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PONDS USER MANUAL
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2.2.7 Wetlands Stormwater Management System
The wetlands stormwater management system design and performance criteria in the
stormwater rule are an initial step by SJRWMD in a field where limited knowledge exists.
Only wetlands which are connected to other waters by an artificial or intermittent water
course or isolated wetlands may be used as stormwater treatment wetlands. Like wet
detention ponds, these systems are designed to slowly release collected stormwater runoff
through an outlet structure. However, the diversion of stormwater into the wetland for
treatment should not adversely affect the hydroperiod of the wetland. In addition, inlet
structures must be designed to preclude channelized flow and residence time within the
wetland should be maximized.
2.2.8 Dry Detention Ponds
Dry detention ponds are normally dry storage areas which are designed to store a defined
quantity of runoff and slowly release the collected runoff through an outlet structure to
adjacent surface waters. After drawdown of the stored runoff is complete, the storage basin
does not hold any water and thus the system is normally dry. Dry detention basins are
similar to retention systems in that the basins are normally dry. The main difference
between the two systems is that retention systems are designed to percolate the stored
runoff into the ground while dry detention systems are designed to discharge the runoff
through an outlet structure. Dry detention systems have limited pollutant removal
efficiency. Their use is therefore limited to small drainage basins (< 5 acres) where high
ground water or slowly permeable soils preclude retention systems.
August 7, 1995