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12 <br /> Stormwater <br /> 1) A Stormwater Impact Statement will be prepared for any proposed improvement to the site. <br /> The Stormwater Impact Statement will include the following information: <br /> a) Written narrative describing existing and proposed conditions, anticipated stormwater <br /> impacts and management structures and strategies to mitigate impacts <br /> b) Description of land uses and area (in square footage) <br /> c) Existing and proposed impervious surface area in square feet for all subareas and project <br /> area <br /> d) Ground cover and uses information <br /> e) Soil information (classification, infiltration rates, depth to groundwater and bedrock) <br /> f) Tim of concentration calculations and assumptions <br /> g) Topography (2-foot contours) <br /> h) Pertinent on-site and off-site drainage condition <br /> i) Upstream and/or downstream volumes <br /> j) Discharges and velocities <br /> k) Backwater elevations and effects on existing drainage conveyance facilities <br /> 1) Location of jurisdictional wetlands and regulatory FEMA Special Flood Hazard Areas <br /> m) Water quality volume calculations <br /> n) Drainage areas and sub-areas delineated <br /> o) Peak discharge calculations and rates (1, 2, and 25-year storms) <br /> p) Hydrographs for pre-and post-development without mitigation, post—development with <br /> mitigation It _qqqwhhh�, <br /> q) Volume calculations and documentation of retention for 2-year storms) <br /> r) 85%total suspended solids (TSS) removal for post-development stormwater run-off <br /> s) Nutrient loading calculations <br /> t) Stormwater best management practice (BMP) sizing calculations <br /> u) Pipe sizing calculations and schedule (include hydraulic grade line and energy grade line <br /> calculations and profiles) <br /> "40� %4—kqq� <br /> 2) A Stormwater Management Plan is required for all new work at the site. The plan will included <br /> proposed and existing contours at a 2 foot intervals. All existing drainage conditions, features <br /> and stormwater piping and structures shall be shown on the plan. All Resource Conservation <br /> District(RCD) areas on the site shall be noted with delineated boundaries. All proposed <br /> stormwater systems and drainage conditions must be shown. A piping system for the new <br /> stormwater system shall be shown with the associated schedule. New roof drains from all <br /> buildings shall be shown to their terminations. All proposed stormwater easements shall be <br /> labeled and provide a 20 foot width at a minimum. All proposed best management practices <br /> shall be shown on the plan with associated details and sections. New plantings and stabilization <br /> techniques shall be noted on this plan. A Stormwater Management Plan will included <br /> compliance with the latest Town of Chapel Hill requirements as well as Jordan Lake Rules, and <br /> shall be approved prior to issuance of a Zoning Compliance Permit. <br /> Lighting/Street and Parking Lots <br /> All street and parking lighting plans will be approved by the Town of Chapel Hill Community Design <br /> Commission (CDC) prior to issuance of a Zoning Compliance Permit. <br /> Southern Orange County Government Services Campus I MASTER PLAN Page 8 <br />