Four Mile Run Sanitary Sewer Relining

Status

Construction

Construction is tentatively scheduled to start in mid-May and anticipated to be completed by fall 2026. The sanitary sewer relining will be done in two phases; see the "Project Timeline" and "Construction Process" sections for more details.

Location

The project limits are Four Mile Run Trail off North Arlington Mill Drive to Wilson Boulevard, then to North Carlin Springs Road to the W&OD Trail south of South Edison Street. Bon Air Park, Bluemont Park and Glencarlyn Park are included in the project area. View map

About the Project

Sanitary Sewer

The sanitary sewer system is a key piece of infrastructure consisting of approximately 465 miles of sewer pipes and 13 lift stations. This intricate network exists to make sure that the wastewater that gets flushed every day from homes and businesses makes its way to the Water Pollution Control Plant (WPCP), where it’s properly cleaned and treated before being recycled back into the environment. Learn more about our sanitary sewer system.

The project will rehabilitate approximately 7,800 linear feet of the 27-inch diameter Four Mile Run large diameter interceptor, via trenchless lining. The project section of interceptor sewer was originally constructed in the 1930s. The interceptor sewer was inspected in 2026, and many sections were deemed to require immediate rehabilitation due to structural deficiencies which allow for significant infiltration and inflow and could lead to structural failure.

Please see the photo gallery for project area exhibit.

Project Process

Cured-In-Place Pipe (CIPP) Process

Cured-in-place pipe (CIPP) is a trenchless rehabilitation process used to repair existing pipelines using a resin (Styrene) saturated felt tube.

CIPP lining involves cleaning the interceptor sewer followed by installation of a resin-impregnated liner to provide structural integrity and reduce groundwater infiltrating into the sanitary sewer. The end result is that the liner functions as a structurally and hydraulically new pipe within the old sewer and there is very minimal open-cut excavation and disruption.

Crews place a flexible liner into the existing sewer. Heated water is forced into the liner, pushing the liner tightly against the existing sewer walls. The heat causes the liner material to “cure” (harden), creating a new pipe within the existing sewer that is free of cracks and holes. The renewed pipe longevity is projected to last 50-70 years.

Example of CIPP using hot water. A boiler truck uses water to cure the liner with a circulation pump.

Project Timeline

Construction is tentatively scheduled to start in mid-May and anticipated to be completed by fall 2026. The sanitary sewer relining will be done in two phases; inclement weather and other potential delays could impact work timelines:

• Phase 1 – Four Mile Run Trail off North Arlington Mill Drive to North Carlin Springs Road (between Bon Air Park and Bluemont Park). Tentative timeline: May 11-June 30, 2026
• Phase 2 – Four Mile Run Trail from North Carlin Springs Road to W&OD Trail south of South Edison Street (on Glencarlyn Park). Tentative timeline: July-August 2026

Construction Process

Most of the work will take place between 9 a.m. and 4 p.m. Monday-Friday; however, there will be some overnight and weekend work since the pipe curing process requires crews to work around the clock and allow 24-36 hours for a pipe segment to cure. Overnight work hours will be from 9 p.m.-7 a.m. Monday-Friday, and weekend hours will be from 9 p.m.-10 a.m. Saturday-Sunday.

Temporary travel lane and bike lane closures will be implemented on Wilson Boulevard to excavate a manhole for lining installation during Phase 1. Temporary closures may also be implemented on segments of the Four Mile Run and W&OD trails as vehicles are moved to staging areas on the side of the trails for lining installation. Planned trail closures will be of very short duration (15-20 minutes).

The resin used in the CIPP process contains Styrene, a chemical with an unpleasant odor similar to strong spray adhesives. Pouring water into basement floor drains and those used for air conditioner condensation can sufficiently reduce the possibility of Styrene odor from entering your home. If the Styrene odor is still present, it could indicate a plumbing issue such as a broken or clogged pipe. 

During the pipe curing phase, pumps and boilers will run constantly, which will cause noise in and around the work area.

We will make every effort to minimize all inconveniences caused by this sanitary sewer relining project and greatly appreciate your patience and understanding during this necessary rehabilitation work.

Photo Gallery