HomeMy WebLinkAboutPermit File BLD-2021-0181 4317 Cherry Court (2) 1T O �QFORCODEco
C,�►, w4 11 y O {� Storm Water Drainage
c, , Minimum Requirements 1 through 5
< ,� t, Minimum Requirement 1 through 9
� � RCOR� `o4, 1891 Ay z ENGINEERING DEPARTMENT
NI C O g ��FIELD 904 6 Street Anacortes, WA 98221
www.anacorteswa.gov
Post Construction Report-12.21.20
Official Use Only: (Information to Inspectors)
Require. Storm Water Fa i ity and other related requirements:
Sediment potential �ow, 80.
Project Address: Orchard Avenue/Cherry Lane Submittal Date:
Parcel Number: P135450 Revision Number: 3/11/21
Permit Number: Reviewer: Rob F
Acceptance Date (COA): 4/5/2021
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.
1
o APPENDIX 8—Vicinty Map, Aerial Exhibit, Downstream Exhibit and 2007 City of Anacortes Stormwater
Comprehensive Plan exerpts
o APPENDIX 9— NRCS/SCS soils information
o APPENDIX 10—WWMH Views & WWHM Report
o APPENDIX 11 — 2014 DOE BMP T5.10B, T5.11, T5.12, and T5.13
o APPENDIX 12 - Excerpts from DOE Manual and City of Anacortes Stormwater Comprehensive Plan
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.
Project Description and Summary:
Summary Table
Existing Proposed
Development Type None/Grass/Pasture Single Family
Residential
Number of Lots _ 1 1 (Lot 4 of Short Plat)
Lot Acreage in SF 20,526 sf(0.4712 acres)
Soil Type(s) #18& #19 per NRCS—Bow Gravelly
Loam-Refer to NRCS/SCS info in
Appendix 9 and the Geotechnical
Report within Appendix#2.
Site Sediment Transport Score (High\Low) 100(Of note this number however
includes future house construction on
the 6 lots which will not occur
simontaniously at the same time as plat
infrastructure so this number actually
is less). Refer to worksheet attached in
Appendix 4
Depth to Ground Water Table (Feet and Inches) Refer to Geotechnical Report prepared
(See completed Soils Analysis (Volume 1, Chapter 3.1.1) by Geotest Services (page 5)provided
at the end of this report in Appendix#2
Infiltration Rate during Rainy Season (Inch\Per Hour) Restrictive layer at varous elevations,
thus infiltration not genearally for the
entire site per Geotechnical Report
(pare 16) copvfirovided at the end of
this report in Appendix#2 however a
small amount of infiltration is
available per the Linda Spicher Soils
testing(Nov 2020) copy is attached.
Two lots (Lot 1 and 6) where the
restrictive soils are at approximately
41"and 54"inches deep future roof
runoff will be mitigated by roof drain
infiltration systems as noted
Impervious Surface (on-site) 1.083 Acres 0.1389 Acres
Impervious Surface (off-site) None None
New and Replaced Hard Surface Total (SF) 0-acres of New and replaced. 0.1389 Acres new
roofs and driveway.
2
Lot Coverage (Percentage) 0% 16.4%
BMP (Required Minimum Requirement 5) BMP T5.13 Post Construction Soils, BMP T5.13 Post
BMP 5.10E Downspout Dispersion, & Construction Soils,
BMP T5.11 and T5.12 Hard Surface BMP 5.10B
Dispersion, and Downspout/Ro f Downspout
Dispersion
Water Quality Method (Minimum Requirement 6) Dead Storage Cell to be provided in Dead Storage Cell to
pond bottom be provided in pond
bottom
Water Quantity Method (Minimum Requirement 7) Detention Pond with control structure Downspout
release to existing ditch Dispersion, Detention
Pond with control
structure release to
existing ditch
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)
See Post Construction Drainage Report, prepared by Ravnik and Associates, dated 12/21/2020. The subject
parcel is approximately 0.1389 acres in size.
The project is located southerly of Cherry Court, approximately 750 feet south of 41st Street. The property is
generally high in the southwest corner, and slopes downhill to the northeast to the low point at the northeast
corner of the site. The project area is currently covered with grass and contains no existing buildings.
Per the DOE Volume 1-Figure I-2.4.1 Flow Chart for Determining Requirements for New Development, all
DOE Minimum Requirements (MR) #1-9 apply to "new impervious surfaces and converted pervious
surfaces': Existing short grass/pasture areas within the site will remain grass, with the exception of
the areas denoted below, such as the new driveway, walkway to house, and house. Grass areas, to remain
grass/landscape area.
Developed Conditions Summary:
Development of this property to construct one new residential structure with attached garage and a hard
surface driveway, and walkway,for a total impervius area of 6,051 s.f.
All roof areas (3,760 s.f.) are to be dispersed on-site. The proposed walkway and patio (34 s.f) will be
dispersed immediately adjacent to said hard surfaces. The driveway (2,662 s.f.) runoff will be collected
and hard lined to the detention pond, where it will be meet water quality and quantity requirements.
Roof downspout dispersion will be used for Lot 5 per BMP T5.10B and with these facilities located so
that they have a minimum 50-feet for the SFR of down gradient dispersion lengths
3
within the lot. Once a minimum of 50 feet of dispersion as designated has been achieved, these dispersed
runoff waters can then be collected and conveyed to the detention system.
Drainage Basin (2007 Storm Comp Plan — City website\publicworks\engineering\comprehensive plans):
What Drainage Basin are you in?Anacortes Subbasin F-4. Identify any downstream drainage issues (Storm
Comp Plan: Noted below If so, describe:
Addressed in said drainage report by Ravnik and Associates.
Complete the Applicability Requirements — Flow Chart (Figure 1-2.4.1 Attached, and Figure 1-2.5.1
Attached)
- Refer to attached highlighted Figure I-2.4.1 and Figure I-2.5.1 which are applicable to this
project
4
Start Here
Does the site have 35% 'Yes See Redevelopment Minimum
cc more of existing Requirements and Flew Chart
impervious ixiverage? Figure 1-24.2)_
No
I:hoes the project convert
Atir acres or male of vegetation to
Dues the project result in lawn ar landscaped areas, or
5,001)square feet, or No convert 2_5 acres ar more of
greater, of new plus OD native vegetation ID pasture?
replaced hard surface •
area?
No
Yes.
Yes Does the project result in 2,00I}
Atir square feet, or greater, of new plus
All Minimum R eau firer rren replaced hard surface area?
apply to the new and replaced
hard surfaces and converted
vegetation arras_ 77/5/ No
V
Does the project have land
•
Minimum Requirements #1 disturbing activities of ,000
through#5 apply to the new Yes square feet or greaten?
and replaced hard surfaces
and the land disturbed.
No
'l F
Mini-ria rrti Requirement#2
applies_
111 Figure I- _4_�I
Flow Chart for Determining Requirements for
New Development
DEPARTMENT o F R EV 15 ECI June.2]15
ECOLOGY Please see hapArvr►x_ecy.wa.9aw+lcap}agf.irnr Far€cipvrk1t notice II-am:Mg perml&slcrs,
Slate DI 1PdaGIh Ingtan limitation DT IlaralItty,and disclaimer.
Does the paler(Is hange 1D Fin'Oantr'I Exempt Waters iper Minimum RequirE#ner t 1MR)#T:?
Yes
REQUIRED: implement the fntioth'rrg EMPs No
where.feasdie:
+ EN P T5_13:Past-Camh- IMI soli Dimity r N the
and Depth Dares the propel pn ect
+ EN P T5.1OA,6,ar C:Downvourl Full trigger only M Rs R1- triggered
I9ritmllor.Dcw''rsoout Dispersion # ?(Per Figure 3.2 or only hilt )
3}s.ET:,or Perioraled bout Figure.3..3 In Appendix No additional
•Camnettans 1 oT the 2013-2015 requirements
+ EMP T5.11 or T5.12:Concentrated Flog !AIWA Phase II Permit
Dispersiam or Sheet FIDw Dispersion &Phase I Perrnit}.
NOT REQUIRED:A,ctriegernent Di file LID Na i:trie project trigger
Perfarmance 131zindard.Applying the other '� amflr MRs i�i -?
EMPs In List R1 CI List#2.
is the pro]eo!inside the IJ 4?
Did the pale t dewel per encase 1a nest
the LID Pertormamce•51arrdaid? Yes v
Is teas pra}eat an a parcel
V114C1I ar 5 acres or larger?
REQUIRED:IRED:Far each Dld the prcieel deweicper .. p._-----1-:
sor , consider re chODee to meet the LID V Yes
b
EMPs In the ceder Performance SUndard? REQUIRED: Meet the LID
listed In List#1 Far that • Perrbrrnamee 5laandMI trim ugh
type of surface. use VIA the use Diane OM PI.$)In the
the first BHP that's 2014 EAVIIIMIAPAI except ice
ccnsIdered Feasible. el. No Rain Gardens the use of
Elloretentien is ac-ceptable}.
NOT REQUIRED:
Achievement DI the LID v tr ME pro Jac!caul meat the
Peril:mance Standard. - REQUIRED: For Each LID Performan,E Standard, It
V surrace,acnstder the EMPs must sa-ak an d be p ranted an
REQUIRED: Meet the LID Perforranee In the order IsIEd In List ExcEptloni, ariar5c .
Standard through the use Df am 6 M Pis)in ice that tytpe or srurrace. use
the 2D14%NV iklWW e1oc.ept fir Rain.ardena 1he fist EMP that Is REQU IRE1:Apply BMP T5.13
(the Use ar b oreterrtion is acceplalale}. considered feasible. Past-Canstnrctien Sol Qualy
and Dep+tn.
REQUIRED ran PrDIects Trimming MR R1•': NOT REQUIRED:
Apply EIMP T5.13 Past Construction Soil Achievement of the LID MDT REQUIRED:Applying the
°silty and Depth. Ferro-mance ndard. UMPs In List 1 or U61 i2.
NOT REQUIRED:Applying the 9 1/41 Pa i _1st
If 1 a List V. 'Recommewled ay EcolDgy for proles-Jiggering FP'Rs R1 -r.5.
illFigure I- _5-A
Flow Chart for Determining LID MR 45
Requirements
DEPARTMENT OF Revtsd JuneD1$
ECOLOGY DIEme see ilrip:/Avww_st-y.wa.gioiertoppgiltlirnii rar aapyrtgirt notice Including permissions,
Slate Di Washington limitation DI Ilabllttyr,and disclaimer.
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
infrmation in tnis step snc, ,C UJeU co nelp piepare me construction toirmwater I-'l
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.
Existing Condition of Lot 4 is that the site is vacant, has been stabilized during the plat
construction. The site slopes from southeast to northwest at approximately 6.0%. Lot 4 is
bounded to the north by Lot 5 and Cherry Court, a public street, and is bounded to the south
by Orchard Place. The site is bounded to the east by Tax Parcel P32116 and to the west by Lot
3. A geotechnical investigation has been conducted onsite which identified an underlying very
dense, brown, slightly gravelly silty sand(weathered glacial till) at 3-4 feet below ground
surface which has very limited infiltration capacity at depth. Per the geotechnical report
(page 16), "conventional infiltration of stormwater on this site is not feasible': Dispersion
methods for runoff from roofs and driveways will be promoted as noted further on within this
report. Recently we have had Linda Spicher, a septic designer do more detailed test pits to
check the availability of infiltration for roof drains on Lots 1 and 6. With the installation of a
perimeter interceptor trench drain this type of onsite stormwater control to mitigate larger
house sizes is feasible when accounting for a very small amount of infiltration in these areas.
A underlying infiltration rate of 0.0267 in/hr and 0.0401 in/hr(coorolating to 4 gallons/sf/day
to 6 gallons/sf/day noted on the information provided by Linda Spicher) has been used. The
Geotechnical report for this project indicated a perched groundwater elevation, which will be
somewhat alleviated due to the interceptor driange system put in place along the south and
west property lines of the project area. Refer to both the septic testing performed by Linda
Spicher and the Geotechnical Report prepared by Geotest for this project located within
Appendix 2 at the end of this report.
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.
Refer to the attached Erosion Control Plan and Site Plan Exhibit showing the proposed
location of new walkway, driveway, SFR, stormwater piping, and dispersion areas.
1-3.1.3 Step 3 - Perform Off-site Analysis (at Local Agency's Option): Use additional Sheets, if
necessary,
7
Per the City of Anacortes Stormwater Comprehensive Plan runoff from this project is
discharged to Ace of Hearts Creek, which conveys runoff northeasterly approximately 0.7-
miles, towards 32nd and M Avenue, then easterly approximately 0.5-miles east to "T"
Avenue. From 32nd and "T"runoff waters are conveyed north in "T"Avenue another 0.2-
miles, before being discharged to Fidallo Bay to the northeast. Refer to the Downstream
Exhibit attached with this report.
1-3.1.4 - Determine Applicable Minimum Requirements
Per the attached Minimum Requirements for new development Figure 2.4.1. Minimum
Requirements #1 through #9 apply to new and converted surfaces proposed with this site.
Refer to attached highlighted Figure 2.4.1.
1-3.1.5 Step 5 - Prepare a Permanent Stormwater Control Plan
See Post Construction Drainage Report,prepared by Ravnik and Associates, dated 12/21/2020.
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
See attached "CHERRY COURT-SWPPP-LOT 04"and the Erosion Control Plan and Site
Plan, Lot 4, Cherry Court.
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
8
See the attached Erosion Control Plan and Site Plan, Lot 4, Cherry Court. A Deparment
2(Ecology NOI/NPDES permit has been issued for this site under#WAR309407
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.
See attached Erosion Control Plan and Site Plan, Lot 4, Cherry Court.
9
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.
See attached "CHERRY COURT-SWPPP-LOT 04"and the Erosion Control Plan and Site
Plan, Lot 4, Cherry Court.
10
Table 4.1.1 Source Control BMP's by SWPPP Element
Element al ElamarnR Element05 Element OS Element AS Element Ell Elementll2 Elamemfl3
BYP or Element Nerve Preserve Estehlhh StebItre Protect Control Maintain Yivnge the Protect Low
1Raget tlenlMark Canatntdlon sob Slopes Pollutions BMPs Protect Impact
Cleerina Limb Access Development
BMP C101: Preserving Natural Vegetation ✓
BMP C102:Buller Iona ✓ ✓
BMP C103:High VIsIbIItl Plastic or Meted ✓ ✓
Fence
BMP C101: ltablkedConstruction ✓
Entrance f Exit
BHP CIOS:Wheel Wash ✓
BMP C10T:Construction RerdlParkbg ✓
Area Stnhlltnlon
BMP C120:Temporary and Permanent ✓
Seeding
BHP C121: Mulching ✓ ✓
BHP C122: Nos and Bleebett t/ ✓
BHP C1w: Platt#Covering ✓
®MP C124: Sodding ✓
BHP C125: iopeollingIComposting ✓
BHP C120: POFyacr 4eiide for Soil Erosion ✓
Prone lien
SLIP Clair Surface Roughening ✓ ✓
BHP C131:GredlennTerraces I ✓
BHP C140: Dust Control ✓
®MP C150: Materials On Hand ✓ t/
BHP C111:Concrete Handling ✓
BMP C112: Saereutting and SuriacEig ✓
Pollution Prevention
B1P C113: Material Delivery,Storage and
Containment
BLIP C71i:Concrete Washout Area ✓
BLIP C11O:Certified Eroslenand ✓ ✓
Sediment Control Lead
BHP C102:Scheduling ✓
11
Table 4.2.1 Runoff Conveyance and Treatment BMP's by SWPPP Element
E3ertr8rd IC E].or. E E7errsent SU 'Velmrnt 17 Fitment iif# Eier,mt Fro Ierrsnk V1P Plertrent FF19
la
IMP OF f ig rrt Name • ' cF�01 et�l Pr ei Ph hv *1:I dinblfl2o Qnntral Cambial Da,
raleck LA+R
Flom R9r14F S*direLrt Slope* 1:raln lib 42:11onnaill PF'enutamts kReterll'p Impact
wrlr;la and Outlets 7ieYo-bprnari!
c240: Into reeptorDike arid. welra .
611.AP C2Ott Gran-Lewd C harursls
•
6 P C2IM Channel L1r .1 ,
& P C2.00: liklitOFfart if ve •
131NW r*3?d: P#pe Slope Dretna
HOW C20d: Su{bsrrfaq Drain' • V '
E
Badly C Q : Lave 9preaAea ,l I I
I`ti115'C207: Chock Cams ,C
I
@MP G200; Yrlarrguiar S4Ik DIM{0e+34easli . 1 . _
1,1
Encased Chick Darr)
12MP C Outlet Pracalian i
6MIPCM: 9torrn Brain IrilirtProteallon• i 1
13MP{ 31_ Eirni#r fBariier i ,
13M 92:P C2 Gravid Filter Berm ,
VMP
BMP C.2.34: VircitalEKI Strip , i ,
Bldg C23E Vejllrtlxe FMIEratIon 'I
-- - - -^
imp ijailik SadFmont Try t../ If •
6MP C241: Te•mya•rary went Parrd / i
MP C251? COni#rizell a Srorrndisile7 ye
Cbeinl[al Yreatmeat I
f3MP Cal:Cometraauon IStamxodur • I •
FlllrallQrr
EIMP C252'Hai pH Nepiraltratlon 1J ICOI ,
IMF'C :pHeanadfarWlphpHWier 1 V - I
12
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 Property Owner:LG Anacortes, LLC; Contact:Anna Nelson
Site Address: 4317 Cherry Court,Anacortes, WA (P )
Prepared By: LGAnacortes, LLC
The Stormwater checklist or building permit determined that:
The 13 elements must be addressed AThese 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 BMP's 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.
IS Retain the duff layer, native top soil, and natural vegetation in an undisturbed state to the maximum
degree practical.
The clearing limits will be marked by using either BMP C233:Silt Fence, or BMP C103:High Visibility
Plastic or Metal Fence, as shown on the Erosion Control Plan. C233 is to be used alonj"the east, west and
north property lines and the C103 along the south and west property lines.
Preservation of the native top soil will be preserved as much as is practical by use of a stock pile as shown on
the Erosion Control Plan. Stock pile location may vary. Stock pile shall be protected as indicated on the
Erosion Control Plan.
ELEMENT 2: Establish Construction Access
aS 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.
13
* 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.
N 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 shall be used as the construction access. Only one access point is proposed.
No wheel wash is proposed.
Any track out shall be cleaned daily by shoveling and/or sweeping. More frequent cleaning as necessary.
ELEMENT 3: Control Flow Rates
N 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.
N 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.
No flow rate controls are designed for the individual lot. However, a detention pond and wet pond were
constructed with a flow control structure outlet. Erosion control BMPs described in ELEMENT 4, below will
reduce velocity of flows.
Down stream, the existing detention pond shall be used to detain developed runoff and provide time for
sediment to be filtered out prior to being discharged from the site.
ELEMENT 4: Install Sediment Controls
N Design, install, and maintain effective erosion controls and sediment controls to minimize the discharge
of pollutants.
N 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.
N 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.
N 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.
N 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.
N Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to
increase sediment removal, and maximize stormwater infiltration.
N 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.
C233:Silt Fence
14
To be place along the perimeter of the site to protect downstream properties from the transport of coarse sediment,
as well as to mark the clearing limits for the construction crew and to alert the public as to the potential dangers of
the ongoing onsite construction activity.
C105:Stabilized Construction Entrance
To be place in the location of the future driveway to provide a stable and clean point of access for construction
vehicles.
C121:Mulching
To provide immediate temporary protection of exposed soil from erosion, as well as conserving moisture.
C123:Plastic Covering
Primarily used to protect the stock pile from erosion. May be used as a short term cover of small areas of exposed
soil. Not intended for large areas.
C140:Dust Control
The primary source of dust control will be by spraying of the disturbed area with water.
C220:Storm Drain Inlet Protection
Onsite inlet protection will use Block& Gravel Curb Inlet Protection.
Offsite inlet protection will use Catch Basin Filters manufactured for use at construction sites.
C207: Check Dams
Where drainage swale are created to convey stormwater, temporary gravel check dams may be used to reduce
velocity and to dissipate flow energy.
The following BMP improvement(s) are proposed for permanent sediment controls:
C124: Sodding
Sodding is to establish permanent turf for immediate erosion protection.
C125: Top Soiling
Provides a suitable growth medium for final site stabilization with vegetation.
Down stream, the existing detention pond shall be used to detain developed runoff and provide time for
sediment to be filtered out prior to being discharged from the site.
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.
N 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
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. (NA)
• Minimize soil compaction and, unless infeasible, preserve topsoil.
The following are temporary soil stabilization BMPs:
C233:Silt Fence
To be place along the perimeter of the site to protect downstream properties from the transport of coarse sediment,
as well as to mark the clearing limits for the construction crew and to alert the public as to the potential dangers of
the ongoing onsite construction activity.
15
C105:Stabilized Construction Entrance
To be place in the location of the future driveway on Latitude Circle, to provide a stable and clean point of access
for construction vehicles.
C121:Mulching
To provide immediate temporary protection of exposed soil from erosion, as well as conserving moisture.
C123:Plastic Covering
Primarily used to protect the stock pile from erosion. May be used as a short term cover of small areas of exposed
soil. Not intended for large areas.
C140:Dust Control
The primary source of dust control will be controlled spraying of the disturbed area with water.
C220:Storm Drain Inlet Protection
Onsite inlet protection will use Block& Gravel Curb Inlet Protection.
Offsite inlet protection will use Catch Basin Filters manufactured for use at construction sites.
C207: Check Dams
Where drainage swale are created to convey stormwater, temporary gravel check dams may be used to reduce
velocity and to dissipate flow energy.
The following are permanent soil stabilization BMPs:
C124:Sodding
Establishes permanent turf for immediate erosion protection.
C125: Top Soiling
Provides a suitable growth medium for final site stabilization with vegetation.
T5.13:Post-Construction Soil Quality and Depth
Establishes soil quality and depth regains greater stormwater functions in the post development landscape,
provides increased treatment of pollutants and sediments that result from development and habitation.
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.
1$ 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.
16
C235:Straw Wattles
Straw Wattles reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain
sediment.
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.
C220:Storm Drain Inlet Protection
Onsite inlet protection will use Block& Gravel Curb Inlet Protection.
Offsite inlet protection will use Catch Basin Filters manufactured for use at construction sites.
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.
C207: Check Dams
Where drainajie swale are created to convey stormwater, temporary jiravel check dams may be used to reduce
velocity and to dissipate flow energy.
ELEMENT 9: Control Pollutants
* Design, install, implement, and maintain effective pollution prevention measures to minimize the
discharge of pollutants.
Q Handle and dispose of all pollutants, including waste materials and demolition debris that occur on-site
7� 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
17
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.
N 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.
N 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.
N 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.
All fuel, lubricants,paint, and/or other hazardous material shall be stored in a lockable, covered storage
container if kept on site.
Note: The contractor is required to have a spill prevention kit on site at all times.
ELEMENT 10: Control De-Watering Not Applicable, no dewatering is anticipated
❑ 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.
18
ELEMENT 11: Maintain BMPs
$t 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.
N 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.
N 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.
N Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from
removal of BMPs or vegetation.
A trained Certified Erosion and Sedimentation Control Lead(CESCL) will be on the job site. CESCL personnel
are trained in and responsible for the proper maintenance of the erosion control BMPs. The CESCL will work
with the City of Anacortes Inspector to maintain all BMPs.
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.
SS 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.
N Inspection and monitoring — Inspect, maintain, and repair all BMPs as needed to assure continued
performance of their intended function.
N Maintain, update, and implement the SWPPP.
N Clearing and grading activities for developments shall be permitted only if conducted using an approved
site development plan (e.g., subdivision approval).
N 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.
N 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.
The project contractor will prepare a SWPPP that will expand on the site's erosion controls as required. The
SWPPP and CESL will assure site is manajed properly
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Note: The project is required to have a CESCL and will need to maintain a project SWPPP for the duration
of construction
ELEMENT 13: Protect Low Impact Development BMPS
If implementing any bioretention facilities or rain gardens, refer to the applicable BMP sections of the
Manual for requirements.
BMP T5.10B Downspout Dispersion and to be implemented on this site. Compaction of soil in dispersion areas to
be avoided.
02/05/2021
Applicant Signature Date
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.
There is no source control pollution anticipated within this Residential Subdivision and thus this
Minimum Requirement is not necessary
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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.
No. This project will not disturb the natural drainage system or outfall from the project site. Runoff
will be detained prior to beingreleased via a control structure at the site's northeast corner, as occurs
today.
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TAB 5 (MINIMUM REQUIREMENT #5)
• Minimum Requirement#5— On-site Stormwater Management
Since this project triggers Minimum Requirements #1 through #9, and is on a parcel located within
the City limits, this project has the choice to either utilize the On-site Stormwater Management
BMP's from List#2 for each type of surface noted on the list; or, can demonstrate compliance with
the LID Performance Standard. This project will use List#2 to meet the requirements of On-site
Stormwater Management as specified below.
Is this project Flow Control Exempt? No (Yes\No) (See Appendix l-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).
Projects triggering Minimum Requirements 1 through 9, must meet the requirements in 1-2.5.5
Minimum Requirement 5— On-site Stormwater Management.
To meet the requirements of MR #5 for this project, each surface on List#2, as listed below, will be
reviewed and BMP's will be considered in the order listed for that type of surface. The first BMP for
the surface that is considered feasible shall be implemented.
Lawn and Landscaped Area:
• BMP T5.13: Post-Construction Soil Quality and Depth. (Refer to DOE Figure V-5.3.3)
Refer to this site for requirements and specifications. All projects are required to utilize this BMP.
http://www.soilsforsalmon.org/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. Since this project triggerings Minimum Requirements 1
through 9, the Test Report will be provided to the Engineering Department.
This submittal will be deferred since this project is not sure who the supplier will be at this time.
Since this project triggers Minimum Requirements 1 through 9, the Test Report will be provided
to the Engineering Department as denoted in directions above.
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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 other 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:
1. BMP T5.30: Full Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Full Dispersion, BMP T5.30, is not feasible as the site is not retaining at least 65% of its natural
forested or native condition.
Or, T5.10A: Downspout Full Infiltration Feasible\Infeasible
If infeasible, explain the criteria:
Full Infiltration, BMP T5.10A, is not feasible as the site does not have outwash or loam soils, and
the underlying soils have an infiltration rate less than 0.3 inches per hour. Due to the low
infiltration rate in the underlying soils this BMP is not required, however will be incorporated
into the design for the future lot development to infiltrate roof water from new houses on Lots 1
and Lot 6 as noted further on in this report as noted.
2. BMP T7.30: Biorention Cells, Swales and Planter Boxes Feasible\Infeasible
If infeasible, explain the criteria:
Bioretention is not feasible as the site's underlying soils have an infiltration rate less than 0.3
inches per hour.
3. BMP T5.10B: Downspout Dispersion Systems Feasible\Infeasible
If infeasible, explain the criteria:
Dispersion is being proposed for roof runoff. Downspout Dispersion System are only functional
when having a vegetated flow path of 25 — 50 feet. The proposed lot will have sufficient room to
provide for a dispersion system for new home and shop roofs.
4. BMP T5.10C: Perforated Stub-out Connections Feasible\Infeasible
If infeasible, explain the criteria:
Not applicable since BMP T5.10B:Downspout Dispersion Systems
are proposed.
Other Hard Surfaces: List#2
1. BMP T.5.30 Full Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Full Dispersion, BMP T5.30, is not feasible as the site is not retaining at least 65% of its natural
forested or native condition.
23
2. BMP T5.15: Permeable Pavements Feasible\Infeasible
If infeasible, explain the criteria:
Permeable Pavement is not feasible per the 2014 DOE Manual as the site's infiltration capacity is
less than 0.30 inches per hour, however this BMP can be incorporated using the low infiltration
rates available if upon site development it is deemed necessary.
3. BMP T7.30: Biorention Cells, Swales and Planter Boxes Feasible\Infeasible
If infeasible, explain the criteria:
Just as for Permeable Pavement, Bioretention is infeasible per the 2014 DOE Manual as the
underlying soils within the site has a lack of infiltration capacity (less than 0.30 inches per hour).
4. BMP T5.12: Sheet Flow Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Sheet Flow Dispersion BMP T5.12 will not be used on proposed Lot 4.
Or, BMP T5.11: Concentrated Flow Dispersion Feasible\Infeasible
If infeasible, explain the criteria:
Lot 4 will not implement Concentrated Flow Dispersion per BMP T5.11, however this BMP will
be used to disperse driveway runoff on some lots as noted at the time of lot development on
driveways which are sloped.
aaz 02/05/2021
Applicant Signature Date
24
TAB 6— (MINUMUM REQUIREMENT 6 - RUNOFF TREATMENT)
Refer to 1.2.5.6 and provide the required information for this Minimum Requirement.
This residential project is responsible for providing Basic Runoff Treatment. Runoff treatment from this
residential project will be provided by the incorporation of a dead storage cell located within the bottom of
the proposed detention pond. Per the post construction WWHM model the 24-hour Online Water Quality
Volume that must be provided for the proposed residential development is 0,09 acre-feet(0.0814 acre feet
asbuilt) or 3,928 cubic feet(3,589 cubic feet asbuilt). Refer to the attached Post Construction WWHM Views
and Report denoting the required volume attached in Appendix 10. The dead storage cell in the bottom of
the pond is has 1.4-feet deep of dead storage volume below the pond's live storage volume asbuilt elevation of
292.65.
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TAB 7— (MINUMUM REQUIREMENT 7 — FLOW CONTROL)
Refer to 1.2.5.7 and provide the required information for this Minimum Requirement.
Runoff from the project basin area, including areas proposed for future development, will be collected and
tight-lined to an above ground detention pond system to be located within the northeast corner of the subject
property. The detention volume has been provided to detain runoff and will release it at controlled rates via a
control structure. The system will release runoff northeasterly to the existing ditch/swale located along the
southerly side of Orchard Avenue, north of the site. The proposed stormwater control structure has been
specifically designed for this project so that when the combined flow duration curve, or the inflow to the
detention pond from the post-developed conditions, is routed to the proposed detention pond, runoff will be
detained and released at a rate not to exceed the established Pre-developed flow durations. The flow curve
depicting the release of stormwater from the proposed detention pond and control structure is identified as
"801 POC1 Mitigated Flow" on the attached Post Construction WWHM exhibits. This mitigated flow
release rate is based on the existing (pre-developed) target flow duration noted as 501 POC 1. Based on the
proposed detention pond and control structure the system provides adequate detention volume and a
controlled release of stormwater so the waters discharged from the site conform to the runoff control
requirements of the 2014 DOE manual. To substantiate that the system is sufficient one must obtain a
"pass" within the WWHM software which assures that the post-developed condition releases stormwater at
rates not to exceed the thresholds identified as the pre-developed,pasture condition.
Using the design information previously noted, WWHM has been used to design confirm the necessary
detention pond volume and size the control structure to--be has been constructed as necessary to mitigate the
increase in runoff generated from the proposed residential development proposed herein. The detention
pond and control structure used with this analysis are as follows:
Proposed Detention Pond:
Detention Pond Bottom Footprint Area: 2,964 square feet
Pond Live Storage Depth: 2.0 ft deep +1 foot freeboard=3 feet deep
Pond Dead Storage Depth 1.4-feet+ 0.5 feet sedimentation depth as required
Pond Dead Storage Bottom Elevation —291.23 291.25
Pond Dead Storage Top Elevation=Live Storage Bottom Elevation-292.63 292.65
Pond Top 2-feet Live Storage Elevation= 294.63 294.65
Pond Top Elevation (incl 1-foot freeboard) =295.63 295.65
Control Structure:
Proposed Notch Weir/Orifice Control Structure
Riser Height: 2.0 ft. (above outlet elevation) =Elevation 294.63 294.65
Riser Diameter: 12 in.
Rectangular Notch Height=0.69feet 0.68 feet(from top of riser)
Rectangular Notch Width=0.040 feet(0.48-inches)
Bottom Orifice Diameter: 0.85 inches 0.85 inches. (0 above outlet elevation)
Previously the 3.11 acre developed drainage basin accounted for lot development to include 3,200 square
feet of house and 1,000 square feet of driveway for each of the five lots as required by the 2014 DOE
Manual. During plat construction, when house site layouts were being considered it became noted that
larger house sites were available within the proposed lots. These lot fit layouts also included anticipated
driveway areas which were also different. The information used for the final design is noted below and is
26
based on current lot fits for the project with what is estimated to be the largest house site that is
anticipated for each lot. Refer to the information for each lot and the right of way area, which includes
the sidewalk and pond areas. Also refer to the attached Post Developed WWMH Report and Views noting
that the pond and control structure along with the onsite LID provisions to be installed with house
construction are sufficient to receive a "pass" Additional onsite downspout/roof drain infiltration
systems were added for Lots I and 6 as detailed below to further mitigate runoff These two roof drain
infiltration systems will only be 0.67-feet deep and will collect clean roof drain runoff from these two lots
and detain them within a drainrock filled trench. An overflow will be provided for both systems which
will provide for an overflow to the storm system (and ultimately the detention pond) during storm events
that exceed the trenches capacity to infiltrate. Conservative infiltration rates of 0.4 gal/sf/day (0.0267
in/hr) for Lot 1 and 0.6 xal/sf/day (0.0401 in/hour) for Lot 6 was assumed as noted within the lot specific
soils information noted by 11/28/20 soils information provided by Linda Spicher at the end of this report.
Within the Spicher test pit numbers 1 and 6 coalatin.to Lots 1 and 6, the restrictive clay layer at these
locations is at 41 to 54-inches deep. With these trenches proposed to only be 0.67-feet deep, there is
sufficient room from the bottom of trench to provide the necessary 12-inch separation to the previously
anticipated perched ground water, which has likely been lowered due to the installation of the trench
drain along the upradient(south and west) sides of the site with this projects road and pond construction.
Right of Way(ROW)Sub-Basin(0.52 ac)
0.19 ac Road
0.05 ac Sidewalk(Modeled as landscape as back sloped to lawn per DOE BMP T5.18)
0.07 ac Pond
0.21 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.52 ac
Lot 1-Sub-Basin(0.39 ac)
0.10 ac House (Roof drains routed to infiltration system 105'x 16.5'x 0.67'deep drainrock filled, 0.4 gal/sf/day*)
0.02 ac Driveway(Sheet Flow Dispersed 50'downhill north)
0.27 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.39 ac
Lot 2-Sub-Basin(0.35 ac)
0.09 ac House (Dispersed over 25'via Dispersion Trench modeled as 50%lawn/50%Roof)
0.02 ac Driveway(Sheet Flow Dispersed downhill north 25'modeled as 50%lawn/50%Driveway)
0.24 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.35 ac
Lot 3-Sub-Basin(0.38 ac)
0.10 ac House
0.03 ac Driveway(Sheet Flow Dispersed 25'downhill north, modeled as 50%lawn/50%Driveway)
0.25 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.38 ac
Lot 4-Sub-Basin(0.48 ac)
0.10 ac House(Dispersed over 50'via Dispersion Trench)
0.07 ac Driveway(Sheet Flow Dispersed 25'downhill east and north, modeled as 50%lawn/50%Driveway)
0.31 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.48 ac
LOT 4
Lot 5-Sub-Basin(0.64 ac) ONSITE LID BMP RQMTS
ROOF: 54 LF "ROOF DRAIN
0.10 ac House (Dispersed over 50'via Dispersion Trench) DISPERSION TRENCH" W/ MIN 50'
DOWN-GRADIENT DISPERSION AREA
DRIVEWAY: NONE RQD 27
Revised 3/31/2021
0.02 ac Garage/Shop (Dispersed over 25'via Dispersion Trench, modeled as 50%lawn/50%Driveway)
0.07 ac Driveway
0.45 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.64 ac
Lot 6-Sub-Basin(0.35 ac)
0.09 ac House(Roof drains routed to infiltration system 78'x 16.5'x 0.67'deep drainrock filled, 0.6 gal/sf/day*)
0.03 ac Driveway (Sheet Flow Dispersed 50'downhill north or east depending on layout)
0.23 ac Lawn (Modeled as Pasture per DOE BMP T5.13)
0.35 ac
Totals ROW+Lots 1-5:
0.52 ac+0.39 ac+0.35 ac+0.38 ac+0.48 ac+0.64 ac+0.35 ac =3.11 ac
*Infiltration per Linda Spicher Soils Infomration dated 11/24/20 (attached)
Using the developed land conditions previously noted, the control structure noted above and an 12-inch
diameter overflow riser, it is estimated that the following mitigated flows will be discharged from the site:
Flow Frequency Return Periods for Mitigated. POC1 (801)
Return Period Flow (cfs)
2 year 0.0263 0.0285
5 year 0.0532 0.0589
10 year 0,0012 0.0909
25 year 04328 0.1510
50 year 0.1869 0.2148
100 year 0.2583 0.2999
An above ground detention pond system is proposed to provide necessary stormwater detention for runoff
control for this project. This detention pond and controlled release system is to be located within the
northeast corner of the site, at the subject property's low point as shown on the attached information. The
proposed detention pond will have a live storage bottom footprint area of approximately 3i096 2,964 square
feet and is designed to have 2.0-feet of live storage depth and an additional foot of freeboard. Refer to the
attached Developed Conditions Drainage Exhibit and WWHM design information located in Appendix 10 at
the end of this report. The detention pond will release runoff via a control structure which will limit the
release of stormwater northeasterly to the existing drainage ditch located along the south side of Orchard
Avenue which currently receives runoff from the subject property. Based on the analysis performed by
WWHM, a 2-foot deep detention pond (with 1-foot of freeboard) with a minimum footprint area of 37096
2,964 square feet and use of the control structure as designed, is sufficient to mitigate the estimated increase
in storm water from the proposed residential development, and the detention system "passes"as noted on the
attached WWHM Report located in Appendix 10. This "pass"signifies that the currently shown stormwater
system is sized as required to provide mitigation as determined by use of a continuous model software,
WWHM, as required by the 2014 DOE manual for the 3.11-acres of runoff subbasin areas as detailed above
for the right of way (including the pond area) and development on Lots 1 -6.
Per DOE Volume III Chapter 3 Section 111-3.2 the Emergency overflow for this pond shall be sufficient to
convey up through the 100-year developed, unmitigated(701) storm event for this project is estimated to
be 0.4 0 0.4770 cfs (developed, mitigated, 801 =0.2585 0.3088 cfs),per the WWHM Post Construction
28
modeling attached. With using the access road as the emergency overflow, it will be 12-feet wide. Based
on the equation noted within the DOE Volume III Chapter 3, Section 111-3.2 Detention Facilities
Emergency Overflow Spillway Capacity equation based on a broad crested wier, and minimum flow depth
of 0.2-feet specified within this section, it will take a width of L=6.78-feet to convey (overflow) during the
100-year event,DOE denoted use of this equation "or 6-feet minimum'; thus the overflow spillway, at 12-
feet wide will have more than sufficient overflow capacity to serve this project as it will be greater than 6-
ft wide.
L=f0100/(3.21H^5/21—2.4H= 6.78 feet
Based on using the "developed, unmitigated"25-year storm event the 3.11-acre basin area is estimated to
generate a total of approximately 0.2929 0.3383 cfs of flow, with the 100-year event only generating
0.4 8 0.4770. The flows are such that it can be noted, though no single pipe carries the entire developed,
unmitigated site runoff the pipes are sufficient carry over double the anticipated 100-year event and
individual further calculations can be provided if requested.
- 6"pipe at the min 1.75% slope has the capacity to carry 0.80 cfs
- 8"pipe at the min 0.5% slope has the capacity to convey 0.94 cfs
-12"pipe at the min 0.3% slope has the capacity to convey 2.11 cfs
With this information it is clear all onsite pipes have the capacity to serve the site as noted on the civil
plans prepared for this project.
29
TAB 8 — (MINUMUM REQUIREMENT 8 —WETLAND PROTECTION)
Refer to 1.2.5.8 and provide the required information for this Minimum Requirement.
There are no wetland areas within the areas of the subject property proposed for construction.
30
TAB 9— (MINUMUM REQUIREMENT 9 — OPERATION AND MAINTENANCE)
Refer to 1.2.5.9 and provide the required information for this Minimum Requirement.
OPERATIONS& MAINTENANCE OF PRIVATELY OWNED DRAINAGE FACILITIES:
Attached herein are general maintenance requirements from the 2014 Department of Ecology Drainage
Manual, Volume V, Section 4.6 as applicable to Detention Ponds, Control Structures, Catch Basins, and Wet
Ponds. These requirements, together with those listed below, shall apply to onsite drainage facilities, and
shall be used as a basis for inspecting and maintaining the drainage facilities within this project. The owner,
or homeowners association of the plat is responsible for assigning an individual to periodically inspect the
storm system improvements herein.
Detention Pond Maintenance is needed when any trash or debris has accumulated which exceeds one cubic
feet per 1,000 square feet (this is about equal to the amount of trash it would take to fill up a standard size
garbage can). This debris shall be cleared from the site. Once every five years, unless evidence suggests
otherwise, an engineer shall inspect the inside of the detention facility and make recommendations for
repairs and modifications as necessary. Once every five years, an inspection and measurement of debris
accumulation depth shall be conducted within the detention pond and shall be removed when the debris
exceeds 10% of the designed pond depth (0.3' or 3.6"). No dumping of grass clippings or debris should be
allowed within the pond area. Refer to the Table 4.5 Maintenance Standards (excerpts attached) from the
2014 DOE Stormwater Manual for specific information regarding maintenance.
Catch Basins throughout the site shall be inspected once a year to identify accumulated levels of silt and
debris within catch basin sumps and general structure integrity. Refer to the attached information from the
2014 DOE Stormwater Manual regarding maintenance of control structures and catch basins.
Control Structure shall be inspected once a year to identify accumulated levels of silt, trash, or debris within
structure along with any structural damage. Any material accumulation 0.5-feet in depth or greater
maintenance is needed to remove the material. Refer to the attached information from the 2014 DOE
Stormwater Manual regarding maintenance of control structures and catch basins.
Stormwater Conveyance Piping shall be inspected once each year, and at not more than five-year intervals,
all storm water pipes shall be flushed. Flushed debris shall be contained and disposed offsite, not allowed to
enter the detention facility.
31
APPENDIX 1 — Survey performed by a Professional Land Surveyor
Refer to attached "Existing Conditions, Site Prep and Erosion Control Sheet"attached for survey
information provided by Lisser and Associates also attached within this Appendix.
32
APPENDIX 2 — Soils Anaylsis (Volume 1, Chapter 3.1.1)
Geotechnical Report for Cherry Court by Geotest Engineers dated February 26th, 2020
Soils Report Linda Spicher dated November 24th, 2020
33
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.
This submittal will deferred since this project is unsure of who the supplier will be. Since this project triggers
Minimum Requirements 1 through 9, the Test Report will be provided to the Engineering Department as
required.
34
DEFERRED SUBMITTAL: PROVIDE A TEST REPORT FROM SOILS SUPPLIER TO THE ENGINEERING
DEPT.
PROJECT INFORMATION "Model Soil Management Plan for BMP T5.13" age# of pages
Complete 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 this plan)
LSite Plan showing,to scale: Areas of undisturbed native vegetation(no amendment required)
New planting beds and turf areas(amendment required)
Type 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.
_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/pages in this Plan)
❑ Product#1: ❑Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 (except mulch,or<35:1 for native plants) "stable"(yes/no)
❑ Product#2: ❑Quantity: cu.yds.
❑ Test Results:_%organic matter C:N ratio<25:1 (except mulch,or<35:1 for native plants) "stable"(yes/no)
❑ Product#3: ❑Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 (except mulch,or<35:1 for native plants) "stable"(yes/no)
Date: Inspector: Approved: Revisions Required:
35
Date: Inspector: Approved: Revisions Required:
APPENDIX 4— Determining Construction Site Sediment Damage Potential (Appendix 7 — NPDES Phase
II Permit)
See attached Construction Site Sediment Transport Potential Worksheet as required for this project.
i.
ii.
iii.
36
iv. 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.
v. 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;
iii. 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.
Ace of Hearts Creek located approximately 125 feet easterly of the area of the site proposed for development
and is noted as a "Fish Bearing"per the Department of Natural Resources FPARS Mapping. Furthermore,
the slopes along the edge of Ace of Hearts Creek are slightly steeper than 25% in some locations.
vi. 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
37
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:
vii. Sheet flow through a vegetated area with dense ground cover
viii. Flow through a wetland not included as a sensitive feature
ix. 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.
Discharge from the sites proposed detention pond will be be released to an existing shallow ditch
located along the south side of Orchard Avenue, which conveys runoff easterly to Ace of Hearts
Creek as occurs today.
x. 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.
Refer to the attached worksheet prepared for this project noting a score of 100 for this site, however
this includes the development of all 6-future home sites, which will all not occur concurrently with
plat infrastructure construction. Not accounting for home development reduces the total score
below the threshold transport rating to "Low".
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°/a 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
*Now that the plat infrastructure is complete, only future home site construction
occur, thus generally less than 1-acre of area will be cleared and/or graded at one
time. With this in mind this could be represented as 30 points rather than 50 points
as noted here.
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
soil group A 0
Hydrologic soil group B 10
Hydrologic soil group C 20
Hydrologic soil group D 40
E. Erosion Potential of predominant soils (Unified Classification System): GW, GP, SW,
SP soils 0
Dual classifications (GW-GM, GP-GM, GW-GC,
GP-GC, SW-SM, SW-SC, SP-SM, SP-SC) 10
GM, GC, SM, SC soils 20
ML, CL, MH, CH soils 40
F. Surface or Groundwater entering site identified and intercepted1:
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
TOTAL POINTS 80
*This now only includes future home site construction, thus generally less than 1-
acre of area will be cleared and/or graded at one time.
APPENDIX 5— Site Plan with all applicable information (Minimum Size 11x17 at a legible scale)
See attached Civil Plans
APPENDIX 6 — Documented Site Photos (Show all directions of the site, including frontage)
Location: View from Orchard Avenue looking southwest
Description of the photo:Subject property looking southwest
Photo taken by:HLN
G
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ile'"
1 fR
k
Y.J < i.:4ii'$6 w• - iii :wry
aL•V+yam} H.-„-.i.
Tii„,..,....„; •,�"fie
�y
_, ....,,, „. .„‘....::...,,,,,..,..1,.. .....uks.....:_v_ .•....„....., . _
_ . .. , _ It,,T.04.....k...,..„.7.04„.„„. ......1p ......$...., , .,
, _ . ,,_...... .„6._._.,t_...,t,....:,..,„...,._ . _ .. .
.......„ _,..;„._.:...„0..... ._-!:_..t...,‘... _,., _ _ _ ,. .
...,.,..
, .
Location: View from private roadway along south side of site
Description of the photo:Subject property looking northwest
Photo taken by:HLN
•
J,y .
- ' 4 ■�. q
r¢.,,o- - fig
Location: View from Orchard Avenue
Description of the photo:Subject property looking southeast along west property line
Photo taken by:HLN
1- Air
gon .
•
3
•
;,Y
itt
1,
Lry,
/ I
Location: View along north side of Orchard Avenue
Description of the photo: Existing ditch outlet at subject property's northeast corner looking east
Photo taken by:HLN
-
aq dl aryl 1 t
At
i, 1_
Location: View along north side of Orchard Avenue
Description of the photo: From subject property's northeast corner looking west
Photo taken bv:HLN
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 City of Anacortes Engineering Department on formalizing the document for recording.
The owner will coordinate with the City for the exact wording to be added to the short plat as needed for
required maintenance for the associated drainage facilities.
APPENDIX 8 —Vicinty Map, Aerial Exhibit, and Downstream Exhibit
APPENDIX 9 — NRCS/SCS Soils Information
APPENDIX 10 —WWHM Views and WWHM Report
APPENDIX 11 —2014 DOE BMP T5.10B, T5.11, T5.12, and T5.13
Appendix 12 - Excerpts from DOE Manual and City of Anacortes Stormwater Comprehensive Plan