By Brian Trompeter
The Fairfax County Board of Supervisors on Feb. 21 unanimously agreed to spend an additional $54,000 on the Tapawingo/Kingsley Urban Bio-retention Project that will be built as part of a joint stormwater initiative with the town of Vienna.
Vienna officials, who are overseeing the project’s design and construction, requested the extra funds – which are on top of $200,000 already provided by the county – to account for rising construction costs and larger bio-retention cells necessary to maximize water-quality benefits.
The Vienna Town Council in April 2018 approved the installation of “choker” curb extensions to slow down traffic where Meadow Lane, S.W, intersects with Tapawingo and Kingsley roads, S.W. In October that year, the Council agreed to pay Urban Ltd. $56,350 to perform survey-and-design work for adding bio-retention areas at those crossings.
The Vienna Department of Public Works in early spring will ask the Town Council to approve a construction contract for the project, said Christine Horner, the department’s acting director.
The joint project not only will improve the local environment and water quality, but also save the Fairfax County government time and administrative costs it otherwise would have incurred if undertaking the project itself, county officials said.
The community where the project will be built sits at the headwaters of Accotink Creek. Stormwater from this area heads to a wet pond called Nutley Pond and then to Hunters Branch, home of a stream-restoration project, before entering Accotink Creek.
That creek has been designated an impaired stream, county officials said, and unmanaged stormwater erodes the waterway and concentrates pollutants downstream. Multiple stormwater-control measures implemented upstream protect downstream ponds, creeks, streams and communities, they said.
“Green stormwater controls are not only an aesthetic benefit provided by integrating nature into the urban built environment, but also planted cells are effective at removing nitrogen [and] phosphorous and in remediating metals that pose health impacts to aquatic life,” officials said in a memorandum to county supervisors. “For this reason, alternatives such as underground-storage basins that offer limited infiltration and water-quality improvement were not preferred.”
County funds may be used only for the project’s design and construction. County officials have the option of paying for construction-cost overruns, provided they do not exceed 10 percent of the project’s estimated total cost.
