(A) A drainage report consisting of plans, calculations and a narrative shall be submitted along with the construction plans for all subdivisions, as defined herein. The drainage report submitted for the first phase of a multi-phase subdivision must address the drainage plan for the entire subdivision and must specify what facilities will be constructed to control runoff such that each phase is in compliance with this chapter. The report must be reviewed and approved by the Village Engineer.
(B) For developments which do not require a final plat, a drainage plan shall be submitted and approved prior to the issuance of a building permit.
(C) The drainage report shall be comprehensive in nature and shall address how all components of the stormwater drainage system are designed and will be constructed to comply with this chapter. Each report shall have, as a minimum, the following items:
(1) Natural land contours at one-foot intervals;
(2) Final grading contours at one-foot intervals;
(3) A construction pad for each lot with spot elevations. The construction pad shall be the proposed finished ground elevation at the building perimeter. The top of building foundation or basement wall elevation shall be a minimum of six inches above the ground elevation adjacent to the foundation or wall;
(4) (a) A finished grade on each lot allowing for a minimum slope of 5% for a minimum of ten feet from any building foundation and a minimum of 2% away from any building beyond the ten-foot limit. Where a swale is used to convey drainage from two or more lots, the swale may have a minimum slope of 1.5%; provided, the swale is constructed as part of the larger development and is final graded and seeded prior to issuance of any building permits.
(b) Exception: where lot lines, walls, slopes or other physical barriers prohibit six inches of fall within ten feet, the final grade shall slope away from the foundation at a minimum slope of 5% and the water shall be directed to drains or swales to ensure drainage away from the structure. Swales shall be sloped a minimum of 2% when located within ten feet of the building foundation. Impervious surfaces within ten feet of the building foundation shall be sloped a minimum of 2% away from the building.
(5) Any and all swales, ditches or other features that may be used to convey stormwater. Spot elevations, grades and typical cross-sections shall be shown for all swales, ditches and defined overland drainage ways;
(6) The lot lines, numbers and building setback lines for all lots;
(7) All stormwater runoff controls and stormwater detention/retention basins;
(8) The location and direction of all stormwater flow into the subdivision and the location and direction of all stormwater flow out of the subdivision; and
(9) Calculations developed for the design of the proposed system.
(Ord. 16-102, passed 4-4-2016)