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Home My WebLink AboutMLA18-00043 Stormwater Calcuation WorksheetDEPARTMENT OF COMMUNITY DEVELOPMENT 621 Sheridan Street, Port Townsend, WA 98368 Tel: 360.379.4450 1 Fax: 360.379.4451 Web: trn� ty.cc,.Irlterticast,�v t.tts%csiriaat�uaulye�cveluptiaent E-mail: dcd;aicojefferson.iva.us 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 5.17 acres An acre contains 43,560 square feet. Multiply the acreage by this figure. Size of parcel in square feet 225,205.2 sq/ft 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 CUTIFILL 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: 2,400 Construction r Does the project convert 3/ acres or more of site for structures _ sq/ft native vegetation to lawn or landscaped areas? Drainfield, septic tank, etc. 2,500 sq/ft Circle: Yes Q 0 Well, utilities, etc. sq/ft Does the project convert 2 t/2 acres or more of 3,170 native vegetation to pasture? Driveway, parking, roads, etc. sglft 1 250 Circle: Yes (& Lawn, landscaping, etc. _, sq/ft Other compacted surface, etc. 0 sq/ft Indicate Total Volumes of Proposed: Total Land Disturbance 9,320 sq/ft Cut 50 Fill 50 (cu/yd) 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 10/20/2014 TOTAL NEW + TOTAL EXISTING* 5,570 i – IMPERVIOUS SURFACE EXISTING Structures (all roof area) 0 sq/ft Sidewalks 0 sq/ft Patios 0 sq/ft Solid Decks 0 sq/ft (without infiltration below) Driveway, parking, roads, etc 0 Other 0 Total Existing 0 sq/ft 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: 2.2 % Does the site have 35% or more of existing impervious surface? Circle: Yes No 77 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 Stormwater 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 property. (LANDOWNER OR AUTHORIZED REPRESENTATIVE SIGNATURE) (DATE) FOR OFFICE USE ONLY SMALL MEDIUM LARGE REDEVELOPMENT Stormwater Site Plan: Yes No stormwater calc worksheet — REV 10f20/2014 2 STORMWATER CALULATION; NEW 2,400 Structures (all roof area) sq/ft 0 Sidewalks sq/ft 0 Patios sglft 0 Solid Decks — `sq/ft (without infiltration below) Driveway, parking, roads, etc 3,170 sq/ft 0 Other sq/ft 5,570 Total New sq/ft TOTAL NEW + TOTAL EXISTING* 5,570 i – IMPERVIOUS SURFACE EXISTING Structures (all roof area) 0 sq/ft Sidewalks 0 sq/ft Patios 0 sq/ft Solid Decks 0 sq/ft (without infiltration below) Driveway, parking, roads, etc 0 Other 0 Total Existing 0 sq/ft 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: 2.2 % Does the site have 35% or more of existing impervious surface? Circle: Yes No 77 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 Stormwater 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 property. (LANDOWNER OR AUTHORIZED REPRESENTATIVE SIGNATURE) (DATE) FOR OFFICE USE ONLY SMALL MEDIUM LARGE REDEVELOPMENT Stormwater Site Plan: Yes No stormwater calc worksheet — REV 10f20/2014 2