§ 151.046  RELEASE RATES.
   (A)   Stormwater management systems for properties required to provide stormwater runoff storage facilities shall be designed to control the rate of discharge from the property for the two-year and 100-year critical duration events. The maximum controlled release rate of stormwater from all developments requiring storage shall not exceed the stormwater runoff rate able to be carried by the downstream stormwater management system and may not exceed the predetermined safe carrying capacity of any limiting downstream restriction. The peak rate of discharge shall not cause an increase in flooding or channel instability downstream when considered in aggregate with other developed properties and downstream drainage capacities.
   (B)   (1)   The peak discharge from events less than or equal to the two-year event shall not be greater than the predevelopment discharge rate for the property.
      (2)   The peak 100-year discharge shall not be greater than 0.15 cfs per acre of property drained.
      (3)   The village reserves the right to require more restrictive release rates for any development within a watershed or sub-watershed which has either limited downstream capacity or observed historical flooding.
      (4)   All concentrated stormwater discharges leaving a site must be conveyed into an existing channel, storm sewer, drainage tile, or overland flow path (with appropriate permission from owners of downstream system) with adequate downstream stormwater capacity and must not result in increased flood and drainage hazard.
      (5)   The design of stormwater management systems shall not result in the interbasin transfer of drainage, unless no reasonable alternative exists and there is no legal restraint preventing the transfer.
(Ord. 07-02, passed 4-16-2007)