Slide 47 of 49
Notes:
The intent of the extreme flood criteria is to prevent flood damage from large storm events, to maintain the boundaries of the ultimate 100 year floodplain, and to protect the physical integrity of stormwater management control structures.
Detention of the 100 year storm to pre-development peak discharge rate is a very expensive and land-consuming way to prevent flood damage from extreme storms. Preventing future development is a much more efficient way to meet extreme flood criteria.
Normally, no control is needed if development is excluded from the 100 year floodplain and the downstream conveyance is adequate.