RETENTION vs. DETENTION BASIN

​In order to effectively manage stormwater for an increasing population (and therefore impervious cover), engineers design sites with retention or detention basins for more storage. Before an area is disturbed or developed, the land is classified as an permeable surface meaning water can infiltrate into the subsurface. Roads, sidewalks, houses, and other structures prevent infiltration, and to accommodate for the quantity of water that is no longer able to infiltrate we build storm sewers that direct water to basins for storage.  In addition to accommodating runoff, basins provide many other benefits including treatment by allowing for settling time and regulating the amount of water being released preventing erosion down a watershed.

Detention Basin

Retention Basin

A detention pond does not contain a permanent pool of water and is designed to store water temporarily before leaving the outfall structure and releasing to a stream. Detention ponds are constructed for flood events and have shorter settling and retention times than retention basins. A retention basin stores water year-round, and the outfall structure contains an orifice at a higher elevation compared to a detention pond. In Ohio, we primarily see retention ponds surrounding developments due to the higher amounts of precipitation we receive compared to out west.
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Many variables are considered when determining size and location of these stormwater control measures. Properties include rainfall intensity in the geographic location, soil type(s), land cover, distance to creek, and total impervious area after development. To learn more about basin sizing & structure requirements you can read through the Ohio EPA Construction General Permit Parts III.G.2.d.ii. and III.G.2.e.

Questions? Contact our office at (513) 695-1337 for more information from your local basin experts! Is there a basin on your property in Warren County? You can view the latest inspection report on its functionality here.