This challenging sanitary sewer project was located in the road right-of-way on a busy north-south commuter route connecting to Interstate 5 and bordering McChord Air Force Base. Our contract on the project called for completion of the work that was started by another contractor who was eventually terminated for failing to complete the project. The previous contractor employed three different tunneling machines during more than thirty months of effort. JWF successfully completed the tunneling in less than eleven months.
The scope of the project called for constructing approximately 5,700 feet of 72-inch sanitary sewer pipeline with fiberglass reinforced pipe. There was approximately 2,450 feet of 72-inch carrier pipe that was installed via pipe jacking and the balance was installed via cut and cover construction. The scope of the project was revised and approximately 1,000 feet of fiberglass reinforced pipe was installed via pipe jacking and the balance of approximately 1,450 feet was installed with steel casing. The steel casing was used when the fiberglass was determined to be incompatible with the soil conditions. Ultimately, approximately 200 feet of the fiberglass reinforced pipe was replaced with steel casing and the balance of the tunnel alignment was completed with steel casing.