Chapter 25. Construction Site Erosion Control
Sec. 25-29. Storm Water Management Plan
(1) PLAN REQUIREMENTS. The storm water management plan required under section 25-28(2) shall contain at a minimum the following information:
(a) Name, address, and telephone number for the following or their designees: landowner; developer; project engineer for practice design and certification; person(s) responsible for installation of BMPs; and person(s) responsible for maintenance of BMPs prior to the transfer, if any, of maintenance responsibility to another party.
(b) A proper legal description of the property proposed to be developed, referenced to the U.S. Public Land Survey system or to block and lot numbers within a recorded land subdivision plat.
(c) Pre-development site conditions, including:
1. One or more site maps at a scale of not less than 1 inch equals 50 feet. The site maps shall show the following: site location and legal property description; predominant soil types and hydrologic soil groups; existing cover type and condition; topographic contours of the site at intervals not to exceed two feet; topography and drainage network including enough of the contiguous properties to show runoff patterns onto, through, and from the site; watercourses that may affect or be affected by runoff from the site; flow path and direction for all storm water conveyance sections; watershed boundaries used in hydrology determinations to show compliance with performance standards; lakes, streams, Army Corps of Engineers certified wetlands, channels, ditches, and other watercourses on and immediately adjacent to the site; limits of the 100 year floodplain; location of wells and wellhead protection areas covering the project area and delineated pursuant to s. NR 811.16, Wis. Adm. Code.
2. Hydrology and pollutant loading computations as needed to show compliance with performance standards. All major assumptions used in developing input parameters shall be clearly stated. The geographic areas used in making the calculations shall be clearly cross-referenced to the required map(s).
(d) Post-development site conditions, including:
1. Explanation of the provisions to preserve and use natural topography and land cover features to minimize changes in peak flow runoff rates and volumes to surface waters and wetlands.
2. Explanation of any restrictions on storm water management measures in the development area imposed by wellhead protection plans and ordinances.
3. One or more site maps at a scale of not less than 1 inch equals 50 feet showing the following: post-construction pervious areas including vegetative cover type and condition; impervious surfaces including all buildings, structures, and pavement; post-construction topographic contours of the site at intervals not to exceed 2 feet; post-construction drainage network including enough of the contiguous properties to show runoff patterns onto, through, and from the site; locations and dimensions of drainage easements; locations of maintenance easements specified in the maintenance agreement; flow path and direction for all storm water conveyance sections; location and type of all storm water management conveyance and treatment practices, including the on-site and off-site tributary drainage area; location and type of conveyance system that will carry runoff from the drainage and treatment practices to the nearest adequate outlet such as a curbed street, storm drain, or natural drainage way; watershed boundaries used in hydrology and pollutant loading calculations and any changes to lakes, streams, wetlands, channels, ditches, and other watercourses on and immediately adjacent to the site.
4. Hydrology and pollutant loading computations as needed to show compliance with performance standards. The computations shall be made for each discharge point in the development, and the geographic areas used in making the calculations shall be clearly cross-referenced to the required map(s).
5. Results of investigations of soils and groundwater required for the placement and design of storm water management measures. Detailed drawings including cross-sections and profiles of all permanent storm water conveyance and treatment practices.
(e) A description and installation schedule for the BMPs needed to meet the performance standards in section 25-27.
(f) A maintenance plan developed for the life of each BMP including the required maintenance activities and maintenance activity schedule.
(g) Cost estimates for the construction, operation, and maintenance of each BMP.
(h) Other information requested in writing by the Director of Public Works or his designee to determine compliance of the proposed BMPs with the provisions of this ordinance.
(i) All site investigations, plans, designs, computations, and drawings shall be certified by a Professional Engineer or Hydrologist licensed in the State of Wisconsin, to be prepared in accordance with accepted engineering practice and requirements of this ordinance.
(2) ALTERNATE REQUIREMENTS. The Director of Public Works or his designee may prescribe alternative submittal requirements for applicants seeking an exemption to on-site storm water management performance standards under section 25-27(5).
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