City announces dredging plans for Four Mile Run

(Updated 7:25 p.m.) While there are still some issues with infrastructure over Four Mile Run, Alexandria and Arlington are moving forward with a project to clean out what’s under it.

In a recent newsletter about flooding infrastructure, the city announced an upcoming meeting to discuss the particulars of a dredging project in Four Mile Run.

“Members of the community are invited to a virtual public meeting on May 17, about a project to dredge Four Mile Run,” the newsletter said. “Dredging Four Mile Run is an important federal flood control measure. Alexandria and Arlington have partnered to dredge Four Mile Run since 1974. Periodic dredging of significant accumulated sediment in the channel that borders the municipalities is required to maintain conveyance capacity and freeboard for the channel as set by the U.S. Army Corps of Engineers.”

U.S. Army Corps of Engineers (USACE)previously determined in a 2021 inspection that soil deposit levels were “unacceptable” due to excessive shoaling — an indication that the creek is too shallow and could present a flooding hazard.

The USACE inspection determined the channel had “excessive shoaling” due to shallow water depths. Dredging the soil deposits will address this shoaling and ensure the channel can handle large, once-in-a-century floods, the county says.

The dredging is included in a federal flood control project, and per an agreement as far back as 1974, Arlington and Alexandria have joint responsibility for maintenance of the channel. The city’s website notes that the north side of the channel is obviously Arlinton’s responsibility, and the south side is Alexandria’s responsibility.

The city website said the project will restore capacity to the channel and clear away debris, vegetation growth and more that’s grown in Four Mile Run.

The dredging project is scheduled to run from September 2022 to February 2023.

H/t to Ronald Gochenour for noting the inspection report and explaining excessive shoaling