[Archived] Four Mile Run to Undergo Spring Cleaning

FOR IMMEDIATE RELEASE  June 30, 2008     

Four Mile Run to Undergo Spring Cleaning
Arlington and Alexandria Collaborate to Ensure Flood Protection for Residents

Beginning in July 2008, the City of Alexandria and Arlington County will conduct maintenance work, including the removal of excessive vegetation and sediment along the Four Mile Run flood control channel. This maintenance effort is required to ensure flood protection for residents and businesses along lower Four Mile Run.

Background
The U.S. Army Corps of Engineers (USACE) constructed the Four Mile Run flood control channel, which extends from I-395 to the stream’s mouth at Ronald Reagan Washington National Airport, in the 1970s following several devastating floods in the Arlandria area. USACE designed the flood channel to a width and depth sufficient to carry Four Mile Run’s flows during major rain events. Over time, sand and gravel build up in the channel, and plants grow on the sandbars, lowering the channel’s capacity for carrying the floodwaters produced by large rain storms. To ensure the protection of homes and properties adjacent to the flood control channel and ensure the structural stability of the flood protection measures, the City of Alexandria and Arlington County periodically must remove the sandbars and vegetation from the channel and close to the levees and floodwalls, in order to maintain the channel’s capacity for safely carrying floodwaters. 

What Residents Will See
Starting in July, residents will see crews and construction equipment working in and near Four Mile Run, removing trees, shrubs, and other vegetation growing in the channel. Sand and gravel deposits may be removed in specific locations as well, depending on the amount of accumulation since the last dredging occurred in early 2006. While measures will be taken to reduce the amount of sediment that becomes re-suspended in the stream channel, residents may see some brownish discoloration of the water as sediment is being removed and for a short period of time afterward.  The sediment and plant material may be temporarily stockpiled in locations adjacent to the stream before it is loaded onto trucks for recycling or disposal. An herbicide called “Rodeo,” which is approved by the Environmental Protection Agency for application on invasive weeds and emergent vegetation along water bodies, will be used sparingly.
Throughout the summer and fall, targeted tree removal will occur on the landward side of floodwall and levee systems. Arlington County’s Urban Forestry staff plan to transplant many of these trees to areas that will not affect the integrity of the flood control structures.

Future Plans
The City of Alexandria and Arlington County are working to limit the need for significant in-stream maintenance in the future. The City and the County have partnered with the USACE and the Northern Virginia Regional Commission on the Four Mile Run Restoration Project, in an effort to return natural stream characteristics to the flood channel corridor, while also maintaining flood protection. The restored stream will reduce sediment deposits within the corridor and also will add vegetation appropriate for a flood control channel. The current channel maintenance activities relate to an existing maintenance agreement with USACE and not the restoration project.

Additional Information

For more information about the Four Mile Run Restoration Project, contact Laura Grape, Northern Virginia Regional Commission Senior Environmental Planner, 703.642.4625 or lgrape@novaregion.org, Jason Papacosma, Arlington County – jpapacosma@arlingtonva.us, or Claudia Hamblin-Katnik, City of Alexandria – claudia.hamblin-katnik@alexandriava.gov.