Civil Engineering · Engineering Glossary
A detention basin is a stormwater management facility that temporarily stores runoff from a developed site during a rain event and releases it slowly to downstream waterways at a controlled rate, limiting peak flows to pre-development levels. Unlike retention ponds, detention basins are designed to drain completely between storm events.
Detention basins are required by local stormwater ordinances when development increases the impervious area of a site, which accelerates and increases runoff. The civil engineer performs hydrologic and hydraulic analysis to size the basin — calculating the storage volume needed to absorb the design storm peak inflow and the outlet structure orifice to control the release rate. Detention basins can be above-ground (dry ponds, wet ponds) or underground (proprietary modular systems under parking lots). Maintenance is critical — accumulated sediment reduces basin capacity over time. Apex Grid designs detention basins as part of civil stormwater management packages for commercial and industrial development.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
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