HomeMy WebLinkAboutBLD2018-00185 - 05 STORMWATERoo
DEPARTMENT OF COMMUNITY
621 Sheridan Street, Port Townsend, WA 98368
TeI: 360.379.4450 | Fax: 360.37 9.445t
Web: www. co,ie fferson.wa. us / cornmunitydevelopment
E-mail: dcd@co.iefferson.wa.us APn
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ST oRMwATER CALCUI.ATION WORKSHEFfl
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DETERMTNTNG STORMWATER MANAGEMENT REqUTREMENTS: This stormwater calculation worksheet should be completed first to
classify the proposal as "small," "medium," or "large." The size determines whether a Stormwater Site Plan is required in
conjunction with a stand-alone stormwater management permit application, building permit application, or other land use approval
application that involves stormwater review. The basic information will also be helpful for completing a Stormwater Site Plan, if
req u i red.
Lond-disturbing activity is any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and
non-vegetative) and/or the existing soil topography. Land disturbing activities include, but are not limited to clearing, grading, filling,
excavation, and compaction associated with stabilization of structures and road construction.
Native vegetation is vegetation comprised on plant species, other than noxious weeds, that are indigenous to the coastal region of
the Pacific Northwest and which reasonably could have been expected to naturally occur on the site. Examples include species such
as Douglas fir, western hemlock, western red cedar, alder, big-leaf maple, and vine maple; shrubs such as willow, elderberry,
salmonberry, and salal; herbaceous plants such as sword fern, foam flower, and fireweed.
lmperuious surface is a hard surface that either prevents or retards the entry of water into the soil mantle as under natural
conditions prior to development. A hard surface area which causes water to run off the surface in greater quantities or at an
increased rate of flow from the flow present under natural conditions priorto development. Common impervious surfaces include,
but are not limited to roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads,
packed earthen materials, and oiled, macadam or othersurfaces which similarly impede the natural infiltration of stormwater.
PARCEL SIZE (I.E.. SITE)
An acre contains 43,560 square feet. Multiply the acreage by this figure'
Qf;oZlo sq/ftSize of parcel in square feet
size of prr""t Z | , 8l ""r",
LAND D]STURBING ACTIVITY. CONVERSION OF NATIVE VEGETATION. AND VOLUME OF CUT/FILL
u/yd)4ro a/q"@!S
native vegetation to pastu re?
Cut Filt
sq/ft
sq/ft
sq/ft
lndicate Total Volumes of Proposed:
Well, utilities, etc.
Drainfield, septic tank, etc.
Lawn, landscaping, etc.6o*a
Does the project convert 2 lz acres or more of
Total Land Disturbance
Answer the following two questions related to
conversion of native vegetation:
Does the project convert "/o acres or more of
native vegetation to lawn or landscaped areas?
Circle: Yes
Circle: Yes
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Driveway, parking, roads, etc. 4go
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Calculate the total area to be cleared, graded, filled,
excavated, andlor compacted for proposed development
project. lnclude in this calculation the area to be cleared for:
Construction site for structures lgl'S
sq/ft
sq/ft
sq/ft
Other compacted surface, etc. /StO
stormwater calc worksheet - REV. 1213012015 1
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STORMWATER CALULATIONS - IMPERVIOUS SURFACE
Total New Total Existing
cr5TOTAL NEW + TOTAL EXISTING**This amount will be used to check total lot coverage
1N)n sqnt
sq/ft
zE1{ sqrt
NEW
Structures (all roof area)
Sidewalks
Patios
Solid Decks
EXISTING
Structures (all roof area)
Sidewalks
Patios
(without infiltration below)
Driveway, parking, roaos, etc 4M sqltt
Other _sq/ft
Driveway, parking, roads, etc
Other
Solid Decks
(without infiltration below)
sq/ft
sq/ft
DEVELOPMENT V. REDEVELOPMENT
Divide the total existino impervious surface above by the size of the parcel and convert to a percentag
Does the site have 35% or more of existinq impervious surface? Circle:
ol
Yes
The follo',viiig questions',vill lielp deteii'iiine wiietliei'the pi"oposeci project is considetecj deveiopment or recieveiopment.
FURTHER INSTRUCTIONS: lf the answer is yes, the proposal is considered redevelopment and the attached Figure 2 should be used
to determine the applicable Minimum Requirements. lf the answer is no, the proposal is considered new development and the
attached Figure l should be used. At this juncture, the applicant should refer to the applicable Flow Chart to determine the
Minimum Requirements for stormwater management. DCD staff will help verify the classification of the project and the application
requirements.
For proponents of "small" projects who must comply only with Minimum Requirement #2-Construction Stormwater Pollution
Prevention-an additional submittal is not required, The proponent is responsible for employing the 12 Elements to control erosion
and prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the
Construction Stormwater Pollution Prevention (SWPP) Best Management Practices (BMPs) Packet. Proponents of "medium"
projects-those that must meet only Minimum Requirements #1 through #5-and for "large" projects-those that must meet all 10
Minimum Requirements-are required to submit a Stormwater Site Plan. DCD has prepared a submittal template of a Stormwater
Site Plan, principally for rural residential projects. Complete the template in the Stormwater Site Plan lnstructions and Submittal
Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Sformwoter Monagement Monuol.
APPLICANT SIGNATURE
By signing the Stormwater Ca latio heet, I as the applicant/owner attest that the information provided herein is true and correct to the
best of my knowledge. I this application is being made with the full knowledge and consent of all owners of the affected
pro
OR REPRESENTATIVE srewalunr)
stormwatBr calc worksheet - REV. 1213012015 2
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DEPARTMENT OF COMMUNITY DEVE
621 Sheridan Street, Port Townsend, WA 98368
Tel: 360.379 .4450 | Fax: 360.379.4451
Web : www. co. iefferson.wa. us/comm u n itvd evel op me nt
E-mail: dcd@co.iefferson.wa.us
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STORMWATER SITE PI-AN SUBMITTAL TEMPI-ATE
please answer all of the following questions to the best of your ability. Where the question calls for depiction on a site map, the
applicant may choose to either indorporate the elements into the general plot plan for the Master Land Use Application or to submit a
separate stormwater site plan map.
Project Overview i
Describe the proposed developed conditions of the site. lndicate position and relative size of proposed improvements on the
site
5
pRoJrct/eppucANT NAME:uu#
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Existing Conditions SummarY
Describe the existing topography. lnd2 map.icate contours on the site
areas on the site malndicateexisti3. Describe
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on the site masoils. lndicate soil4. Describe the existi
Describe the existing site hydrology (i.e., drainage; behavior of water on the site-above, below, and on the ground). lndicate
existing stormwater drainafie to l'n,] from the lite on the site map. Depict separate drainage basins on the site map, if5.
a and indicate ac of
use orexcess levels of noise theeneratedb.
Describe significant geographic features and critical areas (i.e.,ly sensitive areas such as wetlands, streams,7
slo etc on the site.lndicate location on the site ma
stormwater site plan template - rev. 4/7/20'16
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Describe the general vicinity of the site, including adjacent land uses and structures, utilities, roads, and sensitive/critical areas
(streams, wetlands, lakes, steep slopes, etc.).
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This portion of the Stormwater Site Plan consists of the selection and installation of the appropriate stormwater control BMPs
and facilities to remain in place after construction of the project is completed.
"Medium" size projects are required to have the totals calculated of all impervious surfaces, pollution-generating impervious
surfaces, and pollution-generating pervious surfaces to verify that the thresholds for treatment facilities and flow control
fani!itioc nra nnt ovcoorlod
r. Describe the developed site hydrology, as proposed. lndicate whether stormwater will be fully dispersed (i.e., per BMP T5.30
in the Manual) or, if not, what types of stormwater flow control will be utilized for the site or speciflc threshold discharge areas
- within the site. Locate these facilities on the site plan and differentiate proposed facilities from existing facilities.
t)(ner-*tt .ri ? nlzcsE flj4akt.l- nfiitfz*Crlilstt**tl u* de-NEtn 9FR- lmF
Permanent Stormwater Control Plan
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lf the project requires the use of stormwater treatment facilities, describe the types of stormwater treatment facilities proposed
for use on the site. Locate these facilities on the site plan and differentiate proposed facilities from existing facilities. [-his is
for "large" projects or projects that involve the potential for dispersion of contaminants.l
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Describe the performance qoals and standards applicable to the project. zi;;;;";" A"'j";"A;;"6,'i#)isr,, t atLH 5 dntt ?tulr rr/tL (raor*, t11
&ttl frzSrAka Ftt*e B f|,td,L k @rBLq .4> oQJotx*t- ?o?o,
12.the flow control system
13.be the water quality system.
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14. Describe conveyance system analysis and design.
the source of fill material, physical characteristics of fill material, and deposition of excess material
16. proposed methods of placement and compaction consistent with the applicable standards on Appendix Chapter 33 of the
Building
18. Describe for restoration of th
An Operation and Maintenance Manual is required for each flow control and treatment facility. [-his is normally required for
"large" projects only and only those for which facilities are required to control flow or treat runoff.l lf included, list the Manuals
here.
20. List he and i any special reports or conducted to the Stormwater Site Plan.
List other necessary permits and approvals as required by other regulatory agencies. lf those permits or approvals include
conditions that affect'the drainage pian or contain more restrictive drainage-related requirements, describe those conditions or
here
7stormwater site plan template - rev. 4n/2016
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CoNSTRUCTTON STORMWATER POLLUTTON PREVENTION PLAN (SWPPP)
The Construction SWPPP addresses sediment and erosion control during construction. The BMPs indicated by the applicant in the
template that follows must be installed on the ground during all constructlon phases of the project. The proponent is responsible for
preventing sediment and erosion impacts to environmentally sensitive areas and off-site areas. Consult the Construction Stormwater
Pollution Prevention (SWPP) Best Management Practices (BMPs) Packet for guidance, particularly with rural residential
development.
SECTION I- CONSTRUCTION SWPPP NARRATIVE
8
1 Construction Stormwater Pollution Plan Elements. Describe how each of the Construction SWPPP elements has been or
will be addressed. ldentify the type and location of BMPs used to satisfy the required element. lf an element is not applicable to
the proposal, justify in writing. Detailed descriptions of the '13 Elements are found at Volume ll Section 3.3.3 of the Manual
(beginning on page 3-11).
13 Required Elements - Construction SWPPP
1 Limits.ftt*J
Z.oilsn ACUESS.
J Flow Rates.
4. lnstall Sediment Controls.e
5.Soils.
6.P S
7 Protect Drain lnlets.gfu?ertt t*Mfit&*-
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13 Required Elements - Construction SWPPP (continued)
8. Stabilize Channels and Outlets.
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10. Control De-Watering (the act of pumping groundwater or stormwater away from an active construction site).
11. Maintain Best Ma (BMPs).
12.age the P
*trdla.-**
13.Low P'S
Adjacent Areas.
a. Description of the adjacent areas that may be affected by site disturbance (e.g., streams, lakes, wetlands, residential
2.
from the site to
d s)
of water (mlnimum distanceb. Description of the downstream drainage path leading of 400
areas that are on or adjacent to the sitea.
IL
of environmentally
3. EnvironmentallySensitiveAreas.
stormwater site plan template - rev. 4/7/2016
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b. Description of spec irements for working rn or near envrron areas.
4 Erosion Problem Areas. Description of potential erosion problems on site in the context of the characteristics of the on-site
soils (e.9., erodibility, settleability, permeability, depth, texture, soil structure).
5. ConstructionPhasing.
a .-fi1,1 s-Flt/-
b.phasing (if proposed)
6. Construction Schedule. Wet season is October 1 through April 30 (page 2-20 of the Manual).
t.rovide a proposed schedule.
Wet Season Construction es.
a. Purcoosed wet season construction activities.til)Alt-
b.Propgsed wet seasontb(t--construction activities for environmentally sensitive areas.
7. Financial/Ownership Responsibilities
a. ldentifu the orooe-eduld er responslble for the initiation of bonds and/or other financial securities.
b. Describe bonds and/or other evidence of financial responsibility for liability associated with erosion and sedimentation
tm
8. EngineeringCalculations. Provide Calculations on a separate sheet for the following, if applicable.
a. SedimentPonds/Traps
b. Diversions.
c. Watenvays.
d. Runoff/Stormwater Detention Calculations
stormwater site plan template -rev.4[/2016 10
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Sediment and erosion control measures may be depicted on the master land use application plot plan, a stormwater site plan, and/or a
separate Construction SWPPP site plan. This is a checklist to ensure that the on a site plan
a. Vicinity Map
b. Jefferson County Approval Block
c. Erosion and Sediment Control Notes
1. General
t/rc. lndicate boundaries of existing vegetation (e.g., tree lines, pasture areas, etc.).
,l a. ldentify and label areas of potential erosion problems.
Vp ldentify FEMA base flood boundaries and Shoreline Management boundaries (if applicable)
{f , Show existing and proposed contours.
.;U. lndicate drainage basins and direction of flow for individual drainage areas.
u{1. Label final grade contours and identify developed condition drainage basins.
"f Delineate areas that are to be cleared and graded. il iltly
{i. Show all cut and flll slopes indicating top and bottom of slope catch lines.
EFFERSON2.couffryDcDn.
Legal description of subject property
North arrow.
Site Pla
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3. C'onveyanceSystems.,a. Designate locations for swales, interceptor trenches, or ditches'
, b. Show all temporary and permanent drainage pipes, ditches, or cut-off trenches required for erosion & sediment control
c. Provide minimum slope and cover for all temporary pipes or call out pipe inverts.
I
9. Shows grades, dimensions, and direction of flow in all ditches, swales, culverts and pipes.
e. Provide details for bypassing off-site runoff around disturbed areas.
f. lndicate locations and outlets of any dewatering systems.
4. Location of Detention Best Management Practices (BMPs). ldentify location of detention BMPs.
5. Erosion and Sediment Control Facilities.
a. Show the locations of sediment trap(s), pond(s), pipes and structures.
' b. Dimension pond berm widths and inside and outside pond slopes.
c. lndicate the trap/pond storage required and the depth, length, and width dimensions.
d. Provide typical section views through pond and outlet structure.
e. Provide typical details of gravel cone and standpipe, and/or other filtering devices.
f. Detail stabilization techniques for outleUinlet.
g. Detail control/restrictor device location and details.
h. Specify mulch and/or recommended cover of berms and slopes.
i i. Provide rock specifications and detail for rock check dam(s), if applicable.
j. Specify spacing for rock check dams as required.
k. Provide front and side sections of typical rock check dams.
l. lndicate the locations and provide details and specifications for silt fabric.
m. Locate the construction entrance and provide a detail.
6. Detailed Drawings. Any structural practices used that are not referenced in the Ecology Manual should be explained and
illustrated with detailed drawings.
Other Pollutant BMPs. lndicate on the site plan the locations of BMPs to be used for the control of pollutants other than
sediment (e.9., concrete wash water).
7
Monitoring Locations. lndicate on the site plan the water quality sampling locations to be used for monitoring water quality on
the construction site. Sampling stations should be located upstream and downstream of the project site.
8.
stormwater site plan template - rev. 4/7/201 6 11
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Stormwater Site Plan Changes
lf the designer wishes to make changes or revisions to the originally approved Stormwater Site Plan, the proposed revisions shall be
submitted to DCD prior to construction. The submittal shall include substitute pages that include all proposed changes, revised
drawings showing any structural changes, and any other supporting information that explains and supports the reason for the change.
Final Corrected Plan Submittal
lf the project included construction of conveyance systems, treatment facilities, flow control facilities, or structural source control BMPs
(not standard on-site stormwater management BMPs), the applicant shall submit a final corrected plan ("as-builts") when the project is
completed. These should be engineering drawings (stamped by a licensed civil engineer) that accurately represent the project as
constructed.
APPLICANT SIGNATURE
THIS SPACE MAY BE USED FOR ADDITIONAL NOTES, IF NEEDED
By signi ng the Construction SWPP P worksheet,AS th ap plicanUowner attest that the information provided herein IS true and
correct to the best of
the affected
my also certify that this applicatio n is being m ade with the full knowledge nd consent of all
: - 1e42
REPRESENTATIVE SI GNATURE)(onrc)
stormwater site plan template - rev.4/7/2016 12
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DEPARTMENT OF COMMUNITY
621 Sheridan Street, Port Townsend, WA 98368
Tel: 360.379.4450 | Fax: 360.379.4457
Web: www.co.iefferson.wa, us/commu nitvdevelopment
E-mail: dcd@co.iefferson.wa.us
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APR , g ;irl$
STORMWATER MANAGEMENT PERMIT
couNryDcD
urn #pRolecr/nppLtCANT NAME:
Applications for grading projects or land-disturbing activities which require a stormwater management permit shall include the following
information. This information may also be provided on other diagrams, plans, studies, or attachments submitted with the project
application. lf so, please indicate such on this permit application. The Administrator may waive specific submittal requirements determined
to be unnecessary for review of the application.
deposition excess1. Source of fill material
v
Physical characteristics of fill
2. material:{
Building Codethe appl icable standards in theconsistent
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3. Pro methods of placement and compaction
4. Proposed surfacing material
drainagp and erosion
,lY- {rzel*nn)
control
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5. Proposed method(s) of
A,tLA9 utl rlpfi r FI*tJs'
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ip*-r, tJl ilnstN (raxtn*; Gtzgs M:* fu,t-6. Methods for restoration of the site.
7. Demonstrate that instream flow of water will remain unobstructed.
Demonstrate that erosion and sedimentation from outflow channels will be minimized6 means, andother
rtyprope
attests that the information provided herein is true and correct to the best their
is being made with the full knowledge and consent of all owners of the affected property
By
OR
applicati,
REPRESENTATIVE SIGNATURE)(DATE)
suppLer\4BNrAL Appu cerr'd[$€Rsoru
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demonstrate that oond runoff will be controlled to orotect adiacentiltr*r ol' I ilur ts--r[ zs *(wfi b4 . <{gte NW--
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2.5 MinimumRequirements
This section describes the minimum requirements for stormwater
management at development and redevelopment sites. Sectiorr 2.4 should
be consulted to determine which requirements apply to any given project.
Figures 2.4.1 and2.4.2 should be consulted to determine whether the
minimum requirements apply to neW surfaces, replaced Surfaces, or new
and replaced surfaces. Volumes II through V of this manual present Best
Management Practices @MPs) for use in meeting the Minimum
Requirements'
Throughout this chapter, requirements are written in bold and
supplemental guidelines that serve as advice and other materials are
4! in bold'
2.5.1 Minimum Requirement #1: Preparation of Stormwater
Site Plans
All projects meeting the thresholds in section 2.4 shall prepare a
Stormwater Site Plan for local government review. Stormwater Site
plans shatl use site-appropriate development principles' as required
and encouraged by local development codes, to retain native
vegetation and minimize impervious surfaces to the extent feasible.
Stormwater Site Plans shall be prepared in accordance with Chapter
f of this volume.
Obiective
The 2,000 square feet threshold for hard surfaces and 7,000 square foot
thrreshold for land disturbance are chosen to capture most single family
home construction and their equivalent. Note that the scope of the
stormwater site plan only covers compliance with Minimum Requirements
#2 through #5 ifthe thresholds of5,000 square feet ofhard surface or
conversion of'/t acre ofvegetation to lawn or landscape, or conversion of
2.5 acres ofvegetation to pasture are not exceeded.
S uP P leme ntal g uide li n es
Projects proposed by departments and agencies within the local
govemment with jurisdiction must comply with this requirement. The
local govemment shall determine the process for ensuring proper project
review, inspection, and compliance by its own departments and agencies.
Volume I - Minimum Technical Requirements - August 2012
2-t 6
5
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thresholds Local governments should be prepared to demonstrate that by
comparing the number and types of historical projects that would have
been regulated using the Ecology thresholds versus the locar govemment,s
thresholds.
Local governments are allowed to institute a stop-loss provision on the
application of .stormwater requirements to replaced hard surfaces- A stop-
loss provision is an upper limit on the extent to which a requirement is
applied. For instance, there could be a maximum percentage of the
estimated total project costs that are dedicated to meeting stormwater
requirements. A project would not have to incur additional ,stormwater
costs above that maximum though the standard redevelopment
requirements will not be fully achieved. The allowance for a stop-loss
provision pertains to the extent that treatment, flow control and wetlands
... protection requirements are imposed on replaced hard surfaces. It does not'Epply to meeting stormwater requirements for new hard surfaces.
governments can also establish criteria for allowing redevelopment
to pay a fee in lieu of constructing water qualiry or flow control
on a redeveloped site. At a minimum, the fee should be the
an engineering estimate of thecost of meeting all applicable
stormwater
such funds
would have
.for the.project. The local government should use
implementation of stormwater control projects that
slml .benefits to the same receiving water as if the project
Ecology cautionslocal goi'e.rnments about the potential long-tenn
consequences of allowing a.fep-in-lieu of stormwater facilities. Sites that
are allowed to pay a fee continire without stormwater controls. If it is
determined, through futuie basin plarrning for irstance, that controls on
such sites are necessq{ to achieve water quality goals or legal
requirements, the public may bear thdwsts for providing th-ose controls.
underground utility projects that replac\thc gro,nd surface with in-kind
material or ma(erials with similar runoff iharacteristics should not be
subject to rqdevelopment requirements excht construction site erosion
control.
Local govemments are also encouraged to reviery all road projects for
changis in elevations or drainage flowpath that co\ld cause flooding,
upland or sheam erosion, or changes to discharges to wetlands. For
example, adding curbs will result in redirecting flows and possibly causing
new downstream impacts. The local goyernment should set project-
specific requirements to avoid or mitigate those impacts.
had constructed its uired rmprovements.Expenditure of such funds is
subject to other state statutory requirements
Volume I - Minimum Technical Requirements - August 20lZ
2-t5
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2.5.2 Minimum Requirement#2: Construction Stormwater
Pollution Prevention (SWPP)
Thresholds
Allnewdevelopmentandredevelopmentprojectsarerespon$iblefor
preventing "rorion
and discharge of sediment and other pollutants
into receiving waters.
Projects which result in 2,000 square feet or more of new plus
i"pi"""A hard surface area' or rrhich disturb 7,000 square feet or
more of lanrt must prepare a Construction SW?P Plan (SW?PP) as
part of the Stormwater Site Plan (see Sgction 2'5' t)'
Projects that result in less than 2,000 square feet of new plus replaced
hari surface area, or disturb less than 7,000 square feet ofland are
notrequiredtoprepareaConstruclionSWPPP,butmustconsiderall
of the i3 Elements of Construction Stormwater Pollution Prevenlion
anddevelopcontrolsforatlelementsthatpertaintotheprojectsite.
General Requirements
The swPPP shall include a narrative and drawings. All BMPs shall
beclearlyreferencedinthenrrrativeandmarkedonthedrawings.
Ttre S\iliPf narrative shalt include documentation to explain and
justify the pollution prevention decisions made for the project. Each
of tfr* 13 elements must be considered and included in the
Construction swPPP unless site conditions render the element
unnecessary and the exemption from that element is clearly justified
in the narrative of the SW?PP. i
Clearing and grading activities for developments shall be permitted
only if conducied pursunnt to an approved site developmcnt plan (e'g''
,ubdiri.irn approval) that establishes permitted areas of clearing'
grading, cutti-ng, and filling. These permitted clearing and grading
ir."r ,-nU "ny
oth.r areas required to preserve critical or sensitive
areas, buffers, native growth protection easements, or tree retention
areas shall be delineatetl on the site plans and the development site-
The swPPP shall be implemented beginning with initial land
rlisturbance and until final stabilization. sediment and Erosion
control BMPs shall be consistent with the BMPs contained in chapters
3 and 4 of Volume II.
seasonal work Limitations - From October I through April 30'
clearing, grading, and other soil disturbing activities shall only be
p"rmitteJ ir shown to the satisfaction of the local permitting authority
ihut ,ilt-l.d.n runoff will be prevented from leaving the site through a
combination of the following:
l. Site conditions including existing vegetative coverage, slope' soil
type and proximity to receiving waters'
Yolume I - Minimum Technical Requirements - August 2012
2-l 7
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2. Limitations on activities and the extent of disturbed areas.
3. Proposed erosion and sediment control measures.
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 remoyal of
the vegetative cover to soil.
3. Activities where there is one bundred percent infiItration of
surface water runoff within the site in approved and installed
erosion and sediment control facilities.
Project Requirements - Construction Swppp Elements
Element 7: Preserve VegetationlMark Clearing Limits
Before beginning l"nd disturbing activities, includingctearing and
grading' clearty mark all clearing limits, sensitiye areas and tieir
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 practicable.
a
a
a
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Element 2: Establish Construction Access
Limit construction vehicle acce,s g. a,nd, oxit to,ore route; if possi bte.
stabilize access points with a pad of quarry spalls, crushed rock,
or other equivalent BMPs, to minimize tracking of sediment onto
public 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 ofeach day, or more frequently as necessary
(for example, during wet weather). Remove sediment from roads
by shoveling, sweeping, or pick up and transport the sediment to a
controlled sediment disposal area.
Conduct street washing only after sediment is removed in
accordance with the above bullet.
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Control street rvash wast€\'vater by pumping back on-site' or
otherwise prevent it from discharging into systems tributary to
waters of the State.
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Element 3: Control Flow Rates
. Protect properties and walerways downstream of development
sites from erosion and the essociated discharge of turbid wnter$
due to increases in the velocity and peakvolumetric llow rate of
stormwater runolf from the project site'
.Wherenecessarytocomplywiththebulletaboverconstruct
stormwater retention or detention facilities as one of the first steps
ingrading.Assurethatdetentionfacilitiesfunctionproperly
beiore constructing site improvements (e.g. impervious surfaces).
. If permanent infiltration ponds are used for flow control during
construction, protect these facilities from siltation during the
construction Phase.
Element 4: tnstall Sedimenf Controls
r Design, install, and maintain effective erosion controls and
sedimentcontrolstominimizethedischargeofpollutants.';'
. Construct sediment control BMPs (sediment ponds, traps, filters,
etc.) as one of the first steps in grading' These BMPs shall be
.. functionat before other land disturbing aclivities 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, frequenry, 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 runoffleaves a construction site or before discharge to
an infiltration facitity. Runoff from fully stabilized areas may be
discharged without a sediment removal BMP, but must nreet the
flowcontrolpcrformancestandardinElement#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'
. vy'here feasible, design outtet structures that withdrarv impounded
stormryater from the surface to avoid discharging sediment that is
still suspended lower in the water column'
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Element 6: Stabilize Soils
' Stabirize exposed and unworked soits by apprication of effective
BMPs that prevent erosion. Appricabre BMis include, but are notlimited to: temporary and permanent seeding, sodding, murching,
plastic covering, erosion control fabrics and matting, soil
application of polyacryramide (pAn/D, the earry appiication orgravel base early on areas to be paved, and dust control.
r control stormwater vorume and velocity within the site to
minimize soil erosion.
r control stormwater discharges, including both peak flow rates
and total stormwater volume, to minimize erosion at outlets and tominimize downstream channel and stream bank erosion.
r soils must not remain exposed and unworked for more than thetime periods set forth below to prevent erosion:
. During the dry season May I - Sept.30): 7 days
o During the wet season (October I _ April 30): 2 days
o stabilize soils at the end of the shift before a holiday or weekend if
needed based on the weather forecast-
o Stabilize soil stockpiles from erosion, protected with sediment
trapping measures, and where possible, be located away from
storm drain inlets, waterways and drainage channels.
o Minimize the amount of soil exposed during construction activity.
. Minimize the disturbance of steep slopes.
. Minimize soil compaction and, uuless infeasibre, preserve topsoir,
Element 6: Protect S/opes
. Design and construct cut-and-fill slopes in a manner to minimize
erosion. Applicabre practices incrude, but are not rimited to,
reducing continuous rength of srope with terracing and diversions,
reducing slope steepness, end roughening slope srirfaces (for
example, track walking).
. Divert off-site storm-lyater (run on) or,grouud water away from
slopes and disturbed areas with interceptor dikes, pipes and/or
swales. off-site stormwater should be managed separatety from
stormwater generated on the site.
. At the top of slopes, collect drainage in pipe slope drains or
protected channels to prevent erosion.
. Temporary pipe slope drains must handle the peak l0_minute
velocity offlow from a Type lA, lO_year,24_hour frequency
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storm for the developed condition' Alternatively' the l0-year
and l-hour flow rate predicted by an approved continuous
runoff model, increased by a factor of 1'6, may be used' The
hydrologicanalysismustusetheexistinglandcovercondition
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 (WWIIM)
to predict flows, bare soil areas should be modeled as
ttlandscaPed" area-
. 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.
ElementT: Protect Drain lnlets
protect all storm drain inlets made operable during construction
so that stormwater runoff shall not enter the conveyance system
without first being liltered 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 specilied by the product manufacturer).
Element 8: Stabilize Channels and Outlets
. Design, construct, and stabilize all on-site conveyance channels'to
prevent erosion from the following expected peak flows:
. Channels must handle the peak 10-minute velocity of flow
from a Type lA, 10- year,24-hour frequency storm for the
developed condition- Alternatively, the lO-year, 1-hour flow
rate 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
p."di.tiog flow rates from tributary areas outside the project
ii*itr. For tributary areas on the project site, the analysis must
use the temporarT 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.
Provide stabitization, including armoring material, adequate to
prevent erosion ofouttets, adjacent stream banks, slopes and
downstream reaches at the outlets of all conveyance systems.
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Element 9: Control Pollutants
a Design, install, implement and maintain effective pollution
prevention measures to minimize the discharge of pollutants.
Ilandle and dispose of ail poilutants, incruding waste materiars
and demolition debris that occur on-site in a manner that does not
cause contamination of stormwater-
Provide cover, containment, and protection from vandarism for arlchemicals, liquid products, petroleum products, and other
materials that have the potential to pose a threat to human healthor the environment on-site fuering tanks must incrude secondary
containment. Secondary containment means pracing tanks orcontainers within an impervious structure capabre of containing
110% of the volume contained in the largest take rvithin the
containment structure- Doubre-walred tanks do not require
additional secondary containment.
Conduct maintenance, fueling, and repair of heavy equipment and
vehicles using spill prevention and contror measures. crean
contaminated surfaces immediatery fo[owing any spiil incident.
Discharge whoel wash or tire bath wastewater to a separate on-sitetreatment system that prevents discharge to surface water, such asclosed-loop recirculation or upland application, or to the sanitary
sewer, with local sewer district approval.
Appty fertilizers and pesticides in a manner and at apprication
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 sourcqs- The sources for this contamination inctude, but
are not limited to: bulk cement, cement kiln dust, fly ash, new
concrete washing and curing waters, waste streams generated
from concrete grinding ald sawing, exposed uggr"g"t. processes,
dewatering concrete vaults, concrete pumping and mixer washout
waters.
Adjust the pH of stormwater if necessary to prevent violations ofwater quality standards.
Assure that washout of concrete trucks is performed off-site or in
designated concrete washout areas only; Do.not wash out concretetruc}c 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.
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. Obtain written apProval from Ecology before using chemical
treatment other than CO2 or dry ice to adjust pH'
Element 10: Control De-Watering
. Discharge foundation, vault, and trench de-watering water, which
has similar characteristics 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 directty into surface
ivaters of the State, as specified in Element #8, provided the de-
watering flow does not cause erosion or flooding of receiving
waters. 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 otherwise contaminated dewatering water
, separately from stormwater.
o Other treatment or disposal options may include:
1. Inliltration.
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. [Jse of a sedimentation bag with outfall to a ditch or swale for
small volumes of localized dewatering'
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 linal site stabilization or after the
temporary BMPs are no longer needed.
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Element 12: Manage The project
' Phase deveropment projects to the maximum degree practicabre
and take into account seasonal work limitations.
' Inspection and monitoring - rnspect, maintain.and repair a[
BlvrPs as needed to assure continued performance of their
intended function. proiects regulated under the construction
Stormwater General permit must conduct site inspections andmonitoring in accordance with Speciar condition sc or th.
Construction Stormwater General permit.
. Maintaining an updated construction swppp - Maintain, update,and implement the SWPPP.
, Projects that disturb one or more acres must bave site inspections
conducted by a Certified fr,rosion and Sediment contror Lead(CESCL). Project sites disturbing ress than one acre may have acEscl or a person without CESCL certification condu.t
inspections. By the initiation of construction, the SWppp mustidentiff the GESCL or inspector, who must be present on-site oron-call at all times.
. The CESCL or inspector (project sites ress than one acre) must have
the skills to assess the;
. site conditions and construction activities that could impact thequality of stormwater.
. Effectiveness of erosion and sediment contol measures used to
control the quality of stormwater discharges.
. The CESCL or inspector must examine stormwater visually for the
presence ofsuspended sediment, turbidity, discoloration, and oil
sheen. They must evaluate the effectiveness of BMps and dererrnine ifit is necessary to instal, maintain, or repair BMps to improue ttre--'quality of stormwater discharges.
Based on the results of the inspection, construction site operators must
correct the problems identified by:
' Reviewing the SWppp for compliance with the r 3 construction
SWPpp elements and making appropriate revisions within 7 daysofthe inspection.
' Immediately beginning the process of fuily implementing and
maintaining appropriate source contror and/or treatment EMps as
soon as possible, addressing the problems not later than within i 0
days ofthe inspection.If instailation of necessary treatment BMps
is not t'easible within r0 days, the construction sire operato, maf
requesr an extension within the initial lO-day ...pori. period.
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. Documenting BMP implementation and maintenance in the site log
book (sites larger than 1 acre)'
. The CESCL or inspector must inspect all areas disturbed by
"onst*"tion
activiiies, all BMPs, and all stormwater discharge points
at least once every calendar week and within 24 hours of any discharge
fromthesite.(F'orpurposesofthiscondition'individualdischarge
events that last moie than one day do not require daily inspections' For
example, if a stormwater pond discharges continuously over thc course
of a week, only one inspeition is required that week') The CESCL oT
inrp""to. rnuy reduce the inspection frequency for temporary
,iuilitir"a, inactive sites to once every calendar month'
Element 13: Protect Low tmpact Development BMPs
. Protect all Bioretention and Rain Garden BMPs from
sedimentationthroughinstallationandmaintenanceoferosion
and sediment control BMPs on portions of the site that drain into
the Bioretention and/or Rain Garden BMPs' Restore the BMPs to
itreir futty functioning condition if they accumulate sediment
during construction. Restoring the BMP must include removal of
sedimentandanysediment-ladenBioretentioniraingardensoils'
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replacing the removed soils with soils meeting the design
specification.
. Prevent compacting Bioretention and rain garden BMPs by
excluding construciion equipment and foot trafftc' Protect
completed lawn and landicaped areas from compaction due to
construction equiPment'
. Control erosion and avoid introducing sediment from surrounding
land uses onto permeable pavements' Do not allow muddy
construction equipment on th" base material or pavement' Do not
allow sedim"ri-lrd"o runoff onto permeable pavements or base
materials.
. Pavement fouled with sediments or no longer passing an initial
inliltration test must be cleaned using procedures in accordance
with this manual or the manufacturer's procedures'
. Keep all heavy equipment offexisting soils under LID facilities
that have been eicavated to linal grade to retain the infrltration
rate of the soils.
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Objective
To control erosion and prevent scdiment and olher porutants from reavingthe site during the construction- phase of a project. to hare rriryirn.rio*r
stormwater facilities and BMp's for the deveioped site upon
"orpt.tion orconstruction.
S upp leme ntal G ui de lin e s
If a construction swppp is found to be inadequate (with respectto
erosion and sediment control requirements), tnln tne ffun epprorufAuthorityr within the Local Government shourd require that other BMpsbe implemented, as appropriate.
The Plan Approval Authority may allow development of generic
construction SWppp's that appry to commonry'"ondu"t"i priii. ruuaactivities, such as road surface replacement, that higger this mimmumrequirement. They may also develop an abbreviat"Jiwppp ro*.iro.project sites that will disturb less than I acre.
Based on the information provided and/or locar wearher conditions, rhclocal permifting a,thority,may expand or restricr the seusonar ri,ni"tfn o,site disturbance. The Iocar permining authority shar take "nfo..rr"rtaction - such as a notice of vioration, administrative order, p.n"rtylo,stop-work order under the following circumstances:
o lt during the course of any construction activity or soir disturbanceduring the seasonal limitatr'on period, sediment leaves the
"onstructionsite causing a violation of the surface water quality standard; oro If clearing and grading limits or erosion and sediment control
measures shown in the approved plan are not maintained.
Coordination with Utilities and Other Contractors - The primary proiectproponent shall evaluate, with input from utilities and otirer
"onu'"'.-t,o-rs,the stormwater management requirements for theentire prq..i, *f riirgthe utilities, when preparing the Construction SWppp.
Element #13, protect Low Impact Development BMps, is not yet incruded
as a permit condition in the NpDES construction stormwater "G"r;i
Permit. That permit is not scheduled for reissuance until Decemb.r, iots.until that permit is reissued with elemenr #13 added ., u p*rrii.nna-iilnn,
the element may be enforceabre onry through the requirements of rocarstormwater codes that may have been updated to include it. Municipal
Stormwater Permittees must incorporate this element into rocal
requirements per the timelines in their Municipal stormwater permit.
' The Plan Approval Authority is defined as that department within a local government that has been delegatedauthority to approve stormwater site plans.
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2.5.3 Minimum Requirement #3: Source Gontrol of Pollution
Allknown,availableandreasonablesourcecontrolBMPsmustbe
r""ii"a to all projects. Source control BMPs must be selected'
A!ign"a, and maintained according to this manual'
Obiective
The intent of source control BMPs is to prevent stormwater &om coming
..".*""withpollutants'Theyareacost-effectivemeansofreducing
f"if**,t in stormwater, and, therefore, should be a first consideration in
all Projects-
S upp lementsl Guide lines
Anadoptedandimplementedbasinplanora.IotalMaximumDailyLoad
(Til;i, also known as a Water Clean-up Plan) may be used to develop
morestringentsourcecontrolrequirementsthataretailoredtoaspecific
basin.
SourceControlBMPsincludeoperationalBMPsandStructuralSource
co"tror BMPs. See Volume IV for design details of these BMPs. For
construction sites, see Volume ll, Chapter 4'
Stmctural source control BMPs should be identified in the stormwater site
pi* ,ra should.be shown on all applicable plans submitted for local
go.rtan*"nt review and aPProval'
2.5.4MinimumRequirement#4:PreservationofNatural
Drainage SYstems and Outfalls
Natural drainage patterns shall be maintained, and discharges from
it "
pro;*ct site shall occur at the natural location' to the maximum
"-i"r, practicable. The manner by which runoff is discharged from
the project site must not cause a significant adverse impact to
ao*nrtt"r* receiving waters and downgradient properties' All
outfalls require energy dissipation-
Objective
Topreserveandutilizenaturaldrainagesystemstothefullestextent
u".ur$ of the multiple stormwater benefits these systems provide; and to
prevent erosion at and downstream ofthe discharge location'
S upP leme nl al G ui deli n es
creating new drainage patterns results in more site disturbance and more
pr,.rti.i for erosioninh se.dimentation during and after construction.
Lreating new discharge points can create significant stream channel
erosion problems as the receiving water body typically must adjust to the
,'*no*'.Diversionscancausegreaterimpactsthanwouldotherwise
occur by discharging runoffat the natural location'
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where no conveyance system exists at the adjacent downgradient properry
line and the discharge was previously unconcentrated tlow or significantry
lower concentrated flow, then measures must be taken to prevenT
downgradient impacts. Drainage easements from downstream pr'perty
owners may be needed and should be obtained prior to upprorut oi
engineering plans.
The following discharge requirement is recommended:
where no conveyance system exists at the abutting downstream properry
line and the natural (existing) discharge is unconcentrated, any runoff
concentrated by the proposed project must be discharged as follows:
a) lfrhe 1O0-year peak discharge is less than or equal to 0.2 cfs (0.3 cfsusing l5 minule time steps) under existing
"orditions and will remain
less than or equal to 0.2 cfs under deveroped conditions, then the
concentrated runoffmay be discharged onto a rock pad or to any other
system that serves to disperse flows.
b) tfthe I00-year peak discharge is less than or equal to 0.5 cfs (0.75 cfsusing r 5 minute time steps) under existing cooJitions and wii remain
less than or equal to 0.5 cfs under developed conditions, then the
concentrated runoffmay be discharged through a dispersar trench or
other dispersal system, provided the applicant can demonstrate that
there will be no significant adverse impact to dovvnhill properties or
drainage systems.
c) Ifthe 10O-year peak discharge is greater than 0.5 cfs for either existing
or developed conditions, or if a significant adverse impact to
downgradient properties or drainage systems is likely, then a
conveyance system must be provided to convey the concentrated
runoffacross the downstream properties to an acceptabre discharge
point (i-e., an enclosed drainage system or open drainage feature ihere
concentrated runoffcan be discharged without significant adverse
impact).
Stormwater control or treatment structures should not be located within
the expected ZS-year water level elevations for salmonid-bearing *i*r,
Such areas may provide off-channel habitat for juvenile ,utronlis anJ
salmonid fry. Designs for outfall systems to protect against adverse
impacts from concentrated runoffare included in volume v, chapter 4.
2.5.5 Minimum Requirement lf5: On-site Stormwater
Management
Projects shall employ on-site Stormwater Management BIVlps in
lccordance with the following projects thresholds, standards, and liststo inliltrate, disperse, and retain stormwater runoff on-site to the
extent feasible without causing flooding or erosion impacts.
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Projects qualifying as flow control cxempt in accordance with Section
i.S-i ,f tU-it chapter do not have to achieve the LID performance
Fa-odrra, nor consider bioretention, rain gardens' permeable
,rrru-"o,, and full dispersion if using List #l or List #2' However'
Iior" p.oi..ts must implement BMP T5'13; BMPs T5'l0A' B' or C;
and BMP T5.11or T5'12, if feasible'
Proiect Thresholds
Projects triggering only Minimum Requirements #1 through #5 shall
either:
a.Useon-siteStormwaterManagementBMPsfromList#lforall
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 BMPs as described in chapter 7 of
Volume V to achieve the LID Performance Standard'
Projects triggering Minimum Requirements #1 through #9' must meet
the requirements in Table 2.5.1'
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NOTE: This table refers to the Urban Growth Area (UGA) as designated under the
Cr"*t Management Act (GMA) @ of the-state of
;;;ilr;.Iithe Permittee is located in a county that is not subject to planning
,"J.r ,fr" GMA, the city limits shall be used instead'
TableZ.S.lOn-siteStormwaterManagementRequirementsforProiectsTriggeringMinimum Requirements #1 - #9
RequirementProject TYPe and Location
Low lmpact Development Performance
Standard and BMP T5.13; or List #2
(applicant option)'
New development on any parcel inside the
UGA, or new develoPment outside the
UGA on a Parcel less than 5 acres
Low Impact Development Performance
Standard and BMP T5.13.New development outside the UGA on a
parcel of5 acres or larger
Redevelopment on any parcel insideihe
UGA, o. iedevelopment outside the UGA
on a parcel less than 5 acres
Low Impact Development Performance
Standard and BMP T5.13; or List #2
(applicant option).
Low Impact Development Performance
Standard and BMP T5-13.RedeveloPment outside the UGA on a
parcel of5 acres or larger
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Low Impacl Developmenl Performance Srandard
stormwater discharges sh_a, match deveroped discharge durations topre-deveroped durations for the range of pre-deveropeir discharue
rates from 87o ofthe z-year peak flow to 50% ofthe 2-yea, p.r[ norr.Refer to thc standard Frow controt Requirement section in MinimumRequirement#7 for information about the assignment ortrrepre-
developed condition. Project sites that must also mcet mininrrim
requirement #7 - flow conrrol - must match flow duration, b.t r..,8% of the 2-year flow through the full50-year flow.
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List #1: on-sire srormwater Management BMps for projects TriggeringMinimum Requirements #1 through #S
For each surface, consider the BMp,s in the order listed for that typeof surfacc. use the first BMp that is considerert feasibre. No other on_site Stormwater Management BMp is necessary for that surface.Feasibility shall be determined by evaluation against:
l. Design criteria, limitations, and infeasibility criteria identified foreach BMP in this manuall and
2. competing Needs criteria listed in Chapter 5 of vorume v of thismanual.
Lawn and landscaped areas:
o Post-Construction soir euatity and Depth in accordance withBMP T5.13 in Chapter 5 of Volume V
Roofs:
l. f,'ull Dispersion in accordance with BMp T5.30 in Chapter 5 ofvolume v, or Downspout Fu, Infirtration systems in accordancewith BMP T5.r0A in Section 3.r.1 in Chapter 3 of vorume III
2. Rain Gardens in accordance with BMp 15.14 in Chapter 5 ofVolume V, or Bioretention in accordance with Chapter 7 ofVolume V. The rain garden or bioretention facility must h"r" ,minimum horizontar projected surface area berow the overflow
wbich is at least S%" of the area draining to it.
3. Downspout Dispersion systems in accordance with BMp r5.l0Bin Section 3.1.2 in Chapter 3 of Volume III
4. Perforated stub-out connections in accordance with BMp r5.r0cin Section 3.1.3 in Chapter 3 of Votume IfI
Other Hard Surfaces:
1. Full Dispersion in accordance with BMp 15.30 in Chapter s ofVolume V
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2. Pernteable pavementl in accordance with BMP T5'15 in Chapter 5
iiVotu**'i, or Rain Gardens in accordance with IIMP T5'14 in
Ctrapter 5 o[Volume V, or Bioretention in accordance with
it"ir". 7 of of volume v. The rain garden or bioretention facility
rnu*i t rr" a minimum horizontal projectetl surface area belotv the
o,u.flowwhichisatteast5Tooftheareadrainingtoit.
3. Sheet Flow Dispersion in accordance with BMP T5'12' or
Concentrated Flow Dispersion in accordance with BMP T5'11 in
ChaPter 5 of Volume V'
List #2: On-site Stormwaler Management BMPs for Proiects Triggering
Minimum Requirements #1 through #9
For each surface, consider the BMPs in the order listed for that type
oirrirr.*. Use the first BMP that is considered feasible. No other On-
*i," irot*tnater Management BMP is necessalT for that surface'
Feasibility shall be determined by evaluation against:
l.Designcriteria,limitations,andinfeasibilitycriteriaidentifiedfor
each BMP in this manuall and
2. Competing Needs Criteria listed in Chapter 5 of Volume V of this
manual-
Lawn and landscaPed areas:
o Post-Construction Soit Quality and Depth in accordance with
BMP T5-13 in ChaPter 5 of Volume V'
Roofs:
l.FullDispersioninaccordancewithBMPT5.30inChapter5of
VolumeV'orDownspoutFulllnfiltrationSystemsinaccordance
withBMPT5.r0AinSection3.l.linChapter3ofVolumeIII
?,.Bioretention(SeeChapterTofVolumeV)facilitiesthathavea
minimumhorizontallyprojectedsurfaceareabelowtheoyerflow
rvhich is at lerst 596 of the total surface area draining to it.
3. Downspout Dispersion Systems in accordance with BMP T5'108
in Section 3.1.2 in Chapter 3 of Volume III
4.PerforatedStub-outConnectionsinaccordancewithBMPT5.l0C
in Section 3.1.3 in Chapter 3 of Volume III
Other Hard Surfaces:
1. Full Dispersion in accordance with BMP T5'30 in Chapter 5 of
Volume V
rThisisnotarequirerrcnttopavethesesurfaces'Wherepavementisproposed'itmustbepermeabletotheextent
#iur. rir..t tutt dispcnion is employed'
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2. Permeabre pavementr in accordance with BMp r5.r5 in chapter 5of Yolume V
3- Bioretention BMp's (see chapter 7, votume v of rhe sMNrww)that have a minimum horizontaly projected surface "r", b"ro*the overflow which is at reast 5yo of the totar surface area drainingto it.
4. Sheet FIow Dispersion in accordance with BMp T5.12, orconcentrated Frow Dispersion in accordance with rrup rs.rt inChapter 5 of Volume V.
Objective
To use practices distributed across a development that reduce the amountof disruption of the natural hydrologic characteristics of the site.
S upplemental Guidelines
"Flooding or erosion impacts" include flooding of septic systems, crawl
spaces, living areas, outbuildings, etc.; increas"a i". o.
^tgut
gro;; r,sidewalkvroadways; earth movement/settlement ; erosion anJ other
potential damage.
Recent research indicates that traditional devetopmenl techniques inresidential, commercial, and industriar land deveropment .rrr" grosdisruption of the naturar hydrorogic cycte with s"r"r" impacts tJwater andwater-related natural resources.-Based upon gross level apptications orcontinuous runoff modeling and assumptions conceming-minimum flowsneeded to maintain beneficiar uses, watersheds must retain the majority oftheir natural vegetation cover and soils, and developments must ,lnio,ir"their disruption of the natural hydrologic cycle in oider to avoid
significant natural resource degradation in lowland streams.
The BMPs described in Section 3. I of volume III, and Section 5.3.1 ofvolume v are likely insufficient by themselves to prevent significant
hydrologic disruptions and impacts to steams and their natuial ,r**""r.
Therefore, local govemments should look for opportunities to ctrange ttreirlocal development codes to minimize impervious surfaces and retaii
native vegetation in all deveropment situations. Most importantly, to
maintain the beneficial uses of our lowland freshwatercyr,.., *itt-
require land use planning that targets retention of a majority of u ,.e.k,s
watershed in its natural condition, and retains most of ihe benefits of
headwater areas, connected wetlands, riparian, and floodplai, ur.ur.
2-32
o
BMP T5.30: Full Dispersion
Purpose and
Definition
Applications and
Limilations
o
This BMP allows for "fully dispersing" runoff from impervious surfaces
and cleared areas of development sites that protect at least 65% of the site
(or a threshold discharge area on the site) in a forest or native condition.
. Rural single family residential developments should use these
dispersion BMPs wherever possible to minimize effective impervious
surface to less than l0% of the development site.
. Other types of development that retain 65Yo of the site (or a threshold
discharge area on the site) in a forested or native condition may also
use these BMPs to avoid triggering the flow control facility
requirement.
. The preserved area may be a previously cleared area that has been
replanted in accordance with native vegetation landscape
specifications described within this BMP.
. The preserved area should be situated to minimize the clearing of
existing forest cover, to maximize the preservation of wetlands
(though the wetland area and any streams and lakes do not count
tbward the 65% forest or native condition area), and to buffer stream
corridors.
. The preserved area should be placed in a separate tract or protected
through recorded easements fbr individual lots.
. The preserved area should be shown on all property maps and should
be clearly marked during clearing and construction on the site.
. All trees within the preserved area at the time of permit application
shall be retained, aside from approved timber harvest activities
regulated under WAC Title 222, except for Class IV General Forest
Practices that are conversions from timberland to other uses, and the
removal ofdangerous or diseased trees.
. The preserved area may be used for passive recreation and related
facilities, including pedestrian and bicycle trails, nature viewing areas,
fishing and camping areas, and other similar activities that do not
require permanent structures, provided that cleared areas and areas of
compacted soil associated with these areas and facilities do not exceed
eight percent ofthe preserved area.
. The preserved area may contain utilities and utility easements, but not
septic systems. Utilities are defined as potable and wastewater
underground piping, underground wiring, and power and telephone
poles.
Volume V - Runoff 'Ir"",T:;: BMP s - December 20 I 4
o o
Minimum Design Requiremenls for Residenlial Proiects
Developments that preserve 65Yo of a site (or a threshold discharge area of
a site) in a forested or native condition, can disperse runofffrom the
developed portion ofthe site into the native vegetation area as long as the
developed areas draining to the native vegetation do not have impervious
areas that exceed l0% ofthe entire site.
Where a development has less than 65% of a site available to maintain or
create into a forested or native condition, that area may still be used for
full dispersion ofa portion ofthe developed area. The ratio ofthc native
vegetation area to the impervious area, which is dispersed into the native
vegetation, must not be less than 65 to 10. The lawn and landscaping areas
associated with the impervious areas may also be dispersed into the native
vegetation area. The lawn and landscaped arca must comply with BMP
T5.13. All design requirements listed also must be met.
The portion of the developed area which is not managed through full
dispersion can be considered a separate project site. lt must be evaluated
against the thresholds in Figures 2.2 and 2.3 of Volume l, whichever is
appropriate, to determine the applicable minimum requirements.
Additional impervious areas above lhe lloh are allowed, but should not
drain to the native vegetation area, and are subject to the thresholds,
treatment and flow control requirements of this stormwater manual.
Within the context of this dispersion option, the impervious surfaces that
are over and above the l0% maximum can be routed into an appropriately
sized dry well or into an infiltration basin that meets the flow control
standard and does not overflow into the forested or native vegetation area.
Runoffmust be dispersed into the native area in accordance with one or
more of the dispersion devices, and in accordance with the design criteria
and limits for those devices, cited in this BMP. A native vegetation flow
path ofat least 100 feet in length (25 feet for sheet flow from a non-native
pervious surface) must be available along the flowpath that runoff would
follow upon discharge from a dispersion device cited in this BMP. The
native vegetated flowpath must meet all of the following criteria:
. The flow path must be over native vegetated surface
. The flow path must be on-site or in an off-site tract or easement area
reserved for such dispersion
. The slope of the flowpath must be no steeper than l5% for any 2O-foot
reach of the flowpath. Slopes up to 33%o are allowed where level
spreaders are located upstream ofthe dispersion area and at sites
where vegetation can be established.
. The flowpath must be located between the dispersion device and any
downstream drainage feature such as a pipe, ditch, stream, river, pond,
lake, or wetland.
Yolume Y - RunaffTreatment BMPs - December 2014
5-34
o o
. 'Ihe flowpaths for adjacent dispersion devices must be sufficiently
spaced to prevent overlap of flows in the flowpath areas.
For sites with on-site sewage disposal systems, the discharge of runoff
from dispersion devices must be localed downslope of the primary and
reserve drainfield areas. This requirement may be waived by the
permitting jurisdiction if site topography clearly prevents discharged flows
from intersecting the drainfield.
Dispersion devices are not allowed in critical area buffers or on slopes
steeper than20%o, Dispersion devices proposed on slopes steeper than
l5o/o or within 50 feet of a geologically hazardous area ECW
36.704,030(5) must be approved by a geotechnical engineer or
engineering geologist.
The dispersion of runoff must not create flooding or erosion impacts.
. Roof Downspouts
Roof surfaces that comply with the Downspout Full Infiltration BMP
T5.l0A, are considered to be "fully infiltrated" (i.e., zero percent
effective imperviousness). All other roof surfaces are considered to be
"fully dispersed" (i.e., at or approaching zero percent effective
imperviousness) only if they are within a threshold discharge area that
is or will be more than 65% forested (or native vegetative cover) and
less than l0% impervious (total), AND if they either: l) comply with
the Downspout Dispersion requirements of BMP T5. l0B, but with
vegetated flow paths of 100 feet or more through the native vegetation
preserved area; or 2) disperse the roof runoff along with the road
runoff in accordance with the roadway dispersion BMP section below.
. Driveway Dispersion
Driveway surfaces are considered to be "fully dispersed" if they are
within a threshold discharge area that is or will be more than 65%
forested (or native vegetative cover) and less than l0% impervious
(total), AND if they either: 1) comply with BMP 5.1 I for concentrated
flow and BMP T5. l2 for sheet flow- and have flow paths of 100 feet
or more through native vegetation; or, 2) disperse driveway runoff
along with the road runoff in accordance with the roadway dispersion
BMP section below.
o Roadway Dispersion BMPs
Roadway surfaces are considered to be "fully dispersed" if they are
within a threshold discharge area that is or will be more than 65Yo
forested (or native vegetative cover) and less than 10% impervious
(otal), AND if they comply with the following dispersion
requirements:
Yolume V - RunoffTreatment BMPs - December 2014
5-3s
o
DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Sheridan Street, Port Townsend, WA 98368
Tel: 360.379.4450 | Fax: 360.379.4457
Web; www.co.iefferson.wa.us/commu nitvdevelopment
E-mail: dcd@co.iefferson.wa.us
SUPPLEMENTAL APPLICATION
STORMWATER MANAGEMENT PERMIT
o
MLA#PROJECT/APPLICANT NAME:
Applications for grading projects or land-disturbing activities which require a stormwater management permit shall include the following
information. This information may also be provided on other diagrams, plans,
application. lf so, please indicate such on this permit application. The Administrator
to be unnecessary for review of the application.
, studies, or attachme submitted with the project
may waive specific ments determined
excess1Source of fill material and deposition
Physical characteristics of fill2. material:{
Buildirnation3.
#
the appl icable standards in theProofmethodsandconsistentplacementcompaction
4. Proposed surfacing material
and erosion control.5. Proposed method(s) of
6. Methods for r"rtor tN Qorf tW.^ 6tZ*S fVly.t fua-TTTa
7. Demonstrate that instream flow of water will remain unobstructed
LrNA DtS{vn&tfil\.U L5 ttrtNfn*t-
*sFtuLot s .Qatds--
8. Demonstrate that erosion and sedimentation from outflow channels will be minimized etation or other means, and
runoff will controlled tomonstrate property damage.
/
Bys attests that the information provided herein is true and correct to the best of their
I made with the full knowledge and consent of all owners of the affected property.
-7-Le$
n is beingkn
OR
appl
REPRESENTATIVE SIGNATURE)(DATE)
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K#^nt.arJl *ls,x< 'nJ furri ?v:t+.gn*/.'
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1
DEPARTMENT OF COMMUNITY DEV
621 Sheridan Street, Port Townsend, WA 98368
Tel: 360.379.4450 | Fax: 360.379.445'1
Web : www. co. ieffe rson.wa. us/comm u n itvdevel op ment
E-mail: dcd@co.iefferson.wa.us
STORMWATER SITE PI.AN SUBMITTAL
um#pnolrcr/RppLtCANT NAME:
please answer all of the following questions to the best of your ability. Where the question calls for depiction on a site map, the
applicant may choose to either incorporate the elements into the general plot plan for the Master Land Use Application or to submit a
separate stormwater site plan map.
Project Overview i
Describe the proposed developed conditions of the site. lndicate position and relative size of proposed improvements on the
site
5
n
JT
lndicate contours on the site m2.
Existing Conditions Summary
Describe the
3. Describe the etation areas on the sitelndicate
4. Describe the existi soils. lndicate soil on the site
Describe the existing site hydrology (i.e., drainage; behavior of water on the site-above, below, and on the ground). lndicate
existing stormwater drainage to anO from the site on the site map. Depict separate drainage basins on the site map, if5
ble and indicate of
enerated the use orof noiseb.excess
Describe significant geographic features and critical areas (i.e.,entally sensitive areas such as wetlands, streams,7
etc.on the site. lndicate location on the site
stormwater site plan template - rev. 4,7/2016
I,f
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13 the water quality
€lz*-
6
8. Describe the general vicinity of the site, including adjacent land uses and structures, utilities, roads, and sensitive/critical areas
(streams, wetlands, lakes, steep slopes, etc.).
lttblarn Trzorr-xrl ts ,frd*"r.t+( 6 qr*(a-
This portion of the Stormwater Site Plan consists of the selection and installation of the appropriate stormwater control BMPs
and facilities to remain in place after construction of the project is completed.
"Medium" size projects are required to have the totals calculated of all impervious surfaces, pollution-generating impervious
surfaces, and pollution-generating pervious surfaces to verify that the thresholds for treatment facilities and flow control
fanilitiac ara nnt ovcaor{orl
. Describe the developed site hydrology, as proposed. lndicate whether stormwater will be fully dispersed (i.e., per BMP T5.30
in the Manual) or, if not, what types of stormwater flow control will be utilized for the site or specific threshold discharge areas
- within the site. Locate these facilities on the site plan and differentiate proposed facilities from existing facilities.
i(aer.+tt 16 ?n/r-es€. slfrs*l,t-^t^tila2-i6tee.,fit0 vttdle--Ng*l <fL&noF-
o
Permanent Stormwater Control Plan
fi! r)ksle Srt*Aftd(ks.
L\ArL W0xcwti,,Ftdw* ftL flefieilG oR&.aqaffi
L
lf the project requires the use of stormwater treatment facilities, describe the types of stormwater treatment facilities proposed
for use on the site. Locate these facilities on the site plan and differentiate proposed facilities from existing facilities. [his is
for "large" projects or projects that involve the potential for dispersion of contaminants.l
10
Describe the performance goals and standards applicab
*esrzaa At,l i 01L 'D6fuR.,F& tt {,r& aa,ertrtl
11 le to the project.
Ara*A5W' ,f12f,E N. fub{,rv 'frstr$;cp. .<r- rtryruu-')rh,ro,
12 the flow control system
stormwater site plan template - rev. 4[/2016
D+^lD-----4v{tuin-,xt* futu1* Ap+- fr?t{a.&. ?xal*l,.s tJfi*sCIE)br- nL*M€ fipNfi
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14. Describe the conveyance system analysis and design.
15. D the source of fill material, physical characteristics of fill material, and deposition of excess material'
S.t4
Proposed methods of placement and compaction consistent with the applicable standards on Appendix Chapter 33 of the
Building Code.
18. Describe for restoration of
An Operation and Maintenance Manual is required for each flow control and treatment facility. [-his is normally required for
"large" projects only and only those for which facilities are required to control flow or treat runoff.l lf included, list the Manuals
here
20. List h and special reports or conducted to the Stormwater Site Plan.
List other necessary permits and approvals as required by other regulatory agencies. lf those permits or approvals include
conditions that affect the drainage plan or contain more restrictive drainage-related requirements, describe those conditions or
here.
stormwater site plan template - rev.4n12016 7
o o
GONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN (SWPPP)
The Construction SWPPP addresses sedlment and erosion control during construction. The BMPs indicated by the applicant in the
template that follows must be installed on the ground during all construction phases of the project. The proponent'is responsible for
preventing sediment and erosion impacts to environmentally sensitive areas and off-site areas. Consult the Construction Stormwater
Pollution Prevention (SWPP) Best Management Practices (BMPs) Packet for guidance, particularly with rural residential
development.
SECTION I- CONSTRUCTION SWPPP NARRATIVE
8
1 Construction Stormwater Pollution Plan Elements. Describe how each of the Construction SWPPP elements has been or
will be addressed. ldentify the type and location of BMPs used to satisfy the required element. lf an element is not applicable to
the proposal, justify in writing. Detailed descriptions of the 13 Elements are found at Volume ll Section 3.3.3 of the Manual
(beginning on page 3-11).
13 Required Elements - Construction SWPPP
1 Limits 5tr*.'
Z oilsn ACCeSS.
3- Control Flow Rates
4. lnstall
5.ilize Soils
I
6.Slo
7. Protect Drain lnlets.
€tte,out tx ko, urz,*-
stormwater site plan template - rev. 4/7/201 6
Controls.
o o
13 Required Elements - Construction SWPPP (continued)
8. Stabilize Channels and Outlets.
utants.
10. Control De-Watering (the act of pumping groundwater or stormwater away from an active construction site)
11. Maintain Best M P (BMPs)
12 e the Project.
13.Low I P's
Adjacent Areas.
a. Description of the adjacent areas that may be affected by site disturbance (e.g., streams, lakes, wetlands, residential
2.
a
of the downstream drainage path leading from the site to of water (minimum distanceb. Description of 400
/
areas that are on or adjacent to the sitea.Descri of environmentally
3. EnvironmentallySensitiveAreas.
stormwater site plan template - rev. 4/7/201 6
9.
oo
b.Description of for working in or near envi areas.
7/tut
4.Erosion Problem Areas. Description of potential erosion problems on site in the context of the characteristics of the on-site
soils (e.9., erodibility, settleability, permeability, depth, texture, soil structure).
5. Construction Phasing.
a
-fu,,r s"Flu-
b phasing (if proposed)
6. Construction Schedule. Wet season is October 1 through April 30 (page 2-20 of the Manual).
a proposed schedule.
Wet Season Construction
a. Proposed wet season construction activities.tixlu-
b.Prooosed wet seasoniNt-construction activities for environmentally sensitive areas.
7. Financial/Ownership Responsibilities.
a. ld the pro responsible for the initiation of bonds and/or other financial securities.
lA.
b. Describe bonds andior other evidence of financial responsibility for liability associated with erosion and sedimentation
im
8. EngineeringCalculations. Provide Calculations on a separate sheet for the following, if applicable
a.
b.
C.
d.
Sediment Ponds/Traps.
Diversions.
Watenruays.
Runoff/Stormwater Detention Calculations
stormwater site plan template - rev. 4/7i20 16 '10
o a
ON ION AN
Sediment and erosion control measures may be depicted on the master land use application plot plan, a stormwater
separate Construction SWPPP site plan. This is a checklist to ensure that the following are depicted on a site plan:
site plan, and/or a
11
1. General
a. Vicinity Map
b. Jefferson County Approval Block
c. Erosion and Sediment Control Notes
2.Site Plan.
/ ?. Legal description of subject property
{o. North arrow.
Indicate boundaries of existing vegetation (e.9., tree lines, pasture areas, etc.)
ldentify and label areas of potential erosion problems.
3. Gonveyance Systems.
'a. Designate locations for swales, interceptor trenches, or ditches.
, b. Show all temporary and permanent drainage pipes, ditches, or cut-off trenches required for erosion & sediment control
c. Provide minimum slope and cover for all temporary pipes or call out pipe inverts.
lr1. Shows grades, dimensions, and direction of flow in all ditches, swales, culverts and pipes.
e. Provide details for bypassing off-site runoff around disturbed areas.
f. lndicate locations and outlets of any dewatering systems.
.lc.
la.
11-.
,/r,
,./9.
in.
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l:
4. Location of Detention Best Management Practices (BMPs). ldentify location of detention BMPs.
5. Erosion and Sediment Gontrol Facilities.
a. Show the locations of sediment trap(s), pond(s), pipes and structures.
' b. Dimension pond berm widths and inside and outside pond slopes.
c. lndicate the trap/pond storage required and the depth, length, and width dimensions.
d. Provide typical section views through pond and outlet structure.
e. Provide typical details of gravel cone and standpipe, and/or other filtering devices.
f. Detail stabilization techniques for outleUinlet.
g. Detail control/restrictor device location and details.
h. Specify mulch and/or recommended cover of berms and slopes.
, i. Provide rock specifications and detail for rock check dam(s), if applicable.
j. Specify spacing for rock check dams as required.
k. Provide front and side sections of typical rock check dams.
l. lndicate the locations and provide details and specifications for silt fabric.
m. Locate the construction entrance and provide a detail.
6. Detailed Drawings. Any structural practices used that are not referenced in the Ecology Manual should be explained and
illustrated with detailed drawings.
Other Pollutant BMPs. lndicate on the site plan the locations of BMPs to be used for the control of pollutants other than
sediment (e.9., concrete wash water).
7
8.Monitoring Locations. lndicate on the site plan the water quality sampling locations to be used for monitoring water quality on
the construction site. Sampling stations should be located upstream and downstream of the project site.
stormwater sile plan template - rev. 4/7/201 6
Show existing and proposed contours.
lndicate drainage basins and direction of flow for individual drainage areas.
Label final grade contours and identify developed condition drainage basins.
Delineate areas that are to be cleared and graded. n t$fl
Show all cut and fill slopes indicating top and bottom of slope catch lines.
ldentify FEMA base flood boundaries and Shoreline Management boundaries
L0
o o
Stormwater Site Plan Changes
lf the designer wishes to make changes or revisions to the originally approved Stormwater Site Plan, the proposed revisions shall be
submitted 1o DCD prior to construction. The submittal shall include substitute pages that include all proposed changes, revised
drawings showing any structural changes, and any other supporting information that explains and supports the reason for the change.
Finat Corrected Plan Submittal
lf the project included construction of conveyance systems, treatment facilities, flow control facilities, or structural source control BMPs
(not sianiard on-site stormwater management BMPs), the applicant shall submit a final corrected plan ("as-builts") when the project is
completed. These should be engineering drawings (stamped by a licensed civil engineer) that accurately represent the project as
constructed.
APPLICANT SIGNATURE
THIS SPACE MAY BE USED FOR ADDITIONAL NOTES, IF NEEDED:
By signing the Construction SWPPP worksheet, I as the applicanUowner attest that the information provided herein is true and
I also certify that this application is being made with the full knowledge and consent of allcorrect to the best of my
the affected
?^)P^1U
OR REPRESENTATIVE SI (oerc)
stormwater site plan template - rev.4/7/2016