The following information and data provided by an Indiana licensed professional engineer engaged in storm drainage design shall be submitted to the Board at the time of application for a building permit for any development, redevelopment or new construction on real estate which lies within the regulated area:
(A) Topographic and soils maps. A soils map of the proposed development indicating soils names and their hydrologic classification must be provided when Natural Resource Conservation Service (NRCS) hydrologic methods are used. In addition, either cross-sections at 100-foot intervals or a topographic map of the land to be subdivided and adjoining land whose topography may affect the layout or drainage of the development must be provided. The contour intervals shall be 1 foot when slopes are less than 4%, and shall be 2 feet when the slope exceeds 4%. On this map, the following shall be shown:
(1) The location of streams and other floodwater runoff channels, the extent of the floodplains at the established 100-year flood elevation where available (regulatory floodway), and the limits of the floodway, all properly identified;
(2) The normal shoreline of lakes, ponds, swamps and detention basins, their floodplains, and lines of inflow and outflow, if any;
(3) The location of regulated drains (regulated drains were previously known as legal drains), farm drains, inlets and outfalls, if any of record;
(4) Storm, sanitary and combined sewers and outfalls, if any of record;
(5) Septic tank systems and outlets, if any of record; and
(6) Seeps, springs, flowing and other wells, that are visible or of record.
(B) Preliminary drainage plan. A compre- hensive plan, in preliminary form (or in combined preliminary and final form), designed to handle safely the storm water runoff and to detain the increased storm water runoff, must be provided. The plan shall provide or be accompanied by maps or other descriptive materials indicating the feasibility of the drainage plan and showing the following:
(1) The extent and areas of each watershed affecting the design of detention facilities as shown on U.S.G.S. quadrangle maps or other more detailed maps as required by the Board;
(2) The preliminary layout and design of proposed storm sewers, the outfall and outlet locations and approximate elevations, the receiving stream or channel and its 100-year return period water elevation;
(3) The location and design of the proposed street system, especially including depressed pavements used to convey or temporarily store overflow from the heavier rainstorms, and the outlets for the overflow;
(4) The locations, cross-sections and profiles of existing streams and floodplains to be maintained and new channels to be constructed;
(5) The locations, materials, elevations, waterway openings and the basis for design of proposed culverts and bridges;
(6) Existing detention ponds and basins to be maintained, enlarged, or otherwise altered and new ponds or basins to be built and the basis of their design;
(7) The estimated depth and amount of storage required in the new ponds or basins;
(8) The estimated location and percentage of impervious surfaces existing and expected to be constructed when the development is completed; and
(9) Any interim plan which is to be incorporated into the development, pending completion of the development and the final drainage plan.
(C) Valley cross-section. One or more typical cross-sections must be provided showing all existing and proposed channels or other open drainage facilities carried to a point above the 100-year high water elevation; showing the elevation of the existing land and the proposed changes thereto, together with the high water elevations expected from the 100-year storm under the controlled conditions called for by this chapter; and showing the relationship of structures, streets and other facilities.
(D) Site plan. A plan drawn to scale showing dimensions of the site with existing and proposed storm drainage facilities must be provided.
(E) Final drainage plans. Upon approval of the preliminary drainage plans by the Board, final drainage plans shall be submitted to the Board. The final plans shall be stamped by an engineer registered in the State of Indiana, and shall provide or be accompanied by calculations, maps and/or other descriptive material showing the following:
(1) The extent and area of each watershed tributary to the drainage channels in the development;
(2) The street storm sewers and other storm drains to be built, the basis of their design, outfall and outlet locations and elevations, the receiving stream or channel and its high water elevation, and the functioning of the drains during high water conditions;
(3) The parts of the proposed street system where pavements are planned to be depressed sufficiently to convey or temporarily store overflow from storm sewers and over-the-curb runoff resulting from the heavier rainstorms, and the outlets for that overflow;
(4) Existing streams and floodplains to be maintained, and new channels to be constructed, their locations, cross-sections and profiles;
(5) Proposed culverts and bridges to be built, their locations, materials, elevations, waterway openings and basis of their design;
(6) Existing detention basins and ponds to be maintained, enlarged or otherwise altered, and new basins or ponds to be built and the basis of their design;
(7) The estimated location and percentage of impervious surfaces existing and expected to be constructed when the development is completed;
(8) The slope, type and size of all sewers and other waterways; and
(9) For all detention basins, a plot or tabulation of storage volumes with corresponding water surface elevations and a plot or tabulation of the basin outflow rates for those water surface elevations.
(F) Submittal and consideration of plans.
(1) Preliminary and final drainage plans and/or construction plans shall be submitted to the Board 20 days prior to its regularly scheduled meeting. All preliminary plans, final plans, and/or construction plans in compliance with the standards of this chapter shall be approved by the Board. The Board and/or the County Surveyor shall stamp the approval on a copy of the plans and deliver the same to the applicant. The Board shall approve or disapprove any preliminary plans, final plans and/or construction plans within 60 days of submission unless the applicant consents to a continuance or extension. All approvals and disapprovals with written reasons shall be incorporated into the Board minutes.
(2) The town is authorized to review engineering summaries of projects and based upon the same grant exemptions from any and all requirements of this chapter and/or waive any requirements of this chapter. Any applicant may appeal the decision of the engineer to the Board, which shall also be authorized to grant exemptions from any and all requirements of this chapter and/or waive any requirements of this chapter at its discretion.
(Ord. 1995-10 § VII, passed 10-13-1995)