Little Pimmit Run Tributary at Woodland Terrace Stream Restoration
Project Number: SD-000031-234
Project Update: November 17, 2023
The stormwater improvement project is funded for design only. The field assessment for the channel and intersection of North Albemarle Street and Chesterbrook Road was completed in April 2020 to evaluate the project site and identify restoration options.
The 95% plan was received on September 6, 2023. Prior to moving the project to final design, all land rights must be acquired from private properties impacted by the project and all utility conflicts must be resolved. The design is being coordinated with the Fairfax County Department of Transportation (FCDOT) sidewalk project and Virginia Department of Transportation (VDOT) for drainage improvements in the intersection.
The project was identified in the FY 2020 workplan due to repeated flooding at the intersection of North Albemarle Street and Chesterbrook Road and severe stream bank erosion upstream of this intersection. In October 2019, staff of the Stormwater Planning Division initiated the design of the project.
The project is being done in collaboration with the Virginia Department of Transportation (VDOT) to improve the storm sewer system within the VDOT road right-of-way. The Fairfax County Department of Transportation (FCDOT) is also managing a project to install a new sidewalk along Chesterbrook Road. FCDOT’s sidewalk project is being completed in phases. Phase 1 which extends from Kirby Road to Little Pimmit Run near Maddux Lane is complete.
The project assessed approximately 775 linear feet of an unnamed tributary to Little Pimmit Run near the Chesterbrook Road and North Albemarle Street intersection in McLean. The assessment resulted in a project scope that includes approximately 350 linear feet of stream below an outfall at Forest Lane, an additional 425 linear feet of stream between Woodland Terrace and North Albemarle Street, and approximately 225 linear feet of stream along Little Pimmit Run. The culvert at North Albemarle Street regularly has drainage issues with blockages caused by sediment and debris during larger storm events. The relatively low slope of this section prevents the sediment from moving through the pipe and may block the culvert contributing to flooding at the intersection.
The stream segments above and below the enclosed pipe are constrained by adjacent, privately owned land that have excessive erosion of the banks and stream channel incision. The lower reaches of the stream above the culvert at North Albemarle has more open land, is relatively flat and exhibits less erosion and instability. The purpose of the project is to restore the eroding channel to minimize the continued loss of sediment downstream, address flooding issues at the intersection of Chesterbrook Road and North Albemarle Street and improve water quality. The limits of the stream restoration project will be refined through the design iterations and may not include the full length of the assessed stream.
The primary goal of this restoration is to stabilize the channel and prevent future erosion and degradation along the stream. Drainage improvements at the intersection will alleviate future flooding. Restoration of native plantings will also be implemented after construction in order to promote diversity and the development of a healthy ecosystem. This project is part of Fairfax County’s larger efforts to restore many of the county’s degraded streams while also improving overall water quality and the condition of the Chesapeake Bay.
The stream restoration project is located between Forest Lane and North Albemarle Street with drainage improvements at the intersection of Chesterbrook Road and North Albemarle Street.
The project is in the Dranesville District and in the Pimmit Run Watershed.
Upon completion, the project will:
Restore stream channel stability by reducing erosion
Protect surface waters, private property, and county infrastructure
Mitigate flooding at the intersection of North Albemarle Street and Chesterbrook Road
Restore native vegetation and plant diversity
Improve water quality and stop a source of sediment and pollutants that are bound to those sediments that flow into Little Pimmit Run then Pimmit Run to the Potomac River, and thus to the Chesapeake Bay
The project is funded for design.
Coordination with property owners and acquisition of easements is ongoing. Final design is scheduled to be completed in Spring 2024 pending land acquisition and coordination of utilities.
What To Expect
Over the next several months flagging, survey markers, and survey crews may be visible throughout the project area. Contractors and staff will primarily be on foot and wearing high-visibility clothing.
Project Cost and Funding Source
The drainage improvements within the road right-of-way and restoration of the Little Pimmit Run Tributary channel are estimated to cost $9.3 million. Stormwater projects are funded through the county Stormwater Service District. Construction is based on approval of future funding.
For more information email Project Manager Fred.Wilkins@fairfaxcounty.gov, Department of Public Works and Environmental Services, Stormwater Planning Division, or call (703) 509-0511.