Every residential, commercial and industrial development, having a gross aggregate area of one-half acre or more, shall be provided with drainage facilities which will effectively and satisfactorily manage storm water surface runoff, and provide for storm water detention.
(A) In order to ensure each development or redevelopment is in compliance, every developer shall provide the following:
(1) Existing and proposed drainage plans delineating the existing topography and proposed grading topography of the site and at a distance of 50 feet surrounding the site at a maximum of two-foot contour intervals showing the following:
(a) A vicinity map showing the relationship of the site to its general surroundings at a scale of not less than 2,000 feet to one inch;
(b) Title, scale, north arrow, legend, seal of a state-licensed professional engineer, date and name of person preparing plans;
(c) Property boundary, dimensions and approximate acreage;
(d) Building setback lines;
(e) All existing or proposed easements;
(f) All existing and proposed structures and sizes;
(g) Location, size and slope of storm water conduits and drainage swales;
(h) Shoreline of lakes, ponds and detention basins with normal pool water level elevation;
(i) The banks and centerline of streams and channels;
(j) Roads, streets and associated storm water inlets including finished grades;
(k) Base flood elevation, flood fringe and regulatory floodway;
(l) FEMA Map Panel, as appropriate;
(m) Existing and proposed watershed area divisions, and designated overland flow paths;
(n) Cross-section data for open channel flow paths;
(o) Area in square feet, or acres of existing and proposed impervious surface within each watershed;
(p) All known existing, abandoned or proposed water or monitoring well head locations;
(q) All known sanitary or combined sewer lines;
(r) All known septic systems, aeration systems and private disposal systems;
(s) Known farm drains and tiles;
(t) Detention facilities;
(u) The limits of designated regulatory and non-regulatory wetland areas;
(v) Depressional storage areas;
(w) The location and limits of known sinkholes (Karst areas);
(x) Any known designated natural areas, prime farmland; and
(y) Any known proposed environmental mitigation features.
(2) (a) A hydrologic/hydraulic drainage report prepared by a professional engineer licensed in the state shall be provided with design calculations to substantiate the design for all proposed storm sewers; pipe culverts, cross-road culverts; and swales and ditches. Hydraulic encroachment computations shall also be provided to ensure storm water does not unduly encroach onto pavement areas. Proposed drainage areas, land uses, runoff coefficients, flow rates, capacities, velocities and hydraulic grade lines are to be calculated and included in the report. The design of erosion control devices shall also be included in the report. A clearly legible drainage area map shall be provided with the hydraulic calculations indicating existing and proposed watershed and sub-watershed areas.
(b) The drainage report shall also include hydrologic/hydraulic storm water detention calculations detailing existing and proposed watershed drainage areas; design summary of land usages and runoff coefficients; time of concentration computations; computation of peak discharge runoff rates for each design storm and identifying the critical storm event; computation of detention volumes delineating the stage vs. storage for the detention facility in a tabular chart; and a flow rating table of the outflow structure delineating stage vs. flow capacity in a tabular chart.
(3) The location of proposed detention basins detailing the limits of ponding for each design storm and the total available volume, details of outlet structure(s) and details of erosion control device(s) shall be provided.
(4) A statement of certification of all drainage plans, exhibits, calculations and supporting data by a state-licensed professional engineer.
(B) The Village Engineer, on a case by case basis, shall have the authority to require, additional information for a proper review and to grant variations from those requirements in this section which may not apply.
(C) Any storm water design calculations reviewed and approved by the state’s Department of Transportation or Department of Natural Resources, Office of Water Resources, shall serve as fulfilling the requirements in this section; provided that, the developer submits documentation of such approval.
(D) The minimal design requirements of this chapter shall not be construed to relieve the subdivider of any legal responsibilities for downstream/upstream storm water damages inflicted by runoff or backup from the development.
(Prior Code, § 19-325) (Ord. 1448, passed 4-3-2006; Ord. 1700, passed 3-17-2014) Penalty, see § 153.999