About Retention Ponds
General Information Performance Data Water Quality Treatment Process Design


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Water Quality Treatment Process

1. Runoff flows into a forebay that removes large objects and allows larger sediment particles to settle.

2. Runoff exits the forebay though a perforated standpipe and flows into the pond. When forebay capacity is reached, the overflow spills across a weir into the retention pond basin.

3. Water quality treatment is a function of storage volume and retention time, i.e., larger storage volumes and longer retention times promote better treatment. The removal of TSS, some phosphorus, petroleum hydrocarbons, and metals occurs primarily through sedimentation.

4. Several components contribute to biological treatment. Nutrients removal occurs primarily through the activity of macroinvertebrates, microorganisms, and plants. Long-term breakdown of petroleum hydrocarbons is through microbial processes. Metals that accumulate in the sediment may be taken up by the roots of aquatic vegetation.

5. The runoff is conveyed by a perforated standpipe modified with a one-inch outlet which regulates flow from the system.