Stafford Drive Stream Restoration – A Tree Save Alternatives Analysis
Juan Campos, PE
Kimley-Horn and Associates, Inc.
Reston, VA
Satoshi Eto
City of Fairfax
Fairfax, VA
The City of Fairfax, a suburb of Washington D.C., was in the development of a stream restoration design for ~2,500 linear feet of Accotink Creek, a tributary to the Potomac River. During the internal review, City staff raised concerns about the number of trees that needed to be removed to reestablish a connected floodplain. They anticipated there would be substantial public concern as a recent trail project was significantly delayed due to the community’s tree removal concerns.
Kimley-Horn analyzed two alternative designs with the goal of preserving as many existing trees as possible. The first design revised the floodplain from 3:1 slopes to 2:1 and implemented a retaining wall, thus preserving the surrounding wooded viewshed. The second design implemented the same practices but included revised grading to allow portions of the floodplain to remain at existing grade, thus preserving existing trees. Each design was evaluated with HEC-RAS to determine the proposed stream bank shear stress. The results indicated that design alternative two resulted in higher shear stress due to disconnection of the existing floodplain in areas where existing trees were to be preserved. To counteract the increased shear stress, structural practices needed to be incorporated, thus raising the project cost and limiting the project’s natural aesthetic appeal. When presented with the two designs, the City determined that it would accept either option and rely on public input for its final decision.
The design alternatives, along with their respective advantages and disadvantages, were presented to the City’s Park and Recreation Advisory Board (PRAB). PRAB is a citizen advisory group that provides community feedback on all projects on City-owned park property and is a key stakeholder as City Council utilizes their recommendation for a gauge on public opinion. The design alternative’s hydraulic differences were illustrated through the development of shear stress heat maps for ease of understanding. Once empowered with the option to choose and a full understanding of the engineering principles, PRAB members selected design alternative one. They acknowledged it represented a greater short-term impact but preferred the long-term benefits associated with stable bank conditions and a more environmentally appealing stream system.
About Juan Campos, PE
Juan is a licensed water resources engineer that focuses on support for municipal projects to meet local and Chesapeake Bay TMDL POC reduction requirements. Juan’s core expertise lies in his knowledge of the approved design protocols required for restoration and retrofit projects in the Commonwealth of Virginia and the implementation of different strategies and funding mechanism to assist localities with improving their stormwater resiliency efforts. He has executed successful projects in the City of Fairfax, Loudoun County, Fairfax County, City of Fredericksburg, City of Winchester, Prince William County, Montgomery County, City of Baltimore, Fauquier County, and the Virginia State Community College System.
https://www.linkedin.com/in/juan-campos-p-e-971123113/
About Satoshi Eto
Satoshi Eto serves as the Public Works Program Manager for the City of Fairfax, VA. Satoshi is responsible for the administration of the city’s stormwater and wastewater utilities, oversight of construction activities, and coordination of the city’s Municipal Separate Storm Sewer System (MS4) permit. He has been with the City of Fairfax for 19 years and his background is in public infrastructure construction and maintenance, stormwater and environmental regulatory compliance, and stormwater management. He is a 2004 graduate of Virginia Polytechnic Institute & State University and a Certified Public Manager (CPM).