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AE2017-128 Sunridge Townhomes 1
Anstey Engineering
CIVIL ENGINEERING/CONSULTING
Construction Stormwater
Pollution Prevention Plan
Prepared for:
SUNRIDGE_TOWNHOMES_II
Prepared by:
Benjamin P. Anstey, PE
8627 NE 180th Street Bothell, WA 98011
Phone: 206-303-7639
Fax: 425-658-9203
E-mail: benanstey@ansteyengineering.com
Date Prepared:
September 12, 2022
Sep 12, 2021
DEVELOPMENT ENGINEERING
NJanders 09/29/2022
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AE2017-128 Sunridge Townhomes 2 Table of Contents 1. Introduction ............................................................................................................................. 3 1.1 Project Description ........................................................................................................... 3 1.2 Existing and Current Conditions ...................................................................................... 3 2. Construction Stormwater Best Management Practices (BMPs) .............................................. 5 2.1 Element 1: Preserve Vegetation/Mark Clearing Limits ................................................... 5 2.2 Element 2: Establish Construction Access ....................................................................... 5 2.3 Element 3: Control Flow Rates ........................................................................................ 5 2.4 Element 4: Install Sediment Controls .............................................................................. 6 2.5 Element 5: Stabilize Soils ................................................................................................ 6 2.6 Element 6: Protect Slopes ................................................................................................ 7 2.7 Element 7: Protect Drain Inlets ........................................................................................ 8 2.8 Element 8: Stabilize Channels and Outlets ...................................................................... 9 2.9 Element 9: Control Pollutants .......................................................................................... 9 2.10 Element 10: Control De-Watering ................................................................................. 10 2.11 Element 11: Maintain BMPs .......................................................................................... 11 2.12 Element 12: Manage the Project .................................................................................... 11 2.13 Element 13: Protect Low Impact Development BMPs .................................................. 14 3. Pollution Prevention Team .................................................................................................... 15 4. Monitoring and Sampling Requirements ............................................................................... 15 4.1 Site Inspection ................................................................................................................ 15 4.2 Stormwater Turbidity Sampling ..................................................................................... 16 5. Reporting and Recordkeeping ............................................................................................... 17 5.1 Record Keeping .............................................................................................................. 17 5.2 Reporting ........................................................................................................................ 18 6. Appendix/Glossary List ......................................................................................................... 19
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1. Introduction
This Stormwater Pollution Prevention Plan is prepared to implement the sediment control and water
quality measures for the Sunridge Townhomes II project.
The project is proposed with 2 townhome buildings for Sunridge Townhomes II. The Construction
Permit Plans for the project are under review with City of Renton. The owner has started removing
the trees from site in advance using the submitted construction plans assuming that the construction
permit plans will be approved without changes. Owner has removed all the trees from site as per the
arborist report and retained few trees, only the trees listed in construction plans to be retained. But the
existing vegetation on ground has not removed.
With removal of trees, the site has exposed to potential of erosions and pollute city storm water
around the site. The City of Renton inspectors have inspected the site and directed to implement
BMPs for effective Stormwater Pollution Prevention; develop plan and narrative for approval and
recording purpose until Construction Permit Plans for the project has been approved and ready for
implementation.
Site visit meeting with the city of Renton inspectors was conducted to address advance removal of
trees from site and install the BMPs for erosions controls. Source control measures for controlling
pollutants from site are implemented where applicable to stabilize disturbed areas.
TESC plan has been developed to show the exact location of installed and to be installed BMPs for
erosion and sediment control. This narrative report is prepared to document 13 elements of SWPPP
and anticipated Best Management Practices (BMPs) for temporarily/permanent stabilization of site
until Construction Permit Plans for the project are approved and implemented during construction.
1.1 Project Description
Sunridge Townhomes II located at 122XXX SE PETROVITSKY RD on Tax parcels # 073900-
0050. The parcel is located between of 122nd PL and 126th Ave at North Side of Petrovitsky RD in
Renton. The proposed project is located at the North of SE Petrovitsky RD, Renton, WA 98058. The
property is (0.76 Acre) 33,027 square feet in area with 2078 sf of ROW; total 35105 sf area for
proposed development.
The property has no existing development, and covered with grass and trees. The South portion of
site is almost flat. The site has 3.5% +/- moderate slope from NW corner toward SE corner. The
project is proposed with 2 typical townhome buildings for Sunridge Townhomes II.
The Legal Description is: BENSON HEIGHTS, ADD S 260 FT OF W135.25 FT AS MEA ALG W
LN THOF LESS RD in King County Washington.
1.2 Existing and Current Conditions
The proposed project is located at the North of SE Petrovitsky RD, Renton, WA 98058. The property
is (0.76 Acre) 33,027 square feet in area with 2078 sf of ROW; total 35105 sf area for proposed
development. The property has no existing development, and covered with grass and trees. The
South portion of site is almost flat. The site has 3.5% +/- moderate slope from NW corner toward SE
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corner. There are existing catch basins and storm drainage system under Petrovitsky RD on South of
site, which is connected to main storm drainage system and draining to west. The existing lot drains
from North to South to catch basins South of Site at Petrovitsky RD.
The City of Renton Map shows that the site is not located in coal mine area, landslide, erosion hazard
areas, or critical aquifer recharge area (see the City of Renton sensitive area map below). There is a
big Soos Creek stream on the south of the site (about 391ft).
This lot is in the Urban Growth Area. Drainage Basin = Soos Creek. Watershed = Duwamish - Green
River. WRIA= Duwamish-Green (9).
Existing covered area
Total lot area (existing pervious area) (sf) 33,027
Total Ex. Impervious area coverage on site (%) 0%
ROW (sf) 2,071
Access on east side (outside lot) 1,765
Total project area (sf) 36,863
As owner have removed all the trees from site. As of now all trees from the site have been removed
and only small vegetation is remained, no grades have been disturbed. Site has tree shred mulch
stockpile on site.
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2. Construction Stormwater Best Management Practices (BMPs)
There are 13 elements listed below that must be considered in the development of the SWPPP.
Details on each BMP can be found in Appendix D of COR SWDM 2016.
2.1 Element 1: Preserve Vegetation/Mark Clearing Limits
• Before beginning land disturbing activities, including clearing and grading, clearly mark all
clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the
construction area.
• Retain the duff layer, native top soil, and natural vegetation in an undisturbed state to the
maximum degree practical.
Suggested BMPs:
• BMP C103: High Visibility Fence
• BMP C233: Silt Fence
2.2 Element 2: Establish Construction Access
• Limit construction vehicle access and exit to one route, if possible. Minimize construction
site access points along linear projects, such as roadways.
• Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs,
to minimize tracking sediment onto all roads and accesses.
• Locate wheel wash or tire baths onsite, if the stabilized construction entrance is not effective
in preventing tracking sediment onto roads/accesses.
• If sediment is tracked offsite, clean the affected roadway/access thoroughly at the end of each
day, or more frequently as necessary (for example, during wet weather). Remove sediment
from roads by shoveling, sweeping, or pick up and transport the sediment to a controlled
sediment disposal area.
• Street flushing of sediment into stormwater systems is prohibited in Redmond.
• Wheel wash station may be required by the City’s construction inspector if track out is
not controlled with other measures.
Suggested BMPs:
• BMP C105: Stabilized Construction Entrance is established as shown in attached TESC Plan.
2.3 Element 3: Control Flow Rates
• Protect properties and waterways downstream of development sites from erosion and the
associated discharge of turbid waters due to increases in the velocity and peak volumetric
flow rate of stormwater runoff from the project site.
• Where necessary to comply with the bullet above, construct stormwater retention or detention
facilities as one of the first steps in grading. Assure that detention facilities function properly
before constructing site improvements (e.g., impervious surfaces).
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• Permanent infiltration facilities shall not be operational or used to control/treat runoff during
construction. Runoff may be infiltrated in locations other than where permanent infiltration
and LID facilities will be constructed.
Suggested BMPs:
• None
2.4 Element 4: Install Sediment Controls
• Design, install, and maintain effective erosion controls and sediment controls in accordance
with the Redmond Standard Specifications and Details to minimize the discharge of
pollutants.
• Construct sediment control BMPs (sediment ponds, traps, filters, etc.) as one of the first steps
in grading. These BMPs shall be functional before other land disturbing activities take place,
and shall be maintained and removed once the site is stabilized and the inspector approves
removal.
• Minimize sediment discharges from the site. The design, installation and maintenance of
erosion and sediment controls must address factors such as the amount, frequency, intensity
and duration of precipitation, the nature of resulting stormwater runoff, and soil
characteristics, including the range of soil particle sizes expected to be present on the site.
• Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate
sediment removal BMP, before the runoff leaves a construction site or before discharge to an
infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment
removal BMP, but must meet the flow control performance standard in Element #3, bullet
#1. Full stabilization means concrete or asphalt paving; quarry spalls used as ditch lining; or
the use of rolled erosion products, a bonded fiber matrix product, or vegetative cover in a
manner that will fully prevent soil erosion. Redmond inspectors shall determine if an area is
stabilized by means other than pavement or quarry spalls.
• Locate BMPs intended to trap sediment on-site in a manner to avoid interference with the
movement of juvenile salmonids attempting to enter off-channel areas or drainages.
• Where feasible, design outlet structures that withdraw impounded stormwater from the
surface to avoid discharging sediment that is still suspended lower in the water column.
• Earthen structures such as dams, dikes, and diversions shall be seeded and mulched
according to the timing indicated in Element 5.
Suggested BMPs:
• BMP C233: Silt Fence – Install silt fence as shown on the TESC plan
2.5 Element 5: Stabilize Soils
• Stabilize exposed and unworked soils by application of effective BMPs that prevent erosion.
Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding,
mulching, plastic covering, erosion control fabrics and matting, soil application of
polyacrylamide (PAM), the early application of gravel base on areas to be paved, and dust
control.
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• Soil stabilization measures selected should be appropriate for the time of year, site
conditions, estimated duration of use, and potential water quality impacts that stabilization
materials may have on downstream waters or groundwater.
• Control stormwater volume and velocity within the site to minimize soil erosion.
• Control stormwater discharges, including both peak flow rates and total stormwater volume,
to minimize erosion at outlets and to minimize downstream channel and stream bank erosion.
• Soils must not remain exposed and unworked for more than the time periods set forth below
to prevent erosion.
o During the dry season (May 1 – Sept. 30): 7 days
o During the wet season (October 1 – April 30): 2 days
o This condition applies to all soils on site, whether at final grade or not. Redmond
inspectors may adjust time limits depending on site conditions, forecasted weather,
site characteristics, and to protect human safety, habitat, and property downstream.
• Stabilize soils at the end of the shift before a holiday or weekend if needed based on the
weather forecast.
• Stabilize soil stockpiles from erosion; protect with sediment trapping measures; and where
possible, locate away from storm drain inlets, waterways, and drainage channels.
• Minimize the amount of soil exposed during construction activity.
• Do not disturb steep slopes.
• Minimize soil compaction and, unless infeasible, preserve topsoil.
• Linear construction activities, including right-of-way and easement clearing, roadway
development, pipelines, and trenching for utilities, shall be conducted to meet the soil
stabilization requirement. Contractors shall install the bedding materials, roadbeds, structures,
pipelines, or utilities and re-stabilize the disturbed soils so that:
o From October 1 through April 30 no soils shall remain exposed and unworked for
more than 2 days; and
o From May 1 to September 30, no soils shall remain exposed and unworked for more
than 7 days.
Suggested BMPs:
• BMP C120: Temporary and Permanent Seeding
• BMP C121: Mulching
• BMP C123: Plastic Covering
• BMP C124: Sodding
• BMP C125: Topsoiling/Composting
2.6 Element 6: Protect Slopes
• Design and construct cut-and-fill slopes in a manner to minimize erosion.
• Consider soil type and its potential for erosion. Applicable practices include, but are not
limited to, reducing continuous length of slope with terracing and diversions, reducing slope
steepness, and roughening slope surfaces (for example, track walking).
• Divert offsite stormwater (run-on) or groundwater away from slopes and disturbed areas with
interceptor dikes, pipes, and/or swales. Offsite stormwater must be managed separately from
stormwater generated on the site.
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• At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent
erosion.
o Temporary pipe slope drains must handle the peak flow from a 10-year, 24-hour
storm event assuming a NRCS Type 1A rainfall distribution resolved to 10 minute
time steps. Alternatively, the 10-year, 1-hour time step flow rate predicted by an
approved continuous runoff model, increased by a factor of 1.6, may be used. If using
an approved continuous runoff model with a 15-minute (or less) time step, no
correction factor is required. The hydrologic analysis must use the existing land cover
condition for predicting flow rates from tributary areas outside the project limits. For
tributary areas on the project site, the analysis must use the temporary or permanent
project land cover condition, whichever will produce the highest flow rates. If using
the Western Washington Hydrology Model (WWHM) to predict flows, bare soil
areas should be modeled as “landscaped” area.
• Permanent pipe slope drains shall be sized for the 100-year, 24-hour event.
• Provide drainage to remove groundwater intersecting the slope surface of exposed soil areas.
• Place excavated material on the uphill side of trenches, consistent with safety and space
considerations.
• Place check dams at regular intervals within constructed channels that are cut down a slope.
• Provide drainage to remove groundwater intersecting the slope surface of exposed soil areas.
• Stabilize soils on slopes, as specified in Element #5.
Suggested BMPs:
• BMP C120: Temporary and Permanent Seeding
• BMP C121: Mulching
2.7 Element 7: Protect Drain Inlets
• Protect all storm drain inlets made operable during construction so that stormwater runoff
shall not enter the conveyance system without first being filtered or treated to remove
sediment. Catch basins are considered operational when stormwater flows are allowed to
enter the catch basin. If stormwater is allowed to enter the side of the catch basin, inlet
protection is still required for those flows.
• All approach roads shall be kept clean. Approach roads shall have inlet protection if they
could be impacted by the construction site and at the discretion of the City Inspector.
• Clean or remove and replace inlet protection devices when sediment has filled one- third of
the available storage (unless a different standard is specified by the product manufacturer).
• When projects are completed, removal of inlet protection devices is required. Removal will
be done in a way that does not allow the captured sediment to enter or later be washed into
the stormwater inlet.
Suggested BMPs:
• BMP C220: Storm Drain Inlet Protection
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2.8 Element 8: Stabilize Channels and Outlets
• Provide stabilization, including armoring material, adequate to prevent erosion of outlets,
adjacent streambanks, slopes, and downstream reaches at the outlets of all conveyance
systems.
• The preferred method for stabilizing channels is to completely line the channel with a blanket
product first, then add check dams as necessary to function as an anchor and to slow the flow
of water.
Suggested BMPs:
• BMP C209: Outlet Protection
2.9 Element 9: Control Pollutants
• Design, install, implement, and maintain effective pollution prevention measures to minimize
the discharge of pollutants. See Section 8.3 for requirements specific to Critical Aquifer
Recharge Areas.
• Handle and dispose of all pollutants, including waste materials and demolition debris that
occur onsite in a manner that does not cause contamination of soil, groundwater, or
stormwater.
• Provide cover, containment, and protection from vandalism for all chemicals, liquid products,
petroleum products, and other materials that have the potential to pose a threat to human
health or the environment. Onsite fueling tanks must include secondary containment.
Secondary containment means placing tanks or containers within an impervious structure
capable of containing 110 percent of the volume contained in the largest tank within the
containment structure. Double-walled tanks do not require additional secondary containment.
• Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill
prevention and control measures. Clean contaminated surfaces immediately following any
spill incident.
• Conduct 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 using spill
prevention measures, such as drip pans.
• Discharge wheel wash or tire bath wastewater to a separate onsite treatment system that
prevents discharge to surface water, such as closed-loop recirculation or upland land
application, or to the sanitary sewer, with City approval.
• Apply agricultural chemicals, including fertilizers and pesticides in a manner and at
application rates that will not result in loss of chemical to stormwater runoff. Follow
manufacturers’ label requirements for application rates and procedures.
• Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The
sources for this contamination include, but are not limited to: bulk cement, cement kiln dust,
fly ash, new concrete washing and curing waters, waste streams generated from concrete
grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete
pumping and mixer washout waters.
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• Stormwater discharges shall not cause or contribute to a violation of the water quality
standard for pH in the stormwater drainage system or receiving water. Allowable runoff pH
concentrations shall be within the range of 6.5 to 8.5 pH.
• Adjust the pH of stormwater if necessary, to prevent violations of the water quality standards.
• Ensure that washout of concrete trucks is performed offsite or in designated concrete washout
areas only. Do not wash out concrete trucks onto the ground, or into storm drains, open
ditches, streets, or streams. Do not dump excess concrete onsite, except in designated
concrete washout areas. Concrete spillage or concrete discharge to surface waters of the State
is prohibited.
• Obtain written approval from Ecology before using chemical treatment other than CO2 or
dry ice to adjust pH.
• In Critical Aquifer Recharge Areas additional care and pollution control BMPs will be
required by the City to protect the groundwater aquifer/drinking water supply. Review of
SWPPP, TESC civil plans, Seasonal suspension plan, and wet weather plans in Critical
Aquifer Recharge Areas will include more scrutiny and strict application of pollution
controls.
• Spill control materials suitable for applicable chemicals shall be kept on site.
Suggested BMPs:
• BMP C151: Concrete Handling
• BMP C152: Saw cutting and Surfacing Pollution Prevention
• BMP C153: Material Delivery, Storage and Containment
• BMP C154: Concrete Washout Area
See Volume IV – Source Control BMPs
2.10 Element 10: Control De-Watering
• For projects that involve temporary construction dewatering discharges greater than 500
gallons per minute follow the procedures established under City of Redmond Temporary
Construction Dewatering Operating Policy authorized by RMC 13.25. Temporary
construction dewatering shall not cause flooding or reduce the capacity of a stormwater
runoff treatment system.
• For projects that involve temporary construction dewatering of less than 500 gallons per
minute follow the guidelines below.
• Discharge foundation, vault, and trench dewatering water, which have characteristics similar
to stormwater runoff at the site, into a controlled conveyance system before discharge to a
sediment trap or sediment pond.
• Discharge clean, non-turbid dewatering water, such as well-point groundwater, to systems
tributary to, or directly into surface waters of the State, as specified in Element #8, provided
the dewatering flow does not cause erosion or flooding of receiving waters or interfere with
the operation of the system. Do not route clean dewatering water through stormwater
sediment ponds. Note that “surface waters of the State” may exist on a construction site as
well as offsite; for example, a creek running through a site.
• Highly turbid or contaminated dewatering water, such as from construction equipment
operation, clamshell digging, concrete tremie pour, or work inside a cofferdam from
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construction equipment operation, clamshell digging, concrete tremie pour, or work inside a
cofferdam, separately from stormwater.
• Other treatment or disposal options may include:
1. Infiltration.
2. Transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in a
manner that does not pollute waters of the State.
3. Ecology-approved onsite chemical treatment or other suitable treatment technologies.
4. Sanitary or combined sewer discharge with City of Redmond and King County
approval, if there is no other option.
5. Use of a sedimentation bag that discharges to a ditch or swale for small volumes of
localized dewatering. Be prepared for possible bag failure.
Suggested BMPs:
• None
2.11 Element 11: Maintain BMPs
• Maintain and repair all temporary and permanent erosion and sediment control BMPs as
needed to assure continued performance of their intended function in accordance with BMP
specifications.
• Remove all temporary erosion and sediment control BMPs within 30 days after achieving
final site stabilization or after the temporary BMPs are no longer needed.
Suggested BMPs:
• BMP C150: Materials on Hand
2.12 Element 12: Manage the Project
• Phase development projects to the maximum degree practicable and take into account
seasonal work limits.
• Inspection and monitoring – Inspect, maintain, and repair all BMPs as needed to ensure
continued performance of their intended function. Conduct site inspections and monitoring in
accordance with all applicable county and Construction Stormwater General Permit
requirements.
• Maintaining an updated Construction SWPPP – Maintain, update, and implement the
Construction SWPPP in accordance with the Construction Stormwater General Permit
requirements and the requirements outlined in this Element (#12).
• Project sites that disturb 1 acre or more must have site inspections conducted by a Certified
Erosion and Sediment Control Lead (CESCL). Project sites disturbing less than 1 acre may
have a CESCL or a person without CESCL certification conduct inspections. By the
initiation of construction, the Construction SWPPP must identify the CESCL or inspector,
who shall be present onsite or on-call at all times.
Additional Guidance for Site Inspections:
• The CESCL (or other inspector for sites disturbing less than 1 acre) must have the skills to
assess the:
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o Site conditions and construction activities that could impact the quality of stormwater
o Effectiveness of Construction SWPPP measures used to control the quality of
stormwater discharges.
• The CESCL or inspector must examine stormwater visually for the presence of suspended
sediment, turbidity, discoloration, and oil sheen. They must evaluate the effectiveness of
BMPs and determine if it is necessary to install, maintain, or repair BMPs to improve the
quality of stormwater discharges.
• Based on the results of the inspection, construction site operators must correct the problems
identified by:
o Reviewing the Construction SWPPP for compliance with the 13 Construction
SWPPP elements and making appropriate revisions within 7 days of the inspection,
or as directed by the inspector.
o Immediately begin the process of fully implementing and maintaining appropriate
source control and/or treatment BMPs as soon as possible, addressing the problems
no later than within 10 days of the inspection. If installation of necessary treatment
BMPs is not feasible within 10 days, the construction site operator may request an
extension within the initial 10-day response period
o Documenting BMP implementation and maintenance in the site log book (applies
only to sites that have coverage under the Construction Stormwater General Permit).
• The site inspector must inspect all areas disturbed by construction activities, all BMPs, and
all stormwater discharge locations at least once every calendar week and within 24 hours of
any discharge from the site. (For purposes of this condition, individual discharge events that
last more than 1 day do not require daily inspections. For example, if a stormwater pond
discharges continuously over the course of a week, only one inspection is required that
week.) Note that for projects that require a CESCL per BMP C160, additional requirements
may apply. The inspector may reduce the inspection frequency for temporary stabilized,
inactive sites to once every calendar month Coordination with Utilities and Other Contractors
– The primary project proponent shall evaluate, with input from utilities and other
contractors, the stormwater management requirements for the entire project, including the
utilities, when preparing the Construction SWPPP.
Additional Guidance:
• Phasing of Construction:
o Phase development projects where feasible in order to prevent soil erosion and, to the
maximum extent practical, and prevent transporting sediment from the site during
construction. Revegetate exposed areas and maintain that vegetation as an integral
part of the clearing activities for any phase.
• Seasonal Work Limitations:
o From October 1 through April 30, clearing, grading, and other soil disturbing
activities is permitted only if shown to the satisfaction of the county that the site
operator will prevent silt-laden runoff from leaving the site through a combination of
the following:
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o Modify the Construction SWPPP whenever there is a change in the design,
construction, operation, or maintenance at the construction site that has, or could
have, a significant effect on the discharge of pollutants to waters of the State.
o The Construction SWPPP must be modified if, during inspections or investigations
conducted by the owner/operator, or the applicable county or state regulatory
authority, it is determined that the Construction SWPPP is ineffective in eliminating
or significantly minimizing pollutants in stormwater discharges from the site. Modify
the Construction SWPPP as necessary to include additional or modified BMPs
designed to correct problems identified. Complete revisions to the Construction
SWPPP within seven (7) days following the inspection.
Suggested BMPs:
• BMP C150: Materials On Hand
• BMP C162: Scheduling
2.13 Element 13: Protect Low Impact Development BMPs
• Protect all Bioretention and Rain Garden BMPs from sedimentation through installation and
maintenance of Construction SWPPP BMPs on portions of the site that drain into the
Bioretention and/or Rain Garden BMPs. Restore the BMPs to their fully functioning
condition if they accumulate sediment during construction. Restoring the BMP must include
removal of sediment and any sediment-laden Bioretention/Rain Garden soils, and replacing
the removed soils with soils meeting the design specification.
• Prevent compacting Bioretention and Rain Garden BMPs by excluding construction
equipment and foot traffic. Protect completed lawn and landscaped areas from compaction
due to construction equipment.
• Control erosion and avoid introducing sediment from surrounding land uses onto permeable
pavements. Do not allow muddy construction equipment on the base material or pavement.
Do not allow sediment-laden runoff onto permeable pavements, including permeable
pavement subgrade, reservoir course, or wearing course.
• Pavements fouled with sediments or no longer passing an initial infiltration test must be
cleaned using procedures shown in Volume III of this manual or the manufacturer’s
procedures.
• Keep all heavy equipment off existing soils under LID facilities that have been excavated to
final grade to retain the infiltration rate of the soils.
• See Section 3.3 for more details on protecting LID BMPs.
Suggested BMPs:
• BMP C103: High Visibility Fence
• BMP C233: Silt Fence
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3. Pollution Prevention Team
Table – Team Information
Title Name(s) Phone Number
Certified Erosion and
Sediment Control Lead
(CESCL)
Provided by Owner (TBD) TBD
Resident Engineer TBD TBD
Emergency Ecology
Contact
TBD TBD
Emergency Permittee/
Owner Contact
TBD TBD
Non-Emergency Owner
Contact
TBD TBD
Monitoring Personnel Provided by Owner (TBD) TBD
Ecology Regional Office Northwest Regional Office (425) 649-7000
4. Monitoring and Sampling Requirements
Monitoring includes visual inspection, sampling for water quality parameters of concern, and
documentation of the inspection and sampling findings in a site log book. A site log book will be
maintained for all on-site construction activities and will include:
• A record of the implementation of the SWPPP and other permit requirements
• Site inspections
• Stormwater sampling data
A blank form is provided as a template in Appendix D.
The site log book must be maintained on-site within reasonable access to the site and be made
available upon request to Ecology or the local jurisdiction.
4.1 Site Inspection
Site inspections will be conducted at least once every calendar week and within 24 hours
following rain event and any discharge from the site. For sites that are temporarily stabilized and
inactive, the required frequency is reduced to once per calendar month.
All BMPs will be inspected, maintained, and repaired as needed to assure continued performance
of their intended function. Stormwater will be examined for the presence of suspended sediment,
turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the
effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the
BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be
documented in the site log book or forms provided in this document. All new BMPs or design
changes will be documented in the SWPPP as soon as possible.
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4.2 Stormwater Turbidity Sampling
Turbidity Sampling:
Requirements include calibrated turbidity meter or transparency tube to sample site discharges for
compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per
calendar week.
The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency
less than 33 centimeters.
If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to
or greater than 6 cm, the following steps will be conducted:
1. Review the SWPPP for compliance with Special Condition S9. Make appropriate
revisions within 7 days of the date the discharge exceeded the benchmark.
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10 days
of the date the discharge exceeded the benchmark. If installation of necessary treatment
BMPs is not feasible within 10 days, Ecology may approve additional time when the
Permittee requests an extension within the initial 10-day response period.
3. Document BMP implementation and maintenance in the site log book.
If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following
steps will be conducted:
1. Telephone or submit an electronic report to the applicable Ecology Region’s
Environmental Report Tracking System (ERTS) within 24 hours.
https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue
• Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish,
Whatcom): (425) 649-7000
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10 days
of the date the discharge exceeded the benchmark. If installation of necessary treatment
BMPs is not feasible within 10 days, Ecology may approve additional time when the
Permittee requests an extension within the initial 10-day response period
3. Document BMP implementation and maintenance in the site log book.
4. Continue to sample discharges daily until one of the following is true:
• Turbidity is 25 NTU (or lower).
• Transparency is 33 cm (or greater).
• Compliance with the water quality limit for turbidity is achieved.
o 1 - 5 NTU over background turbidity, if background is less than 50 NTU
o 1% - 10% over background turbidity, if background is 50 NTU or greater
The discharge stops or is eliminated.
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pH Sampling:
pH monitoring is required for “Significant concrete work” (i.e. greater than 1000 cubic yards
poured concrete or recycled concrete over the life of the project).The use of engineered soils (soil
amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust
[CKD] or fly ash) also requires pH monitoring.
For significant concrete work, pH sampling will start the first day concrete is poured and
continue until it is cured, typically three (3) weeks after the last pour.
For engineered soils and recycled concrete, pH sampling begins when engineered soils or
recycled concrete are first exposed to precipitation and continues until the area is fully stabilized.
If the measured pH is 8.5 or greater, the following measures will be taken:
1. Prevent high pH water from entering storm sewer systems or surface water.
2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate
technology such as carbon dioxide (CO2) sparging (liquid or dry ice).
3. Written approval will be obtained from Ecology prior to the use of chemical treatment
other than CO2 sparging or dry ice.
5. Reporting and Recordkeeping
5.1 Record Keeping
Site Log Book:
A site log book will be maintained for all on-site construction activities and will include:
• A record of the implementation of the SWPPP and other permit requirements
• Site inspections
• Sample logs
Records Retention:
Records of all monitoring information (site log book, inspection reports/checklists, etc.), this
Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit
requirements will be retained during the life of the construction project and for a minimum of three
years following the termination of permit coverage in accordance with permit condition
S5.C.additional or modified BMPs are necessary for compliance. An updated timeline for BMP
implementation will be prepared.
Access to Plans and Records:
The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained on
site or within reasonable access to the site and will be made immediately available upon request to
Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days
of receipt of a written request for the SWPPP from Ecology. Any other information requested by
Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP
will be provided to the public when requested in writing in accordance with permit condition S5.G.
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Updating the SWPPP:
In accordance with Conditions S3, S4.B, and S9.B.3 of the General Permit, this SWPPP will be
modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in
stormwater discharges from the site or there has been a change in design, construction, operation, or
maintenance at the site that has a significant effect on the discharge, or potential for discharge, of
pollutants to the waters of the State. The SWPPP will be modified within seven days of
determination based on inspection(s) that additional or modified BMPs are necessary to correct
problems identified, and an updated timeline for BMP implementation will be prepared.
5.2 Reporting
Discharge Monitoring Reports:
Discharge Monitoring Report (DMR) forms will not be submitted to Ecology because water
quality sampling is not being conducted at the site.
Notification of Noncompliance:
If any of the terms and conditions of the permit are not met, and it causes a threat to human
health or the environment, the following steps will be taken in accordance with permit section
S5.F:
Ecology will be immediately notified of the failure to comply.
Immediate action will be taken to control the noncompliance issue and to correct the problem. If
applicable, sampling and analysis of any noncompliance will be repeated immediately and the
results submitted to Ecology within five (5) days of becoming aware of the violation.
A detailed written report describing the noncompliance will be submitted to Ecology within five
(5) days, unless requested earlier by Ecology.
In accordance with permit condition S2.A, a complete application form will be submitted to
Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General
Permit.
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6. Appendix/Glossary List
A. Site Map
B. BMP Details
C. Site Inspection Form
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Construction Stormwater Site Inspection Form Page 1 Project Name Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter
Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un-worked soils been stabilized with effective BMP to prevent erosion and sediment deposition?
Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on-site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources?
Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? 13 Protect LID Is all Bioretention and Rain Garden Facilities protected from sedimentation with appropriate BMPs? Is the Bioretention and Rain Garden protected against over compaction of construction equipment and foot traffic to retain its infiltration capabilities? Permeable pavements are clean and free of sediment and sediment laden-water runoff. Muddy construction equipment has not been on the base material or pavement. Have soiled permeable pavements been cleaned of sediments and pass infiltration test as required by stormwater manual methodology? Heavy equipment has been kept off existing soils under LID facilities to retain infiltration rate. E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits
Construction Stormwater Site Inspection Form Page 5 F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: