Detention Basin Retrofits – Baltimore, MD

Two businesses in the Baltimore area contacted Liberty when they became aware that stormwater management on their properties needed improvements due to changes in Maryland Department of the Environment (MDE) regulations. In both cases, Liberty was able to retrofit their existing stormwater management systems into water treatment facilities that meet current MDE standards.

The Chesapeake Bay water restoration regulations require that certain stormwater dischargers over 5 acres in size in the Chesapeake Bay watershed must implement restoration of 20% of untreated impervious industrial area for the reduction of nutrients.

The first industrial property is a 16-acre adhesives manufacturing plant, with two large manufacturing buildings and impervious area totaling 7.7 acres. An existing stormwater basin on the property was not designed to current standards. Water Quality Volume calculations indicated the need to restore 40,112 gallons, or over 5,000 cubic feet, of stormwater.

Based on this calculation and the characteristics of the site, Liberty designed a Micropool Extended Detention Pond for the client. Installation involved using as much as possible of the existing stormwater management system, but adding a sediment forebay, a diversion berm, improved outlet control, and new vegetation.

The second industrial property is a 6.8-acre chemical distributor, with just over 5 acres of impervious area. Similar to the first client, this property had existing stormwater management that did not meet current standards. While some of the needed design elements were present, the pond was insufficient to meet the required restoration of 20% of untreated impervious industrial area.

Here again, Liberty was able to retrofit the existing pond to meet MDE standards by adding a sediment forebay, a diversion baffle, and an upgraded outlet control structure. The resulting stormwater management basin will treat 4,400 cubic feet of stormwater.

Both clients now have stormwater treatment basins that are compliant and that will enhance the value of their property well into the future.