(A) Basins shall be constructed to detain temporarily the storm water runoff which exceeds the maximum peak flow rate authorized by this chapter. The volume of storage provided in these basins, together with storage as may be authorized in other on-site facilities shall be sufficient to control excess runoff from the 100-year storm.
(B) The following design principles shall be observed:
(1) The maximum volume of water stored and subsequently released at the design release rate shall not result in a storage duration in excess of 3 hours unless additional storms occur within the period;
(2) The maximum planned depth of storm water stored (without a permanent pool) shall not exceed 4 feet;
(3) All storm water detention facilities shall be separated by not less than 50 feet from any building or structure to be occupied and, unless otherwise indicated by the Board, shall be entirely fenced;
(4) All excavated excess spoil may be spread so as to provide for aesthetic and recreational features, such as sliding hills, sports fields and the like. Slopes no steeper than 4 horizontal to l vertical for safety, erosion control, stability and ease of maintenance shall be permitted;
(5) Safety screens having a maximum opening of 6 inches shall be provided for any pipe or opening to prevent children or large animals from crawling into the structures;
(6) Danger signs shall be mounted at appropriate locations to warn of deep water, possible flooding conditions during storm periods and other dangers that exist. Fencing shall be provided unless deemed unnecessary by the Board;
(7) Outlet control structures shall be designed to operate as simply as possible and shall require little or no maintenance and/or attention for proper operation. They shall limit discharges into existing or planned downstream channels or conduits so as not to exceed the predetermined maximum authorized peak flow rate;
(8) Emergency overflow facilities such as a weir or spillway shall be provided for the release of exceptional storm runoffs or in emergency conditions, should the normal discharge devices become totally or partially inoperative. The overflow facility shall be of such design that its operation is automatic and does not require manual attention;
(9) Grass or other suitable vegetative cover shall be provided throughout the entire basin area. Grass should be cut regularly at approximately monthly intervals during the growing season or as required;
(10) Debris and trash removal and other necessary maintenance shall be performed on a regular basis to assure continued operation in conformance to design; and
(11) (a) A report shall be submitted to the Board describing the following:
1. The proposed development;
2. The current land use conditions;
3. The method of hydraulic and hydrologic analysis used, including any assumptions or special conditions;
4. The results of the analysis; and
5. The recommended drainage control facilities.
(b) Hydraulic and hydrologic calculations, including input and output files, shall be included as appendices to the report.
(Ord. 1995-10 § XIV G, passed 10-13-1995)