are addressed in the CSWPPP.
To aid in the implementation of the CSWPPP, the members of the SWPP Team include the
following: General Contractor, City of Yelm Inspector, Owner, the geotechnical engineering
consultant, and AHBL.
The General Contractor will ensure that all housekeeping and monitoring procedures are
implemented, while the CESCL will ensure the integrity of the structural BMPs. The SWPP Team
will observe construction and erosion control practices and recommend revisions or additions to
the CSWPPP and drawings.
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This analysis is based on data and records either supplied to or obtained by AHBL, Inc. These
documents are referenced within the text of the analysis. The analysis has been prepared utilizing
procedures and practices within the standard accepted practices of the industry.
AHBL, Inc.
Charles Stout, PE
Project Engineer
CHS/lsk
March 2021
Q:\2020\2200807\10_CIV\NON_CAD\REPORTS\20210319 RPT (SWPPP) 2200807.10.docx
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Exhibit 1
Vicinity Maps
2215 North 30th Street,
Suite 300,
Tacoma, WA 98403
253.383.2422 TEL
253.383.2572 FAX
JOB NO:
DATE:
YELM SCHOOL DISTRICT FIELD UPGRADES
RIDGELINE MIDDLE SCHOOL
VICINITY MAP
1
3/19/2021
2200807.10
N
VICINITY MAP
SCALE: 1" = 1/4 MILE (1,320')
SITE
2215 North 30th Street,
Suite 300,
Tacoma, WA 98403
253.383.2422 TEL
253.383.2572 FAX
JOB NO:
DATE:
YELM SCHOOL DISTRICT FIELD UPGRADES
YELM HIGH SCHOOL
VICINITY MAP
1
3/19/2021
2200807.10
N
VICINITY MAP
SCALE: 1" = 1/4 MILE (1,320')
W
Y
E
L
M
A
V
E
SOLBERG ST NW
LONGMIRE ST NW
CULLENS RD SESITE
Construction Stormwater Pollution Prevention Plan
Yelm Middle School
2200807.10
Exhibit 2
Erosion Control Plans (11X17)
356356IP
IP
IP
IP
IP
IP
IP
IP
CL
CL
CL
CL
SF
SF
SF
REMOVE EXISTING
SAND BOX
REMOVE EXISTING
SAND BOX
REMOVE EXISTING RUBBER TRACK
REMOVE EXISTING TRACK SURFACING
REMOVE
EXISTING
GOAL POST
REMOVE EXISTING GOAL POST
REMOVE EXISTING
SHOT-PUT PAD AND
THROWING AREA
REMOVE EXISTING
DISCUS PAD,
POSTS, AND CAGE
HYDROSEED ALL
DISTURBED AREAS
REMOVE ALL EXISTING
UTILITIES WITHIN FIELD AREA
PROTECT EXISTING TRACK CURBING
PROTECT EXISTING TRACK CURBING
PROTECT EXISTING UTILITY
REMOVE EXISTING CONCRETE SIDEWALK.
PROTECT EXISTING STAIRS.
REMOVE EXISTING CONCRETE SIDEWALK.
PROTECT EXISTING STAIRS.
REMOVE EXISTING CURB
PROTECT EXISTING CURB
REMOVE EXISTING CURB
77.3'
28.9'
17.5'
REMOVE EXISTING CURB
PROTECT EXISTING IRRIGATION
PROTECT EXISTING
IRRIGATION
EXISTING GRAVEL ACCESS ROAD SHALL
BE PROTECTED AND UTILIZED AS
STABILIZED CONSTRUCTION ENTRANCE
CLEARING LIMITS
TESC LEGEND
FILTER FABRIC FENCE
CL
FF
REMOVE EXISTING UTILITY
IP INLET PROTECTION
2215 North 30th Street, Suite 300, Tacoma, WA 98403
253.383.2422TEL www.ahbl.comWEB
TACOMA SEATTLE SPOKANE TRI-CITIES
Know what's below.
before you dig.Call
R
253.383.2572 FAX
YELM SCHOOL DISTRICT
FIELD UPGRADES
RIDGELINE MIDDLE
SCHOOL
YELM SCHOOL
DISTRICT #2
404 E YELM AVE
YELM, WA 98597
CHRIS HANSEN
2200807.10
03/18/2021
PERMIT SET
CHS SBK TCS
8
YELM SCHOOL DISTRICT FIELD UPGRADES- RIDGELINE MIDDLE SCHOOL
A PORTION OF THE SW 1/4 OF THE NE 1/4 OF SEC. 25, TWN. 17N., RGE. 01 E. W.M.
CITY OF YELM, THURSTON COUNTY, WASHINGTON
GRAPHIC SCALE
0 30 60
1" = 30 FEET
15
N
DATE: March 19, 2021 FILENAME: Q:\2020\2200807\10_CIV\CAD\RMS\2200807-SH-TESC.dwg
C1.00
TESC AND
DEMOLITION PLAN
2
PER BMP C120 (TEMPORARY AND PERMANENT SEEDING) OF THE 2012 WASHINGTON STATE DEPARTMENT OF ECOLOGY DOE
STORMWATER MANAGEMENT MANUAL FOR WESTERN WASHINGTON:
1.BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR
DIKES, SWALES, LEVEL SPREADERS AND SEDIMENTATION BASINS.
2.THE SEEDBED SHALL BE FIRM WITH A FAIRLY FINE SURFACE, FOLLOWING SURFACE ROUGHENING.
3.TEMPORARY SEEDING SHALL BE THE FOLLOWING MIXTURE APPLIED VIA BROADCAST APPLICATION:
40% CHEWINGS FESCUE (FESTUCA RUBRA VAR. COMMUTATA OR POD ANNA)
50% PERENNIAL RYE (LOLIUM PERENNE)
10% REDTOP OR COLONIAL BENTGRASS (AGROSTIS ALBA OR AGROSTIS TENUIS)
SEED MIX SHALL NOT CONTAIN CLOVER (TRIFOLIUM REPENS)
REFER TO LANDSCAPE PLANS FOR PERMANENT SEED MIX. ALTERNATIVE SEED MIXES APPROVED BY THE ENGINEER MAY BE
USED.
4.TEMPORARY SEED INSTALLED BY HAND SHALL BE:
a.COVERED BY STRAW, MULCH, OR TOPSOIL
b.APPLIED AT A RATE OF 120 POUNDS PER ACRE, WHICH CAN BE REDUCED IF SOIL AMENDMENTS OR SLOW-RELEASE
FERTILIZERS ARE USED.
5.THE OPTIMUM SEEDING WINDOWS FOR WESTERN WASHINGTON ARE APRIL 1 THROUGH JUNE 30 AND SEPTEMBER 1 THROUGH
OCTOBER 1.
6.SEED BEDS PLANTED BETWEEN BETWEEN JULY 1 AND AUGUST 30 WILL REQUIRE IRRIGATION UNTIL 75 PERCENT GRASS COVER
IS ESTABLISHED. OTHER MAINTENANCE WILL BE REQUIRED AS NECESSARY TO FOSTER AND PROTECT THE ROOT STRUCTURE.
7.SEED BEDS PLANTED BETWEEN OCTOBER 1 AND MARCH 30 WILL REQUIRE A COVER OF MULCH WITH STRAW OR AN EROSION
CONTROL BLANKET UNTIL 75 PERCENT GRASS COVER IS ESTABLISHED. ARMORING OF THE SEED BED WILL BE NECESSARY TO
FOSTER AND PROTECT THE ROOT STRUCTURE. (E.G., GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING).
9.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.
10.FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS RECOMMENDATIONS. AMOUNTS USED SHOULD BE MINIMIZED,
ESPECIALLY ADJACENT TO WATER BODIES AND WETLANDS.
TEMPORARY SEEDING NOTES FOR EROSION CONTROL
1.PLASTIC SHEETING SHALL HAVE A MINIMUM THICKNESS OF 6
MILS AND SHALL MEET THE REQUIREMENTS OF THE WSDOT
STANDARD SPECIFICATIONS SECTION 9-14.5.
2.COVERING SHALL BE INSTALLED AND MAINTAINED TIGHTLY IN
PLACE BY USING SANDBAGS OR TIRES ON ROPES WITH A
MAXIMUM 10-FOOT GRID SPACING IN ALL DIRECTIONS. ALL
SEAMS SHALL BE TAPED OR WEIGHTED DOWN FULL LENGTH
AND THERE SHALL BE AT LEAST A 12 INCH OVERLAP OF ALL
SEAMS.
3.CLEAR PLASTIC COVERING SHALL BE INSTALLED IMMEDIATELY
ON AREAS SEEDED BETWEEN NOVEMBER 1 AND MARCH 31
AND REMAIN UNTIL VEGETATION IS FIRMLY ESTABLISHED.
4.WHEN THE COVERING IS USED ON UN-SEEDED SLOPES, IT
SHALL BE KEPT IN PLACE UNTIL THE NEXT SEEDING PERIOD.
5.PLASTIC COVERING SHEETS SHALL BE BURIED TWO FEET AT
THE TOP OF SLOPES IN ORDER TO PREVENT SURFACE WATER
FLOW BENEATH SHEETS.
6.PROPER MAINTENANCE INCLUDES REGULAR CHECKS FOR
RIPS AND DISLODGED ENDS.
PLASTIC COVERING NOTES:
3
C1.01
2
C1.01
2215 North 30th Street, Suite 300, Tacoma, WA 98403
253.383.2422TEL www.ahbl.comWEB
TACOMA SEATTLE SPOKANE TRI-CITIES
Know what's below.
before you dig.Call
R
253.383.2572 FAX
YELM SCHOOL DISTRICT
FIELD UPGRADES
RIDGELINE MIDDLE
SCHOOL
YELM SCHOOL
DISTRICT #2
404 E YELM AVE
YELM, WA 98597
CHRIS HANSEN
2200807.10
03/18/2021
PERMIT SET
CHS SBK TCS
8
YELM SCHOOL DISTRICT FIELD UPGRADES- RIDGELINE MIDDLE SCHOOL
A PORTION OF THE SW 1/4 OF THE NE 1/4 OF SEC. 25, TWN. 17N., RGE. 01 E. W.M.
CITY OF YELM, THURSTON COUNTY, WASHINGTON
C1.01
TESC AND
DEMOLITION NOTES
AND DETAILS
3
1.CONTRACTOR IS RESPONSIBLE FOR ENSURING THAT ALL UTILITIES HAVE BEEN
DISCONNECTED PRIOR TO COMMENCING DEMOLITION.
2.DEMOLITION: IT IS THE INTENT OF THE WORK UNDER THIS CONTRACT TO
INCLUDE THE DEMOLITION OF ALL EXISTING BUILDINGS, PAVING, UTILITIES
AND OTHER EXISTING SITE IMPROVEMENTS INCLUDING THEIR UNDERGROUND
COMPONENTS AS INDICATED BY THIS DRAWING AND AS REQUIRED FOR NEW
CONSTRUCTION. IT IS THE CONTRACTOR'S RESPONSIBILITY TO FULLY REVIEW
THE SITE CONDITIONS AND TO CORRELATE THESE OBSERVATIONS WITH THE
PROJECT WORK AND INCLUDE ALL NECESSARY DEMOLITION, WHETHER
SHOWN OR NOT, AND INCLUDE ALL SUCH COSTS IN THE BASE BID.
3.CLEARING: IT IS THE INTENT OF THE WORK UNDER THIS CONTRACT TO
CONDUCT ALL CLEARING NECESSARY TO BE ABLE TO COMPLETE ALL THE
WORK OF THIS PROJECT.
4.CONTRACTOR SHALL LEGALLY DISPOSE OF THE OWNER'S PROPERTY, ALL
DEMOLISHED AND REMOVED MATERIALS, UNLESS INDICATED OTHERWISE.
5.IT IS THE RESPONSIBILITY OF THE CONTRACTOR TO COMPLETELY
COORDINATE UTILITY DEMOLITION WITH NEW CONSTRUCTION. CONTRACTOR
SHALL ENSURE THAT ADEQUATE FIRE PROTECTION IN ACCORDANCE WITH
THE FIRE MARSHALL REQUIREMENTS IS PROVIDED FOR THE NEW BUILDING.
6.COORDINATE POWER DEMOLITION WITH THE CITY OF YELM AND ELECTRICAL
PLANS. CONTRACTOR TO ENSURE THAT DEMOLITION OF LINES WILL NOT
COMPROMISE POWER TO OTHER AREAS.
7.POWER AND CABLE SERVING BUILDINGS AND LIGHT POLES TO REMAIN RUN
THROUGH THIS SITE. CONTRACTOR SHALL INSTALL NEW SERVICES TO
BUILDINGS AND LIGHT POLES REMAINING PRIOR TO DEMOLISHING EXISTING
LINES.
8.GAS DISCONNECTION BY P.S.E. CONTRACTOR TO COORDINATE WORK WITH
PSE. CONTRACTOR TO DEMOLISH ABANDONED SERVICE. CONTRACTOR TO
ENSURE THAT DEMOLITION OF GAS LINES WILL NOT IMPACT GAS SERVICE TO
OTHER AREAS. NO DISRUPTION IN SERVICE ALLOWED.
9.ANY ABANDONED SIDE SEWER(S) SHALL BE PLUGGED OR CAPPED AT THE
RIGHT-OF-WAY OR PROPERTY LINE.
10.CONTRACTOR SHALL MINIMIZE DUST GENERATION ONSITE BY SPRINKLING THE
SITE WITH WATER UNTIL SURFACE IS WET. SEE BMP C140.
11.SAWCUT CONCRETE SIDEWALK AT THE NEAREST JOINT.
12.REMOVAL OF THE EXISTING UNDERGROUND OIL TANK AND ASSOCIATED
APPURTENANCES REQUIRES AN UNDERGROUND STORAGE TANK (UST)
REMOVAL PERMIT FROM THURSTON COUNTY HEALTH DEPARTMENT.
13.REFER TO LANDSCAPE ARCHITECTURE DRAWINGS FOR INVASIVE SPECIES
REMOVAL REQUIREMENTS AND TREE PROTECTION REQUIREMENTS.
14.REFER TO HAZARDOUS MATERIAL DRAWING H1.10 FOR LEAD AND ARSENIC
SOIL MIXING REQUIREMENTS.
15.THE CLEARING LIMITS DEPICTED ON THESE PLANS REPRESENT THE EDGE OF
CIVIL-RELATED WORK SUCH AS GRADING, UTILITY, STORM DRAINAGE, AND
PAVING IMPROVEMENTS. WORK SUCH AS ARSENIC AND LEAD SOIL
REMEDIATION AND ASSOCIATED STABILIZATION AND INVASIVE SPECIES
REMOVAL MAY OCCUR BEYOND THE CLEARING LIMITS. REFER TO THE
HAZARDOUS MATERIAL DRAWINGS AND LANDSCAPE ARCHITECTURE
DRAWINGS FOR ADDITIONAL INFORMATION.
16.ALL MONUMENTS DISTURBED AS A RESULT OF CONSTRUCTION ACTIVITIES
SHALL BE REPLACED PER WAC 332-120 AT NOT ADDITIONAL COST TO THE
OWNER. CONTRACTOR SHALL APPLY FOR PERMIT FROM THE DEPARTMENT OF
NATURAL RESOURCES AS NECESSARY.
DEMOLITION NOTES
8' MAX.
1
1
PROVIDE SAND BAGS 10'
O.C. TO HOLD PLASTIC
COVERING IN PLACE
STOCKPILE
AREA
EXISTING
GRADE
1
1
NOTES:
1.STOCKPILES SHALL BE STABILIZED WITH PLASTIC COVERING OR OTHER APPROVED
DEVICE.
2.SEDIMENT LEACHING FROM STOCKPILES SHALL BE PREVENTED DURING ALL
SEASONS.
1 NOT TO SCALE
STOCKPILE
48"36"
GEOTEXTILE
FABRIC
OVERFLOW
(TO BYPASS
PEAK STORM
VOLUMES)
24"
EXISTING
CATCH BASIN
SEDIMENT ACCUMULATION
NOTES:
1.FILTERS SHALL BE i NSPECTED AFTER EACH STORM EVENT AND
CLEANED OR REPLACED WHEN 1/3 FULL.
2.INSTALL INLET PROTECTION IN ALL NEW STORM STRUCTURES
THAT WILL COLLECT STORMWATER AS THEY ARE INSTALLED.
ADAPTOR SKIRT RETRIEVAL STRAP
2" X 4" WOOD
POSTS,
STANDARD OR
BETTER,
OR STEEL
FENCE POST
BURY BOTTOM OF
FILTER MATERIAL
IN 8"X12" TRENCH
2" X 4" BY 14 GA.
WIRE FABRIC OR
EQUIVALENT
ORANGE FILTER FABRIC
MATERIAL 60" WIDE ROLLS -
USE RINGS TO ATTACH
ATTACH TO WIRE FABRIC 2" X 4" WOOD POST
OR STEEL FENCE
POST
PROVIDE 3/4" - 1 1/2" WASHED
GRAVEL BACKFILL IN TRENCH AND
ON BOTH SIDES OF FILTER FENCE
FABRIC ON THE SURFACE
2" X 2" BY 14 GA. WIRE
FABRIC OR EQUIVALENT,
AFFIX TO POST
FILTER FABRIC MATERIAL
MIRAFI 100 NS OR EQUIVALENT
SIDE VIEW
FRONT VIEW
CHAINLINK FENCE
6' MAX.
EXISTING
GRADE2.0'2.5'5.0'8"
2.0' MIN.5.0'1.0'2.0'0.5'2 NOT TO SCALE
INLET PROTECTION
3 NOT TO SCALE
SILT FENCE
1.MULCH MATERIALS USED SHALL BE STRAW AND SHALL BE APPLIED AT THE
RATE OF 1.5 TO 2.5 TONS/ACRE MIN 2" THICK.
2.MULCHES SHALL BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES GREATER
THAN 2:1.
3.MULCHING SHALL BE USED IMMEDIATELY AFTER SEEDING OR IN AREAS WHICH
CANNOT BE SEEDED BECAUSE OF THE SEASON.
4.ALL AREAS NEEDING MULCH SHALL BE COVERED BY NOVEMBER FIRST (1).
1.STOCKPILES SHALL BE STABILIZED (WITH PLASTIC
COVERING OR OTHER APPROVED DEVICE) DAILY
BETWEEN NOVEMBER 1 AND MARCH 31.
2.IN ANY SEASON, SEDIMENT LEACHING FROM STOCK
PILES MUST BE PREVENTED.
3.TOPSOIL SHALL NOT BE PLACED WHILE IN A FROZEN
OR MUDDY CONDITION, WHEN THE SUBGRADE IS
EXCESSIVELY WET, OR WHEN CONDITIONS EXIST THAT
MAY OTHERWISE BE DETRIMENTAL TO PROPER
GRADING OR PROPOSED SODDING OR SEEDING.
4.PREVIOUSLY ESTABLISHED GRADES ON THE AREAS TO
BE TOPSOILED SHALL BE MAINTAINED ACCORDING TO
THE APPROVED PLAN.
5.ALL STOCKPILES SHALL BE COVERED WITH PLASTIC
COVERING. SEE PLASTIC COVERING NOTES ON THIS
SHEET.
SOIL STOCKPILE NOTES
MULCHING NOTES:
1.ON-SITE EROSION CONTROL MEASURES SHALL BE THE RESPONSIBILITY OF THE
CONTRACTOR. ANY PROBLEMS OCCURRING BEFORE FINAL ACCEPTANCE OF THE
STORM SYSTEM BY THE OWNER, SHALL BE CORRECTED BY THE CONTRACTOR.
2.IN CASE EROSION OR SEDIMENTATION OCCURS TO ADJACENT PROPERTY, ALL
CONSTRUCTION WORK THAT WILL AGGRAVATE THE SITUATION MUST CEASE AND THE
CONTRACTOR SHALL IMMEDIATELY COMMENCE RESTORATION OR MITIGATION
MEASURES. RESTORATION ACTIVITY SHALL CONTINUE UNTIL SUCH TIME AS THE
PROBLEM IS RECTIFIED.
3.ALL APPLICABLE EROSION AND SEDIMENTATION CONTROL DEVICES SHOWN ON
THESE DRAWINGS SHALL BE INSTALLED PRIOR TO OR AS THE FIRST STAGE OF SITE
PREPARATION FOR SAID PHASE OF CONSTRUCTION
4.THE CITY OF YELM AND OWNER/ENGINEER SHALL BE RESPONSIBLE FOR THE
INSPECTION AND ACCEPTANCE OF ALL CLEARING AND GRADE WORK AND EROSION
EROSION AND SEDIMENTATION CONTROL FACILITIES.
5.THE APPLICANT AND/OR CONTRACTOR SHALL NOTIFY THE CITY OF YELM AND
OWNER/ENGINEER FORTY-EIGHT HOURS IN ADVANCE OF EACH REQUIRED EROSION
AND SEDIMENTATION CONTROL INSPECTION:
INSPECTION NO.1 - INSTALLATION OF EROSION CONTROL FACILITIES/PRIOR TO
CLEARING
INSPECTION NO.2 - COMPLETION OF CLEARING
INSPECTION NO.3 - UPON COMPLETION OF EXCAVATION, FILLING, AND EARTHWORK.
INSPECTION NO.4 - COMPLETION OF PROJECT
INSPECTION NO.5 - AS NEEDED TO DETERMINE COMPLIANCE WITH APPROVED PLANS
AND/OR SPECIFICATIONS (DOES NOT REQUIRE ADVANCED NOTICE).
6.ALL WORK ASSOCIATED WITH THE STABILIZING THE DISTURBED AREAS SHALL BE IN
ACCORDANCE WITH THE 2014 WASHINGTON STATE DEPARTMENT OF ECOLOGY DOE
STORMWATER MANAGEMENT MANUAL FOR WESTERN WASHINGTON.
7.ALL NECESSARY FACILITIES SHALL BE MAINTAINED ON SITE TO PREVENT DEBRIS,
DUST, AND MUD FROM ACCUMULATING ON THE PUBLIC RIGHT-OF-WAY.
8.THE CONTRACTOR SHALL ADHERE TO STORMWATER POLLUTION PREVENTION PLAN
(SWPPP). THE SWPPP AND THE CONSTRUCTION GENERAL PERMIT (CGP) MUST BE
FOLLOWED AS APPROPRIATE UNTIL FINAL STABILIZATION HAS OCCURRED. THE
SWPPP IS A LIVING DOCUMENT AND MUST BE UPDATED WHEN SITE CONDITIONS
CHANGE.
9.CONTRACTOR TO HAVE WATER TRUCK ONSITE DURING CONSTRUCTION TO CONTROL
DUST. WATER SITE AS NECESSARY TO CONTROL DUST. OWNER AND ENGINEER WILL
HAVE AUTHORITY TO STOP CONSTRUCTION IF DUST IS NOT ADEQUATELY
CONTROLLED.
10.CONTRACTOR TO DETERMINE AREAS FOR LAY DOWN, STOCK PILE, TRAILERS &
PARKING. COORDINATE WITH GC/CM.
11.CONTRACTOR TO REMOVE CONSTRUCTION DEBRIS, MUD, ROCKS, DIRT, ETC FROM
EXISTING ROAD DAILY.
12.PROVIDE INLET PROTECTION AS NEW CATCH BASINS/AREA DRAINS ARE
CONSTRUCTED.
13.CONTRACTOR SHALL ACCEPT, MAINTAIN, AND REMOVE AT PROJECT COMPLETION ALL
EXISTING TESC MEASURES CURRENTLY INSTALLED ONSITE.
14.COORDINATE ALL EARTHWORK ACTIVITIES WITH GEOTECHNICAL ENGINEER. SEE
GEOTECHNICAL REPORT PREPARED BY LANDAU ASSOCIATES DATED AUGUST 1, 2019
REGARDING RECOMMENDATIONS FOR STRIPPING DEPTH, SUBGRADE PREPARATION,
UTILITY TRENCH EXCAVATION, CONSTRUCTION DEWATERING, REUSE OF ONSITE
MATERIALS AS STRUCTURAL FILL, AND STRUCTURAL FILL PLACEMENT AND
COMPACTION.
15.ALL LIMITS OF CLEARING AND AREAS OF VEGETATION PRESERVATION AS
PRESCRIBED ON THE PLANS SHALL BE CLEARLY FLAGGED BY THE PROJECT
SURVEYOR IN THE FIELD AND OBSERVED DURING CONSTRUCTION.
16.ALL TEMPORARY SEDIMENTATION AND EROSION CONTROL MEASURES, AND
PROTECTIVE MEASURES FOR CRITICAL AREAS AND SIGNIFICANT TREES SHALL BE
INSTALLED PRIOR TO INITIATING ANY CONSTRUCTION ACTIVITIES.
17.ALL REQUIRED SEDIMENTATION AND EROSION CONTROL FACILITIES MUST BE
CONSTRUCTED AND IN OPERATION PRIOR TO ANY LAND CLEARING AND/OR OTHER
CONSTRUCTION TO ENSURE THAT SEDIMENT LADEN WATER DOES NOT ENTER ANY
EXISTING DRAINAGE SYSTEM. THE CONTRACTOR SHALL SCHEDULE AN INSPECTION
OF THE EROSION CONTROL FACILITIES PRIOR TO ANY LAND CLEARING AND/OR
OTHER CONSTRUCTION. ALL EROSION AND SEDIMENT FACILITIES SHALL BE
MAINTAINED IN A SATISFACTORY CONDITION AS DETERMINED BY THE E.S.C.L UNTIL
SUCH TIME THAT CLEARING AND/OR CONSTRUCTION IS COMPLETED AND THE
POTENTIAL FOR ON-SITE EROSION HAS PASSED. THE IMPLEMENTATION,
MAINTENANCE, REPLACEMENT, AND ADDITIONS TO THE EROSION AND
SEDIMENTATION CONTROL SYSTEMS SHALL BE THE RESPONSIBILITY OF THE
CONTRACTOR.
18.THE EROSION AND SEDIMENTATION CONTROL SYSTEM FACILITIES DEPICTED ON
THESE PLANS ARE INTENDED TO BE MINIMUM REQUIREMENTS TO MEET ANTICIPATED
SITE CONDITIONS. AS CONSTRUCTION PROGRESSES AND UNEXPECTED OR
SEASONAL CONDITIONS DICTATE, FACILITIES WILL BE NECESSARY TO ENSURE
COMPLETE SILTATION CONTROL ON THE SITE. DURING THE COURSE OF
CONSTRUCTION, IT SHALL BE THE OBLIGATION AND RESPONSIBILITY OF THE
CONTRACTOR TO ADDRESS ANY NEW CONDITIONS THAT MAY BE CREATED BY HIS
ACTIVITIES AND TO PROVIDE ADDITIONAL FACILITIES, OVER AND ABOVE THE MINIMUM
REQUIREMENTS, AS MAY BE NEEDED TO PROTECT ADJACENT PROPERTIES,
SENSITIVE AREAS, NATURAL WATER COURSES, AND/OR STORM DRAINAGE SYSTEMS.
19.ANY DISTURBED AREA WHICH HAS BEEN STRIPPED OF VEGETATION AND WHERE NO
FURTHER WORK IS ANTICIPATED FOR A PERIOD OF 7 DAYS OR MORE DURING THE
DRY SEASON (MAY 1-SEPT 30) OR 2 DAYS OR MORE IN THE WET SEASON (OCT 1-APR
30), SHALL BE IMMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING, OR
OTHER APPROVED EROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF
YEAR IN QUESTION. GRASS SEEDING ALONE WILL BE ACCEPTABLE ONLY DURING THE
MONTHS OF MAY THROUGH SEPTEMBER INCLUSIVE. SEEDING MAY PROCEED
OUTSIDE THE SPECIFIED TIME PERIOD WHENEVER IT IS IN THE INTEREST OF THE
CONTRACTOR BUT SHALL BE AUGMENTED WITH MULCHING, NETTING, OR OTHER
TREATMENT APPROVED BY THE ENGINEER.
20.NO TEMPORARY OR PERMANENT STOCKPILING OF MATERIALS OR EQUIPMENT SHALL
OCCUR WITHIN CRITICAL AREAS OR ASSOCIATED BUFFERS, OR THE CRITICAL ROOT
ZONE FOR VEGETATION PROPOSED FOR RETENTION.
GENERAL EROSION CONTROL NOTES
1
3
3
2
2
2
2
2
5
5
1
CL
FF
CL
CL
FF
2
CLEARING LIMITS
TESC LEGEND
FILTER FABRIC FENCE
CL
FF 2
C1.01
2215 North 30th Street, Suite 300, Tacoma, WA 98403
253.383.2422TEL www.ahbl.comWEB
TACOMA SEATTLE SPOKANE TRI-CITIES
Know what's below.
before you dig.Call
R
253.383.2572 FAX
YELM SCHOOL DISTRICT
FIELD UPGRADES YELM
HIGH SCHOOL
YELM SCHOOL
DISTRICT #2
404 E YELM AVE
YELM, WA 98597
CHRIS HANSEN
2200807.10
03/18/2021
PERMIT SET
CHS SBK TCS
8
YELM SCHOOL DISTRICT FIELD UPGRADES- YELM HIGH SCHOOL
A PORTION OF THE N 1/2 OF THE NW 1/4 OF SEC. 24, TWN. 17N., RGE. 01 E. W.M.
CITY OF YELM, THURSTON COUNTY, WASHINGTON
DATE: March 19, 2021 FILENAME: Q:\2020\2200807\10_CIV\CAD\YHS\2200807-SH-TESC-YHS.dwg
C1.00
TESC AND
DEMOLITION PLAN
4
N
GRAPHIC SCALE
0 30 60
1" = 30 FEET
15
KEYNOTES
PROTECT EXISTING ELECTRICAL
PROTECT EXISTING CHAINLINK FENCE. FENCING MAY BE
REMOVED FOR CONSTRUCTION FIELD INSTALL. FENCING MUST BE
REINSTALLED WITH WIRING AND BOTTOM BARS WHERE CURRENT
BOTTOM BARS EXISTING
REMOVE AND DEMOLISH EXISITNG WOOD 2-BY CURBING
REMOVE EXISTING CONCRETE
PROTECT EXISTING DUGOUT CONCRETE
1
2
3
4
5
4
4
5
5
STANDARD TESC NOTES:
1.APPROVAL OF THIS EROSION AND SEDIMENTATION CONTROL PLAN DOES
NOT CONSTITUTE AN APPROVAL OF PERMANENT ROAD OR DRAINAGE
DESIGN (E.G., SIZE AND LOCATION OF ROADS, PIPES, RESTRICTORS,
CHANNELS, RETENTION FACILITIES, UTILITIES, ETC.).
2.THE IMPLEMENTATION OF THESE EROSION AND SEDIMENT CONTROL
PLANS AND THE CONSTRUCTION, MAINTENANCE, REPLACEMENT, AND
UPGRADING OF THESE ESC FACILITIES IS THE RESPONSIBILITY OF THE
APPLICANT/CONTRACTOR UNTIL ALL CONSTRUCTION IS COMPLETED AND
APPROVED AND VEGETATION/LANDSCAPING IS ESTABLISHED.
3.THE BOUNDARIES OF THE CLEARING LIMITS SHOWN ON THIS PLAN SHALL
BE CLEARLY FLAGGED IN THE FIELD PRIOR TO CONSTRUCTION. DURING
THE CONSTRUCTION PERIOD, NO DISTURBANCE BEYOND THE FLAGGED
CLEARING LIMITS SHALL BE PERMITTED. THE FLAGGING SHALL BE
MAINTAINED BY THE APPLICANT/CONTRACTOR FOR THE DURATION OF
CONSTRUCTION.
4.THE ESC FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED IN
CONJUNCTION WITH ALL CLEARING AND GRADING ACTIVITIES, AND IN
SUCH A MANNER AS TO INSURE THAT SEDIMENT AND SEDIMENT LADEN
WATER DO NOT ENTER THE DRAINAGE SYSTEM, ROADWAYS, OR VIOLATE
APPLICABLE WATER STANDARDS.
5.THE ESC FACILITIES SHOWN ON THIS PLAN ARE THE MINIMUM
REQUIREMENTS FOR ANTICIPATED SITE CONDITIONS. DURING THE
CONSTRUCTION PERIOD, THESE ESC FACILITIES SHALL BE UPGRADED AS
NEEDED FOR UNEXPECTED STORM EVENTS AND TO ENSURE THAT
SEDIMENT AND SEDIMENT-LADEN WATER DO NOT LEAVE THE SITE.
6.THE ESC FACILITIES SHALL BE INSPECTED DAILY BY THE
APPLICANT/CONTRACTOR AND MAINTAINED AS NECESSARY TO ENSURE
THEIR CONTINUED FUNCTIONING.
7.THE ESC FACILITIES ON INACTIVE SITES SHALL BE INSPECTED AND
MAINTAINED A MINIMUM OF ONCE A MONTH OR WITHIN THE 48 HOURS
FOLLOWING A MAJOR STORM EVENT.
8.AT NO TIME SHALL MORE THAN 1 FOOT OF SEDIMENT BE ALLOWED TO
ACCUMULATE WITHIN A TRAPPED CATCH BASIN. ALL CATCH BASINS AND
CONVEYANCE LINES SHALL BE CLEANED PRIOR TO PAVING. THE
CLEANING OPERATION SHALL NOT FLUSH SEDIMENT LADEN WATER INTO
THE INFILTRATION SYSTEM.
9.STABILIZED CONSTRUCTION ENTRANCES SHALL BE INSTALLED AT THE
BEGINNING OF CONSTRUCTION AND MAINTAINED FOR THE DURATION OF
THE PROJECT. ADDITIONAL MEASURES MAY BE REQUIRED TO INSURE
THAT ALL PAVED AREAS ARE KEPT CLEAN FOR THE DURATION OF THE
PROJECT.
DEMO LEGEND
REMOVE EXISTING CONCRETE
STRIPPING NOTES:
1.AREAS WITHIN CLEARING LIMITS SHALL HAVE TOPSOILS
STRIPPED 6" MINIMUM.
2.AREAS OF INFIELD MAY HAVE EXISTING UNDERDRAIN SYSTEM.
THIS SYSTEM MAY BE LEFT IN PLACE IF NOT IN CONFLICT WITH
PROPOSED FIELD UNDERDRAIN AND TURF PROFILE.
EXISTING NATURAL TURF ACCESS ROAD
SHALL BE PROTECTED AND UTILIZED AS
STABILIZED CONSTRUCTION ENTRANCE
C1.01
TESC AND
DEMOLITION NOTES
AND DETAILS
5
1.CONTRACTOR IS RESPONSIBLE FOR ENSURING THAT ALL UTILITIES HAVE BEEN
DISCONNECTED PRIOR TO COMMENCING DEMOLITION.
2.DEMOLITION: IT IS THE INTENT OF THE WORK UNDER THIS CONTRACT TO INCLUDE
THE DEMOLITION OF ALL EXISTING BUILDINGS, PAVING, UTILITIES AND OTHER
EXISTING SITE IMPROVEMENTS INCLUDING THEIR UNDERGROUND COMPONENTS
AS INDICATED BY THIS DRAWING AND AS REQUIRED FOR NEW CONSTRUCTION. IT
IS THE CONTRACTOR'S RESPONSIBILITY TO FULLY REVIEW THE SITE CONDITIONS
AND TO CORRELATE THESE OBSERVATIONS WITH THE PROJECT WORK AND
INCLUDE ALL NECESSARY DEMOLITION, WHETHER SHOWN OR NOT, AND INCLUDE
ALL SUCH COSTS IN THE BASE BID.
3.CLEARING: IT IS THE INTENT OF THE WORK UNDER THIS CONTRACT TO CONDUCT
ALL CLEARING NECESSARY TO BE ABLE TO COMPLETE ALL THE WORK OF THIS
PROJECT.
4.CONTRACTOR SHALL LEGALLY DISPOSE OF THE OWNER'S PROPERTY, ALL
DEMOLISHED AND REMOVED MATERIALS, UNLESS INDICATED OTHERWISE.
5.IT IS THE RESPONSIBILITY OF THE CONTRACTOR TO COMPLETELY COORDINATE
UTILITY DEMOLITION WITH NEW CONSTRUCTION. CONTRACTOR SHALL ENSURE
THAT ADEQUATE FIRE PROTECTION IN ACCORDANCE WITH THE FIRE MARSHALL
REQUIREMENTS IS PROVIDED FOR THE NEW BUILDING.
6.COORDINATE POWER DEMOLITION WITH THE CITY OF YELM AND ELECTRICAL
PLANS. CONTRACTOR TO ENSURE THAT DEMOLITION OF LINES WILL NOT
COMPROMISE POWER TO OTHER AREAS.
7.POWER AND CABLE SERVING BUILDINGS AND LIGHT POLES TO REMAIN RUN
THROUGH THIS SITE. CONTRACTOR SHALL INSTALL NEW SERVICES TO BUILDINGS
AND LIGHT POLES REMAINING PRIOR TO DEMOLISHING EXISTING LINES.
8.GAS DISCONNECTION BY P.S.E. CONTRACTOR TO COORDINATE WORK WITH PSE.
CONTRACTOR TO DEMOLISH ABANDONED SERVICE. CONTRACTOR TO ENSURE
THAT DEMOLITION OF GAS LINES WILL NOT IMPACT GAS SERVICE TO OTHER
AREAS. NO DISRUPTION IN SERVICE ALLOWED.
9.ANY ABANDONED SIDE SEWER(S) SHALL BE PLUGGED OR CAPPED AT THE
RIGHT-OF-WAY OR PROPERTY LINE.
10.CONTRACTOR SHALL MINIMIZE DUST GENERATION ONSITE BY SPRINKLING THE
SITE WITH WATER UNTIL SURFACE IS WET. SEE BMP C140.
11.SAWCUT CONCRETE SIDEWALK AT THE NEAREST JOINT.
12.REMOVAL OF THE EXISTING UNDERGROUND OIL TANK AND ASSOCIATED
APPURTENANCES REQUIRES AN UNDERGROUND STORAGE TANK (UST) REMOVAL
PERMIT FROM THURSTON COUNTY HEALTH DEPARTMENT.
13.REFER TO LANDSCAPE ARCHITECTURE DRAWINGS FOR INVASIVE SPECIES
REMOVAL REQUIREMENTS AND TREE PROTECTION REQUIREMENTS.
14.REFER TO HAZARDOUS MATERIAL DRAWING H1.10 FOR LEAD AND ARSENIC SOIL
MIXING REQUIREMENTS.
15.THE CLEARING LIMITS DEPICTED ON THESE PLANS REPRESENT THE EDGE OF
CIVIL-RELATED WORK SUCH AS GRADING, UTILITY, STORM DRAINAGE, AND PAVING
IMPROVEMENTS. WORK SUCH AS ARSENIC AND LEAD SOIL REMEDIATION AND
ASSOCIATED STABILIZATION AND INVASIVE SPECIES REMOVAL MAY OCCUR
BEYOND THE CLEARING LIMITS. REFER TO THE HAZARDOUS MATERIAL DRAWINGS
AND LANDSCAPE ARCHITECTURE DRAWINGS FOR ADDITIONAL INFORMATION.
16.ALL MONUMENTS DISTURBED AS A RESULT OF CONSTRUCTION ACTIVITIES SHALL
BE REPLACED PER WAC 332-120 AT NOT ADDITIONAL COST TO THE OWNER.
CONTRACTOR SHALL APPLY FOR PERMIT FROM THE DEPARTMENT OF NATURAL
RESOURCES AS NECESSARY.
DEMOLITION NOTES
8' MAX.
1
1
PROVIDE SAND BAGS 10'
O.C. TO HOLD PLASTIC
COVERING IN PLACE
STOCKPILE
AREA
EXISTING
GRADE
1
1
NOTES:
1.STOCKPILES SHALL BE STABILIZED WITH PLASTIC COVERING OR OTHER APPROVED
DEVICE.
2.SEDIMENT LEACHING FROM STOCKPILES SHALL BE PREVENTED DURING ALL
SEASONS.
1 NOT TO SCALE
STOCKPILE
2" X 4" WOOD
POSTS,
STANDARD OR
BETTER,
OR STEEL
FENCE POST
BURY BOTTOM OF
FILTER MATERIAL
IN 8"X12" TRENCH
2" X 4" BY 14 GA.
WIRE FABRIC OR
EQUIVALENT
ORANGE FILTER FABRIC
MATERIAL 60" WIDE ROLLS -
USE RINGS TO ATTACH
ATTACH TO WIRE FABRIC 2" X 4" WOOD POST
OR STEEL FENCE
POST
PROVIDE 3/4" - 1 1/2" WASHED
GRAVEL BACKFILL IN TRENCH AND
ON BOTH SIDES OF FILTER FENCE
FABRIC ON THE SURFACE
2" X 2" BY 14 GA. WIRE
FABRIC OR EQUIVALENT,
AFFIX TO POST
FILTER FABRIC MATERIAL
MIRAFI 100 NS OR EQUIVALENT
SIDE VIEW
FRONT VIEW
CHAINLINK FENCE
6' MAX.
EXISTING
GRADE2.0'2.5'5.0'8"
2.0' MIN.5.0'1.0'2.0'0.5'3 NOT TO SCALE
SILT FENCE
1.STOCKPILES SHALL BE STABILIZED (WITH PLASTIC
COVERING OR OTHER APPROVED DEVICE) DAILY
BETWEEN NOVEMBER 1 AND MARCH 31.
2.IN ANY SEASON, SEDIMENT LEACHING FROM STOCK
PILES MUST BE PREVENTED.
3.TOPSOIL SHALL NOT BE PLACED WHILE IN A FROZEN
OR MUDDY CONDITION, WHEN THE SUBGRADE IS
EXCESSIVELY WET, OR WHEN CONDITIONS EXIST THAT
MAY OTHERWISE BE DETRIMENTAL TO PROPER
GRADING OR PROPOSED SODDING OR SEEDING.
4.PREVIOUSLY ESTABLISHED GRADES ON THE AREAS TO
BE TOPSOILED SHALL BE MAINTAINED ACCORDING TO
THE APPROVED PLAN.
5.ALL STOCKPILES SHALL BE COVERED WITH PLASTIC
COVERING. SEE PLASTIC COVERING NOTES ON THIS
SHEET.
SOIL STOCKPILE NOTES
1.ON-SITE EROSION CONTROL MEASURES SHALL BE THE RESPONSIBILITY OF THE
CONTRACTOR. ANY PROBLEMS OCCURRING BEFORE FINAL ACCEPTANCE OF THE
STORM SYSTEM BY THE OWNER, SHALL BE CORRECTED BY THE CONTRACTOR.
2.IN CASE EROSION OR SEDIMENTATION OCCURS TO ADJACENT PROPERTY, ALL
CONSTRUCTION WORK THAT WILL AGGRAVATE THE SITUATION MUST CEASE AND THE
CONTRACTOR SHALL IMMEDIATELY COMMENCE RESTORATION OR MITIGATION
MEASURES. RESTORATION ACTIVITY SHALL CONTINUE UNTIL SUCH TIME AS THE
PROBLEM IS RECTIFIED.
3.ALL APPLICABLE EROSION AND SEDIMENTATION CONTROL DEVICES SHOWN ON
THESE DRAWINGS SHALL BE INSTALLED PRIOR TO OR AS THE FIRST STAGE OF SITE
PREPARATION FOR SAID PHASE OF CONSTRUCTION
4.THE CITY OF YELM AND OWNER/ENGINEER SHALL BE RESPONSIBLE FOR THE
INSPECTION AND ACCEPTANCE OF ALL CLEARING AND GRADE WORK AND EROSION
EROSION AND SEDIMENTATION CONTROL FACILITIES.
5.THE APPLICANT AND/OR CONTRACTOR SHALL NOTIFY THE CITY OF YELM AND
OWNER/ENGINEER FORTY-EIGHT HOURS IN ADVANCE OF EACH REQUIRED EROSION
AND SEDIMENTATION CONTROL INSPECTION:
INSPECTION NO.1 - INSTALLATION OF EROSION CONTROL FACILITIES/PRIOR TO
CLEARING
INSPECTION NO.2 - COMPLETION OF CLEARING
INSPECTION NO.3 - UPON COMPLETION OF EXCAVATION, FILLING, AND EARTHWORK.
INSPECTION NO.4 - COMPLETION OF PROJECT
INSPECTION NO.5 - AS NEEDED TO DETERMINE COMPLIANCE WITH APPROVED PLANS
AND/OR SPECIFICATIONS (DOES NOT REQUIRE ADVANCED NOTICE).
6.ALL WORK ASSOCIATED WITH THE STABILIZING THE DISTURBED AREAS SHALL BE IN
ACCORDANCE WITH THE 2014 WASHINGTON STATE DEPARTMENT OF ECOLOGY DOE
STORMWATER MANAGEMENT MANUAL FOR WESTERN WASHINGTON.
7.ALL NECESSARY FACILITIES SHALL BE MAINTAINED ON SITE TO PREVENT DEBRIS,
DUST, AND MUD FROM ACCUMULATING ON THE PUBLIC RIGHT-OF-WAY.
8.THE CONTRACTOR SHALL ADHERE TO STORMWATER POLLUTION PREVENTION PLAN
(SWPPP). THE SWPPP AND THE CONSTRUCTION GENERAL PERMIT (CGP) MUST BE
FOLLOWED AS APPROPRIATE UNTIL FINAL STABILIZATION HAS OCCURRED. THE
SWPPP IS A LIVING DOCUMENT AND MUST BE UPDATED WHEN SITE CONDITIONS
CHANGE.
9.CONTRACTOR TO HAVE WATER TRUCK ONSITE DURING CONSTRUCTION TO CONTROL
DUST. WATER SITE AS NECESSARY TO CONTROL DUST. OWNER AND ENGINEER WILL
HAVE AUTHORITY TO STOP CONSTRUCTION IF DUST IS NOT ADEQUATELY
CONTROLLED.
10.CONTRACTOR TO DETERMINE AREAS FOR LAY DOWN, STOCK PILE, TRAILERS &
PARKING. COORDINATE WITH GC/CM.
11.CONTRACTOR TO REMOVE CONSTRUCTION DEBRIS, MUD, ROCKS, DIRT, ETC FROM
EXISTING ROAD DAILY.
12.PROVIDE INLET PROTECTION AS NEW CATCH BASINS/AREA DRAINS ARE
CONSTRUCTED.
13.CONTRACTOR SHALL ACCEPT, MAINTAIN, AND REMOVE AT PROJECT COMPLETION ALL
EXISTING TESC MEASURES CURRENTLY INSTALLED ONSITE.
14.COORDINATE ALL EARTHWORK ACTIVITIES WITH GEOTECHNICAL ENGINEER. SEE
GEOTECHNICAL REPORT PREPARED BY LANDAU ASSOCIATES DATED AUGUST 1, 2019
REGARDING RECOMMENDATIONS FOR STRIPPING DEPTH, SUBGRADE PREPARATION,
UTILITY TRENCH EXCAVATION, CONSTRUCTION DEWATERING, REUSE OF ONSITE
MATERIALS AS STRUCTURAL FILL, AND STRUCTURAL FILL PLACEMENT AND
COMPACTION.
15.ALL LIMITS OF CLEARING AND AREAS OF VEGETATION PRESERVATION AS
PRESCRIBED ON THE PLANS SHALL BE CLEARLY FLAGGED BY THE PROJECT
SURVEYOR IN THE FIELD AND OBSERVED DURING CONSTRUCTION.
16.ALL TEMPORARY SEDIMENTATION AND EROSION CONTROL MEASURES, AND
PROTECTIVE MEASURES FOR CRITICAL AREAS AND SIGNIFICANT TREES SHALL BE
INSTALLED PRIOR TO INITIATING ANY CONSTRUCTION ACTIVITIES.
17.ALL REQUIRED SEDIMENTATION AND EROSION CONTROL FACILITIES MUST BE
CONSTRUCTED AND IN OPERATION PRIOR TO ANY LAND CLEARING AND/OR OTHER
CONSTRUCTION TO ENSURE THAT SEDIMENT LADEN WATER DOES NOT ENTER ANY
EXISTING DRAINAGE SYSTEM. THE CONTRACTOR SHALL SCHEDULE AN INSPECTION
OF THE EROSION CONTROL FACILITIES PRIOR TO ANY LAND CLEARING AND/OR
OTHER CONSTRUCTION. ALL EROSION AND SEDIMENT FACILITIES SHALL BE
MAINTAINED IN A SATISFACTORY CONDITION AS DETERMINED BY THE E.S.C.L UNTIL
SUCH TIME THAT CLEARING AND/OR CONSTRUCTION IS COMPLETED AND THE
POTENTIAL FOR ON-SITE EROSION HAS PASSED. THE IMPLEMENTATION,
MAINTENANCE, REPLACEMENT, AND ADDITIONS TO THE EROSION AND
SEDIMENTATION CONTROL SYSTEMS SHALL BE THE RESPONSIBILITY OF THE
CONTRACTOR.
18.THE EROSION AND SEDIMENTATION CONTROL SYSTEM FACILITIES DEPICTED ON
THESE PLANS ARE INTENDED TO BE MINIMUM REQUIREMENTS TO MEET ANTICIPATED
SITE CONDITIONS. AS CONSTRUCTION PROGRESSES AND UNEXPECTED OR
SEASONAL CONDITIONS DICTATE, FACILITIES WILL BE NECESSARY TO ENSURE
COMPLETE SILTATION CONTROL ON THE SITE. DURING THE COURSE OF
CONSTRUCTION, IT SHALL BE THE OBLIGATION AND RESPONSIBILITY OF THE
CONTRACTOR TO ADDRESS ANY NEW CONDITIONS THAT MAY BE CREATED BY HIS
ACTIVITIES AND TO PROVIDE ADDITIONAL FACILITIES, OVER AND ABOVE THE MINIMUM
REQUIREMENTS, AS MAY BE NEEDED TO PROTECT ADJACENT PROPERTIES,
SENSITIVE AREAS, NATURAL WATER COURSES, AND/OR STORM DRAINAGE SYSTEMS.
19.ANY DISTURBED AREA WHICH HAS BEEN STRIPPED OF VEGETATION AND WHERE NO
FURTHER WORK IS ANTICIPATED FOR A PERIOD OF 7 DAYS OR MORE DURING THE
DRY SEASON (MAY 1-SEPT 30) OR 2 DAYS OR MORE IN THE WET SEASON (OCT 1-APR
30), SHALL BE IMMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING, OR
OTHER APPROVED EROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF
YEAR IN QUESTION. GRASS SEEDING ALONE WILL BE ACCEPTABLE ONLY DURING THE
MONTHS OF MAY THROUGH SEPTEMBER INCLUSIVE. SEEDING MAY PROCEED
OUTSIDE THE SPECIFIED TIME PERIOD WHENEVER IT IS IN THE INTEREST OF THE
CONTRACTOR BUT SHALL BE AUGMENTED WITH MULCHING, NETTING, OR OTHER
TREATMENT APPROVED BY THE ENGINEER.
20.NO TEMPORARY OR PERMANENT STOCKPILING OF MATERIALS OR EQUIPMENT SHALL
OCCUR WITHIN CRITICAL AREAS OR ASSOCIATED BUFFERS, OR THE CRITICAL ROOT
ZONE FOR VEGETATION PROPOSED FOR RETENTION.
GENERAL EROSION CONTROL NOTES
2215 North 30th Street, Suite 300, Tacoma, WA 98403
253.383.2422TEL www.ahbl.comWEB
TACOMA SEATTLE SPOKANE TRI-CITIES
Know what's below.
before you dig.Call
R
253.383.2572 FAX
YELM SCHOOL DISTRICT
FIELD UPGRADES YELM
HIGH SCHOOL
YELM SCHOOL
DISTRICT #2
404 E YELM AVE
YELM, WA 98597
CHRIS HANSEN
2200807.10
03/18/2021
PERMIT SET
CHS SBK TCS
8
YELM SCHOOL DISTRICT FIELD UPGRADES- YELM HIGH SCHOOL
A PORTION OF THE N 1/2 OF THE NW 1/4 OF SEC. 24, TWN. 17N., RGE. 01 E. W.M.
CITY OF YELM, THURSTON COUNTY, WASHINGTON
Construction Stormwater Pollution Prevention Plan
Yelm Middle School
2200807.10
Exhibit 3
Inspection Logs
Construction Stormwater Pollution Prevention Plan
Yelm Middle School Exhibit 4 – 1
2200807.10
Yelm School District Field Upgrades
Stormwater Pollution Prevention Plan
Inspection and Maintenance Report Form
To be completed every 7 days and within 24 hours of a rainfall event of 0.5 inches or more
Inspector: Date:
Inspector's Qualifications:
Days since last rainfall: Amount of last rainfall: inches
Stabilization Measures
Drainage Area Date Since
Last
Disturbance
Date of Next
Disturbance
Stabilized
(yes/No)
Stabilized With Condition
Stabilization required:
To be performed by: On or before:
Construction Stormwater Pollution Prevention Plan
Yelm Middle School Exhibit 4 – 2
2200807.10
Yelm School District Field Upgrades
Stormwater Pollution Prevention Plan
Inspection and Maintenance Report Form
Structural Controls:
Date:
Inlet Protection
Drainage Area
Perimeter
Has Silt Reached 1/3 of
holding capacity?
Is Inlet Protection
Properly Secured?
Is There Evidence of
tearing or Overtopping?
Maintenance required for inlet protection:
To be performed by: On or before:
Construction Stormwater Pollution Prevention Plan
Yelm Middle School Exhibit 4 – 3
2200807.10
Yelm School District Field Upgrades
Stormwater Pollution Prevention Plan
Inspection and Maintenance Report Form
Changes required to the pollution prevention plan:
Reasons for changes:
I certify under penalty of law that this document and all attachments were prepared under my
direction or supervision in accordance with a system designed to assure that qualified personnel
properly gathered and evaluated the information submitted. Based on my inquiry of the person
or persons who manage the system, or those persons directly responsible for gathering the
information, the information submitted is, to the best of my knowledge and belief, true, accurate,
and complete. I am aware that there are significant penalties for submitting false information,
including the possibility of fine and imprisonment for knowing violations.
Signature: Date: ____________________
Construction Stormwater Pollution Prevention Plan
Yelm Middle School
2200807.10
Exhibit 4
Best Management Practices (BMPs)
BMP C101 .................................. Preserving Natural Vegetation
BMP C102 ................................. Buffer Zones
BMP C103 .................................. High Visibility Plastic or Metal Fence
BMP C106 .................................. Wheel Wash
BMP C120 .................................. Temporary and Permanent Seeding
BMP C121 .................................. Mulching
BMP C123 .................................. Plastic Covering
BMP C125 .................................. Topsoiling / Composting
BMP C140 .................................. Dust Control
BMP C150 .................................. Materials on Hand
BMP C151 .................................. Concrete Handling
BMP C152 .................................. Sawcutting and Surface Pollution Prevention
BMP C153 .................................. Material Delivery, Containment & Storage
BMP C154 .................................. Concrete Washout Area
BMP C160 .................................. Certified Erosion and Sediment Control Lead
BMP C162 .................................. Scheduling
BMP C200 .................................. Interceptor Dike and Swale
BMP C201 .................................. Grass-Lined Channels
BMP C207 .................................. Check Dams
BMP C220 .................................. Inlet Protection
BMP C233 .................................. Silt Fence
BMP C240 .................................. Sediment Trap
BMP C101: Preserving Natural Vegetation
Purpose
The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site
disturbance is the single most effective method for reducing erosion. For example, conifers can hold
up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never
reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the
tree can be released slowly to the ground after the storm.
Conditions of Use
Natural vegetation should be preserved on steep slopes, near perennial and intermittent water-
courses or swales, and on building sites in wooded areas.
. As required by local governments.
Phase construction to preserve natural vegetation on the project site for as long as possible
during the construction period.
Design and Installation Specifications
Natural vegetation can be preserved in natural clumps or as individual trees, shrubs and vines.
The preservation of individual plants is more difficult because heavy equipment is generally used to
remove unwanted vegetation. The points to remember when attempting to save individual plants
are:
. Is the plant worth saving? Consider the location, species, size, age, vigor, and the work
involved. Local governments may also have ordinances to save natural vegetation and trees.
Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground
disturbance away from the trees at least as far out as the dripline.
Plants need protection from three kinds of injuries:
Construction Equipment- This injury can be above or below the ground level. Damage results
from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone around
plants to be saved prior to construction can prevent construction equipment injuries.
Grade Changes- Changing the natural ground level will alter grades, which affects the plant's
ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause prob-
lems although sensitivity between species does vary and should be checked. Trees can typ-
ically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less.
When there are major changes in grade, it may become necessary to supply air to the roots of
plants. This can be done by placing a layer of gravel and a tile system over the roots before the
fill is made. The tile system should be laid out on the original grade leading from a dry well
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 271
around the tree trunk. The system should then be covered with small stones to allow air to cir-
culate over the root area.
Lowering the natural ground level can seriously damage trees and shrubs. The highest per-
centage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can
cause serious injury. To protect the roots it may be necessary to terrace the immediate area
around the plants to be saved. If roots are exposed, construction of retaining walls may be
needed to keep the soil in place. Plants can also be preserved by leaving them on an undis-
turbed, gently sloping mound. To increase the chances for survival, it is best to limit grade
changes and other soil disturbances to areas outside the dripline of the plant.
Excavations - Protect trees and other plants when excavating for drainfields, power, water,
and sewer lines. Where possible, the trenches should be routed around trees and large
shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand
tools or with power augers. If it is not possible to route the trench around plants to be saved,
then the following should be observed:
Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a
wood dressing like asphalt base paint if roots will be exposed for more than 24 -hours.
o Backfill the trench as soon as possible.
Tunnel beneath root systems as close to the center of the main trunk to preserve most
of the important feeder roots.
Some problems that can be encountered with a few specific trees are:
• Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not
readily adjust to changes in environment and special care should be taken to protect these
trees.
. The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hemlock
is moderate. The danger of windthrow increases where dense stands have been thinned.
Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low
windthrow hazard.
• Cottonwoods, maples, and willows have water -seeking roots. These can cause trouble in
sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions
that other trees would not.
. Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir, Noble fir, Sitka
spruce, Western red cedar, Western hemlock, Pacific dogwood, and Red alder can cause ser-
ious disease problems. Disease can become established through damaged limbs, trunks,
roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect
attack.
Maintenance Standards
Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been
removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be
repaired or replaced immediately and visibility restored.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 272
If tree roots have been exposed or injured, "prune" cleanly with an appropriate pruning saw or top-
pers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees
(fir, hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier.
BMP C102: Buffer Zones
Purpose
Creation of an undisturbed area or strip of natural vegetation or an established suitable planting that
will provide a living filter to reduce soil erosion and stormwater runoff velocities.
Conditions of Use
Buffer zones are used along streams, wetlands and other bodies of water that need protection from
erosion and sedimentation. Contractors can use vegetative buffer zone BMPs to protect natural
swales and they can incorporate them into the natural landscaping of an area.
Do not use critical -areas buffer zones as sediment treatment areas. These areas shall remain com-
pletely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow
the use of the expanded area for removal of sediment.
The types of buffer zones can change the level of protection required as shown below
Designated Critical Area Buffers - buffers that protect Critical Areas, as defined by the Washington
State Growth Management Act, and are established and managed by the local permitting authority.
These should not be disturbed and must protected with sediment control BMPs to prevent impacts.
The local permitting authority may expand the buffer widths temporarily to allow the use of the expan
ded area for removal of sediment.
Vegetative Buffer Zones - areas that may be identified in undisturbed vegetation areas or managed
vegetation areas that are outside any Designated Critical Area Buffer. They may be utilized to
provide an additional sediment control area and/or reduce runoff velocities. If being used for pre-
servation of natural vegetation, they should be arranged in clumps or strips. They can be used to pro-
tect natural swales and incorporated into the natural landscaping area.
Design and Installation Specifications
• Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest
and most successful method.
• Leave all unstable steep slopes in natural vegetation.
• Mark clearing limits and keep all equipment and construction debris out of the natural areas
and buffer zones. Steel construction fencing is the most effective method to protect sensitive
areas and buffers. Alternatively, wire -backed silt fence on steel posts is marginally effective.
Flagging alone is typically not effective.
• Keep all excavations outside the dripline of trees and shrubs.
• Do not push debris or extra soil into the buffer zone area because it will cause damage by
2019 Stormwater Management Manual for Western Washington
Volume 11- Chapter 3 - Page 273
burying and smothering vegetation.
. Vegetative buffer zones for streams, lakes or other waterways shall be established by the
local permitting authority or other state or federal permits or approvals.
Maintenance Standards
Inspect the area frequently to make sure flagging remains in place and the area remains undis-
turbed. Replace all damaged flagging immediately. Remove all materials located in the buffer area
that may impede the ability of the vegetation to act as a filter.
BMP C103: High -Visibility Fence
Purpose
High -visibility fencing is intended to:
• Restrict clearing to approved limits.
• Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undis-
turbed.
. Limit construction traffic to designated construction entrances, exits, or internal roads.
• Protect areas where marking with survey tape may not provide adequate protection.
Conditions of Use
To establish clearing limits plastic, fabric, or metal fence may be used:
. At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared.
. As necessary to control vehicle access to and on the site.
Design and Installation Specifications
High -visibility plastic fence shall be composed of a high-density polyethylene material and shall beat
least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center
(maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches
with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as
a top stringer to prevent sagging between posts. The fence color shall be high -visibility orange. The
fence tensile strength shall be 360 lbs/ft using the ASTM D4595 testing method.
If appropriate install fabric silt fence in accordance with BMP C233: Silt Fence 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.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 274
Maintenance Standards
If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and
visibility restored.
BMP C105: Stabilized Construction Access
Purpose
Stabilized construction accesses are established to reduce the amount of sediment transported onto
paved roads outside the project site by vehicles or equipment. This is done by constructing a sta-
bilized pad of quarry spalls at entrances and exits for project sites.
Conditions of Use
Construction accesses 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 subdivision construction sites, provide a stabilized construction access for each res-
idence, 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 and configuration.
On large commercial, highway, and road projects, the designer should include enough extra mater-
ials in the contract to allow for additional stabilized accesses not shown in the initial Construction
SWPPP. It is difficult to determine exactly where access to these projects will take place; additional
materials will enable the contractor to install them where needed.
Design and Installation Specifications
See Figure 11-3.1: Stabilized Construction Access for details. Note: the 1 00'minimum length of the
access shall be reduced to the maximum practicable size when the size or configuration of the site
does not allow the full length (100').
Construct stabilized construction accesses 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 con-
crete, cement, or calcium chloride for construction access stabilization because these products raise
pH levels in stormwater and concrete discharge to 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 standards listed in Table 11-3.2: Stabilized Con-
struction Access Geotextile Standards.
Table II -3.2: Stabilized Construction Access
Geotextile Standards
Geotextile Property I Required Value
Grab Tensile Strength (ASTM D4751) 1 200 psi min.
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Volume 11- Chapter 3 - Page 275
Approved as Functionally Equivalent
Ecology has approved products as able to meet the requirements of this BMP. The products did not
pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions
may choose not to accept these products, or may require additional testing prior to consideration for
local use. Products that Ecology has approved as functionally equivalent are available for review on
Ecology's website at:
httiDs://ecologv.wa.gov/Requlations-Permits/Guidance-technical-assistance/Stormwater-Der-
mittee-guidance-resources/Emerging-stormwater-treatment-technologies
BMP C106: Wheel Wash
Purpose
Wheel washes reduce the amount of sediment transported onto paved roads by washing dirt from
the wheels of motor vehicles prior to the motor vehicles leaving the construction site.
Conditions of Use
• Use a wheel wash when BMP C105: Stabilized Construction Access is not preventing sed-
iment from being tracked off site.
• Wheel washing is generally an effective BMP when installed with careful attention to topo-
graphy. For example, a wheel wash can be detrimental if installed at the top of a slope abut-
ting a right-of-way where the water from the dripping truck can run unimpeded into the street.
• Pressure washing combined with an adequately sized and surfaced pad with direct drainage
to a large 10 -foot x 10 -foot sump can be very effective.
• Wheel wash wastewater is not stormwater. It is commonly called process water, and must be
discharged to a separate on-site treatment system that prevents discharge to waters of the
State, or to the sanitary sewer with local sewer district approval.
• Wheel washes may use closed-loop recirculation systems to conserve water use.
• Wheel wash wastewater shall not include wastewater from concrete washout areas.
• When practical, the wheel wash should be placed in sequence with BMP C105: Stabilized
Construction Access. Locate the wheel wash such that vehicles exiting the wheel wash will
enter directly onto BMP C105: Stabilized Construction Access. In order to achieve this, BMP
C105: Stabilized Construction Access may need to be extended beyond the standard install-
ation to meet the exit of the wheel wash.
Design and Installation Specifications
Suggested details are shown in Figure II -3.2: Wheel Wash. The Local Permitting Authority may
allow other designs. A minimum of 6 inches of asphalt treated base (ATB) over crushed base mater-
ial or 8 inches over a good subgrade is recommended to pave the wheel wash.
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Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will
work well to test clearance.
Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck
tongues with water.
Midpoint spray nozzles are only needed in extremely muddy conditions.
Wheel wash systems should be designed with a small grade change, 6- to 12 -inches for a 10 -foot -
wide pond, to allow sediment to flow to the low side of pond to help prevent re -suspension of sed-
iment. A drainpipe with a 2- to 3 -foot riser should be installed on the low side of the pond to allow for
easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation in a
closed-loop system. Polyacrylamide (PAM) added to the wheel wash water at a rate of 0.25 - 0.5
pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time. If PAM is
already being used for dust or erosion control and is being applied by a water truck, the same truck
can be used to change the wash water.
Maintenance Standards
The wheel wash should start out each day with fresh water.
The wheel wash water should be changed a minimum of once per day. On large earthworkjobs
where more than 10-20 trucks per hour are expected, the wheel wash water will need to be changed
more often.
Approved as Functionally Equivalent
Ecology has approved products as able to meet the requirements of this BMP. The products did not
pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions
may choose not to accept these products, or may require additional testing prior to consideration for
local use. Products that Ecology has approved as functionally equivalent are available for review on
Ecology's website at:
https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per-
mittee-quidance-resources/Emerging-stormwater-treatment-technoloqies
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Figure II -3.2: Wheel Wash
3" trash pump with
6" sewer pipe with A floats on suction hose
butterfly valves /-2" schedule 40
8'x 8' sump with 5' of catch � 1 %z " schedule 40 for sprayers
�— midpoint spray nozzles, if needed
2% slope 5:1 slope 5:1 slope
�► i 2% slope
1:1 slope y
6" ATB construction entrance
15' ATB apron to protect
ground from splashing water A Ball valves Asphalt curb on the low road
side to direct water back to pond
Plan View 6" sleeve under road
15' 15' 20' 15' 50'
6" sleeve
Locate invert of top pipe 1'
above bottom of wheel wash
8'x8'sump —,-
Drain pipe
Notes:
1. Build 8'x 8' sump to accomodate
cleaning by trackhoe.
�r f�
DEPARTMENT OF
ECOLOGY
Elevation View
18
Water level
3'
Curb
�12'
II 1:1 slope
Section A -A
Wheel Wash
NOT TO SCALE
Revised June 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
State of Washington limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 282
Crushed rock, gravel base, etc., shall be added as required to maintain a stable driving surface and
to stabilize any areas that have eroded.
Following construction, these areas shall be restored to pre -construction condition or better to pre-
vent future erosion.
Perform street cleaning at the end of each day or more often if necessary
BMP C120: Temporary and Permanent Seeding
Purpose
Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative cover is one of
the most effective methods of reducing erosion.
Conditions of Use
Use seeding throughout the project on disturbed areas that have reached final grade or that will
remain unworked for more than 30 days.
The optimum seeding windows for western Washington are April 1 through June 30 and September
1 through October 1.
Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is established.
Between October 1 and March 30 seeding requires a cover of mulch 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 pro-
tection.
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 sta-
bilization 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. See BMP T5.13: Post -Construction Soil
Qualitv and Depth.
Design and Installation Specifications
General
. Install channels intended for vegetation before starting major earthwork and hydroseed with a
Bonded Fiber Matrix. For vegetated channels that will have high flows, install erosion control
blankets over the top of hydroseed. Before allowing water to flow in vegetated channels,
establish 75 percent vegetation cover. If vegetated channels cannot be established by seed
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before water flow; install sod in the channel bottom — over top of hydromulch and erosion con-
trol blankets.
• 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 per-
cent 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. See BMP T5.13: Post -Construction Soil Quality
and Depth.
. 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:
o Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in
the first lift.
ID Phase 2- Install the rest of the mulch and tackifier over the first lift.
Or, enhance vegetation by:
Installing the mulch, seed, fertilizer, and tackifier in one lift.
o Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per
acre.
Hold straw in place with a standard tackifier.
Both of these approaches will increase cost moderately but will greatly improve and enhance
vegetative establishment. The increased cost may be offset by the reduced need for:
Irrigation.
o Reapplication of mulch.
Repair of failed slope surfaces.
This technique works with standard hydromulch (1,500 pounds per acre minimum) and Bon-
ded Fiber Matrix/ Mechanically Bonded Fiber Matrix (BFM/MBFMs) (3,000 pounds per acre
minimum).
Seed may be installed by hand if:
Temporary and covered by straw, mulch, or topsoil.
Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or
erosion blankets.
. The seed mixes listed in Table 11-3.4: Temporary and Permanent Seed Mixes include
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recommended mixes for both temporary and permanent seeding.
Apply these mixes, with the exception of the wet area seed mix, at a rate of 120 pounds per
acre. This rate can be reduced if soil amendments or slow-release fertilizers are used. Apply
the wet area seed mix at a rate of 60 pounds per acre.
Consult the local suppliers or the local conservation district for their recommendations. 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,
depending on the soil type and hydrology of the area.
Table II -3.4: Temporary and Permanent Seed Mixes
Common Name
Latin Name
% Weight
% Purity
% Germination
Temporary Erosion Control Seed Mix
A standard mix for areas requiring a temporary vegetative cover.
Chewings or
Festuca rubra var.
annual blue grass
commutate or Poa
40
98
90
anna
Perennial rye
Lolium perenne
50
98
90
Redtop or colonial
Agrostis alba or
5
92
85
bentgrass
Agrostis tenuis
White dutch clover
Trifolium repens
5
98
90
Landscaping Seed Mix
A recommended mix for landscaping seed.
Perennial rye blend
Lolium perenne
70
98
90
Chewings and red
Festuca rubra var.
fescue blend
commutate or Fes-
30
98
90
tuca rubra
Low -Growing Turf Seed Mix
A turf seed mix for dry situations where there is no need for watering. This mix requires very little main-
tenance.
Dwarf tall fescue
Festuca arundin-
45
98
90
(several varieties)
acea var.
Dwarf perennial
Lolium perenne
30
98
90
rye (Barclay)
var. barclay
Red fescue
Festuca rubra
20
98
90
Colonial bentgrass
Agrostis tenuis
5
98
90
Bioswale Seed Mix
A seed mix for bioswales and other intermittently wet areas.
Tall or meadow fes-
Festuca arundin-
75-80
98
90
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Table II -3.4: Temporary and Permanent Seed Mixes (continued)
Common Name
Latin Name
% Weight
% Purity
% Germination
acea or Festuca
cue
elatior
Seaside/Creeping
Agrostis palustris
10-15
92
85
bentgrass
Redtop bentgrass
Agrostis alba or
5-10
90
80
Agrostis gigantea
Wet Area Seed Mix
A low -growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wet-
lands. Consult Hydraulic Permit Authority (H PA) for seed mixes if applicable.
Tall or meadow fes-
Festuca arundin-
acea or Festuca
60-70
98
90
cue
elatior
Seaside/Creeping
Agrostis palustris
10-15
98
85
bentgrass
Meadow foxtail
Alepocurus praten-
10-15
90
80
sis
Alsike clover
Trifolium hybridum
1-6
98
90
Redtop bentgrass
Agrostis alba
1-6
92
85
Meadow Seed Mix
A recommended meadow seed mix for infrequently maintained areas or non -maintained areas where col-
onization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seed-
ing 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.
Redtop or Oregon
Agrostis alba or
bentgrass
Agrostis ore-
20
92
85
gonensis
Red fescue
Festuca rubra
70
98
90
White dutch clover
Trifolium repens
10
98
90
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,
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permanent areas shall use soil amendments to achieve organic matter and permeability per-
formance 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 (includ-
ing 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 agit-
ate, 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
with approximately 10 percent tackifier. Achieve a minimum of 95 percent soil coverage during
application. Numerous products are available commercially. Most products require 24-36
hours to cure before rainfall and cannot be installed on wet or saturated soils. Generally,
products come in 40-50 pound bags and include all necessary ingredients except for seed and
fertilizer.
• Install products per manufacturer's instructions.
• 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:1 V, blanket installers may require ropes and harnesses
for safety.
• Installing BFM and MBFMs can save at least $1,000 per acre compared to blankets.
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Maintenance Standards
Reseed any seeded areas that fail to establish at least 75 percent cover (100 percent cover for areas
that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such
as sodding, mulching, nets, or blankets.
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 run-
off.
Approved as Functionally Equivalent
Ecology has approved products as able to meet the requirements of this BMP. The products did not
pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions
may choose not to accept these products, or may require additional testing prior to consideration for
local use. Products that Ecology has approved as functionally equivalent are available for review on
Ecology's website at:
https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per-
mittee-guidance-resources/Emeraina-stormwater-treatment-technologies
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 are a 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.
During the wet season on slopes steeper than 3H:1 V 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, or kenaf;
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compost;
. or blends of these.
Tackifier shall be plant -based, such as guar or alpha plantago, or chemical -based such as poly-
acrylamide or polymers.
Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application.
Recycled cellulose may contain polychlorinated biphenyl (PCBs). Ecology recommends that
products should be evaluated for PCBs prior to use.
Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use. PAM
shall not be directly applied to water or allowed to enter a water body.
Any mulch or tackifier product used shall be installed per the manufacturer's instructions.
Design and Installation Specifications
For mulch materials, application rates, and specifications, see Table II -3.6: Mulch Standards and
Guidelines. Consult with the local supplier or the local conservation district for their recom-
mendations. Increase the application rate 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 size grad-
ations listed in Table II -3.5: Size Gradations of Compost as Mulch Material when tested in accord-
ance with Test Method 02.02-B found in Test Methods for the Examination of Composting and
Compost (Thompson, 2001).
Table II -3.5: Size Gradations of Compost as Mulch Material
Sieve Size
Percent Passing
3"
100%
1"
90%-100%
3/4"
70%-100%
1/4"
40%-100%
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 the Hydraulic Permit Authority (H PA) for
mulch mixes if applicable.
Maintenance Standards
The thickness of the mulch cover must be maintained.
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.
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Table II
-3.6: Mulch Standards and Guidelines
Mulch Mater-
Guideline
Description
ial
Quality
Air-dried; free from undesirable seed and coarse material.
Standards
Application
2"-3" thick; 5 bales per 1,000 sf or 2-3 tons per acre
Rates
Cost-effective protection when applied with adequate thickness. Hand -
application generally requires greater thickness than blown straw. The
Straw
thickness of straw may be reduced by half 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
Remarks
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 flot-
ation).
Quality
No growth inhibiting factors.
Standards
Application
Approx. 35-45 lbs per 1,000 sf or 1,500 - 2,000 lbs per acre
Hydromulch
Rates
Shall be applied with hydromulcher. Shall not be used without seed and
Remarks
tackifier unless the application rate is at least doubled. Fibers longer than
about 3/4 -1 inch clog hydromulch equipment. Fibers should be kept to less
than 3/4 inch.
Quality
No visible water or dust during handling. Must be produced per WAC 173 -
Standards
350, Solid Waste Handling Standards, but may have up to 35% biosolids.
Application
2" thick min.; approx. 100 tons per acre (approx. 750 lbs per cubic yard)
Rates
More effective control can be obtained by increasing thickness to 3". Excel -
Compost
lent mulch for protecting final grades until landscaping because it can be dir-
ectly seeded or tilled into soil as an amendment. Compost used for mulch
Remarks
has a coarser size gradation than compost used for BMP C125: Topsoiling
/ Composting or BMP T5.13: Post -Construction Soil Quality and Depth. It
is more stable and practical to use in wet areas and during rainy weather
conditions. Do not use near wetlands or near phosphorous impaired water
bodies.
Quality
Gradations from fines to 6 inches in length for texture, variation, and inter -
Chipped
Standards
locking properties. Include a mix of various sizes so that the average size
Site Veget-
is between 2- and 4- inches.
ation
Application
Rates
2" thick min.;
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Table 11-3.6: Mulch Standards and Guidelines (continued)
Mulch Mater-
Guideline
Description
ial
This is a cost-effective way to dispose of debris from clearing and grub-
bing, and it eliminates the problems associated with burning. Generally, it
should not be used on slopes above approx. 10% because of its tendency
to be transported by runoff. It is not recommended within 200 feet of sur -
Remarks
face waters. If permanent seeding or planting is expected shortly after
mulch, the decomposition of the chipped vegetation may tie up nutrients
important to grass establishment.
Note: thick application of this material over existing grass, herbaceous spe-
cies, and some groundcovers could smother and kill vegetation.
Quality
No visible water or dust during handling. Must be purchased from a supplier
Standards
with a Solid Waste Handling Permit or one exempt from solid waste reg-
ulations.
Application
2" thick min.; approx. 100 tons per acre (approx. 750 lbs. per cubic yard)
Wood-
Rates
Based
This material is often called "wood straw" or "hog fuel". The use of mulch
Mulch
ultimately improves the organic matter in the soil. Special caution is
Remarks
advised regarding the source and composition of wood -based mulches. Its
preparation typically does not provide any weed seed control, so evidence
of residual vegetation in its composition or known inclusion of weed plants
or seeds should be monitored and prevented (or minimized).
Quality
A blend of loose, long, thin wood pieces derived from native conifer or
Standards
deciduous trees with high length -to -width ratio.
Application
2" thick min.
Rates
Wood
Cost-effective protection when applied with adequate thickness. A min -
Strand
imum of 95 -percent of the wood strand shall have lengths between 2 and
Mulch
10 -inches, with a width and thickness between 1/16 and 1/2 -inches. The
Remarks
mulch shall not contain resin, tannin, or other compounds in quantities that
would be detrimental to plant life. Sawdust or wood shavings shall not be
used as mulch. [Specification 9-14.4(4) from the Standard Specifications
for Road, Bridge, and Municipal Construction (WSDOT, 2016)
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BMP C123: Plastic Covering
Purpose
Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas.
Conditions of Use
Plastic covering may be used on disturbed areas that require cover measures for less than 30 days,
except as stated below.
• Plastic is particularly useful for protecting cut and fill slopes and stockpiles. However, the rel-
atively rapid breakdown of most polyethylene sheeting makes it unsuitable for applications
greater than six months.
• 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.
. Although the plastic material is inexpensive to purchase, the cost of installation, maintenance,
removal, and disposal add to the total costs of this BMP.
. 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 convey
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:
• Temporary ditch liner.
• Pond liner in temporary sediment pond.
• Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel
being stored.
• Emergency slope protection during heavy rains.
• Temporary drainpipe ("elephant trunk") used to direct water.
Design and Installation Specifications
Plastic slope cover must be installed as follows:
1. Run plastic up and down the slope, not across the slope.
2. Plastic maybe installed perpendicular to a slope if the slope length is less than 10 feet.
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3. Provide a minimum of 8 -inch overlap at the seams.
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 Standards
• Torn sheets must be replaced and open seams repaired.
. Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radi-
ation.
• Completely remove plastic when no longer needed.
• Dispose of old tires used to weight down plastic sheeting appropriately.
Approved as Functionally Equivalent
Ecology has approved products as able to meet the requirements of this BMP. The products did not
pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions
may choose not to accept these products, or may require additional testing prior to consideration for
local use. Products that Ecology has approved as functionally equivalent are available for review on
Ecology's website at:
https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per-
mittee-guidance-resources/Emerging-stormwater-treatment-technologies
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BMP C125: Topsoiling / Composting
Purpose
Topsoiling and composting provide a suitable growth medium for final site stabilization with veget-
ation. While not a permanent cover practice in itself, topsoiling and composting are an integral com-
ponent 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 BMP C 120: Temporary and Per-
manent Seeding, BMP C121: Mulching, or BMP C124: Sodding. Implementation of this BMP may
meet the post -construction requirements of BMP T5.13: Post -Construction Soil Quality and Depth.
Native soils and disturbed soils that have been organically amended not only retain much more
stormwater, but also serve as effective biofilters for urban pollutants and, by supporting more vig-
orous plant growth, reduce the water, fertilizer and pesticides needed to support installed land-
scapes. Topsoil does not include any subsoils but only the material from the top several inches
including organic debris.
Conditions of Use
• Permanent landscaped areas shall contain healthy topsoil that reduces the need for fertilizers,
improves overall topsoil quality, provides for better vegetative health and vitality, improves
hydrologic characteristics, and reduces the need for irrigation.
. Leave native soils and the duff layer undisturbed to the maximum extent practicable. Stripping
of existing, properly functioning soil system and vegetation for the purpose of topsoiling during
construction is not acceptable. Preserve existing soil systems in undisturbed and uncom-
pacted conditions if functioning properly.
. Areas that already have good topsoil, such as undisturbed areas, do not require soil amend-
ments.
• Restore, to the maximum extent practical, native soils disturbed during clearing and grading to
a condition equal to or better than the original site condition's moisture -holding capacity. Use
on-site native topsoil, incorporate amendments into on-site soil, or import blended topsoil to
meet this requirement.
. Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of
critically low pH (high acid) levels.
• Beware of where the topsoil comes from, and what vegetation was on site before disturbance.
Invasive plant seeds may be included and could cause problems for establishing native plants,
landscaped areas, or grasses.
. Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root
growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will
provide optimum conditions for establishing grasses. Use commercially available mycorrhiza
products when using off-site topsoil.
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Design and Installation Specifications
Meet the following requirements for disturbed areas that will be developed as lawn or landscaped
areas at the completed project site:
Maximize the depth of the topsoil wherever possible to provide the maximum possible infilt-
ration capacity and beneficial growth medium. Topsoil shall have:
• A minimum depth of 8 -inches. Scarify subsoils below the topsoil layer at least 4 -inches
with some incorporation of the upper material to avoid stratified layers, where feasible.
Ripping or re -structuring the subgrade may also provide additional benefits regarding
the overall infiltration and interflow dynamics of the soil system.
• A minimum organic content of 10% dry weight in planting beds, and 5% organic matter
content in turf areas. Incorporate organic amendments to a minimum 8 -inch depth
except where tree roots or other natural features limit the depth of incorporation.
• A pH between 6.0 and 8.0 or matching the pH of the undisturbed soil.
• If blended topsoil is imported, then fines should be limited to 25 percent passing through
a 200 sieve.
• Mulch planting beds with 2 inches of organic material
. Accomplish the required organic content, depth, and pH by returning native topsoil to the site,
importing topsoil of sufficient organic content, and/or incorporating organic amendments.
When using the option of incorporating amendments to meet the organic content requirement,
use compost that meets the compost specification for Bioretention (See BMP T7.30: Biore-
tention), with the exception that the compost may have up to 35% biosolids or manure.
. Sections 3 through 7 of Building Soil. Guidelines and Resources for Implementing Soil Quality
and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington
(Stenn et al., 2016), provides useful guidance for implementing whichever option is chosen. It
includes guidance for pre -approved default strategies and guidance for custom strategies.
Check with your local jurisdiction concerning its acceptance of this guidance.
• The final composition and construction of the soil system will result in a natural selection or
favoring of certain plant species over time. For example, incorporation of topsoil may favor
grasses, while layering with mildly acidic, high -carbon amendments may favor more woody
vegetation.
. Allow sufficient time in scheduling for topsoil spreading prior to seeding, sodding, or planting.
• Take care when applying top soil to subsoils with contrasting textures. Sandy topsoil over
clayey subsoil is a particularly poor combination, as water creeps along the junction between
the soil layers and causes the topsoil to slough. If topsoil and subsoil are not properly bonded,
water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The
best method to promote bonding is to actually work the topsoil into the layer below for a depth
of at least 6 inches.
• Field exploration of the site shall be made to determine if there is surface soil of sufficient
quantity and quality to justify stripping. Topsoil shall be friable and loamy (loam, sandy loam,
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silt loam, sandy clay loam, and clay loam). Avoid areas of natural ground water recharge.
. Stripping shall be confined to the immediate construction area. A 4 -inch to 6 -inch stripping
depth is common, but depth may vary depending on the particular soil. All surface runoff con-
trol structures shall be in place prior to stripping.
• Do not place topsoil while in a frozen or muddy condition, when the subgrade is excessively
wet, or when conditions exist that may otherwise be detrimental to proper grading or pro-
posed sodding or seeding.
. In any areas requiring grading, remove and stockpile the duff layer and topsoil on site in a des-
ignated, controlled area, not adjacent to public resources and critical areas. Reapply stock-
piled topsoil to other portions of the site where feasible.
• Locate the topsoil stockpile so that it meets specifications and does not interfere with work on
the site. It may be possible to locate more than one pile in proximity to areas where topsoil will
be used.
. Stockpiling of topsoil shall occur in the following manner:
o Side slopes of the stockpile shall not exceed 2H:1 V.
o Between October 1 and April 30:
■ An interceptor dike with gravel outlet and silt fence shall surround all topsoil.
■ Within 2 days complete erosion control seeding, or covering stockpiles with clear
plastic, or other mulching materials.
Between May 1 and September 30:
■ An interceptor dike with gravel outlet and silt fence shall surround all topsoil if the
stockpile will remain in place for a longer period of time than active construction
grading.
■ Within 7 days complete erosion control seeding, or covering stockpiles with clear
plastic, or other mulching materials.
When native topsoil is to be stockpiled and reused the following should apply to ensure that
the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed:
o Re -install topsoil within 4 to 6 weeks.
o Do not allow the saturation of topsoil with water.
Do not use plastic covering.
Maintenance Standards
Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have
eroded.
Establish soil quality and depth toward the end of construction and once established, protect
from compaction, such as from large machinery use, and from erosion.
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Plant and mulch soil after installation.
Leave plant debris or its equivalent on the soil surface to replenish organic matter.
Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides,
rather than continuing to implement formerly established practices.
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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
Use dust control in areas (including roadways) subject to surface and air movement of dust where
on-site or off-site impacts to roadways, drainage ways, or surface waters are likely.
Design and Installation Specifications
. Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulching,
or paving is impractical, apply gravel or landscaping rock.
• Limit dust generation by clearing only those areas where immediate activity will take place,
leaving the remaining area(s) in the original condition. Maintain the original ground cover as
long as practical.
• Construct natural or artificial windbreaks or windscreens. These may be designed as enclos-
ures for small dust sources.
. Sprinkle the site with water until the surface is wet. Repeat as needed. To prevent carryout of
mud onto the street, refer to BMP C 105: Stabilized Construction Access and BMP C 106:
Wheel Wash.
. 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 sup-
pressant. Local governments may approve other dust palliatives such as calcium chloride or
PAM.
• PAM (BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection) added to water at a rate
of 0.5 pounds per 1,000 gallons of water per acre and applied from a water truck is more effect-
ive 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 trans-
ported by wind. Adding PAM may reduce the quantity of water needed for dust control. Note
that the application rate specified here applies to this BMP, and is not the same application
rate that is specified in BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection, but the
downstream protections still apply.
Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use.
PAM shall not be directly applied to water or allowed to enter a water body.
. Contact your local Air Pollution Control Authority for guidance and training on other dust con-
trol measures. Compliance with the local Air Pollution Control Authority constitutes
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compliance with this BMP.
• Use vacuum street sweepers.
• Remove mud and other dirt promptly so it does not dry and then turn into dust.
. 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.
• Use geotextile fabrics to increase the strength of new roads or roads undergoing recon-
struction.
• Encourage the use of alternate, paved routes, if available.
• 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.
• Limit dust -causing work on windy days.
• Pave unpaved permanent roads and other trafficked areas.
Maintenance Standards
Respray area as necessary to keep dust to a minimum.
BMP C150: Materials on Hand
Purpose
Keep quantities of erosion prevention and sediment control materials on the project site at all times
to be used for regular maintenance and emergency situations such as unexpected heavy rains. Hav-
ing these materials on-site reduces the time needed to replace existing or implement new BMPs
when inspections indicate that existing BMPs are not meeting the Construction SWPPP require-
ments. 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
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pipe, sandbags, geotextile fabric and steel "T" posts.
• Materials should be stockpiled and readily available before any site clearing, grubbing, or
earthwork begins. A large contractor or project proponent 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.
Design and Installation Specifications
Depending on project type, size, complexity, and length, materials and quantities will vary. A good
minimum list of items that will cover numerous situations includes:
. Clear Plastic, 6 mil
• Drainpipe, 6 or 8 inch diameter
• Sandbags, filled
• Straw Bales for mulching
. Quarry Spalls
. Washed Gravel
• Geotextile Fabric
. Catch Basin Inserts
. Steel "T" Posts
• Silt fence material
• Straw Wattles
Maintenance Standards
. All materials with the exception of the quarry spalls, steel "T" posts, and gravel should be kept
covered and out of both sun and rain.
• Re -stock materials 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 dis-
charge to waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, con-
crete process water, and concrete slurry from entering waters of the State.
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Conditions of Use
Any time concrete is used, utilize these management practices. Concrete construction project com-
ponents include, but are not limited to:
• Curbs
• Sidewalks
. Roads
• Bridges
• Foundations
• Floors
• Runways
Disposal options for concrete, in order of preference are:
1. Off-site disposal
2. Concrete wash-out areas (see BMP C154: Concrete Washout Area)
3. De minimus washout to formed areas awaiting concrete
Design and Installation Specifications
Wash concrete truck drums at an approved off-site location or in designated concrete
washout areas only. Do not wash out concrete trucks onto the ground (including formed areas
awaiting concrete), or into storm drains, open ditches, streets, or streams. Refer to BMP
C1 54: Concrete Washout Area 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 as allowed in BMP C154: Concrete Washout Area.
. Wash small concrete handling equipment (e.g. hand tools, screeds, shovels, rakes, floats,
trowels, and wheelbarrows) into designated concrete washout areas or into formed areas
awaiting concrete pour.
. At no time shall concrete be washed off into the footprint of an area where an infiltration fea-
ture will be installed.
. Wash equipment difficult to move, such as concrete paving machines, in areas that do not dir-
ectly drain to natural or constructed stormwater conveyance or potential infiltration areas.
• Do not allow washwater from areas, such as concrete aggregate driveways, to drain directly
(without detention or treatment) to natural or constructed stormwater conveyances.
• Contain washwater and leftover product in a lined container when no designated concrete
washout areas (or formed areas, allowed as described above) are available. Dispose of con-
tained concrete and concrete washwater (process water) properly.
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. Always use forms or solid barriers for concrete pours, such as pilings, within 15 -feet of surface
waters.
Refer to BMP C252: Treating and Disposing of High pH Water for pH adjustment require-
ments.
Refer to the Construction Stormwater General Permit (CSWGP) for pH monitoring require-
ments if the project involves one of the following activities:
Significant concrete work (as defined in the CSWGP)
The use of soils amended with (but not limited to) Portland cement -treated base,
cement kiln dust or fly ash.
Discharging stormwater to segments of water bodies on the 303(d) list (Category 5) for
high pH.
Maintenance Standards
Check containers for holes in the liner daily during concrete pours and repair the same day.
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 waters of the State is prohibited. Use this BMP to
minimize and eliminate process water and slurry created through sawcutting or surfacing from enter-
ing waters of the State.
Conditions of Use
Utilize these management practices anytime sawcutting or surfacing operations take place. Saw -
cutting and surfacing operations include, but are not limited to:
• Sawing
• Coring
• Grinding
• Roughening
• Hydro -demolition
• Bridge and road surfacing
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Design and Installation Specifications
. Vacuum slurry and cuttings during cutting and surfacing operations.
. Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight.
. Slurry and cuttings shall not drain to any natural or constructed drainage conveyance includ-
ing 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 sur-
face 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 of process water in a manner that does not violate ground water or surface
water quality standards.
• Handle and dispose of cleaning waste material and demolition debris in a manner that does
not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at an
appropriate disposal site.
Maintenance Standards
Continually monitor operations to determine whether slurry, cuttings, or process water could enter
waters of the state. If inspections show that a violation of water quality standards could occur, stop
operations and immediately implement preventive measures such as berms, barriers, secondary
containment, and/or vacuum trucks.
BMP C153: Material Delivery, Storage, and
Containment
Purpose
Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or watercourses
from material delivery and storage. Minimize the storage of hazardous materials on-site, store mater-
ials in a designated area, and install secondary containment.
Conditions of Use
Use at construction sites with delivery and storage of the following materials:
• Petroleum products such as fuel, oil and grease
• Soil stabilizers and binders (e.g., Polyacrylamide)
• Fertilizers, pesticides and herbicides
• Detergents
. Asphalt and concrete compounds
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• Hazardous chemicals such as acids, lime, adhesives, paints, solvents, and curing compounds
. Any other material that maybe detrimental if released to the environment
Design and Installation Specifications
. The temporary storage area should be located away from vehicular traffic, near the con-
struction entrance(s), and away from waterways or storm drains.
• Safety Data Sheets (SDS) should be supplied for all materials stored. Chemicals should be
kept in their original labeled containers.
• Hazardous material storage on-site should be minimized.
• Hazardous materials should be handled as infrequently as possible.
• During the wet weather season (Oct 1 —April 30), consider storing materials in a covered
area.
. Materials should be stored in secondary containments, such as an earthen dike, horse trough,
or even a children's wading pool for non-reactive materials such as detergents, oil, grease,
and paints. Small amounts of material may be secondarily contained in "bus boy" trays or con-
crete mixing trays.
• Do not store chemicals, drums, or bagged materials directly on the ground. Place these items
on a pallet and, when possible, within secondary containment.
. If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater
on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of
drums, preventing water from collecting.
• Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be
stored in approved containers and drums and shall not be overfilled. Containers and drums
shall be stored in temporary secondary containment facilities.
• Temporary secondary containment facilities shall provide for a spill containment volume able
to contain 10% of the total enclosed container volume of all containers, or 110% of the capa-
city of the largest container within its boundary, whichever is greater.
. Secondary containment facilities shall be impervious to the materials stored therein for a min-
imum contact time of 72 hours.
• Sufficient separation should be provided between stored containers to allow for spill cleanup
and emergency response access.
• During the wet weather season (Oct 1 —April 30), each secondary containment facility shall
be covered during non -working days, prior to and during rain events.
• Keep material storage areas clean, organized and equipped with an ample supply of appro-
priate spill clean-up material (spill kit).
. The spill kit should include, at a minimum:
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1 -Water Resistant Nylon Bag
o 3 -Oil Absorbent Socks 3" x 4'
2 -Oil Absorbent Socks 3" x 10'
12 -Oil Absorbent Pads 17"x19"
1 -Pair Splash Resistant Goggles
3 -Pair Nitrile Gloves
0 10 -Disposable Bags with Ties
Instructions
Maintenance Standards
• Secondary containment facilities shall be maintained free of accumulated rainwater and spills.
In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed
into drums. These liquids shall be handled as hazardous waste unless testing determines
them to be non -hazardous.
• Re -stock spill kit materials as needed.
BMP C154: Concrete Washout Area
Purpose
Prevent or reduce the discharge of pollutants from concrete waste to stormwater by conducting
washout off-site, or performing on-site washout in a designated area.
Conditions of Use
Concrete washout areas 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 truck drums are washed on-site.
Note that auxiliary concrete truck components (e.g. chutes and hoses) and small concrete
handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheel-
barrows) may be washed into formed areas awaiting concrete pour.
At no time shall concrete be washed off into the footprint of an area where an infiltration feature will
be installed.
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Design and Installation Specifications
Implementation
. Perform washout of concrete truck drums at an approved off-site location or in designated con-
crete washout areas only.
• Do not wash out concrete onto non -formed areas, or into storm drains, open ditches, streets,
or streams.
• Wash equipment difficult to move, such as concrete paving machines, in areas that do not dir-
ectly drain to natural or constructed stormwater conveyance or potential infiltration areas.
• Do not allow excess concrete to be dumped on-site, except in designated concrete washout
areas as allowed above.
. 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.
• Concrete washout areas shall be constructed and maintained in sufficient quantity and size to
contain all liquid and concrete waste generated by washout operations.
Education
• Discuss the concrete management techniques described in this BMP with the ready -mix con-
crete supplier before any deliveries are made.
• Educate employees and subcontractors on the concrete waste management techniques
described in this BMP.
. Arrange for the 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 concrete washout area to inform concrete equip-
ment operators to utilize the proper facilities.
Contracts
Incorporate requirements for concrete waste management into concrete supplier and subcontractor
agreements.
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Location and Placement
• Locate concrete washout areas at least 50 feet from sensitive areas such as storm drains,
open ditches, water bodies, or wetlands.
. Allow convenient access to the concrete washout area for concrete trucks, preferably near the
area where the concrete is being poured.
. If trucks need to leave a paved area to access the concrete washout area, prevent track -out
with a pad of rock or quarry spalls (see BMP C 105: Stabilized Construction Access). These
areas should be far enough away from other construction traffic to reduce the likelihood of acci-
dental damage and spills.
• The number of concrete washout areas you install should depend on the expected demand
for storage capacity.
• On large sites with extensive concrete work, concrete washout areas should be placed in mul-
tiple locations for ease of use by concrete truck drivers.
Concrete Truck Washout Procedures
Washout of concrete truck drums shall be performed in designated concrete washout areas
only.
Concrete washout from concrete pumper bins can be washed into concrete pumper trucks
and discharged into designated concrete washout areas or properly disposed of off-site.
Concrete Washout Area Installation
. Concrete washout areas should be constructed as shown in the figures below, with a recom-
mended 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.
• Lath and flagging should be commercial type.
• Liner seams shall be installed in accordance with manufacturers' recommendations.
• Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the
plastic lining material.
Maintenance Standards
Inspection and Maintenance
• Inspect and verify that concrete washout areas are in place prior to the commencement of con-
crete work.
. Once concrete wastes are washed into the designated washout area and allowed to harden,
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the concrete should be broken up, removed, and disposed of per applicable solid waste reg-
ulations. Dispose of hardened concrete on a regular basis.
• During periods of concrete work, inspect the concrete washout areas daily to verify continued
performance.
Check overall condition and performance.
Check remaining capacity (% full).
• If using self -installed concrete washout areas, verify plastic liners are intact and side-
walls are not damaged.
• If using prefabricated containers, check for leaks.
• Maintain the concrete washout areas to provide adequate holding capacity with a minimum
freeboard of 12 inches.
. Concrete washout areas must be cleaned, or new concrete washout areas must be con-
structed and ready for use once the concrete washout area is 75% full.
If the concrete washout area 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 discharge to the sanitary sewer without local approval.
• Place a secure, non -collapsing, non -water collecting cover over the concrete washout
area prior to predicted wet weather to prevent accumulation and overflow of pre-
cipitation.
• Remove and dispose of hardened concrete and return the structure to a functional con-
dition. Concrete may be reused on-site or hauled away for disposal or recycling.
When you remove materials from a self -installed concrete washout area, build a new struc-
ture; 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 Concrete Washout Areas
• When concrete washout areas are no longer required for the work, the hardened concrete,
slurries and liquids shall be removed and properly disposed of.
• Materials used to construct concrete washout areas 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 concrete
washout areas shall be backfilled, repaired, and stabilized to prevent erosion.
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Figure II -3.7: Concrete Washout Area with Wood Planks
Plan
Lath and flagging
on 3 sides
Sandbag
3erm —\T Sandbag
10 mil plastic lining
Fj
1m
lining
Berm
Section A -A
Notes:
1. Actual layout
determined in the field
Type"Below Grade" 2. A concrete washout
sign shall be installed
within 10 m of the
temporary concrete
washout facility.
Wood frame
B securely fastened
around entire
perimeter with two
stakes
10 mil
f plastic lining
Stake (typ.)
iil plastic lining
2x12 rough Plan
wood frame
Tvae "Above Grade" with Wood Planks
NOT TO SCALE
Concrete Washout Area with Wood Planks
Revised June 2016
DEPARTMENT OF
ECOLOGY please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
State of Washington limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 324
Figure II -3.8: Concrete Washout Area with Straw Bales
Straw bale
U 915 mm
Concrete Washout Sign
Detail
(or equivalent)
10 mil plastic lining
Binding wire
Staples
Native material
(2 per bale)
(optional)
■
Wood or
Plywood
metal stakes
1200 mm x 610 mm
Wood post
(2 per bale)
painted white
(89 mm x 89 mm
Lag screws
x 2.4 m)
Section 13-13(12.5
mm) i !CONCRETEI
Black letters
j I wasHouT I l
o
150 mm height
915 mm 1
3m Minimum
Stake (typ)
13L
Varies
Straw bale J
(typ•)
DEPARTMENT OF
ECOLOGY
State of Washington
Plan
U
U 915 mm
Concrete Washout Sign
Detail
(or equivalent)
■
Straw bale J
(typ•)
DEPARTMENT OF
ECOLOGY
State of Washington
Plan
U
U 915 mm
Concrete Washout Sign
Detail
(or equivalent)
10 mil plastic lining
t -0 50 mm
200 mm II S 3.05 mm dia.
f I steel wire
Staple Detail
Notes:
1. Actual layout
determined in the field.
2. The concrete washout
sign shall be installed
within 10 m of the
temporary concrete
washout facility.
Type "Above Grade" with Straw Bales
NOT TO SCALE
Concrete Washout Area with Straw Bales
Revised June 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 325
Figure 11-3.9: Prefabricated Concrete Washout Container w/Ramp
DEPARTMENT OF
ECOLOGY
State of Washington
NOT TO SCALE
Prefabricated Concrete Washout Container
w/Ramp
Revised June 2016
Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11- Chapter 3 - Page 326
BMP C160: Certified Erosion and Sediment Control
Lead
Purpose
The project proponent designates at least one person as the responsible representative in charge of
erosion and sediment control (ESC), and water quality protection. The designated person shall be
responsible for ensuring compliance with all local, state, and federal erosion and sediment control
and water quality requirements. Construction sites one acre or larger that discharge to waters of the
State must designate a Certified Erosion and Sediment Control Lead (CESCL) as the responsible
representative.
Conditions of Use
A CESCL shall be made available on projects one acre or larger that discharge stormwater to sur-
face waters of the state. Sites less than one acre may have a person without CESCL certification
conduct inspections.
The CESCL shall:
Have a current certificate proving attendance in an erosion and sediment control training
course that meets the minimum ESC training and certification requirements established by
Ecology.
Ecology has provided the minimum requirements for CESCL course training, as well as a list
of ESC training and certification providers at:
https://ecology.wa.gov/Regulations-Permits/Permits-certifications/Certified-erosion-sed-
imPnt-r.nntrol
OR
Be a Certified Professional in Erosion and Sediment Control (CPESC). For additional inform-
ation go to:
http://www.envirocertintl.org/cpesc/
Specifications
. CESCL certification shall remain valid for three years.
. The CESCL shall have authority to act on behalf of the contractor or project proponent and
shall be available, or on-call, 24 hours per day throughout the period of construction.
. The Construction SWPPP shall include the name, telephone number, fax number, and
address of the designated CESCL. See II -2 Construction Stormwater Pollution Prevention
Plans (Construction SWPPPs).
. A CESCL may provide inspection and compliance services for multiple construction projects
in the same geographic region, but must be on site whenever earthwork activities are
2019 Stormwater Management Manual for Western Washington
Volume // - Chapter 3 - Page 327
occurring that could generate release of turbid water.
Duties and responsibilities of the CESCL shall include, but are not limited to the following:
• Maintaining a permit file on site at all times which includes the Construction SWPPP
and any associated permits and plans.
• Directing BMP installation, inspection, maintenance, modification, and removal.
• Updating all project drawings and the Construction SWPPP with changes made.
• Completing any sampling requirements including reporting results using electronic Dis-
charge Monitoring Reports (WebDMR).
• Facilitate, participate in, and take corrective actions resulting from inspections per-
formed by outside agencies or the owner.
• Keeping daily logs, and inspection reports. Inspection reports should include:
■ Inspection date/time.
■ Weather information; general conditions during inspection and approximate
amount of precipitation since the last inspection.
■ Visual monitoring results, including a description of discharged stormwater. The
presence of suspended sediment, turbid water, discoloration, and oil sheen shall
be noted, as applicable.
■ Any water quality monitoring performed during inspection.
■ General comments and notes, including a brief description of any BMP repairs,
maintenance or installations made as a result of the inspection.
■ A summary or list of all BMPs implemented, including observations of all
erosion/sediment control structures or practices. The following shall be noted:
1. Locations of BMPs inspected.
2. Locations of BMPs that need maintenance.
3. Locations of BMPs that failed to operate as designed or intended.
4. Locations of where additional or different BMPs are required.
BMP C162: Scheduling
Purpose
Sequencing a construction project reduces the amount and duration of soil exposed to erosion by
wind, rain, runoff, and vehicle tracking.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 328
Conditions of Use
The construction sequence schedule is an orderly listing of all major land -disturbing activities
together with the necessary erosion and sedimentation control measures planned for the project.
This type of schedule guides the contractor on work to be done before other work is started so that
serious erosion and sedimentation problems can be avoided.
Following a specified work schedule that coordinates the timing of land -disturbing activities and the
installation of control measures is perhaps the most cost-effective way of controlling erosion during
construction. The removal of ground cover leaves a site vulnerable to erosion. Construction sequen-
cing that limits land clearing, provides timely installation of erosion and sedimentation controls, and
restores protective cover quickly can significantly reduce the erosion potential of a site.
Design Considerations
. Minimize construction during rainy periods.
Schedule projects to disturb only small portions of the site at any one time. Complete grading
as soon as possible. Immediately stabilize the disturbed portion before grading the next por-
tion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses.
11-3.3 Construction Runoff BMPs
BMP C200: Interceptor Dike and Swale
Purpose
Provide a dike of compacted soil or a swale at the top or base of a disturbed slope or along the peri-
meter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept
the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can
prevent storm runoff from entering the work area or sediment -laden runoff from leaving the con-
struction site.
Conditions of Use
Use an interceptor dike or swale where runoff from an exposed site or disturbed slope must be con-
veyed to an erosion control BMP which can safely convey the stormwater.
. Locate upslope of a construction site to prevent runoff from entering the disturbed area.
. When placed horizontally across a disturbed slope, it reduces the amount and velocity of run-
off flowing down the slope.
Locate downslope to collect runoff from a disturbed area and direct it to a sediment BMP (e.g.
BMP C240: Sediment Trap or BMP C241: Sediment Pond (Temporary)).
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 329
Design and Installation Specifications
• Dike and/or swale and channel must be stabilized with temporary or permanent vegetation or
other channel protection during construction.
• Steep grades require channel protection and check dams.
• Review construction for areas where overtopping may occur.
• Can be used at the top of new fill before vegetation is established.
• May be used as a permanent diversion channel to carry the runoff.
. Contributing area for an individual dike or swale should be one acre or less.
• Design the dike and/or swale to contain flows calculated by one of the following methods:
• Single Event Hydrograph Method: The peak volumetric flow rate calculated using a 10 -
minute time step from a Type 1A, 10 -year, 24-hour frequency storm for the worst-case
land cover condition.
OR
• Continuous Simulation Method: The 10 -year peak flow rate, as determined by an
approved continuous runoff model with a 15 -minute time step for the worst-case land
cover condition.
Worst-case land cover conditions (i.e., producing the most runoff) should be used for analysis
(in most cases, this would be the land cover conditions just prior to final landscaping).
Interceptor Dikes
Interceptor dikes shall meet the following criteria:
. Top Width: 2 feet minimum.
• Height: 1.5 feet minimum on berm.
• Side Slope: 2H:1V or flatter.
. Grade: Depends on topography, however, dike system minimum is 0.5%, and maximum is
1 %.
• Compaction: Minimum of 90 percent ASTM D698 standard proctor.
• Stabilization: Depends on velocity and reach. Inspect regularly to ensure stability.
. Ground Slopes <5%: Seed and mulch applied within 5 days of dike construction (see BMP
C121: Mulching).
• Ground Slopes 5 - 40%: Dependent on runoff velocities and dike materials. Stabilization
should be done immediately using either sod or riprap, or other measures to avoid erosion.
. The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 330
occur at the outlet. Provide energy dissipation measures as necessary. Sediment -laden runoff
must be released through a sediment trapping facility.
Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel
crossing.
. See Table II -3.8: Horizontal Spacing of Interceptor Dikes Along Ground Slope for recom-
mended horizontal spacing between dikes.
Table II -3.8: Horizontal Spacing of
Interceptor Dikes Along Ground
Slope
Average Slope
Slope Percent
Flowpath Length
20H:1 V or less
3-5%
300 feet
(10 to 20)H:1 V
5-10%
200 feet
(4 to 10)H:1 V
10-25%
100 feet
(2 to 4)H:1V
25-50%
50 feet
Interceptor Swales
Interceptor swales shall meet the following criteria:
Bottom Width: 2 feet minimum; the cross-section bottom shall be level.
Depth: 1 -foot minimum.
. Side Slope: 2H:1 V or flatter.
. Grade: Maximum 5 percent, with positive drainage to a suitable outlet (such as BMP C241:
Sediment Pond (Temporary)).
Stabilization: Seed as per BMP C120: Temporary and Permanent Seeding, or BMP C202:
Riprap Channel Lining, 12 inches thick riprap pressed into the bank and extending at least 8
inches vertical from the bottom.
Maintenance Standards
. Inspect diversion dikes and interceptor swales once a week and after every rainfall. Imme-
diately remove sediment from the flow area.
Damage caused by construction traffic or other activity must be repaired before the end of
each working day.
Check outlets and make timely repairs as needed to avoid gully formation. When the area
below the temporary diversion dike is permanently stabilized, remove the dike and fill and sta-
bilize the channel to blend with the natural surface.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 331
BMP C201: Grass -Lined Channels
Purpose
To provide a channel with a vegetative lining for conveyance of runoff. The purpose of the vegetative
lining is to prevent transport of sediment and erosion.
Conditions of Use
This practice applies to construction sites where concentrated runoff needs to be directed to prevent
erosion or flooding.
Use this BMP when a vegetative lining can provide sufficient stability for the channel cross sec-
tion and at lower velocities of water (normally dependent on grade). This means that the chan-
nel slopes are generally less than 5 percent and space is available for a relatively large cross
section.
. Typical uses include roadside ditches, channels at property boundaries, outlets for diversions,
and other channels and drainage ditches in low areas.
Channels that will be vegetated should be installed before major earthwork and hydroseeded
with a bonded fiber matrix (BFM). The vegetation should be well established (i.e., 75 percent
cover) before water is allowed to flow in the ditch unless BMP C 122: Nets and Blankets is
used to protect the channel. With channels that will have high flows, erosion control blankets
should be installed over the hydroseed. If vegetation cannot be established from seed before
water is allowed in the ditch, sod should be installed in the bottom of the ditch in lieu of hydro -
mulch and blankets.
Design and Installation Specifications
See Figure II -3.10: Typical Grass -Lined Channels
Locate channels where they can conform to the topography and other features such as roads. Use
natural drainage systems to the greatest extent possible
. Avoid sharp changes in alignment or bends and changes in grade.
Do not reshape the landscape to fit the drainage channel.
The maximum design velocity shall be based on soil conditions, type of vegetation, and
method of revegetation, but at no time shall velocity exceed 5 feet/second. The channel shall
not be overtopped by the peak volumetric flow rate calculated by one of the following meth-
ods:
Single Event Hydrograph Method: The peak volumetric flow rate calculated using a 10 -
minute time step from a Type 1A, 10 -year, 24-hour frequency storm for the worst-case
land cover condition.
o Continuous Simulation Method: The 10 -year peak flow rate, as determined by an
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 332
approved continuous runoff model with a 15 -minute time step for the worst-case land
cover condition..
Worst-case land cover conditions (i.e., producing the most runoff) should be used for analysis
(in most cases, this would be the land cover conditions just prior to final landscaping).
. Where the grass -lined channel will also function as a permanent stormwater conveyance facil-
ity, consult the drainage conveyance requirements of the local jurisdiction.
. An established grass or vegetated lining is required before the channel can be used to convey
stormwater, unless stabilized with nets or blankets (See BMP C122: Nets and Blankets).
. If design velocity of a channel to be vegetated by seeding exceeds 2 ft/sec, a temporary chan-
nel liner is required. Geotextile or special mulch protection such as fiberglass roving or straw
and netting provides stability until the vegetation is fully established. See Figure II -3.11: Tem-
porary Channel Liners.
• Check dams shall be removed when the grass has matured sufficiently to protect the ditch or
swale unless the slope of the swale is greater than 4 percent. The area beneath the check
dams shall be seeded and mulched immediately after dam removal.
. If vegetation is established by sodding, the permissible velocity for established vegetation may
be used and no temporary liner is needed.
. Do not subject the grass -lined channel to sedimentation from disturbed areas. Use sediment -
trapping BMPs upstream of the channel.
. V-shaped grass channels generally apply where the quantity of water is small, such as in short
reaches along roadsides. The V-shaped cross section is least desirable because it is difficult
to stabilize the bottom where velocities may be high.
. Trapezoidal grass channels are used where runoff volumes are large and slope is low so that
velocities are nonerosive to vegetated linings. (Note: it is difficult to construct small parabolic
shaped channels.)
• Subsurface drainage or riprap channel bottoms may be necessary on sites that are subject to
prolonged wet conditions due to long duration flows or a high water table.
• Provide outlet protection at culvert ends and at channel intersections.
. Grass channels, at a minimum, should carry peak runoff for temporary construction drainage
facilities from the 10 -year, 24-hour storm without eroding. Where flood hazard exists, increase
the capacity according to the potential damage.
. Grassed channel side slopes generally are constructed 3H:1 V or flatter to aid in the estab-
lishment of vegetation and for maintenance.
. Construct channels a minimum of 0.2 foot larger around the periphery to allow for soil bulking
during seedbed preparations and sod buildup.
Maintenance Standards
During the establishment period, check grass -lined channels after every rainfall.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 333
. After grass is established, periodically check the channel; check it after every heavy rainfall
event. Immediately make repairs.
Check the channel outlet and all road crossings for bank stability and evidence of piping or
scour holes.
Remove all significant sediment accumulations to maintain the designed carrying capacity.
Keep the grass in a healthy, vigorous condition at all times, since it is the primary erosion pro-
tection for the channel.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 334
Figure II -3.10: Typical Grass -Lined Channels
Tvoical V -Shaped Channel Cross -Section
With Rock
Center y�A
(
\/\�/�\// \\\ ��\r 150-2 Fabric)
Grass -Lined
Filter Fabric
Typical Parabolic Channel Cross -Section
With Rock Center
for Base Flow
6" - 9"
(150-225mm) /
With Channel Key in Fabric\� Filter Fabric
Liner
Typical Trapezoidal Channel Cross -Section
Overcut channel 2" (50mm) to allow
bulking during seedbed preparation
and growth of vegetation.
DEPARTMENT OF
ECOLOGY
State of Washington
Filter Fabric
With Rock Center
for Base Flow
NOT TO SCALE
Typical Grass -Lined Channels
Revised June 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 335
Figure II -3.11: Temporary Channel Liners
Overlap 6"
(150mm) minimum
Excavate channel
to design grade
and cross section
Design Depth •,
Overcut channel 2' (50mm) to allow
bulking during seedbed preparation
P -
P Typical installation with
erosion control blankets
or turf reinforcement mats
Intermittent Check Slot Longitudinal Anchor Trench
Shingle -lap spliced ends or begin
new roll in an intermittent check slot
Prepare soil and apply seed before I
installing blankets, mats, or other r{' u_
temporary channel liner system
Notes: /
1. Design velocities exceeding 2 ft/sec
m/sec) require temporary blankets, mats,
or similar liners to protect seed and soil
until vegetation becomes established.
2. Grass -lined channels with design velocities
exceeding 6 ft/sec (2 m/sec) should include
turf reinforcement mats.
DEPARTMENT OF
ECOLOGY
State of Washington
Temporary Channel Liners
Longitudinal
anchor trench
NOT TO SCALE
Revised July 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 336
BMP C207: Check Dams
Purpose
Construction of check dams across a swale or ditch reduces the velocity of concentrated flow and dis-
sipates energy at the check dam.
Conditions of Use
Use check dams where temporary 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.
Design and Installation Specifications
• 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 (do not dump the rock to form the 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 check dam should form a triangle when viewed from the side. This prevents undercutting
as water flows over the face of the check dam rather than falling directly onto the ditch bottom.
• 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 combined with sumps work more effectively at slowing flow and retaining sed-
iment than 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 install-
ations with very minor regrading. They may be left as either spillways, in which case accu-
mulated sediment would be graded and seeded, or as check dams to prevent further
sediment from leaving the site.
• The maximum spacing between check dams shall be such that the downstream toe of the
2019 Stormwater Management Manual for Western Washington
Volume 11- Chapter 3 - Page 351
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 check 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: 1 V 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.
• See Figure II -3.16: Rock Check Dam.
Maintenance Standards
Check dams shall be monitored for performance and sediment accumulation during and after each
rainfall that produces runoff. 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. See BMP C202: Riprap Channel Lining.
Approved as Functionally Equivalent
Ecology has approved products as able to meet the requirements of this BMP. The products did not
pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions
may choose not to accept these products, or may require additional testing prior to consideration for
local use. Products that Ecology has approved as functionally equivalent are available for review on
Ecology's website at:
httos://ecoloay.wa.aov/Reaulations-Permits/Guidance-technical-assistance/Stormwater-Der-
mittee-auidance-resources/Emeraina-stormwater-treatment-technoloaies
2019 Stormwater Management Manual for Western Washington
Volume 11- Chapter 3 - Page 352
Figure 11-3.16: Rock Check Dam
View Looking Upstream
A 18"
12" (0.5m)
(150mm)
Note:
Key stone into channel banks and extend it
beyond the abutments a minimum of 18"
(0.5m) to prevent flow around dam. A
Section A -A
1
(0.6m)
Spacing Between Check Dams
'L' = the distance such that points
'A' and 'B' are of equal elevation.
DEPARTMENT OF
ECOLOGY
State of Washington
Rock Check Dam
NOT TO SCALE
Revised June 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 353
BMP C220: Inlet Protection
Purpose
Inlet protection prevents coarse sediment from entering drainage systems prior to permanent sta-
bilization of the disturbed area.
Conditions of Use
Use inlet protection at inlets that are operational before permanent stabilization of the disturbed
areas that contribute runoff to the inlet. Provide protection for all storm drain inlets downslope and
within 500 feet of a disturbed or construction area, unless those inlets are preceded by a sediment
trapping BMP.
Also consider inlet protection for lawn and yard drains on new home construction. These small and
numerous drains coupled with lack of gutters 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 II -3.10: Storm Drain Inlet Protection lists several options for inlet protection. All of the methods
for inlet protection tend to plug and require a high frequency of maintenance. Limit contributing drain-
age areas for an individual inlet to one acre or less. If possible, provide emergency overflows with
additional end -of -pipe treatment where stormwater ponding would cause a hazard.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 356
Table II -3.10: Storm Drain Inlet Protection
Type of Inlet Pro-
Emergency
Applicable for
tection
Overflow
Paved/ Earthen Sur-
Conditions of Use
faces
Drop Inlet Protection
Excavated drop
Yes, temporary
Applicable for heavy flows. Easy
inlet protection
flooding may
Earthen
to maintain. Large area requirement:
occur
30'x30'/acre
Block and gravel
Applicable for heavy concentrated flows.
drop inlet pro-
Yes
Paved or Earthen
Will not pond.
tection
Gravel and wire
Applicable for heavy concentrated flows.
drop inlet pro-
No
Paved or Earthen
Will pond. Can withstand traffic.
tection
Catch basin filters
I Yes
Paved or Earthen
Frequent maintenance required.
Curb Inlet Protection
Curb inlet pro-
Small capacity
Used for sturdy, more compact install-
tection with
overflow
Paved
ation.
wooden weir
Block and gravel
curb inlet pro-
Yes
Paved
Sturdy, but limited filtration.
tection
Culvert Inlet Protection
Culvert inlet sed-
N/A
N/A
18 month expected life.
iment trap
Design and Installation Specifications
Excavated Drop Inlet Protection
Excavated drop inlet protection consists of an excavated impoundment around the storm drain inlet.
Sediment settles out of the stormwater prior to entering the storm drain. Design and installation spe-
cifications for excavated drop inlet protection include:
. Provide a depth of 1-2 ft as measured from the crest of the inlet structure.
. Slope sides of excavation should be no steeper than 2H:1 V.
. Minimum volume of excavation is 35 cubic yards.
Shape the excavation to fit the site, with the longest dimension oriented toward the longest
inflow area.
. Install provisions for draining to prevent standing water.
. Clear the area of all debris.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 357
• 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.
• Build a temporary dike, if necessary, to the down slope side of the structure to prevent bypass
flow.
Block and Gravel Filter
A block and gravel filter is a barrier formed around the inlet with standard concrete blocks and gravel.
See Figure 11-3.17: Block and Gravel Filter. Design and installation specifications for block gravel fil-
ters include:
• Provide a height of 1 to 2 feet above the inlet.
• Recess the first row of blocks 2 -inches into the ground for stability.
. Support subsequent courses by placing a pressure treated wood 2x4 through the block open-
ing.
• Do not use mortar.
• Lay some blocks in the bottom row on their side to allow for dewatering the pool.
• Place hardware cloth or comparable wire mesh with'/2-inch openings over all block openings.
• Place gravel to just below the top of blocks on slopes of 2H:1 V or flatter.
. An alternative design is a gravel berm surrounding the inlet, as follows:
• Provide a slope of 3H:1 V on the upstream side of the berm.
• Provide a slope of 2H:1 V on the downstream side of the berm.
• Provide a 1 -foot wide level stone area between the gravel berm and the inlet.
• Use stones 3 inches in diameter or larger on the upstream slope of the berm.
• Use gravel 1/2- to 3/4 -inch at a minimum thickness of 1 -foot on the downstream slope of
the berm.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 358
Figure II -3.17: Block and Gravel Filter
Drain grate
A"
Plan View
crete block
Gravel backfill
Concrete block
Wire screen or
filter fabric
Gravel backfill Overflow
water
� Ponding height
s --,on ! L^II�IIVV2Ierllll II I I >1 lr�nno'-c
Drop inlet
Section A -A
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.
NOT TO SCALE
Block and Gravel Filter
Revised June 2016
DEPARTMENT OF
ECOLOGY Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
State of Washington limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 359
Gravel and Wire Mesh Filter
Gravel and wire mesh filters are gravel barriers placed over the top of the inlet. This method does not
provide an overflow. Design and installation specifications for gravel and wire mesh filters include:
• Use a hardware cloth or comparable wire mesh with'/2-inch openings.
• Place wire mesh over the drop inlet so that the wire extends a minimum of 1 -foot bey-
ond each side of the inlet structure.
• Overlap the strips if more than one strip of mesh is necessary.
• Place coarse aggregate over the wire mesh.
Provide at least a 12 -inch depth of aggregate over the entire inlet opening and extend at
least 18 -inches on all sides.
Catch Basin Filters
Catch basin filters are designed by manufacturers for construction sites. The limited sediment stor-
age capacity increases the amount of inspection and maintenance required, which may be daily for
heavy sediment loads. To reduce maintenance requirements, combine a catch basin 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. Design and install-
ation specifications for catch basin filters include:
• 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 catch basin filter in the catch basin just below the grating.
Curb Inlet Protection with Wooden Weir
Curb inlet protection with wooden weir is an option that consists of a barrier formed around a curb
inlet with a wooden frame and gravel. Design and installation specifications for curb inlet protection
with wooden weirs include:
. Use wire mesh with'/2-inch openings.
• Use extra strength filter cloth.
• Construct a frame.
. Attach the wire and filter fabric to the frame.
. Pile coarse washed aggregate against the wire and fabric.
• Place weight on the frame anchors.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 360
Block and Gravel Curb Inlet Protection
Block and gravel curb inlet protection is a barrier formed around a curb inlet with concrete blocks and
gravel. See Figure II -3.18: Block and Gravel Curb Inlet Protection. Design and installation spe-
cifications for block and gravel curb inlet protection include:
• Use wire mesh with'/2-inch openings.
• Place two concrete blocks on their sides abutting the curb at either side of the inlet opening.
These are spacer blocks.
• Place a 2x4 stud through the outer holes of each spacer block to align the front blocks.
• Place blocks on their sides across the front of the inlet and abutting the spacer blocks.
• Place wire mesh over the outside vertical face.
• Pile coarse aggregate against the wire to the top of the barrier.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 361
Figure II -3.18: Block and Gravel Curb Inlet Protection
Back of sidewalk
Back of curb
Wire scre
filter 1
%a
Drain gravel Plan View
M,
Ponding height
3/ inch (20 mm)
Drain gravel Overflow
Curb inlet
Wire screen or
filter fabric 2x4 Wood stud
(100x50 Timber stud)
Catch basin
Concrete block
Section A -A
ud
block
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. NOT TO SCALE
Block and Gravel Curb Inlet Protection
Revised June 2016
DEPARTMENT OF
ECOLOGY Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
State of Washington limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 362
Curb and Gutter Sediment Barrier
Curb and gutter sediment barrier is a sandbag or rock berm (riprap and aggregate) 3 feet high and 3
feet wide in a horseshoe shape. See Figure II -3.19: Curb and Gutter Barrier. Design and installation
specifications for curb and gutter sediment barrier include:
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 upstream side of the berm. Size the
trap to sediment trap standards for protecting a culvert inlet.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 363
Figure 11-3.19: Curb and Gutter Barrier
Back of sidewalk
Burlap sacks to
overlap onto curb Back of curb
Runoff � �I �l I��H— Curb inlet
Runoff Spillway I II II II II �I
Catch basin
Plan View
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. NOT TO SCALE
DEPARTMENT OF
ECOLOGY
State of Washington
Curb and Gutter Barrier
Revised June 2016
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limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 364
Maintenance Standards
Inspect all forms of inlet protection frequently, especially after storm events. Clean and
replace clogged catch basin filters. For rock and gravel filters, pull away the rocks from the
inlet and clean or replace. An alternative approach would be to use the clogged rock as fill and
put fresh rock 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 Functionally Equivalent
Ecology has approved products as able to meet the requirements of this BMP. The products did not
pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions
may choose not to accept these products, or may require additional testing prior to consideration for
local use. Products that Ecology has approved as functionally equivalent are available for review on
Ecology's website at:
https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per-
mittee-guidance-resources/Emerging-stormwater-treatment-technologies
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 365
BMP C233: Silt Fence
Purpose
Silt fence reduces the transport of coarse sediment from a construction site by providing a temporary
physical barrier to sediment and reducing the runoff velocities of overland flow.
Conditions of Use
Silt fence may be used downslope of all disturbed areas.
. Silt fence shall prevent sediment carried by runoff 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 trapping BMP.
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.
2019 Stormwater Management Manual for Western Washington
Volume 11- Chapter 3 - Page 370
Figure II -3.22: Silt Fence
Joints in geotextile fabric shall be
spliced at posts. Use staples, wire rings
or equivalent to attach fabric to posts
2"x2" by 14 Ga. wire or equivalent,
if standard strength fabric used
Minimum I 6' max
4"x4" trench I � I
u
Post spacing may be increased 2"x2" wood posts, steel
to 8' if wire backing is used fence posts, or equivalent
DEPARTMENT OF
ECOLOGY
State of Washington
2"x2" by 14 Ga. wire or equivalent,
if standard strength fabric used
Geotextile fabric
2' min
Backfill trench with
native soil or %4'
1.5" washed gravel
Minimum'//ii
4"x4" trench
2"x2" wood posts, steel
fence posts, or equivalent
Silt Fence
NOT TO SCALE
Revised July 2017
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 371
Design and Installation Specifications
Use in combination with other construction stormwater BMPs.
Maximum slope steepness (perpendicular to the silt fence line) 1 H:1 V.
Maximum sheet or overland flow path length to the silt fence of 100 feet.
Do not allow flows greater than 0.5 cfs.
Use geotextile fabric that meets 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 11-3.11: Geotextile Fabric Standards for Silt Fence):
Table II -3.11: Geotextile Fabric Standards for Silt Fence
Geotextile Property
Minimum Average Roll Value
0.60 mm maximum for slit film woven (#30 sieve).
Polymeric Mesh AOS
0.30 mm maximum for all other geotextile types (#50 sieve).
(ASTM D4751)
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 geotextiles with wire mesh, chicken wire, 2 -inch x 2 -inch wire,
safety fence, or jute mesh to increase the strength of the geotextile. Silt fence materials are
available that have synthetic mesh backing attached.
Silt fence 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 the local jurisdiction.
Refer to Figure II -3.22: Silt Fence for standard silt fence details. Include the following Stand-
ard 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.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 372
3. The silt fence shall have a 2 -feet min. and a 2'/2 -feet max. height above the original
ground surface.
4. The geotextile fabric shall be sewn together at the point of manufacture to form fabric
lengths as required. Locate all sewn seams at support posts. Alternatively, two sections
of silt fence can be overlapped, provided that the overlap is long enough and that the
adjacent silt fence sections are close enough together to prevent silt laden water from
escaping through the fence at the overlap.
5. Attach the geotextile fabric on the up-slope side of the posts and secure with staples,
wire, or in accordance with the manufacturer's recommendations. Attach the geotextile
fabric to the posts in a manner that reduces the potential for tearing.
6. Support the geotextile 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 geotextile 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 geotextile fabric it
supports.
8. Bury the bottom of the geotextile fabric 4 -inches min. below the ground surface. Backfill
and tamp soil in place over the buried portion of the geotextile fabric, so that no flow can
pass beneath the silt fence and scouring cannot occur. When wire or polymeric back-up
support mesh is used, the wire or polymeric mesh shall extend into the ground 3 -inches
min.
9. Drive or place the silt 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 pre-
vent overturning of the fence due to sediment loading.
10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a max-
imum of 6 -feet. Posts shall consist of either:
• Wood with minimum dimensions of 2 inches by 2 inches by 3 feet. Wood 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,
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 373
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
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.
. Check dams shall be approximately 1 -foot deep at the back of the fence. 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.
• Check dams shall consist of crushed surfacing base course, gravel backfill for
walls, or shoulder ballast. Check dams shall be located every 10 feet along the
fence where the fence must cross contours.
Refer to Figure II -3.23: Silt Fence Installation by Slicing Method for slicing method details. The
following are specifications for silt fence installation using the slicing method:
1. The base of both end posts must be at least 2- to 4 -inches above the top of the geo-
textile 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 geotextile fabric, enabling posts to support the geotextile fabric from
upstream water pressure.
4. Install posts with the nipples facing away from the geotextile fabric.
5. Attach the geotextile fabric to each post with three ties, all spaced within the top 8 -
inches of the fabric. Attach each tie diagonally 45 degrees through the fabric, with each
puncture at least 1 -inch vertically apart. Each tie should be positioned to hang on a post
nipple when tightening to prevent sagging.
6. Wrap approximately 6 -inches of the geotextile fabric around the end posts and secure
with 3 ties.
7. No more than 24 -inches of a 36 -inch geotextile fabric is allowed above ground level.
8. Compact the soil immediately next to the geotextile 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 the fabric deeper into the ground if necessary.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 374
Figure II -3.23: Silt Fence Installation by Slicing Method
Ponding height max. 24"
Attach fabric to
upstream side of post
FLOW -
Drive over each side of
silt fence 2 to 4 times
with device exerting 60
p.s.i. or greater
100%
POST SPACING:
7' max. on open runs
4' max. on pooling areas
POST DEPTH:
As much below ground
as fabric above ground
100% com
No more than 24" of a 36"
fabric is allowed above ground
Top of Fabric
Belt
top 8"
Diagonal attachment
doubles strength
Attachment Details:
• Gather fabric at posts, if needed.
• Utilize three ties per post, all within top 8"
of fabric.
• Position each tie diagonally, puncturing
holes vertically a minimum of 1" apart.
• Hang each tie on a post nipple and tighten
securely. Use cable ties (50 lbs) or soft
wire.
Horizontal
Horizontal chisel point
(76 mm width)
Slicing blade
(18 mm width)
Vibratory plow is not acceptable because of horizontal compaction
DEPARTMENT OF
ECOLOGY
State of Washington
r
Completed Installation
NOT TO SCALE
Silt Fence Installation by Slicing Method
Revised June 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 375
fill
Horizontal
Horizontal chisel point
(76 mm width)
Slicing blade
(18 mm width)
Vibratory plow is not acceptable because of horizontal compaction
DEPARTMENT OF
ECOLOGY
State of Washington
r
Completed Installation
NOT TO SCALE
Silt Fence Installation by Slicing Method
Revised June 2016
Please see http;//www.ecy.wa.gov/copyright.html for copyright notice including permissions,
limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 375
Maintenance Standards
• Repair any damage immediately.
. Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment trap-
ping BMP.
• Check the uphill side of the silt 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 and remove the trapped sediment.
• Remove sediment deposits when the deposit reaches approximately one-third the height of
the silt fence, or install a second silt fence.
• Replace geotextile fabric that has deteriorated due to ultraviolet breakdown.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 376
BMP C240: Sediment Trap
Purpose
A sediment trap is a small temporary ponding area with a gravel outlet used to collect and store sed-
iment from sites 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
Sediment traps are 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 tributary area is permanently protected against erosion by veget-
ation and/or structures.
Sediment traps 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.
Projects that are constructing permanent Flow Control BMPs, or Runoff Treatment BMPs
that use ponding for treatment, may use the rough -graded or final -graded permanent BMP
footprint for the temporary sediment trap. When permanent BMP footprints are used as tem-
porary sediment traps, the surface area requirement of the sediment trap must be met. If the
surface area requirement of the sediment trap is larger than the surface area of the per-
manent BMP, then the sediment trap shall be enlarged beyond the permanent BMP footprint
to comply with the surface area requirement.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 383
. A floating pond skimmer maybe used for the sediment trap outlet if approved by the Local Per-
mitting Authority.
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.
Design and Installation Specifications
See Figure II -3.26: Cross Section of Sediment Trap and Figure 11-3.27: Sediment Trap Outlet
for details.
. 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:
where
Q2 =
SA = FS(Q2/Vs)
Option 1 - Single Event Hydrograph Method:
Q2 =Peak volumetric flow rate calculated using a 10 -minute time step from a Type 1 A,
2 -year, 24-hour frequency storm for the developed condition. The 10 -year peak volu-
metric flow rate shall be used if the project size, expected timing and duration of con-
struction, or downstream conditions warrant a higher level of protection.
Option 2 - For construction sites that are less than 1 acre, the Rational Method may be
used to determine Q2.
Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle with
an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has a set-
tling velocity (Vs) of 0.00096 ft/sec.
FS = A safety factor of 2 to account for non -ideal settling.
Therefore, the equation for computing sediment trap surface area becomes:
SA = 2 x Q2/0.00096
or
2080 square feet per cfs of inflow
Sediment trap depth shall be 3.5 feet minimum from the bottom of the trap to the top of the
overflow weir.
To aid in determining sediment depth, all sediment traps shall have a staff gauge with a prom-
inent mark 1 -foot above the bottom of the trap.
2019 Stormwater Management Manual for Western Washington
Volume 11 - Chapter 3 - Page 384
Design the discharge from the sediment trap by using the guidance for discharge from tem-
porary sediment ponds in BMP C241: Sediment Pond (Temporary).
Maintenance Standards
. Sediment shall be removed from the trap when it reaches 1 -foot in depth.
. Any damage to the trap embankments or slopes shall be repaired.
2019 Stormwater Management Manual for Western Washington
Volume 11- Chapter 3 - Page 385
Figure II -3.26: Cross Section of Sediment Trap
Surface area determined
at top of weir
1' Min.
— J-
3.5' - 5'
1.5' Min.
Flat Bottom
Note: Trap may be formed by berm or by
partial or complete excavation.
DEPARTMENT OF
ECOLOGY
State of Washington
%4" - 1.5"
Washed gravel
Geotextile
2" - 4" Rock
Rip Rap
Discharge to
stabilized
conveyance,
outlet, or level
spreader
NOT TO SCALE
Cross Section of Sediment Trap
Revised June 2016
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limitation of liability, and disclaimer.
2019 Stormwater Management Manual for Western Washington
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