West Ashley Sewer Tunnel & Influent Pump Station
Southland Renda JV
This $50.7 million project is Phase V of the Charleston Water System (CWS) sewer tunnel improvements program, replacing an existing deep tunnel from the Croghan Spur to the Plum Island Waste Water Treatment Plant (PIWWTP). Other improvements consist of the construction of a new influent pump station, new pile-supported 48-in. force main, installation of near surface connection at the PIWWTP, two shaft sites and surface collection improvements in the Country Club of Charleston and along Harborview Road. The shafts consist of a 60-ft ID at PIWWTP and 20-ft ID at Croghan, both built using the caisson sinking method, and 30-in. drop pipe at Porter Gaud. The 8,300 ft tunnel will be excavated with an 86-in. diameter single shield tunnel boring machine, manufactured by Southland Contracting, and supported with ribs and lagging boards.
The project is currently about 10 percent complete with the 60-ft ID caisson down 30 ft. The 60-ft ID caisson, with 2-ft thick walls, will reach a depth of 130 ft.
Other parties involved on the project include project designers Black & Veatch, Hanzen and Sawyer, and Hussey, Gay, Bell & DeYoung.
Operations Manager: Kent Vest; Project Manager: Enrique Baez; Superintendent: John Lindsey; Project Engineer: Steven Ricker. Black & Veatch RPR: Keith Fraiser.