Grey Infrastructure – Stormwater Basins
Map of stormwater management basins by type in the Raritan Basin
Stormwater basins are meant to protect downstream areas from flooding and erosion by capturing and then slowly releasing rainwater and melting snows. They generally take the form of retention basins, detention basins, infiltration basins or some hybrid of these. Retention basins have an outlet higher than the base elevation of the basin and may retain a permanent pool of water. Retention basins can enhance the quality of released waters by capturing sediment and attached pollutants. Detention basins have outlets at base elevation of the basin and so usually dry out between precipitation events. Detention basins are designed to control peak stormwater flows. Infiltration basins are constructed of pervious materials that capture suspended solids and recharge to groundwater. All types of stormwater management basins require regular maintenance to ensure they function as designed.
Nearly 65% of stormwater basins in Raritan are detention or retention basins and not as effective in recharging groundwater as infiltration basins. Many need retrofits. There is no comprehensive inventory of basin conditions though numerous applications, databases and technologies could be built on to make data more available.