An adequate storm drainage system shall be provided for each subdivision and documented in the Stormwater Management Plan. The design of said system shall be based on a minimum five-year frequency.
(a) Rainfall intensity, runoff coefficients and concentration times used in computing flows and structure sizes shall be in accordance with the tables, charts and the data established in the Stormwater Management Plan for such calculations. All areas which contribute storm water to the proposed storm drainage system must be considered on the determination of the sizes of pipes, structures and channels.
(b) Drainage plans shall be accompanied by two (2) copies of the design computations and a topographic map showing existing and proposed contours and indicating design increments. Hydraulic gradient checks for less frequent storms may also be required by the Village Engineer where deemed appropriate.
(c) Culvert sizes shall be determined by using the Rational design method and shall be based on a minimum ten-year frequency rainfall, or other more stringent methodology as required by the Village Engineer and the Stormwater Management Plan.
(d) Bridges shall be based on a fifty-year frequency storm using the design method contained in Ohio Department of Natural Resources Bulletin #45.
(e) Detention ponds or basins shall be provided where necessary to control the volume and velocity of storm water leaving the site. Detention ponds and basins shall be designed to meet and exceed the Stormwater Management Plan. Such facilities shall be approved by the Village Engineer and the Lake County Soil and Water Conservation District.
(f) Storm sewer and drainage system connections shall be provided to every lot at least to the building setback line, and easements shall be provided by the subdivider for maintenance. The subdivider shall provide for the continued maintenance or for a property owner association or for an agreement for such continued maintenance that meets the approval of the Village Solicitor and the Planning Commission. All downspouts shall be connected. Such connections shall be to underground piping. No above ground drainage pipe shall be permitted.
(g) Footer drains shall be connected to storm sewers or drainage system as required by the Lake County Building Department standards. The building contractor or excavator shall test and determine the water level at the excavation site and notify the Village Engineer of this level before the foundation is placed.
(h) Storm sewers shall be constructed of materials approved for use by the Village Engineer based on performance standards as established by the Ohio Department of Transportation (ODOT).
(i) Manholes shall be provided at all changes in alignment, end points, and grade changes of storm sewers and at such other locations as necessary to provide sufficient maintenance access and maintain a maximum interval between manholes on storm sewers of three hundred-fifty feet (350) for pipes sizes twelve (12) inches to twenty-four (24) inches and five hundred (500) feet for pipe sizes greater than twenty-four (24) inches or shorter distance intervals as required by the Village Engineer.
(j) Storm inlet or catch basin grates shall be of a type design to permit safe crossing by bicycles and other pedestrian traffic as approved by the Ohio Department of Transportation (ODOT).
(Ord. 19-10. Passed 11-7-19.)