The project is on hold for easement acquisition. A 65 percent design will be developed after needed easements for construction are acquired.
The stream stabilization and restoration project was identified in the Fiscal Year 2020 work plan and was originally included as a potential project in the Pimmit Run watershed plan. The project is in a wooded area, between a residential neighborhood and the George C. Marshall High School campus. The stream receives runoff from these areas and from portions of Tysons and Interstate 495. The stream channel exhibits eroded and over-widened banks, head-cuts and the potential for further bed and bank instability. There are also exposed sanitary sewer lines and failing storm drains along the stream channel and floodplain.
The project area is generally identified as a floodplain and a Resource Protection Area. The project will restore approximately 2,000 linear feet of degraded natural channel of Pimmit Run between a box culvert at Interstate 495 to a box culvert near Pimmit Run Lane, and approximately 300 linear feet of outfall leading to it. The project area stream drains about 256 acres of surrounding neighborhoods that includes communities upstream of Interstate 495. Restoration objectives include stream stabilization, water quality improvement, aquatic and riparian habitat enhancement, and reconnection of the channel with its floodplain. It is anticipated that the restoration will provide additional biological improvements with habitat features introduced to the restored stream channel and native vegetation plantings along the riparian corridor.
The stream restoration project is located along the headwaters of Pimmit Run, between Interstate I-495 and the box culvert near Pimmit Run Lane; after which the stream is piped for about one mile before it outfalls to a concrete channel east of Leesburg Pike (Route 7).
The project is in the Providence District and in the Pimmit Run Watershed.
Restoration of the ecological function of the stream corridor
Creation of a safe and sustainable stream valley for the community
Protection of surface waters, private property, and county infrastructure
Restoration of native vegetation and plant diversity
Stream stabilization and improvement in water quality including reduction in nutrients and sediment that flow downstream to the Potomac River and Chesapeake Bay
Improved habitat for wildlife
Design is currently on hold for easement acquisition.
What to Expect
Easements are required to construct the project. County staff will be in contact with the homeowners and the homeowner association where easements are required.
Project Cost and Funding Source
Restoring the section of Pimmit Run as part of this project is estimated to cost $3.95 million. Stormwater projects are funded through the county Stormwater Service District.
Presentations to the Community
Public meetings for the project will be scheduled online due to COVID-19 restrictions. Notifications about upcoming meetings will be sent to the homeowner association and property owners who are adjacent to the project area.
A virtual public meeting was held on September 29, 2020 to present to the community the proposed stream restoration project at George Marshall High School in a tributary to Pimmit Run.
For more information please email Project Manager Sajan Pokharel, Department of Public Works and Environmental Services, Stormwater Planning Division, or call (703) 324-5687, TTY 711.