Crook Branch at Mantua Elementary School (SD-000031-135)

Project Background

The proposed restoration project was identified in the Accotink Creek Watershed Management Plan (AC9220-9221). The stream channel exhibits eroded and over-widened banks, head-cuts, and the potential for further bed and bank instability. Restoration objectives include stream stabilization, water quality improvement, aquatic and riparian habitat enhancement, reconnection of the channel with its floodplain, asphalt trail improvements, a new pedestrian bridge, sanitary sewer replacement, and waterline replacement.

 

 

 

 

Employees of the Stormwater Planning Division initiated the design of the project in October 2016. The design team includes the engineering design consultant Wetland Studies and Solutions, Inc, Fairfax Water, county staff from the Stormwater Management Program, Utilities Design and Construction, Urban Forestry, Wastewater Management, Land Acquisition, residents along the project area, Civic Associations and other organizations within the community.

Project Description

The project includes restoration of approximately 2,800 linear feet of Crook Branch, its tributaries, stormwater outfalls and the floodplain.

The primary goals of the restoration are:

Improve Water Quality

• Stabilize streambed and banks.
  • Reduce sediment and nutrient inputs into the stream system.
  • Install grade control structures.
  • Restore channel dimension and alignment to a form that is appropriate for current and future hydrologic conditions of the watershed.
• Improve floodplain connectivity and ecological processes.
  • Increase frequency and residence time of water on floodplain.
  • Reduce force and volume of water within the channel during storm and flood events.
  • Naturally process nutrients and sediments on the floodplain and within the streambed.
• Improve habitat for the biological community.
  • Native landscaping.
  • Floodplain wetlands.
  • Streambed and flow diversity.
• Protect property and infrastructure.
  • Replace two aging sanitary sewer lines.
  • Replace Fairfax Water waterline.
  • Remove and replace the pedestrian bridge.
  • Repair asphalt trail with protective handrails.

Project Location

Project Benefits

The benefits of this project include the protection of property, infrastructure, health and safety, and water quality improvements.

• Property will be protected by providing a stable stream bed, banks and alignment, which will reduce the rate of stream bank erosion and channel migration. Trees at risk of falling will be removed or protected where possible and native vegetation will be installed to hold soil in place and provide habitat.
• Health and safety will be protected by improved water quality within the floodplain, protection of public utilities, such as sanitary sewer lines, and pedestrian bridge and asphalt trail replacement or improvement, and stabilization of stream banks.
• Improvement of water quality will be provided through the removal of Nitrogen, Phosphorous and Total Suspended Solids.
• Forest health will be improved through removal of invasive plant species, installation of native plants and restoration of wetlands.

Timeline

The project design is scheduled to begin construction in winter 2021-2022 and is scheduled to be completed during the summer of 2023.

What to Expect

A Pardon Our Dust meeting will be scheduled in the fall of 2021. Once construction begins, access and deliveries will enter the site from proposed access points of Glenbrook Court, Colesbury Place, and Glade Hill Road. The typical work week is Monday through Friday starting after 7:00 a.m. Note that at some periods during construction, work may occur on weekends. Construction activities on weekends will occur after 9 a.m. These start times are in accordance with the Fairfax County Noise Ordinance.

Project Cost and Funding Source

Design of the Crook Branch at Mantua Elementary School stream restoration project is funded for $777,000. Construction funding has been encumbered for Fiscal Year 2022. Stormwater projects are funded through the county Stormwater Service District.

PRESENTATIONS TO THE COMMUNITY

Contact

For more information email Project Manager Vivian.Bui@fairfaxcounty.gov, Stormwater Planning Division, Department of Public Works and Environmental Services, or call 703-324-5609, TTY 711.