Beach Mill Road Channel Restoration

Fairfax County, Virginia

Beach Mill Road Channel Restoration

Fairfax County, Virginia

As part of Bowman’s Basic Ordering Agreement task order contract with Fairfax County’s Stormwater Planning Division, Bowman provided environmental consulting services, conceptual and final engineering design, and construction phase administration for this stream restoration project.

Bowman’s team of environmental scientists performed a wetland delineation and stream mitigation evaluation. A Water Quality Impact Assessment report, and small whorled pogonia survey were prepared. Ultimately, a wetland permit was secured for the construction associated with the stream repairs.

The project involved improvements to approximately 200 linear feet of deeply incised and eroded stream channel. Prior attempts at stabilizing and repairing the channel were evident, and had failed. Bowman’s engineers and scientists proposed raising the stream bed invert elevation back to prior historical levels, and installing a series of structural stream stabilization devices including: cascading step pools; riffles; rock cross vanes; and an imbricated stone lined dissipation basin. These practices, along with a detailed landscaping program, combined to provide structural and vegetative protection against the hydraulic forces associated with the stream flow during normal base flow conditions, and during larger flows associated with predicted storm events.

The Bowman Engineering team prepared conceptual stream restoration plans which assisted in the design development for the project. A detailed hydrologic and hydraulic analysis utilizing TR-55 and HEC-RAS analysis was performed on the existing stream channel, and on the proposed channel with the suggested improvements in place to evaluate the conceptual design. Final engineering construction drawings were prepared and processed through approval. Bowman’s engineers and scientists were on site during construction to assist the contractor, and monitor the progress of the project. The project was completed in August 2013.