Photo by Dawn Howeth Infiltration Stormwater best management practice located at Roma’s in Tappahannock, Virginia.


cover without having to address the water quality impacts of their development. However, certain jurisdictions may allow a higher impervious cover percentage based upon statistical analysis of prior development impervious cover ratios. If you exceed the default impervious cover


percentage or already have impervious cover on your property totaling more than the jurisdiction’s allowable impervious cover percentage, you must mitigate the additional pollutant load contained in the stormwater run-off back to the appropriate pre-development


allowable default value. This mitigation typically consists of the installation of a stormwater best management practice which are designed to reduce the pollutant load being discharged to the Chesapeake Bay. Examples of stormwater best management practices include filter strips, water quality swales, biofiltration practices more commonly known as “rain gardens,” infiltration trenches and several engineered devices such as sand filters and pre-manufactured water quality inlets. These practices are installed to collect and treat stormwater by reducing its sediment and nutrient loads from impervious cover areas. Several of these practices as well as ponds, detention basins and other holding structures may be used in combination to address both the water quality and water quantity reductions required for the improvement of property within the jurisdictions governed by the Bay Act. Once installed, most stormwater practices require inspection and maintenance to operate properly. This may be as simple as removing debris and grass cutting within filter strips and swales to removal and replacement of stone within


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July/August 2011


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