SECTION 6.09. STORM WATER MANAGEMENT PLAN.
(1) STORM WATER MANGEMENT PLAN REQUIREMENTS. The Storm Water Management Plan required under Section 6.07(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 storm water management practices; and person(s) responsible for maintenance of storm water management practices 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 100 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 a scale not to exceed 2 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, 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 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 100 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 a scale 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
4. Hydrology and pollutant loading computations as needed to show compliance with performance 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 Detailed drawings including cross-sections and profiles of all permanent storm water conveyance and treatment practices.
[e] A description and installation schedule for the storm water management practices needed to meet the performance standards in s. 6.07.
[f] A maintenance plan developed for the life of each storm water management practice including the required maintenance activities and maintenance activity schedule.
[g] Cost estimates for the construction, operation, and maintenance of each storm water management practice.
[h] Other information requested in writing by the Village to determine compliance of the proposed storm water management measures with the provisions of this ordinance.
[i] All site investigations, plans, designs, computations, and drawings shall be certified by a licensed professional engineer to be prepared in accordance with accepted engineering practice and requirements of this ordinance.
[j] ANTICIPATED IMPACTS. The plan shall contain a description of the following anticipated impacts of stormwater runoff from the proposed development, redevelopment, or land division as managed by the facilities and measures recommended in the plan:
1. Computed runoff discharge rate as indicated by Chapter 13 MMSD rules and NR 151 WDNR regulations;
2. Computed runoff volume for the 1.5-inch, 4-hour rainfall with a Huff Distribution;
3. All major assumptions used in developing input parameters shall be clearly stated. The computations shall be made for each discharge point in to and out of the site, and the geographic areas used in making the calculations shall be clearly cross-referenced to the required map(s), including off-site tributary watershed areas;
4. Changes in the locations and conveyance capacities of stormwater discharge points from and to the site concerned;
5. Adequacy of receiving storm sewer, engineered stormwater management facility or watercourse to convey or store the anticipated peak rate of stormwater discharge from the site concerned, giving due consideration to existing and off-site flows;
6. Changes in the location and extent of the 100-year recurrence interval flood hazard area of any perennial watercourse location within, through, or within 100 feet of, the site concerned;
7. Results of investigations of soils and groundwater required for the placement and design of stormwater management measures; and
8. Changes in ground water elevations referred to National Geodetic Vertical Datum of 1929 or to Village Datum with prior written approval from the Village.
[k] PROPOSED STORMWATER MANAGEMENT FACILITIES AND MEASURES. The plan shall include a definitive description of the proposed stormwater management facilities and measures for the control of the quantity and quality of the anticipated stormwater runoff from the proposed development, redevelopment, or land division.
1. All site investigations, plans, designs, computations, and drawings shall be certified as prepared in accordance with accepted current engineering practice and in accordance with “WDNR Storm water post-construction technical standards,” “WDNR Storm water construction technical standards,” and “Standard Specifications for Sewer and Water Construction in Wisconsin.”
2. The description of the proposed management facilities shall include:
3. For detention and retention facilities: locations, areas, depths, volumes, inlet and outlet configurations, and elevation of the bottoms, and of key inlet and outlet control structures; all elevations being referred to National Geodetic Vertical Datum of 1929 or to Village Datum with prior written approval from the Village;
4. For conveyance facilities: locations of inlets and manholes and associated rim and invert elevations, and pipe sizes, slope and materials; locations, elevations, and cross sections of ditches, swales and channels; and culvert sizes, inlet and outlet configurations and elevations; all elevations being referred to National Geodetic Vertical Datum of 1929 or to Village Datum with prior written approval from the Village;
5. Design computations and all applicable assumptions for the stormwater conveyance (open channel, closed pipe, etc.) system;
6. Detailed drawings including cross-sections and profiles of all permanent stormwater conveyance and treatment practices;
7. Design computations and all applicable assumptions for stormwater quality practices (sedimentation type, filtration type, infiltration type) as needed to show that practices are appropriately sized to accommodate runoff from the 1.5-inch rainfall;
8. Erosion Control Plan in accordance with the “WDNR Storm water construction technical standards,” published and periodically updated by the Wisconsin Department of Natural Resources;
9. Measures to abate any potential pollution of surface and ground waters;
10. A schedule for the construction of the recommended stormwater management facilities and estimates of attendant capital and operation and maintenance costs;
11. A maintenance plan developed for the life of each stormwater management practice including the required maintenance activities and maintenance activity schedule;
12. Other information as needed by the Village to determine compliance of the proposed stormwater management measures with the provisions of this Section.
(2) ALTERNATE REQUIREMENTS. The Village may prescribe alternative submittal requirements for applicants seeking an exemption to on-site storm water management performance standards under Section 6.07 (5).