HomeMy WebLinkAbout05- Stormwater Calculation Worksheet Whipple�g5�ON cow DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Sheridan Strcct, fort 1'ownsend, WA 98368
W-Fd:360.379.4450 1 Fax: 360.379.4451
Web: www.co.icffetsan.wa.us/cominunit`'dcvcl-opment
O� I," -mad: dcdna?co.jcffetsota.wa.us
STORMWATER CALCULATION WORKSHEET
MLA# PROJ ECT/APP H CANT NAME:
DETERMINING STORMWATER MANAGEMENT REQUIREMENTS: 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
required,
PARCEL SIZE (I.E., SITE)
Size of parcel & Li r acres An acre contains 43,560 square feet. Multiply the acreage by this figure.
Size of parcel in square feet { J sqlft
If
Land -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.
LAND DISTURBING ACTIVITY CONVERSION OF NATIVE VEGETATION AND VOLUME OF CUT/FILL
Calculate the total area to be cleared, graded, filled,
excavated, and/or compacted for proposed development
project. Include in this calculation the area to be cleared for:
Construction site for structures U sq/ft
Drainfield, septic tank, etc. n.ZA sg/ft
Well, utilities, etc. Y1% sg/ft
Driveway, parking, roads, etc. 56D sglft
Lawn, landscaping, etc.
sglft
Other compacted surface, etc. 6o50 sglft
Total Land Disturbance 31 c'�Lfq sglft
Answer the following two questions related to
conversion of native vegetation:
Does the project convert % acres or more of
native vegetation to lawn or landscaped areas?
Circle: Yes No
Does the project convert 2'/z acres or more of
native vegetation to pasture?
Circle: Yes No
Indicate Total Volumes of Proposed:
Cut 3 1 e, Fill (culyd)
Impervious 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 prior to 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 other surfaces which similarly impede the natural infiltration of stormwater,
stormwater talc worksheet — REV. 1 D12I2014
STORMWATER CALULATIONS — IMPERVIOUS SURFACE
NEW
Structures (all roof area) ai J sq/ft
Sidewalks sq/ft
Patios
Solid Decks
(without infiltration below)
sq/ft
sq/ft
Driveway, parking, roads, etc 300 sq/ft
Other sq/ft
Total New 2 d sglft
TOTAL NEW + TOTAL EXISTING* 7 U Z sq/ t
EXISTING �h
Structures (all roof area) sq/ft
Sidewalks sq/Tt
Patios sq/ft
Solid Decks sq/ft
(without infiltration below)
Driveway, parking, roads, etc �� sq/ft
Other
sq/ft
Total Existing 4 160 sglft
*This amount will be used to check total lot coverage.
The following questions will help determine whether the proposed project is considered development or redevelopment.
DEVELOPMENT v. REDEVELOPMENT
Divide the total existing impervious surface above by the size of the parcel and convert to a percentage: ��%
Does the site have 35% or more of existin impervious surface? Circle: Yes 11 No
21
FURTHER INSTRUCTIONS: If the answer is yes, the proposal is considered redevelopment and the attached Figure 2 should be used
to determine the applicable Minimum Requirements. If the answer is no, the proposal is considered new development and the
attached Figure 1 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 42—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 Instructions and Submittal
Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Stormwater Management Monuol.
APPLICANT SIGNATURE
By signing the Stormwater Calculation Worksheet, l 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
property.
LANDOWNER OR AUTHORIZED REPRESENTATIVE SIG NAT
JD -27`2D7
(DATE)
Stormwater talc worksheat — REV. 1012012014