HomeMy WebLinkAboutPermit File BLD-2020-0359 807 24th Street (3) Storm Water Minimum Requirements #2
ENGINEERING DEPARTMENT
904 6th Street Anacortes,WA 98221
‘711,11 C re(4
www.anacorteswa.gov
Official Use Only: (Information to Inspectors)
Required Storm Water Facility and other related requirements:
Sediment score Low. existing structure is being moved slightly to the west and a new foundation is being installed
Project Address: 5 . I a,i'��S-\ Submittal Date:
Parcel Number: P c 200-1 Revision Number:
Permit Number: Acceptance Date (COA): 7/20/2020
Reviewer: Rob F.
FRONT OF REPORT
Submittal Checklist:
o TAB 1 - Drainage Analysis— Minimum Requirement#2
o APPENDIX 1 - Survey performed by a Professional Land Surveyor
o APPENDIX 2 - Model Soil Management Plan for BMP T5.13
o APPENDIX 3 - Determining Construction Site Sediment Damage Potential (Appendix 7)
o APPENDIX 4 - Site Plan with all applicable information (Minimum Size 11x17 —30 scale)
o APPENDIX 5 - Documented Site Photos (North, South, East and West)
Project Description: (What is it you are looking to do? Provide details regarding, but not limited to, Lot SF,
Home SF, New and Replaced Hard Surface)
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Existing Site Conditions Summary:
(Additionally, provide information on previous permits, if any, like Grade and Fill, Clear and Grade, topography,
vegetation, drainage, Critical Areas adjacent to the site and how it may affect this project if soils are disturbed,
Soils Type (Included in Soils Analysis Report), Erosion Problem Areas, Construction PhasinglSequence)
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Version Date: December 19, 2018
Developed Conditions Summary:
(Additionally, to be shown on the site plan. Identify cut and fill areas, proposed slopes of all hard
surfaces , proposed contours) / ( d -r
Site Sediment Transport Score: Total Points (High\Low) (See Determining Construction Site
Sediment Damage Potential(Appendix 7)
Complete the Applicability Requirements— Flow Chart (Figure I-2.4.1 Attached, Figure 1-2.4.2 Attached
and Figure I-2.5.1 Attached)
- Highlight the path and attach
DOE Stormwater Management Manual Minimum Requirements: (MR#1 to MR#5 only).
Refer to the 2012 Department of Ecology Manual, as amended in 2014 for further required information.
Version Date: December 19, 2018
13 Elements of SWPPP
(Construction Stormwater Pollution Prevention Plan)
Please check off boxes to show that each element has been read and understood. Provide details where
applicable and if certain aspects are unnecessary or exempt, clearly justify. Details of the 13 Elements and the
correlating BMPs are listed Above from the 2014 Stormwater Management Manual for Western Washington
(SWMMWW). A link is provided on the City of Anacortes website, under Planning, Community, & Economic
Development Department, as well as under Stormwater on the Engineering Division of Public Work's page.
Owner Name:
Site Address:
Prepared By:
The Stormwater checklist or building permit determined that:
ri The 13 elements must be addressed a These elements must be addressed
for construction activity adding under for construction activity adding 2,000
2,000 sq. ft. of hard surface area. sq. ft. or more of hard surface area.
This means that an attached narrative
and site plan are required with this
document.
Under each element, explain the best management practices (BMPs) used or justify reasoning for
those that will not be used. If needed, please attach a narrative to further explain plans or justification.
ELEMENT 1: Preserve Vegetation/Mark Clearing Limits
Li 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.
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Version Date: December 19, 2018
ELEMENT 2: Establish Construction Access
Limit construction vehicle access and exit to one route, if possible.
Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs, to minimize
tracking onto roads.
Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in
preventing tracking sediment onto roads.
• If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more
frequently as necessary (ex: wet weather). Remove sediment from roads by shoveling, sweeping, or
pick up and transport the sediment to a controlled sediment disposal area.
❑ Conduct street washing only after sediment is removed in accordance with the above bullet.
❑ Control street wash wastewater by pumping back on site or otherwise preventing it from discharging
into systems tributary to waters of the State.
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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 improvement (e.g. impervious surfaces).
❑ If permanent infiltration ponds are used for flow control during construction, protect these facilities from
siltation during the construction phase.
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Version Date: December 19, 2018
ELEMENT 4: Install Sediment Controls
LI Design, install, and maintain effective erosion controls and sediment controls 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.
❑ 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.
❑ 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.
• Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to
increase sediment removal, and maximize stormwater infiltration.
❑ 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.
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ELEMENT 5: Stabilize Soils
Li 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 early on areas to be paved, and dust control.
• 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.
Li 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 (Oct 1 —Apr 30): 2 days
❑ 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, be
Version Date: December 19, 2018
located away from storm drain inlets, waterways, and drainage channels.
H Minimize the amount of soil exposed during construction activity.
❑ Minimize the disturbance of steep slopes.
❑ Minimize soil compaction and, unless infeasible, preserve topsoil.
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ELEMENT 6: Protect Slopes
Li Design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include,
but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope
steepness, and roughening slope surfaces (Ex: track walking).
❑ Divert off-site stormwater (run-on) or ground water away from slopes and disturbed areas with
interceptor dikes, pipes, and/or swales. Off-site stormwater should be managed separately from
stormwater generated on the site.
❑ At the top of slopes, collect drainage in pipe slop drains or protected channels to prevent erosion.
o *Temporary pipe slope drains must handle the peak volumetric flow rate calculated using a 10-
minute time step from a Type 1A, 10-year, 24-hour frequency storm for the developed condition.
Alternatively, the 10-year, 1-hour flow rate predicted/indicated by an approved continuous runoff
model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing
land cover condition for predicting flow rates from tributary areas outside the project limits. For
tributary areas on the project site, the analysis must use the temporary or permanent project
land cover condition, whichever will produce the highest flow rates. If using the Western
Washington Hydrology Model (WWHM)to predict flows, bare soil areas should be modeled as
"landscaped" area.
o Where 15-minute time steps are available in an approved continuous runoff model, they may be
used directly without a correction factor.
❑ 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.
LI Consider soil types and its potential for erosion.
❑ Stabilize soils on slopes, as specified in Element 5.
�J BMP combinations are the most effective method of protecting slopes with disturbed soils. Ex: Use both
mulching and straw erosion control blankets.
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Version Date: December 19, 2018
ELEMENT 7: Protect Drain Inlets
❑ Protect all storm drain inlets made operable during construction so that stormwater runoff does not
enter the conveyance system without first being filtered or treated to remove sediment.
❑ 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).
❑ Where possible, protect all existing storm drain inlets so that stormwater runoff does not enter the
conveyance system without first being filtered or treated to remove sediment.
❑ Keep all approach roads clean. Do not allow sediment and street wash water to enter storm drains
without prior and adequate treatment unless treatment is provided before the storm drain discharges to
waters of the State.
L] Inlets should be inspected weekly at a minimum and daily during storm events.
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Storm swale along 24th will be protected. Road will be swept as needed and sediment socks will
be installed as needed along 24th and R.
ELEMENT 8: Stabilize Channels and Outlets
❑ Design, construct, and stabilize all on-site conveyance channels to prevent erosion from the following
expected peak flows:
o *Channels must handle same peak volumetric flow rate as temporary pipe slope drains listed in
Element 6, above.
❑ 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 best 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.
Flat site with existing house that is moving slightly.
Version Date: December 19, 2018
ELEMENT 9: Control Pollutants
LI Design, install, implement, and maintain effective pollution prevention measures to minimize the
discharge of pollutants.
❑ Handle and dispose of all pollutants, including waste materials and demolition debris that occur on-site
in a manner that does not cause contamination of stormwater.
❑ Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum
products, and other materials that have the potential to pose a threat to human health or the
environment. On-site fueling tanks must include secondary containment. Secondary containment
means placing tanks or containers within an impervious structure capable of containing 110% of the
volume contained in the largest tank within the containment structure. Double-walled tanks do not
require additional secondary containment.
❑ Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill prevention and
control measures. Clean contaminated surfaces immediately following any spill incident.
1 Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents
discharge to surface water, such as closed-loop recirculation or upland land application, or to the
sanitary sewer, with local sewer district approval. Wheel wash or tire bath wastewater should not
include wastewater from concrete washout areas.
• Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of
chemical to stormwater runoff. Follow manufacturers' label requirements for application rates and
procedures.
• 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. Adjust
the pH of stormwater if necessary to prevent violations of the water quality standards.
❑ Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas
only. Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or
streams. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete
spillage or concrete discharge to surface waters of the State is prohibited. Do not use upland land
applications for discharging wastewater from concrete washout areas.
❑ Obtain written approval from Ecology and provide to the City before using chemical treatment other
than CO2 or dry ice to adjust pH.
❑ Woody debris may be chopped and spread on site.
❑ 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.
❑ Clean contaminated surfaces immediately following any discharge or spill incident. Emergency repairs
may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle.
Version Date: December 19, 2018
ELEMENT 10: Control De-Watering
U 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 de-watering water, such as well-point ground water, to systems tributary to,
or directly into surface waters of the State, as specified in Element 8, provided the de-watering 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 off site; for example, a creek running through a site.
❑ Handle highly turbid or contaminated dewatering water separately from stormwater.
❑ Other treatment or disposal options may include:
1. Infiltration
2. Transport off-site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that
does not pollute state waters.
3. Ecology-approved on-site chemical treatment or other suitable treatment technologies.
4. Sanitary or combined sewer discharge with local sewer district approval, if there is no other
option.
5. Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized
dewatering.
❑ Construction equipment operation, clamshell digging, concrete tremie pour, or work inside a cofferdam
can create highly turbid or contaminated dewatering water.
❑ Discharging sediment-laden (muddy) water into waters of the State likely constitutes a violation of water
quality standards for turbidity. The easiest way to avoid discharging muddy water is through infiltration
and preserving vegetation.
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ELEMENT 11: Maintain BMPs
7 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. Some temporary erosion and sediment
Version Date: December 19, 2018
control BMPs are bio-degradable and designed to remain in place following construction such as
compost socks.
[_I Provide protection to all BMPs installed for the permanent control of stormwater from sediment and
compaction. All BMPs that are to remain in place following completion of construction shall be
examined and placed in full operating conditions. If sediment enters the BMPs during construction, it
shall be removed and the facility shall be returned to the conditions specified in the construction
documents.
LI Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from
removal of BMPs or vegetation.
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ELEMENT 12: Manage the Project— Projects subject to Minimum Requirements 1-9 must have a Certified
Erosion and Sediment Control Lead (CESCL)for site inspections. Projects subject to Minimum Requirements
1-5 do not require the inspector to be certified. By the initiation of construction, the SWPPP must identify the
CESCL or inspector, who shall be present on-site or on-call at all times.
• Phase development projects to the maximum degree practicable and take into account seasonal work
limits to prevent soil erosion and prevent transporting sediment from the site during construction.
❑ Inspection and monitoring — inspect, maintain, and repair all BMPs as needed to assure continued
performance of their intended function.
• Maintain, update, and implement the SWPPP.
❑ Clearing and grading activities for developments shall be permitted only if conducted using an approved
site development plan (e.g., subdivision approval).
❑ From Oct 1 through Apr 30, clearing, grading, and other soil disturbing activities is permitted only if
shown that the site operator will prevent silt-laden runoff from leaving the site through a combination of
the following:
1. Site conditions including existing vegetative coverage, slope, soil type, and proximity to
receiving waters.
2. Limit activities and the extent of disturbed areas.
3. Proposed erosion and sediment control measures.
Weather conditions can influence the seasonal limitation on site disturbance. The City of Anacortes has
the authority to take enforcement action per AMC 19.76 Stormwater.
❑ The following activities are exempt from the seasonal clearing and grading limitations:
1. Routine maintenance and necessary repair of erosion and sediment control BMPs;
2. Routine maintenance of public facilities or existing utility structures that do not expose the soil or
result in the removal of the vegetative cover to soil
3. Activities where there is 100% infiltration of surface water runoff within the site in approved and
installed erosion and sediment control facilities.
Version Date: December 19, 2018
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ELEMENT 13: Protect Low impact Development BMPS
X If implementing any bioretention facilities or rain gardens, refer to the applicable BMP sections of the
Manual for requirements.
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Applicant Signature Date
Version Date: December 19, 2018
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HERRIGSTAD ENGINEERING & SURVEYING Proposed Boundary Line Ad justment
4320 WHISTLE LAKE ROAD 807 24th Street, Anacortes
ANACORTES, WA 98221 299-8804 Completed October' 26, 2019