The following information and data provided by an Indiana licensed professional engineer or land surveyor engaged in storm drainage design shall be submitted to the Board at the time of application for Primary Plat Approval for any major subdivision development, redevelopment or new construction, or at the time of application for an Improvement Location Permit (ILP) for any commercial, industrial, or institutional development, redevelopment or new construction on real estate which lies within the regulated area.
(A) Topographic map and site plan. A plan drawn to scale showing the land to be improved, dimensions of the site, and a topographic map of the land and such adjoining land whose topography may affect the layout or drainage of the development. The map shall use United States Geological Survey (USGS) contour information at intervals of one foot when slopes are less than 4% and two feet when the slope exceeds 4%. On this plan the following information shall be shown:
(1) Delineation of the drainage area in which the development is located.
(2) Natural or man-made streams, rivers or ditches, the extent of the floodplains at the established 100-year flood elevation and the limits of the floodway, all properly defined.
(3) The location of lakes, ponds, marsh or swamp areas, their floodplains and lines of inflow and outflow, if any.
(4) The existing surface water flow direction within the drainage area.
(5) Existing drainage facilities, regulated drains, farm drains, culverts, storm drains, inlets and outfalls, if any of record.
(6) Sanitary or combined sewers and outfalls, septic tank systems and outlets, if any of record.
(7) Proposed contours and grading plan using the same contour intervals as shown for the existing condition.
(8) Proposed drainage plan showing storm drains, culverts, wet-bottom/dry-bottom detention basins, and all proposed easements over such drainage facilities.
(B) Soils map. A soils map of the proposed development indicating soil names and their hydrologic classification, as well as identification of the existing ground cover.
(C) Drainage facilities plan and calculations. A comprehensive study of the storm water drainage design to handle safely the storm water runoff and to detain the increased storm water runoff must be provided. The plan shall give consideration to both water entering the development from adjacent land and water within the boundaries of the development. In addition, the plan shall indicate the feasibility of the drainage plan, shall indicate the methods of dispersion, detention and the adequacy of downstream facilities. The plan shall show at a minimum:
(1) The layout and design of the proposed storm sewers, the basis of their design, outfall and outlet locations and elevations, the receiving stream or channel and its 100-year return period water elevation, and the functioning of drains during high water conditions.
(2) he 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 such overflow.
(3) The locations, cross-sections and profiles of existing streams and floodplains to be maintained, and new channels to be constructed.
(4) The materials, elevations, waterway openings, and the basis for design of proposed culverts and bridges.
(5) 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.
(6) The estimated location and percentage of impervious surfaces existing and expected to be constructed when the development is completed.
(7) The slope, type and size of all sewers and other waterways.
(8) 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.
(9) Any interim plan that is to be incorporated into the development pending completion of the development.
(D) Submittal and consideration of plans.
(1) Two sets of drainage plans and calculations shall be submitted to the Board 20 days prior to their regularly scheduled meeting. All drainage plans and calculations in compliance with the standards of this chapter shall be approved by the Board. The Board and/or the County Surveyor shall stamp such approval on a copy of such plans and deliver the same to the applicant. The Board shall approve or disapprove any drainage plans and calculations 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 City Engineer or Street Commissioner, or other city personnel directed by the Board, is authorized to review engineering summaries of projects and, based upon the same, recommend to the Board exemptions from any and all requirements of this chapter.
(Ord. 00-22, passed 12-28-00) Penalty, see § 157.99