(A) (1) The subdivider shall provide each lot with a free outlet for surface and subsurface drainage. Storm drainage design may be prepared for the subdivider by a registered professional engineer, registered land surveyor or registered landscape architect. Drainage design by architects shall not be allowed.
(2) The analysis shall be based upon the rational formula (Q=CIA): where Q = discharge rate; C = runoff coefficient; I = intensity inches/hour; and A= area (acres).
(3) Times of concentration, storm frequencies and other variable factors to be used in the design shall be for ten-year and 100-year storm events and discussed with and approved by the County Surveyor during the preliminary consideration of the subdivision. The engineer or surveyor preparing said analysis shall provide the County Surveyor with a copy of the computations used in the completion of the analysis and design.
(B) Stormwater sewer systems on- and off-site shall be separate and independent of the sanitary sewer system. Storm sewers including surface inlets, detention/retention areas, open ditches, swales and pipes shall be provided by the subdivider.
(C) Any person proposing to locate a structure or a use within 100 feet of any stream or main drainage channel, the Director may require with the application for an improvement location permit, a statement from the Indiana Department of Natural Resources stating that the structure is outside of the 100-year floodplain. No building or other permanent structure shall be permitted within 75 feet of the top of the bank of any open drain or centerline of any tile drain unless written permission is obtained from the County Board of Commissioners.
(D) The subdivider shall furnish the Commission a complete set of plans and profiles as approved in writing by the County Surveyor.
(E) All plans and workmanship shall be in compliance with applicable county ordinances.
(F) (1) Whenever a subdivision is traversed by a watercourse, drainageway, channel or stream, there shall be provided a drainage right-of-way which shall be for the purpose of widening, improving or protecting the stream and its floodplain.
(2) To ensure proper drainage right-of-way width, the following requirements shall be incorporated in the final plat or site plan.
(a) Side yard easements with drainage structures or swales shall be a minimum of 15 feet per half.
(b) Rear yard easements with drainage structure or swales shall be a minimum of 15 feet per half.
(c) Perimeter easements with drainage structure of swales shall be a minimum of 30 feet if the abutting properties have no adjacent drainage easement and in cases of abutting properties having drainage easements the aggregate of the easements shall be no less than 30 feet and the new easement shall be no less than 20 feet.
(d) Easements must run continuously from right-of-way to right-of-way and not dead end.
(e) Open channel easements shall be a minimum of 25 feet as measured from the top of bank on each side plus the width of the channel from top of bank to top of bank.
(f) Areas of the 100-year floodplain shall be covered by a drainage easement.
(g) Easements for open channels and floodplain areas shall be a straight line when possible between lot lines. Location of easements shall be dimensioned along lot lines. In cases of easements not being a straight line between lot lines, all points of the easement segments shall be dimensioned from and on lot lines.
(h) Detention areas shall be protected by easements a minimum of 20 feet as measured horizontally from the 100 year high water elevation.
(i) Drainage easements of 15 feet shall be required along both sides of streets on which road side ditches are used.
(j) Surveyor may require additional easement widths depending upon size and depth of pipe or structure, topography, soil conditions and other conditions.
(G) (1) County streets shall be provided with an adequate storm drainage system consisting of curbs, gutters and storm sewers, or side ditches and culverts, as determined by the Commission.
(2) A six-inch perforated tile shall be place on each side of all streets and:
(a) Be two feet zero inches below and parallel with the pavement;
(b) Flow to the low point and into the storm drainage system;
(c) Said tile shall be bedded with and trench backfilled with #8 stone up to 12 inches for entire length of trench; and
(d) 1. In all lots, said tile shall have a “tee” installed and stubbed to ground surface with a removable plug for future connection and surface clean out.
2. Said tile shall only be used for basement, footing, crawl space drains and subsurface perimeter drains. Downspout or other surface water is prohibited.
(H) When vegetation has been removed from a slope and the possibility of soil erosion occurs, the subdivider shall be required to seed or otherwise prevent damage to adjacent property or accumulation on street surfaces. These erosion-control measures shall be in accordance with § 154.115.
(I) Drainage swales or ditches along dedicated roadways and within rights-of-way, or on dedicated easements, are not to be altered in any way without written permission from the County Commissioners. Property owners must maintain these swales as sodded grassways or other non-eroding surfaces. Water from roofs or parking areas must be contained on the property long enough so that drainage swales or ditches will not be damaged by such water. Driveways may be constructed over these swales or ditches only when appropriate size culverts or other approved structures have been permitted by the Surveyor.
(Ord. passed 7-20-1992)