Laserfiche WebLink
SECTION 3 – STORMWATER <br />26 <br />3-1.5 FLOOD ROUTING AND EMERGENCY SPILLWAY <br />1.) Stormwater basins shall have a secondary outfall (emergency spillway) that is designed to pass <br />the peak 100-year inflow. <br />2.) The spillway must direct the emergency overflows away from buildings and other structures. <br />3.) Overflow paths throughout the development resulting from the peak 100-year storm event, <br />shall be determined, clearly shown on the plans and contained in permanent drainage <br />easements. <br />4.) Emergency spillways must be resistant to vertical movement; concrete grade beams, if present, <br />must extend below frost line. <br />3-1.6 FREEBOARD AND FLOOD PROTECTION GRADE <br />1.) Stormwater storage facilities shall have a minimum of 1-foot freeboard. Freeboard is the <br />vertical difference between the storage facility’s top and the water surface resulting from the <br />peak 100-year passing over the emergency spillway. <br />i.All berms and levees shall not be considered a regulated dam as specified in Indiana <br />Department of Natural Resources’ (IDNR) Indiana Dam Safety Inspection Manual. <br />2.) All buildings adjacent to a stormwater storage facility or in the overflow path shall have a <br />Minimum Flood Protection Grade established. The elevation shall be 2 feet above the water <br />surface elevation of the peak 100-year inflow passing over the emergency spillway (1 foot <br />above the freeboard elevation).