Completed in 2017 by Southland Contracting, the Highway 4, Phase IV Tunnel Project consisted of installation of approximately 3,400 linear feet of 84-inch liner plate tunnel with 42-inch ductile iron carrier pipe. The tunnel was excavated by hand mining and with a rock Tunnel Boring Machine (TBM). Ground conditions range from silty sand to hard rock consisting of Biotite Gneiss and Mica Schist. The rock portion of the tunnel consisted of rock with unconfined compressive tests between 8,000-20,000 with an average of 16,000 psi.
Project Details
- Owner: Cobb County – Marietta Water Authority
- Location: Marietta, Georgia, United States
- Performed as: Southland Contracting, Inc.
- Project value: $12,044,760.00
- Completion Date: April 2017