HomeMy WebLinkAboutBLD2015-00108 - 05 STORMWATER • •
C4 c s°N ooe t DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Sheridan Street,Port Townsend,WA 98368
i 447 'a Tel:360.379.4450 I Fax:360.379.4451
Web:www.co.jefferson.wa.us/communityclevelopment
E-mail:dcd(n)co.jefferson.wa.us
9`SNI N G�O�
STORMWATER CALCULATION WORKSHEET
MLA# PROJECT/APPLICANT 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 4'05 acres An acre contains 43,560 square feet. Multiply the acreage by this figure.
Size of parcel in square feet 176,440 sot
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, Answer the following two questions related to
excavated, and/or compacted for proposed development conversion of native vegetation:
project. Include in this calculation the area to be cleared for:
Does the project convert%acres or more of
Construction site for structures 0 sq/ft native vegetation to lawn or landscaped areas?
Drainfield, septic tank,etc. 0 sq/ft Circle: Yes No
Well, utilities,etc. 0 sq/ft Does the project convert 2''A acres or more of
native vegetation to pasture?
Driveway, parking, roads, etc. 0 sq/ft
Circle: Yes (No)
Lawn, landscaping,etc.
a sq/ft
Other compacted surface, etc. 0 sq/ft Indicate Total Volumes of Prnpon�sed• _
Total Land Disturbance 0 sq/ft Cut . I S I! u
Impervious surface is a hard surface that either prevents or retards the entry of water into thit\RI ma2tle?R,5under t.lral
conditions prior to development. A hard surface area which causes water to run off the surface in greater quantities oriat an
increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces inch.de,
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 stormwatler---!
stormwalerealc worksheet—REV 1012012014 1
• •
STORMWATER CALULATIONS–IMPERVIOUS SURFACE
NEW EXISTING
Structures(all roof area) _ sq/ft Structures(all roof area) 33,910 sq/ft
Sidewalks 0 _sq/ft Sidewalks 3,600 sq/ft
Patios 0 sq/ft Patios 0 sq/ft
Solid Decks 0 sq/ft Solid Decks 0 sq/ft
(without infiltration below) (without infiltration below)
Driveway, parking, roads, etc 0 sq/ft Driveway, parking, roads, etc 95,850 sq/ft
Other 13 sq/ft Other 450 sq/ft
Total New 13 sq/ft Total Existing 133,810 sq/ft
TOTAL NEW+TOTAL EXISTING* 133,825 sq/ft 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: 75.8 %
Does the site have 35%or more of existing impervious surface? Circle: Yes ✓ No
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 #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 Instructions and Submittal
Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Storm water Management Manual.
APPLICANT SIGNATURE
By signing the Stormwater 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 E n
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stormwater talc worksheet—REV.10/20/2014 2