Stormwater Detention Storage

Detention storage holds collected stormwater and releases it at a controlled rate. Storage facilities can be either constructed above ground as a pond or placed below ground as a vault. Surface systems can be designed as either dry or wet features during dry weather periods. Buried vaults can be prefabricated concrete, corrugated aluminum, polyethylene, or fiberglass structures.


The controlled release structure should be designed by an engineer. Buried systems are relatively expensive and surface systems consume land when water depths in the detention pond are kept shallow. In slope areas surface features should be lined to prohibit infiltration in the soils. Buried storage areas should slowly discharge to tightlines. Consequently, drywells which allow infiltration into soils near slopes are not recommended.


Surface features can be a landscape amenity. Detention facilities can keep existing drainage system from exceeding capacity. Buried storage is not visible. Reduces erosion potential to slope or beach areas. Excellent application for very small or space limited lots.


For buried storage the cost per 100 cubic feet is relatively expensive. Depending on storage volume required, surface water features need a dedicated space on the property (away from slope crest). Systems require maintenance.