Vienna rain garden project expected to help slow traffic gets more county funding

A stormwater retention project in Vienna that officials say will help contain runoff and slow down traffic is set to get another infusion of Fairfax County funds.

The county’s Board of Supervisors authorized staff last week to provide an additional $54,000 for the Town of Vienna’s Tapawingo and Kingsley road urban bioretention project. The vote took place without discussion at the board’s Feb. 21 meeting.

The money will come in addition to $200,000 that the county already allocated to the project under a funding agreement originally signed in October 2018.

“The increased Project cost is attributable to rising construction costs and larger bioretention cells needed to maximize water quality benefits,” county staff said in a memo explaining their recommendation that the agreement be amended.

The project will add two bioretention areas — or rain gardens — along Meadow Lane SW: one at the Tapawingo Road intersection and another further south at the Kingsley Road intersection.

To accommodate the cells, the existing corner pavement will be demolished and replaced with extended curbs, according to Vienna plans. The cells will be covered with a combination of perennial plants, such as switchgrass and bee balm, as well as grass sod.

According to county staff, the cells will treat stormwater runoff as it goes into Hunter’s Branch of the Accotink Creek watershed, providing “nutrient reduction and improved water quality.”

“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, phosphorous and in remediating metals that pose health impacts to aquatic life,” staff said. “For this reason, alternatives such as underground storage basins that offer limited infiltration and water quality improvement were not preferred.”

In addition to the stormwater benefits, town officials anticipate the curb extensions will help calm traffic on Meadow Lane, a 30-foot-wide street in a residential neighborhood, county staff said.

The road’s travel lanes at the Tapawingo and Kingsley intersections will be restricted to 20 feet wide, according to Vienna project manager Alan Chen.

The design, which was developed by Urban Ltd., also proposes 10-foot-wide crosswalks on all four sides of the Tapawingo intersection and on the north and east sides of the Kingsley intersection. The final design was presented at a community meeting on Nov. 3, 2021.

Under the 2018 agreement, Fairfax County agreed to cover the design and construction cost of the stormwater facilities. The additional funds authorized last week will cover the increased construction costs for the bioretention areas — but not for the curb extensions, Chen said.

The curb extensions and other remaining costs are Vienna’s responsibility, Chen told FFXnow. The town council will vote on whether to approve $84,564 for the project and the amended funding agreement on April 10.

In all, the project will cost just under $338,565. Assuming the town council approves Vienna’s portion and the new agreement, the town anticipates construction will begin in May.

Photo via Fairfax County