Four Mile Run Dredge Project


3100 S. Glebe road,  22206  View Map

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The contractor will begin mobilizing and preparing the area for the dredging work starting in late July, 2022, such as doing survey work, setting up the Maintenance of Transportation, installing signs, etc.  Dredging work will begin in September, 2022 and take approximately 4-6 months The project team will take significant efforts to keep resident inconveniences to a minimum. Impacts to adjacent residences will include construction noise, traffic restrictions, and on-street parking restrictions. A portion of Troy Park close to S. Glebe Road will be closed for about three months. Construction hours for this project will be accordance with the Noise Ordinance. 

About the Project

The Four Mile Run Dredge Project consists of removing soil and rocks from the open channel of Four Mile Run and Long Branch tributaries to maintain the capacity of the flood channel, which helps to reduce flood risk in neighborhoods near Long Branch and lower Four Mile Run. 

Four Mile Run is a nine-mile long stream with a 19.6 square mile highly urbanized watershed, including portions of Arlington and Fairfax Counties and the Cities of Alexandria and Falls Church. The lower portion from I-395 downstream to National Airport is within a hardened flood-control channel that marks a shared boundary between Arlington County and the City of Alexandria. This stretch of Four Mile Run has neighborhoods and businesses that were subjected to repeated flooding beginning in the 1940s.

In response to this flooding, Arlington County and the City of Alexandria worked with the U.S. Army Corps of Engineers (USACE) to design and build a flood-control channel in the lower portion of Four Mile Run. The Four Mile Run East and West Levee System is a USACE federally authorized and constructed flood risk management project that was first authorized in 1970, modified in 1971, and reauthorized in 1974.  The project was constructed between 1974 and 1984. Required maintenance of the flood channel includes clearing of soil, rocks, vegetation growth, and stabilizing some areas of the bank as required by the USACE annual inspection program.

The maintenance that will be completed during the Four Mile Run Dredge Project includes:

  • Dredging, or removing soil deposits, to preserve the capacity of the channel to convey a 100 year storm,
  • Repairing erosion damage
  • Fixing stream corridor degradation 
  • Clearing debris, vegetation growth, and shoaling
  • Maintaining storm sewer infrastructure in the banks of the project

Public Engagement

The project falls is a Communicate level of engagement, because it addresses maintenance of the Four Mile Run streambed that is required by the Army Corps of Engineers, will help reduce flood risk along the Long Branch Tributary and will not significantly change any facilities, program or services provided to the community. The project will disrupt access and parking to a small portion of Troy Park, but that work will be completed within a month. 

Date      Activity      Materials     
 March 24, 2021   County Board approved MOA with Alexandria   
 December 2, 2021  Presentation to Four Mile Run Joint Task Force  Presentation 
 March 19, 2022    County Board approved construction contract      
 May 17, 2022, 7 PM 

  Community Meeting 

 Presentation(PDF, 7MB)

 Meeting Video