§ 20-212. Stormwater drainage facilities.

The subdivider shall construct stormwater drainage facilities, adequate to serve the subdivision, which shall include, but not be limited to, curbs and gutters, catchbasins and inlets, storm sewers, road ditches, open channels, water retention structures, water detention structures, temporary sedimentation basins, and settling basins. All such facilities shall be of adequate size and grade to hydraulically accommodate the maximum potential volumes of flow and shall be so designed as to prevent and control soil erosion and sedimentation and to present no hazard to life or property. In addition:

(1)

The town shall require the installation of stormwater detention and retention facilities which shall be designed so that the post development runoff shall not exceed pre-development rates, velocities, or volumes.

(2)

Unpaved road ditches and street gutters shall be permitted and shall be shaped and seeded and/or sodded as grassed waterways. Where the velocity of flow is in excess of four feet per second on soils having a severe or very severe erosion hazard and in excess of six feet per second on soils having moderate, slight, or very slight erosion hazard, or where deemed necessary, the subdivider shall install a paved invert or check dams, flumes, or other energy dissipating devices.

(3)

Shoreland/wetland and isolated wetland drainage facilities.

a.

Stormwater detention/retention facilities shall not be allowed in wetland areas.

b.

Stormwater discharges or discharges of urban stormwater pollutants to wetlands may be appropriate when the increase or decrease in the runoff volume do not negatively change the wetland functional value. Where such changes are proposed, the impact of the proposal on wetland functional values shall be assessed using a methodology acceptable to the town and the Wisconsin Department of Natural Resources (WDNR).

(4)

The design criteria, the size, type, grades and installation of all stormwater drains and sewers and the cross section, invert and erosion control paving, check dams, flumes or other energy dissipating structures and seeding and/or sodding or open channels and unpaved road ditches proposed to be constructed shall be in accordance with the plans and standard specifications approved by the town board and the county department of parks and land use-land conservation division.

(5)

The subdivider shall assume the cost of installing all storm sewers within the proposed subdivision, including the added cost of installing storm sewers which are necessary to serve tributary drainage areas lying outside of the proposed subdivision.

(Ord. of 9-8-2017, § 12-9-8)