CAI-NJ Dec. 2019 (w) (1)

STORM WATER... from page 38.

often called “wet ponds” and are designed to be an artificial lake with vegetation around the perimeter. When to be concerned — (heavy storms are the exception to the rules): • If the detention basin contains areas of ponding that remain past the 72-hour window, is flat, and un-maintainable, it is very import- ant to have a professional inspect the basin to determine the cause and provide recommendations for improvements. • For retention basins, over time silt may accumulate along the bottom of the basin. This silt accumulation reduces the design capacity of the basin and resultant effectiveness. Dredging is a procedure that removes the silt by mechanical means in order to achieve the design capacity of the basin. “Avoid Drowning in Repairs” Any area that appears to be a drain- age deficiency should always be ana- lyzed by a professional experienced in site work. A professional analysis defining the source of the problem is necessary. Investigations should include the analysis of the existing soils, contrib- uting drainage areas (amount of runoff entering the area), existing drainage structure locations, existing underground utility locations, existing grades, and limits of the deficient condition. Once the drainage deficiency is identified, an exact and effective plan and specification of the repair should be prepared in order to ensure a pos- itive result for your community. Proper materials (inlet pipe, pipe types and

Swale

Berm

Photos courtesy CAI-NJ.

Retention Pond

Detention Pond

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