In 2012, Marsh Properties received a notice from the city of Charlotte, N.C., that an inspection was scheduled to be performed on an existing detention pond at the Providence Park Apartments. Prior to this notice, the facility had not been regularly maintained; therefore, it required substantial work to bring it into compliance. This included the removal of excess vegetation and sediment buildup, and installation of a riprap ring around the primary outlet—a 6-in. orifice.
After the work was completed, the pond continued to experience challenges due to frequent clogging of the outlet structure. The detention basin is located in a natural area, while the primary 6-in. orifice of the outlet structure is located in a depressed area and often would clog with leaves, branches, trash or other debris.
SW Products suggested that the outlet structure be modified to include a riser structure and a Marlee Float Skimmer. The skimmer design would handle the base flow and smaller storm events, while reducing clogging with its shielded orifice. The new design resulted in lower flow rates during the 2- and 10-year storms, as well as extended detention of the water quality storm event.
As a result, the design met most of the requirements of the City of Charlotte Stormwater Fee Credit Policy. This success resulted in a storm water fee credit of 95%, which then resulted in savings of more than $20,000 per year for the property. The savings can offset the cost of installation of the new riser structure and outlet system.