Fairfax County, Virginia
Owner: Reston Association
Wetland Studies and Solutions, Inc. (WSSI), managing member of Northern Virginia Stream Restoration, L.C., has partnered with the Reston Association (RA) to restore approximately 14 miles of degraded streams in Phase I of the NVSRB. We have restored ±9 miles of stream since the project began in February of 2008.
In order to gain regulatory approval of the NVSRB, WSSI worked closely with federal and state agencies to develop a “currency” (Stream Credit Units or SCUs) for assessing stream impacts and required mitigation. The resulting “Virginia Stream Impact Assessment Manual” (SIAM) developed by WSSI was approved by the U.S. Army Corps of Engineers (COE) and the Virginia Department of Environmental Quality (DEQ) for use in the NVSRB and formed the basis for the “Unified Stream Methodology” (USM) developed by the COE and DEQ for use throughout Virginia.
The streams are being restored through the use of Natural Channel Design (NCD) techniques that include raising the bed to reconnect higher storm flows with the floodplain. Design flow rates were developed through assessment of various design protocols, including hydrologic modeling using HEC-HMS. Hydraulic performance of the restoration designs were confirmed using HEC-RAS.
In order to gain public acceptance of the projects, WSSI employed a comprehensive public outreach campaign. WSSI staff has conducted over 50 community meetings and over 40 with local plan approval authorities (RA Design Review Board and RA Board).
Construction started in February 2008, with WSSI providing full time construction inspection and oversight. Following construction, WSSI is responsible for 10 years of monitoring and maintenance activities to ensure successful restorations are achieved. These activities include monitoring the dimension, pattern, and profile of the restored reaches, in-stream structures, riparian vegetation, and benthic macroinvertebrate community.