Impervious Calculation Worksheet

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IMPERVIOUS CALCULATION WORKSHEET Instructions: 1. Calculate the area in square feet of all existing and proposed impervious surfaces on your lot within 300ft of the OHWM. 2. Divide the surface area of existing and proposed impervious surfaces on the portion of a lot or parcel that is within 300 feet of the Ordinary High Water Mark (OHWM) by the total area of that portion of the lot or parcel that is within 300 feet of the OHWM (the area shaded in gray below). 3. Multiply the result by 100. Impervious Surface SQ.FT. Driveway(s), [Concrete, Pavers, Gravel, etc.] Garage(s), Pads [Concrete, Pavers, Gravel, etc.] Walkway(s), [Concrete, Pavers, Gravel, etc.] House Patio(s), Pool(s), Pool Apro n(s) Outbuilding(s), Any Slab(s) Lean-to(s) Other Impervious Area(s), [Retaining Walls, Block, etc.] Other TOTAL IMPERVIOUS SURFACE ( ) ÷ ( )×(100)= Total SQ.FT. of TotalSQ.FT.of Impervious Surfaces Shoreland Lot Total % of (Within 300’ of the OHWM) (Within 300’ of the OHWM) Impervious Surface Note: “Impervious Surface” means an area that releases as runoff all or a majority of the precipitation that falls on it. “Impervious surface” excludes frozen soil but includes rooftops, sidewalks, driveways, parking lots, and streets unless specifically designed, constructed, and maintained to be pervious. Staff can make additional impervious determinations based upon site specific circumstances. This handout is intended to summarize the standards, not replace the actual ordinance. For more information refer to Chapter 16 St. Croix County Shoreland Overlay Districts Community Development 715-386-4680 St. Croix County Government Center 715-245-4250 Fax [email protected] 1101 Carmichael Road, Hudson, WI 54016 www.sccwi.gov PREPARE A PLOT PLAN / SKETCH OF YOUR PROPERTY SKETCH MUST INCLUDE ALL OF THE FOLLOWING: 1. All structures, proposed and existing 2. Location of any accessory structure including those authorized in 16.320 3. Driveways and roads fronting property 4. Lot line locations 5. Water body locations and unique natural features such as wetlands, steep slopes, etc. 6. Septic system and well location 7. Identify the existing shoreland buffer depth and view corridors, if applicable 8. Identify any areas that you propose to grade or fill BODY OF WATER ORDINARY HIGH WATER MARK (OHWM) PROPERTY LINE PROPERTY 300 FEET PROPERTY LINE PROPERTY LINE Staff notes: .

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