Public Works and Environmental Services

Fairfax County, Virginia

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TTY 711

12000 Government Center Parkway
Suite 448 Fairfax, VA 22035

Christopher S. Herrington,

Carderock / Scotts Run Sewer Rehabilitation Project (WW-000026-004)

Project Update: August 17, 2021

The project is under permit review by the National Park Service and the Maryland Department of the Environment.

Project Background

The Carderock / Scotts Run Sewer is a 24-to-30-inch sewer that conveys flow from Fairfax County to the District of Columbia Water and Sewer Authority (DC Water) Potomac Interceptor (PI). Flow crosses under the Potomac River where a 30-inch gravity sewer then conveys the flow to the PI in Potomac, Maryland.

Previously, Fairfax County found corrosion in the manholes, and received complaints of sewer odors in the Carderock Recreation Area. In addition, the county performed a detailed televised inspection of the 30-inch sewer in the recreation area in 2018 and discovered corrosion in the sewer and a long segment of sewer which is apparently sagging.

Project Description

Picture 2 - Carderock Scotts Run
The parking lot and the public restrooms are in the proposed work area.

Major elements of this project include:

  • Installation of a cured-in-place-pipe (CIPP) liner to rehabilitate approximately 1,366 linear feet of the Carderock / Scotts Run Sewer.
  • Replacement and relocation of 3 manholes and installation of 2 new manholes.
  • Installation of an odor control facility.
  • Open-cut replacement of up to approximately 210 linear feet of pipe to eliminate a potential sag.

Project Location

The project is located on National Park Service property, in the Carderock Recreation Area in Potomac, MD.

Project Phase

The project is in the permitting phase.

Project Benefits

The environmental benefits of the project are:

  • Reduced nuisance sewer odors
  • Reliable conveyance of sewage flows to the Potomac Interceptor


After permits are received, the construction project will be advertised, bid and awarded. Construction is expected to last approximately 10 months.

What to Expect

During construction, some parking spots and areas of the park will be closed to visitors. There will also be some traffic detours. County employees will work with the National Park Service to minimize project impacts.

Project Cost and Funding Source

This project is funded through the Fairfax County Capital Improvement Program.


For more information, please email Philip Hwang, Senior Engineer III , Wastewater Design and Construction Division, Department of Public Works and Environmental Services, or call 703-324-5111, TTY 711.

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