HomeMy WebLinkAboutPermit File BLD-2022-0750 3420 Oakes Avenue (3) FDpcoDEco
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m Minimum Requirements 1 through 5
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�C0 r rOFIELD Se ENGINEERING DEPARTMENT
iO4-4 904 6th Street Anacortes, WA 98221
www.anacorteswa.gov
Official Use Only: (Information to Inspectors)
Required Storm Water Facility and other related requirements:
Sediment transport score low, 95.
Reviewed as #2 only.
Project Address: 3420 Oakes Ave. Submittal Date: 9/22/22
Parcel Number: P58533,P31712 Revision Number:
Permit Number: Reviewer: R.1F.
Acceptance Date (COA): 9/22/22
FRONT OF REPORT:
Submittal Checklist: (All items listed below are required for a complete submittal)
o Cover Sheet (Preparer to Provide): Project title, Location, Revision dates, Engineer's Stamp
o TAB 1: Minimum Requirement#1 — Preparation of Stormwater Site Plans
o TAB 2: Minimum Requirement#2 —Construction Stormwater Pollution Prevention (SWPP)
o TAB 3: Minimum Requirement#3 — Source Control of Pollution
o TAB 4: Minimum Requirement#4 — Preservation of Natural Drainage Systems and Outfalls
o TAB 5: Minimum Requirement#5 —On-site Stormwater Managements
o TAB 6: Minimum Requirement#6 — Runoff Treatment
o TAB 7: Minimum Requirement#7 — Flow Control
o TAB 8: Minimum Requirement#8 —Wetland Protection
o TAB 9: Minimum Requirement#9 —Operation and Maintenance
o APPENDIX 1 - Survey performed by a Professional Land Surveyor
o APPENDIX 2 - Soils Analysis (Volume 1, Chapter 3.1.1)
o APPENDIX 3 - Model Soil Management Plan for BMP T5.13
o APPENDIX 4 - Determining Construction Site Sediment Damage Potential (Appendix 7)
o APPENDIX 5 - Site Plan with all applicable information (Minimum Size 11x17 — 30 scale)
o APPENDIX 6 - Documented Site Photos (North, South, East and West)
o APPENDIX 7 - Drainage BMP Facility Maintenance Covenant, if applicable. To be recorded prior to the
Temporary Certificate of Occupancy, Certificate of Occupancy or Final Acceptance.
Stormwater Management Requirements:
o Refer to the 2012\14 Department of Ecology Manual, as amended in 2014 for further required
information.
o See also, City of Anacortes Municipal Code 19.76 for additional information
o See also, current Engineering Development Standards, Chapter 2- Storm Drainage for additional
information.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Project Description and Summary:
Summar Table
Existing Proposed
Development Type SFR
Number of Lots 2
Lot Acreage in SF 14,450.4 S.F.
Soil Type(s)
Site Sediment Transport Score (High\Low)
Depth to Ground Water Table (Feet and Inches)
(See completed Soils Analysis (Volume 1, Chapter 3.1.1)
Infiltration Rate during Rainy Season Inch\Per Hour
Impervious Surface on-site 4319 S.F. 1179 S.F.
Impervious Surface (off-site)
New and Replaced Hard Surface Total (SF)
Lot Coverage (Percentage) 18.9%total 24.5%total
BMP (Required Minimum Requirement 5) BMP T5.13 Post Construction Soils
Water Quality Method (Minimum Requirement 6)
Water Quantity Method (Minimum Requirement 7)
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 Phasing l Sequence)
There is an existing home on the site. No change in site grades are proposed. A short rock or block
retaining wall might be needed next to driveway to keep driveway flat. There will be little excavating
required. Site is waterfront. Project takes place on non-water side of property.
Developed Conditions Summary:
(Additionally, to be shown on the site plan. Identify cut and fill areas, proposed slopes of all hard
surfaces , proposed contours)
Hard surfaces will have little slope, this area of the property is pretty flat. No fill areas are proposed.
There will be some excavation for foundation footings, but construction is slab on grade.
Drainage Basin (2007 Storm Comp Plan — City website\pubIicworks\engi nee ring\comprehensive plans):
What Drainage Basin are you in? Identify any downstream drainage issues (Storm Comp Plan:
If so, describe:
Complete the Applicability Requirements — Flow Chart (Figure 1-2.4.1 Attached, Figure 1-2.4.2 Attached
and Figure 1-2.5.1 Attached)
- Highlight the path and attach
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Start Here
Does the site have 35% Yes See Redevelopment Minimum
or more of existing Requirements and Flow Chart
impervious coverage' (Figure 1-2.4.2)_
No
woes the project convert
acres or more of vegetation to
Does the project result in lawn or landscaped areas, or
5.COC square feet, or No convert 2.5 acres or more of
greater, of new plus native veygetaaon to pasture^
replaced hard surface
area?
No
Yes
Yes
Does the project result in 2,00C
square feet, or greater, of new plus
All Minimum Requirements replaced hard surface area?
apply to the new and replaced
hard surfaces and converted
vegetation areas_ Yes NO
ly
Does the project have land
Minimum Requirements ai disturbing activities of7.000
through #5 apply to the new Yes
square feet or greater?
and replaced hard surfaces
and the land disturbed. No
Minimum Requirement #
applies
Figure 1-2.4.
Flow Chart for Determining Requirements for
New Development
DEPARTMENT OF Re:tsed .une201E
ECOLOGY Dlease See,1C4^1{UNN'ecy.N'a.gOW'cgoyrVnl hn#for COPY mgnt notiw InCiLdln^y permisslc.'Is
-ate o• wasnington mitadon atllaDlllty.and d►sclarrer.
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Does the project result in 2,000 square feet, or more, of new plus replaced hard surface area?
OR
Does the land disturbing activiy total 7.000 square feet or greater?
Yes No
Minimum Requiremens #' through *5
apply to the new and replaced hard Minimum Requirement #2 applies_
surfaces and the land disturbed.
Next Question
Does the project add 5.000 square feet or more o`new hard surfaces"
OR
,Convert 34 acres or more o`vegetation to lawn or landscaped areas"'
OR
Convert 2.5 acres or more of native vegetation to pas-u re.7
IF Yes No
All Minimum Requirements apply Next Question Is this a roar
to the new hard surfaces and the N o
related project
converted vegetation areas_
Yes
Does the project add E,0123 so uare fee: or more of new hard surfaces*?
YIF
es No
Is the total of new plus replaced hard surfaces
Do the new hard 5.000 square feet or more.
surfaces add 50% or No No additional No AND
more to the existing requirements. does the value of the proposed improvemer*
hard surfaces withir - including interior improvements -exceed
the project limits? 50% of the assessed value Ivor replacemen-
value) of the existing site improvements
Yes All Minimum Requirements apply to the new and replaced
hard surfaces and converted vegetation areas. Yes
Figure 1-2.4.2
Flow Chart for Determining Requirements for
Redevelopment
DEPARTMENT OF Revised une201E
ECOLOGY please see n[fp,.%* *•ecy.wa.gov/copyyVf)thtrnr br oDpymgnt notice Including perm"la-is
j:ate of wasnington IlmItawn off Ilaollity,and d►sclaimer.
versrun vale: rvcrverrruer�, zvrr rrevrou3 v�rsivn ua�e vcrcrr�err, zv-ry
:�:es Ttve :rc.ect c Ss.:r3r-ge Flo+A Cantroi ExE-Tot Wa:e's goer Nlr rwm ReR3Ire-Tent ;MR i * 1'
TV;;
REQUIRED:Implefnent the lolow na E1;Ps No
where feasDle:
• BMP T5.13" Post-Construction Son Quai Name
3na Depth Does:he orojec: DMeot
• BMP TS_10A,B,or C: Dowrsooul Full trtgger t?nly MRs;:• - triggered
InIft,non,DoNrsoom Dlspers+or *57 leer Flgure 3.2 or snty NR�21 No aadttloral
.),s:ems,or Perforated =t Lout Fgure 3.3 n Apoerdix
Connectons 1 of J*2013-201 a requrements
• BMP T5.11 orT5.12: Concentrate: _ :�A Viiii Phase II Permit
Dispersion or Ghee:Flow Dlspei : b Phase I DerTt;.
NOT REQUIRED:Ach►evement of me LID No ime project xggesea
Peffonnance Standard.Applying 111e omer Yes
BMPs In LC r' or Jst i=2. only MRs�1 -iF9 i
Is the project Insloe:he JGA?
►I :re cro.ect ce-.elo-oer Cht•3s2:a meet
No
e LID DePL'Tan S:3mdab' Yes..
is me;-oiF-.t on a parrzi
No of 5 acres arger7
R =__ F or each Did the proiecl developer No Yes
sur'a:r. Cclrsder the cnoose tD meet the LID
BMP's Ir the order Performance Standard' REQUIRED: Meet me LID
Isted in List*1 for:rat Performance Standard mrough
type of surface. Jse Yes me use of any BMP(6)In *
me first BMP mats 2014 SWMMWW except -
considered feasitre. Yes No Rain Gardens �Me use of
Bloretention is acceptable;.
NOT REQUIRED:
Achevement oR me LID if the protect can't meet the
Performance Standard. REQUIRED: For each LID Performance Standard, It
surface,conslderthe BMPs must seek and be granted an
REQUIRED: Meet the LID Performance r order Isted n _Ist#2 exceptfontvarlance.
Standard mrough the use V ary 811111 in 3t type of sirface. Jsa-
me 2D14 SwMi1iii1i exoeot for Ran Gardens Me W.BMP that Is REQUIRED:Apply BMP T5.13
Rhe use of I>wetentlon is acceptable:. conslaered leas ble. D46t-COnsbilmon.Sol Quality
Id Depth.
REQUIRED for araects TrImerna MR -' NOT REQUIRED:
Apply BMP T5.13 Post Cons•.ruc on Achle:eprent of the LID NOT REQUIRED:Applying the
Qualry ana Depm. Performance Standard. BMP6 In LW*1 or Ust X2.
NOT REQUIRED:ApM-Ic_ tria E%#:)s I _is'
91 or LIs1 4112.
'ReComme'1dE;J oy =_oology for pro)ec;ts trtggertng MRs;icl -95.
Figure 1-2.,5►. 1
qW Flow c iart for Determining LID NIR #5
Requirements
DEPARTMENT OF Re,sedJure20'=
ECOLOGY Please see nrp::,%-*w ecy.wa.gov.-topyv gf)thfrnr for oopyrlgnt none inclt.ding per-
Slate of wasnington iimltaton or, Ilaonrty,and disclatner.
version uate: ivovemoer zy,--zuzrrrreviousversiorruare:ucroAer t, zLri
TAB 1 (MINIMUM REQUIREMENT #1)
• 1-2.5.1 Minimum Requirement#1 — Prepare a Stormwater Site Plan
1.3 — Preparation of a Stormwater Site Plan
- 1.3.1 — Stormwater Site Plans: Step-by-Step
Note: The level of detail needed for each step depends upon the project size. Provide a narrative
description of each step.
1-3.1.1 Step 1 - Site Analysis: Collect and Analyze Information on Existing Conditions
Site analysis shall be submitted as part of the Existing Conditions Summary above. Part of the
information in this step should be used to help prepare the Construction Stormwater Pollution
Prevention Plan. Purpose of the Site Analysis is to provide for a Low Impact Development site
design that is intended to compliment the predeveloped conditions of the site.
1-3.1.2 Step 2 - Prepare Preliminary Development Layout
Based upon the analysis of existing site conditions, locate the buildings, roads, parking lots,
landscaping features, on-site stormwater management BMP's, and preliminary location of
stormwater treatment and retention/detention facilities for the proposed development.
1-3.1.3 Step 3 - Perform Off-site Analysis (at Local Agency's Option): Use additional Sheets, if
necessary,
Ecology recommends that local governments require an off-site analysis for projects that add
5,000 SF or more of new hard surfaces, or convert% acres of vegetation to lawn or landscape
areas, or convert 2.5 acres of forested area to pasture.
Off-site analysis extends to '/4 mile downstream of the project site.
1-3.1.4 - Determine Applicable Minimum Requirements
Establish project size thresholds for the application of Minimum Requirements to new
development and redevelopment projects. Figures 2.4.1 Attached and 2.4.2 Attached
provide the same thresholds in a flow chart format. Based on the preliminary layout, determine
whether Minimum Requirements #1 through #5 apply to the project; or, whether Minimum
Requirements#1 through #9 apply.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Please note, that Minimum Requirement#1 through #5 may trigger additional Minimum
Requirements, such as Flow Control.
1-3.1.5 Step 5 - Prepare a Permanent Stormwater Control Plan
(Refer to this section of the Ecology Manual for requirements.)
1-3.1.6 Step 6 - Prepare a Construction Stormwater Pollution Prevention Plan (MR#2 — 13
Elements)
Refer to Chapter 11-3— Planning for a detailed description of each element. See also attached
Tables 4.1.1 (Source Control BMP's by SWPPP Element) and Table 4.2.1 (Runoff Conveyance
and Treatment BMP's by SWPPP Element).
See attached 13 Elements of a SWPPP, please complete and attached
1-3.1.7 Step 7 - Complete the stormwater site plan
The Stormwater Site Plan encompasses the entire submittal to the Local Agency with drainage
review authority. Refer to this section of the Manual for further clarification of each item and
what is required. See below:
• Project Overview
• Existing Conditions Summary
• Off-site Analysis Report
• Permanent Stormwater Control Plan
• Construction Stormwater Pollution Prevention Plan
• Special Reports and Studies
• Other Permits
• Operation and Maintenance Manual
• Declaration of Covenant for Privately Maintained Flow Control and Treatment Facilities.
(See attached Drainage BMP Maintenance Covenant BMP Agreement)
• Declaration of Covenant for Privately Maintained On-site Stormwater BMP's (See
attached Drainage BMP Maintenance Covenant BMP Agreement)
• Bond Quantities Worksheet, if applicable
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
1-3.1.8 Step 8 - Check Compliance with all Applicable Minimum Requirements
A Stormwater Site Plan as designed and implemented should specifically fulfill all Minimum
Requirements applicable to the project. The Stormwater Site Plan should be reviewed to check
that these requirements are satisfied.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 2 (MINIMUM REQUIREMENT #2)
• 1-2.5.2 Minimum Requirement#2 — Construction Stormwater Pollution Prevention Plan (SWPP)
- All projects are required to complete Minimum Requirement 2.
- Refer to the 13 Elements of the SWPP (See document below, complete and attach)
- See attached Table 4.1.1, Table 4.2.1 and Table
- Provide Engineering Calculations as an attachment for Sediment Ponds\Traps, Diversions,
Waterways and Runoff/Stormwater Detention Calculations.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Table 4.1.1 Source Control BMP's by SWPPP Element
Element#1 Element#2 Element#13
Element#5 Element#6 Element#9 Element#11 Element#12
BMPor Element Name Preserve Establish Stabilize Protect Control Maintain Managethe Protect Low
Vegetation/Mark Construction Soils Slopes Pollutants BMPs Project Impact
Clearin Limits Access Development
BMP C101: Preserving Natural Vegetation ✓
BMP C102:Buffer Zones ✓ ✓
BMP C103:High Visibility Plastic or Metal ✓ ✓
Fence
BMPC105: Stabilized Construction ✓
Entrance/Exit
BMP C106: Wheel Wash ✓
BMP C107: Construction Road/Parking ✓
Area Stabilization
BMP C120:Temporary and Permanent ✓ ✓
Seeding
BMP C121: Mulching ✓ ✓
BMP C122: Nets and Blankets ✓ ✓
BMP C123: Plastic Covering ✓
BMP C124: Sodding ✓
BMP C125: Topsoiling/Composting ✓
BMP C126: Polyacrylartide for Soil Erosion ✓
Protection
BMP C130: Surface Roughening ✓ ✓
BMPC131: Gradient Terraces ✓ ✓
BMPC140: Dust Control ✓
BMP C150: Materials On Hand ✓ ✓
BMP C151: Concrete Handling ✓
BMP C152: Saweutting and Surfacing ✓
Pollution Prevention
BMP C153: Material Delivery,Storage and ✓
Containment
BMP C154: Concrete Washout Area ✓
BMP C160: Certified Erosion and ✓ ✓
Sediment Control Lead
BMP C162:Scheduling ✓
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Table 4.2.1 Runoff Conveyance and Treatment BMP's by SWPPP Element
BsnrsM ilm Bement 1t8 Elen+ent M
Elernerrtrsi ElemertlAS EbmentM7 ElemeMflFJ Elerrsnt>:10
BMP or Elmnant Name Control Install Protect Noted Stabilize Control Control De- Protect I.ow
Flaw Raies 34dirrrent Slopes Drain Inlets Channels Parrrtants Watering Impact
Controls so Outlets 3eyelownent
OUP G200: Interceptor Dike and Swsla ✓ ✓
8MP C20,1: Grates-Lned Channels ✓
SUP C202:Chennel Lining ✓
IMP C203: "'ator Bars ✓ ✓
I
BMP C204: Pipe Slope 0 rain A ✓
MAIM C206: Subsurface Drains ✓
BMP C206: Level Spreader ✓
WAP C207: Ctwck Dam ✓
HMP C20s: Trlangularsitt Dike(apokextlle ✓ I ✓
Encased Check Dart
eMP C20B: OuIW P clect:on
BMP CM Stone Drain Inlet Proteellon ✓
BMP C231: Brush Barrier ✓ ✓
BMP C232: Oravel Filter Berm ✓
AMP C233: Snit Fence ✓ ✓
BMP C234: Vogelsled Strip ✓ ✓
8MP C235: Wattles ✓
BMP C238:Vegitstive FlltMion ✓
BPAP C240: Sodiawnt Trap ✓ ✓
BMP C241: Temporary Sed iii"M Pond ./ ✓
BIAP C250: Construction Slorn waler ✓
Chetrlcal Trealrnent
BMP C251:Construction Stonntwaor
FIRreAlon
BMP C25Z Hipp pH Neutraiizstlan Using
02
BMP CM pH Control for High pH%t rI t ✓
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
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:
F The 13 elements must be addressed E 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, provide the BMPs that will be applicable to your project. Use the attached Tables
provided.
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.
BMP C233: Silt fence will be installed on downslope sides of construction zone. Silt fence will mark
clearing limits and protect natural foliage area.
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.
BMP C105: Construction access already exists, at the existing paved driveway.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
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.
The building site is pretty flat, erosion should not be a major issue.
BMP C233 Silt fence is to be utilized
BMP C234: vegetated strip -- a vegetated strip will be retained around most of the building, including
at downslope side.
ELEMENT 4: Install Sediment Controls
❑ 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.
BMP C123: plastic covering over soil stockpile
BMP C233: silt fence
BMP C234: vegetated strips
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 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.
❑ 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
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
forecast.
❑ Stabilize soil stockpiles from erosion, protect with sediment trapping measures, and where possible, be
located away from storm drain inlets, waterways, and drainage channels.
❑ Minimize the amount of soil exposed during construction activity.
❑ Minimize the disturbance of steep slopes.
❑ Minimize soil compaction and, unless infeasible, preserve topsoil.
BMP C234: Vegetated strips to be retained around building site.
BMP C123: Soil stockpile will be covered with visqueen.
BMP C162: Scheduling -- when roof is completed gutters/downspouts will be installed as soon as
possible and storm water will be directed appropriately.
ELEMENT 6: Protect Slopes
❑ 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.
Consider soil types and its potential for erosion.
Stabilize soils on slopes, as specified in Element 5.
❑ BMP combinations are the most effective method of protecting slopes with disturbed soils. Ex: Use both
mulching and straw erosion control blankets.
There is significant vegetation between construction zone and significant slope. Any water flow will go
to vegetated area before reaching slope.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
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.
Inlets should be inspected weekly at a minimum and daily during storm events.
WSDOT standard plan F-40.20.00 BMP C220 storm drain inlet protection.
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.
No channels or outlets on this project.
ELEMENT 9: Control Pollutants
❑ 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.
❑ 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.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
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.
BMP C154: Designated concrete washout area.
Contractor is required to have a spill prevention kit.
ELEMENT 10: Control De-Watering
❑ 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.
If de-watering is deemed necessary, de-watering bags will be used to help remove sediment from the
pumped water.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
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. Some temporary erosion and sediment
control BMPs are bio-degradable and designed to remain in place following construction such as
compost socks.
❑ 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.
❑ Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from
removal of BMPs or vegetation.
Temporary BMP's will be removed after construction and maintained during construction.
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.
Erosion and sediment control measures to be used:
BMP C233 Silt fence. BMP C234 Vegetated strips.
BMP C123 Temporary soil stockpile covered with visqueen.
Extent of disturbed area will be limited.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
ELEMENT 13: Protect Low Impact Development BMPS
n If implementing any bioretention facilities or rain gardens, refer to the applicable BMP sections of the
Manual for requirements.
No bioretention facilities or rain gardens are to be implemented.
Applicant Signature Date
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 3 (MINIMUM REQUIREMENT #3)
• 1-2.5.3 Minimum Requirement#3 — Source Control of Pollution
All known, available and reasonable source control BMP's must be applied to all projects. Source
control BMP's must be selected, designed, maintained according to the reference Ecology Manual.
The intent of source control BMP's is to prevent stormwater from coming in contact with pollutants.
They are a cost-effective means of reducing pollutants in stormwater, and, therefore, should be
considered in all projects.
Single Family Residential Construction Projects and Residential Subdivisions are Exempt from
this Minimum Requirement
All Commercial Properties, Industrial Properties, and Multi-Family Properties, Boatyards, Sand and
Gravel Mining Opertations are required to comply with this Minimum Requirement.
Refer to Chapter IV-2.1 Applicable (Mandatory) Operationsal Source Control BMP's
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 4 (MINIMUM REQUIREMENT #4)
• Minimum Requirement#4— Preservation of Natural Drainage Systems and Outfalls
Natural drainage patterns shall be maintained and discharges from the project shall occur at the natural
location, to maximum extent practicable. The manner by which runoff is discharged from the project site
must not cause a significant adverse impact to downstream receiving waters and down gradient
properties. All outfalls require energy dissipation.
The objective is to preserve and utilize drainage systems to the fullest extent because of the multiple
stormwater benefits these systems provide; and to prevent erosion at the downstream of the discharge
location.
Refer to the reference manual for supplemental guidelines and additional information under this
section.
Will this project disturb the Natural Drainage System or Outfall of the project Site? Yes\No. If
yes, refer to section 1.2.5.4 for Supplemental Guidelines for additional information.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 5 (MINIMUM REQUIREMENT #5)
• Minimum Requirement#5—On-site Stormwater Management
Project thresholds that trigger Minimum Requirements #1 through #5, shall utilize the On-site
Stormwater Management BMP's from List#1 for all surfaces within each type of surface in List#1; or,
Demonstrate compliance with the LID Performance Standard. Projects selecting this option cannot use
Rain Gardens. They may choose to use Bioretention BMP's as described in Chapter V-7— Infiltration
and Bioretention Treatment Facilities to achieve the LID Performance Standard.
Refer to this section of the reference Manual for all Feasibility or Infeasibility Criteria for List #1
and List#2.
Is this project Flow Control Exempt? (Yes\No) (See Appendix I-E. Flow Control-Exempt
Surface Water). If yes, provide reasoning from the applicability section of 1-2.5.7 Minimum
Requirement#7: Flow Control). If No, then the project triggers Minimum Requirement#7 (1-2.5.7) and
possibly Minimum Requirement#8 (1-2.5.8).
If the project is Flow Control Exempt, select from the list below (Skip List 1 and List 2).
o BMP T5.13 Post Construction Soils Quality and Depth
o BMP T5.10A: Downspout Full Infiltration, or;
o BMP T5.10B Downspout Dispersion Systems, or;
o BMP T5.10C: Performated Stub-out Connections, or;
o BMP T5.11 Concentrated Flow Dispersion, or;
o BMP T5.12 Sheet Flow Dispersion
Projects triggering only Minimum Requirements 1 through 5, shall either:
A. Use On-site Stormwater Management BMP's from List#1 for all surfaces within each type of
surface in List#1, or;
B. Demonstrate compliance with the LID Performance Standard. Projects selecting this option cannot
use Rain Gardens. They may choose to use Bioretention BMP's as described in Chapter V-7
Infiltration and Bioretention Treatments Facilities to achieve the LID Performance Standard.
If a project will utilize the LID Performance Standard, then provide and attach reports and
calculations.
Stormwater discharges shall match developed discharge durations to pre-developed durations for
the range of pre-developed discharge rates from 8% of the 2-year peak flow to 50% of the 2-year
peak flow. Refer to the Standard Flow Control Requirement section in Minimum Requirement 7 for
information abou the assignment of the pre-developed conditions. Project sites that mus also meet
Minimum Requirement 7— Flow Control, must match flow durations between 8% of the 2-year flow
through the full 50 year flow.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Projects triggering Minimum Requirements 1 through 9, must meet the requirements in 1-2.5.5
Minimum Requirement 5— On-site Stormwater Management.
o Refer to Table 1-2.5.1 On-site Stormwater Management Requirements for Projects Triggering
Minimum Requirements 1 through 9 in the Department of Ecology Manual.
All sites are required to utilize BMP T5.13 — Post Construction Soil Quality and Depth.
For each surface, consider the BMP's in the order listed for that type of surface. Use the first BMP that
is considered feasible. No other on-site Stormwater Management BMP is necessary for that surface.
Feasiblity shall be determined by evaluation against:
1. Design criteria, limitations and infeasiblity criteria identified for each BMP in this manual, and;
2. Competing needs criteria listed in Chapter V-5— On-site Stormwater Management.
Lawn and Landscaped Area:
• BMP T5.13: Post-Construction Soil Quality and Depth. (Attach Detail in Report)
Refer to this site for requirements and specifications. All projects are required to utilize this BMP.
http://www.soilsforsalmon.orq/pdf/Soil BMP Manual.pdf
See Appendix 3 for the "Model Soil Management Plan for BMP T5.13" to be submitted with
Drainage Report and Application Material.
An alternate document acceptable to the City of Anacortes is a Test Report provided by the Soils
Supplier that identifies the soils to be used meet the specifications outlined under Minimum
Requirement 5. The specifications are in both WSDOT and CSI Formats. For specifications, refer to
the above referenced PDF.
This submittal can be a deferred submittal since most projects are not sure who the supplier will be
at the time of building permit application. For projects that trigger Minimum Requirements 1 through
5, the Test Report will be provided to the Building Department. Projects triggering Minimum
Requirements 1 through 9, the Test Report will be provided to the Engineering Department.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
List #1 — Protect Triggering Minimum Requirement 1 through 5
For each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that
is considered feasible. No ther On-site Stormwater Management BMP is necessary for that surface.
Provide feasible detail under each BMP with maintenance and operations specifications in Minimum
Requirement 5.
Roofs: List#1
1. BMP T5.30: Full Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Or, T5.10A: Downspout Full Infiltration Feasible\Infeasible
If infeasible, explain the criteria:
2. BMP T5.14A: Rain Gardens Feasible\Infeasible
If infeasible, explain the criteria:
Or, BMP T7.30: Bioretention Cells, Swales, and Planter Boxes Feasible\Infeasible
If infeasible, explain the criteria:
3. BMP T5.10B: Downspout Dispersion Systems Feasible\Infeasible
If infeasible, explain the criteria:
4. BMP T5.10C: Perforated Stub-out Connections Feasible\Infeasible
If infeasible, explain the criteria:
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Other Hard Surfaces: List#1
1. BMP T.5.30 Full Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
2. BMP T5.15: Permeable Pavements Feasible\Infeasible
If infeasible, explain the criteria:
Or, BMP T.14.A: Rain Gardens Feasible\Infeasible
If infeasible, explain the criteria:
Or, BMP T7.30: Biorention Cells, Swales and Planter Boxes Feasible\Infeasible
If infeasible, explain the criteria:
3. BMP T5.12: Sheet Flow Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Or, BMP T5.11: Concentrated Flow Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Applicant Signature Date
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
List #2 — Project Triggering Minimum Requirement 1 through 9
For each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that
is considered feasible. No ther On-site Stormwater Management BMP is necessary for that surface.
Provide feasible detail under each BMP with maintenance and operations specifications in Minimum
Requirement 5.
Roofs: List#2
1. BMP T5.30: Full Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Or, T5.10A: Downspout Full Infiltration Feasible\Infeasible
If infeasible, explain the criteria:
2. BMP T7.30: Biorention Cells, Swales and Planter Boxes Feasible\Infeasible
If infeasible, explain the criteria:
3. BMP T5.10B: Downspout Dispersion Systems Feasible\Infeasible
If infeasible, explain the criteria:
4. BMP T5.10C: Perforated Stub-out Connections Feasible\Infeasible
If infeasible, explain the criteria:
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Other Hard Surfaces: List#2
1. BMP T.5.30 Full Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
2. BMP T5.15: Permeable Pavements Feasible\Infeasible
If infeasible, explain the criteria:
3. BMP T7.30: Biorention Cells, Swales and Planter Boxes Feasible\Infeasible
If infeasible, explain the criteria:
4. BMP T5.12: Sheet Flow Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Or, BMP T5.11: Concentrated Flow Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Applicant Signature Date
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 6—(MINUMUM REQUIREMENT 6 - RUNOFF TREATMENT)
Refer to 1.2.5.6 and provide the required information for this Minimum Requirement.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 7 —(MINUMUM REQUIREMENT 7 — FLOW CONTROL)
Refer to 1.2.5.7 and provide the required information for this Minimum Requirement.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 8 —(MINUMUM REQUIREMENT 8 —WETLAND PROTECTION)
Refer to 1.2.5.8 and provide the required information for this Minimum Requirement.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
TAB 9 —(MINUMUM REQUIREMENT 9 — OPERATION AND MAINTENANCE)
Refer to 1.2.5.9 and provide the required information for this Minimum Requirement.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
APPENDIX 1 —Survey performed by a Professional Land Surveyor
The object of this appendix is to ensure that the property has a minimum of 3 out of 5 property corners
visible to ensure that the structures are placed within the required setbacks.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
APPENDIX 2 —Soils Anaylsis (Volume 1, Chapter 3.1.1)
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
APPENDIX 3 — Model Soil Management Plan for BMP T5.13
An alternate document acceptable to the City of Anacortes is a Test Report provided by the Soils Supplier that
identifies the soils to be used meet the specifications outlined under Minimum Requirement 5. The
specifications are in both WSDOT and CSI Formats. For specifications, refer to the above referenced PDF.
This submittal can be a deferred submittal since most projects are not sure who the supplier will be at the time
of building permit application. For projects that trigger Minimum Requirements 1 through 5, the Test Report will
be provided to the Building Department. Projects triggering Minimum Requirements 1 through 9, the Test
Report will be provided to the Engineering Department.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
DEFERRED SUBMITTAL: PROVIDE A TEST REPORT FROM SOILS SUPPLIER TO THE BUILDING DEPT.
PROJECT INFORMATION "Model Soil Management Plan for BMP T5.13" age# of pages
Com lete all information on page 1;only site address and permit number on additional pages.
Site Address/Lot No.:
Permit Type: Permit Number:
Permit Holder: Phone:
Mailing Address:
Contact Person: Phone:
Plan Prepared By:
ATTACHMENTS REQUIRED Check off required items that are attached to thisplan)
Site Plan showing,to scale: =Areas of undisturbed native vegetation(no amendment required)
=New planting beds and turf areas(amendment required)
e of soil improvement proposed for each area
Soil test results(required if proposing custom amendment rates
Product test results for proposed amendments
AREA# (should match Area#on Site Plan)
PLANTING TYPE =Turf undisturbed native vegetation
=Planting Beds Other:
SQUARE FOOTAGE OF THIS AREA: square feet
SCARIFICATION inches(depth)of scarification needed to achieve finished total 12"loosened depth.
=Subsoil will be scarified
PRE-APPROVED inches of compost or imported topsoil applied
AMENDMENT METHOD: X 3_1 (conversion factor, inches to cubic yards) PRODUCT:
=Topsoil import =cu.yards per 1,000 sq. ft.
=Amend with compost X ,000s sq.ft.in this area
=Stockpile and amend =cubic yards of amendment QUANTITY: CU.YDS.
cu.yds. stockpiled) needed to cover this area to designated depth)
CUSTOM AMENDMENT Attach test results and calculations.
=Topsoil import inches organic matter or topsoil import PRODUCT:
=Topsoil&compost lift X 3.1
=Amend =cu.yards/ 1,000 sq. ft.
0_Stockpile and amend X _,000s sq.ft. in this area
( cu.yds.stockpiled) =cubic yards of amendment -> -> QUANTITY: CU.YDS.
MULCH _,000 sq.ft. PRODUCT:
X 6.2 (conversion, to give 2 inch mulch depth)
=cubic yards of mulch —>--+—>--+--+--+ QUANTITY: CU.YDS.
TOTAL AMENDMENT/TOPSOIL/MULCH FOR ALL AREAS (complete on page 1 only, totaling all areas/ a es in this Plan
❑ Product#1: ❑ Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 exce t mulch,or<35:1 for nativeplants) "stable" es/no
❑ Product#2: ❑ Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 exce t mulch,or<35:1 for nativeplants) "stable" es/no
❑ Product#3: ❑ Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 (except mulch,or<35:1 for nativeplants) "stable" es/no
Date: Inspector: Approved: Revisions Required:
Date: Inspector: Approved: Revisions Required:
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
APPENDIX 4 — Determining Construction Site Sediment Damage Potential (Appendix 7 — NPDES Phase
II Permit)
Note: See attached. All projects within the City of Anacortes are required to complete that document under
Appendix 4.
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
Western Washington Phase H Stormwater Permit
APPENDIX 7 - Determining Construction Site
Sediment Damage Potential
The following rating system allows objective evaluation of a particular development site's potential to
discharge sediment. Permittees may use the rating system below or develop alternative process
designed to identify site-specific features which indicate that the site must be inspected prior to clearing
and construction. Any alternative evaluation process must be documented and provide for equivalent
environmental review.
Step one is to determine if there is a sediment/erosion sensitive feature downstream of the development
site. If there is such a site downstream complete step two, assessment of hydraulic nearness. If there is
a sediment/erosion sensitive feature and it is hydraulically near the site then go to step three to
determine the construction site sediment transport potential.
ii. STEP 1 — Sediment/Erosion Sensitive Feature Identification
Sediment/erosion sensitive features are areas subject to significant degradation due to the effect of
sediment deposition or erosion. Special protection must be provided to protect them.
Sediment/erosion sensitive features include but are not limited to:
i. Salmonid bearing fresh water streams and their tributaries or freshwater streams that
would be Salmonid bearing if not for anthropogenic barriers;
ii. Lakes;
ill. Category I, II, and III wetlands;
iv. Marine near-shore habitat;
V. Sites containing contaminated soils where erosion could cause dispersal of
contaminants; and
vi. Steep slopes (25% or greater) associated with one of the above features.
Identify any sediment/erosion sensitive features, and proceed to step two. If there are none the assessment
is complete.
STEP 2 — Hydraulic Nearness Assessment
Sites are hydraulically near a feature if the pollutant load and peak quantity of runoff from the site will not
be naturally attenuated before entering the feature. The conditions that render a site hydraulically near
to a feature include, but are not limited to, the following:
i. The feature or a buffer to protect the feature is within 200 feet downstream of the site.
ii. Runoff from the site is tight-lined to the feature or flows to the feature through a channel
or ditch.
August 1, 2013, Modified January 16, 2015 Appendix 7- Determining Sediment Damage
Potential Page 1 of 3
Version Date: November 29, 2021 Previous Version Date: October 7, 2019
A site is not hydraulically near a feature if one of the following takes place to provide attenuation
before runoff from the site enters the feature:
iv. Sheet flow through a vegetated area with dense ground cover
V. Flow through a wetland not included as a sensitive feature
vi. Flow through a significant shallow or adverse slope, not in a conveyance
channel, between the site and the sensitive feature.
Identify any of the sediment/erosion sensitive features from step one that are hydraulically near
the site, and proceed to step three. If none of the sediment/erosion sensitive features are
hydraulically near the site, the assessment is complete.
vii. STEP 3 — Construction Site Sediment Transport Potential
Using the worksheet below, determine the total points for each development site. Assign points
based on the most critical condition that affects 10% or more of the site.
If soil testing has been performed on site, the results should be used to determine the
predominant soil type on the site. Otherwise, soil information should be obtained from the
county soil survey to determine Hydrologic Soil Group (Table of Engineering Index Properties
for step 1.D) and Erosion Potential (Table of Water Features for step 1.E)
When using the county soil survey, the dominant soil type may be in question, particularly when
the site falls on a boundary between two soil types or when one of two soil types may be present
on a site. In this case, the soil type resulting in the most points on the rating system will be
assumed unless site soil tests indicate that another soil type dominates the site.
Use the point score from Step 3 to determine whether the development site has a high potential
for sediment transport off of the site.
Total Score Transport Rating
<100 Low
100 High
A high transport rating indicates a higher risk that the site will generate sediment contaminated
runoff.
Construction Site Sediment Transport Potential Worksheet
A. Existing slope of site (average, weighted by aerial extent): Points
2% or less ...0
>2-5% ..............................................................................................5
>5-10% .......................................................................................... 15
>10-15% ........................................................................................30
>15% .............................................................................................50
B. Site Area to be cleared and/or graded:
<5,000 sq. ft ...................................................................................0
5,000 sq. ft. — 1 acre.....................................................................30
>1 acres .......................................................................................50
C. Quantity of cut and/or fill on site:
<500 cubic yards............................................................................0
500 — 5,000 cubic yards ................................................................... 5
>5,000 — 10,000 cubic yards.........................................................10
>10,000 —20,000 cubic yards.......................................................25
>20,000 cubic yards .....................................................................40
D. Runoff potential of predominant soils (Natural Resources Conservation Service): Hydrologic
soilgroup A....................................................................................0
Hydrologic soil group B.................................................................10
Hydrologic soil group C................................................................(
Hydrologic soil group D.................................................................40
E. Erosion Potential of predominant soils (Unified Classification System): GW, GP, SW,
SPsoils..........................................................................................0
Dual classifications (GW-GM, GP-GM, GW-GC,
GP-GC, SW-SM, SW-SC, SP-SM, SP-SC)..........................
GM, GC, SM, SC soils................................................................. 20
ML, CL, MH, CH soils...................................................................40
F. Surface or Groundwater entering site identified and intercepted 1:
Yes.................................................................................................0
No ................................................................................................25
G. Depth of cut or height of fill >10 feet:
Yes...............................................................................................25
No...........................................................................................................0
H. Clearing and grading will occur in the wet season (October 1 — May 1): Yes 50
No...........................................................................................................0
TOTALPOINTS............................................................................................. 95
1 If no surface or groundwater enters site, give 0 points.
APPENDIX 5—Site Plan with all applicable information (Minimum Size 11x17 at a legible scale)
APPENDIX 6 — Documented Site Photos (Show all directions of the site, including
frontage)
(Insert Photo Here)
Location:
Description of the photo:
Photo taken by:
APPENDIX 7 — Drainage BMP Facility Maintenance Covenant
Note: To be recorded prior to: 1) Temporary Certificate of Occupancy; 2) Final Certificate of Occupancy, and
or; 3) Final Acceptance of the project.
This is Covenant is required for any Permanent Stormwater Facility constructed on a project site. The applicant
should work with the the City of Anacortes Engineering Department on formalizing the document for recording.
5r
IM
c
Taken from west property line, looking east towards front entry of house. Note: garage addition is to go
south of this.
SN
- I
Taken from south side of property, looking to the north, looking at building site.The garage addition is
to go next to the existing garage.
ELEMENT 13: Protect Low Impact Development BMPS
i] If implementing any bioretention facilities or rain gardens, refer to the applicable BMP sections of the
Manual for requirements.
No bioretention facilities or rain gardens are to be implemented.
A plicant Si nat rh Date
Version Date: November 29, 2021 Previous Version Date: October 7, 2019