HomeMy WebLinkAboutBLD2018-00545 - 05 SW REPORT/\,tlrntl}.{ea. tP S. ["tt^ 7 S
DEPARTMENT OF COMMUNITY DEVELO
621 Shcridan Street, l)ort'l'ownscr:d, W,\ 98368
'l' el 360.379.1450 | Fax: 360.379.4451
Vtb: www.co.ietTcrson.wa.us / communitydeveloPment
l',-m,r il : dci@,gr.jsllssoq.Eus
STORMWATER CALCULATION WORKSHEET
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DETERMINII{G SIORMWATER MANAGEMENT REQUIREMENTS: This stormwater calculation worksheet should be completed flrst 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 manatement 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
required.
Land4lsturbtng acttvv 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 disturbinS activities include, but are not limited to clearing, grading, filling,
excavation, and compaction associated with stabilization of structures and road construction.
Natfue vegetotlon 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.
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lmpervlous sufice is a hard surface that either prevents or retards the entry of water into the soil mantle as under natural
conditions prlor to development. A hard surface area which causes water to run off the surface in greater quantities or at en
increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include,
but are not limited to roof tops, walkways, patios, driveways, parlqing lots or storage areas, concrete or asphalt paving, gravel roads,
packed earthen materials, and oiled, macadam or other surfaces uJhicn similarly impede the natural infiltration of stormwater.
stormtor calc workshcst - REV. 1MOi2O11
PARCEL SIZE (I.E.. SITEI
An acre contains 43,560 square bet. Multiply the acreage by this figure.
L1 sq/ftSize of parcel in square bel
sizeof parcel Z'47 ,"n"
LAND DISTURBING ACTIVITY. CONVERSION OF NATTVE VEGETATION. AND VOLUME OF CUT/FILL
Calculate the total area to be cleared, graded, filled'
excavated, and/or compacted for proposed development
project. lnclude in this calculation the area to be cleared for:
Construction site for structures 75 O O sqtlt
Answer the following two questions related to
conversion of native vegetation:
Does the poect convert /, acres or more of
native vegetation to lawn or landscaped areas?
Circle: Yes @
Does the project convert 2Yz acres or more of
native vegetation to pasture?
Circle: Yes @
sq/ft
sq/ft
Oxist?naDrainfield, septic tank, etc.
Well, utilities, etc.
bLawn, landscaping, etc.
Other compacted surface, etc.lndlcate Total Volumes of Proposed:
cut 60 Fin 5 O (cu/yd)
Driveway, parking, roads, etc. ?:(r s{ ing solft
sq/ft
sq/ft
rqrft
0oo
Total Lend Dlrturbance ?2 O O
STORMWATER CALCUI.ATIOiIS - IMPERVIOUS SURFACE
TOTAL NEW + TOTAL EXISTING' 55*b .qN
Total New
This amount will be used to check total lot co\rerage.
Totat Exlstlns TooO
"qm
oo Driveway, parking, roads, etc ?oo 4
Other sq/ft
354, .qn
NEW
Structures (allroof area) Z14t "qfi
EXIST!NG
Structures (all roof area) sq/ft
Sidewalks sq/ft
Patios
Solid Decks
(without infiltration below)
Driveway, parking, roads, etc
Other
Sidewalks
Patios
Solid Decks
(without infi ltration betow)
a o
The following questions will help determine whether the proposed project is considered development or redevelopment.
FURTHER INSTRUCIIONS: 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 Flgure t 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 f2-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 Preventlon (SWPP) Best Manatement Prastlces (BMPs) Packet. Proponents of "medium"
projects-those that must meet only Minimum Requirements f1 through #5-and fot "la?ge" proiects-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 Instructlons and Submlttal
Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Stormwater Manogement Monuol.
APPLICANT SIGNATURE
DEVELOPMENT v. REDEVELOPMENT
Divide the total g.!g!!Eg impervious surface above by the size of the parcel and convert to a percentage
Does the site have 35Yo or more of existino impervious surface? Circle:
o/o
@trYes
By signing the Stormurater Calculation Worksheet, I as the applicant/owner attest that the information provided herein is true and correct to the
best of my knowledge. I also certify that this application is being made with the full knowledge and consent of all owners of the affected
oR AUTHof,lzEo REpnselrarve srexlrune)
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2storrweter calc wo.kshe€t - REV. 1WOD014
Slto Plrn: