Sewer Tunnel Replacement Project
West Ashley Tunnel Project Update
(February 5, 2013)—Bid results now available. Details
Read press release announcing contract award.
Charleston Water System is in the process of replacing the network of deep tunnels that carry raw sewage—not stormwater—to our Plum Island Treatment Plant.
With an estimated total cost of $186 million, it is one of the largest infrastructure projects in Charleston Water System’s history, funded primarily by revenue bonds supported by current sewer rates.
The original tunnel system was built in the late 1960s to collect wastewater from shallow sewer lines and deliver it to the treatment plant. Over time, the highly corrosive nature of wastewater damaged the carrier pipe inside the tunnel and the tunnel structure itself.
After discovering this severe deterioration in 1998, Charleston Water System began an aggressive, multi-phased effort to replace the tunnels. Engineers feared that if the tunnels were not replaced, a major collapse could block the tunnel and cause sewer overflows—a potentially serious threat to public health and water quality in the Charleston Harbor.
As of January 2013, three sections of the original tunnel system have been replaced and a fourth section added. Construction is expected to begin on the fifth phase, the West Ashley Tunnel, in Spring 2013, which will replace the last remaining section of the original tunnel system.
The existing West Ashley Tunnel carries wastewater from West Ashley, parts of Johns Island, and the Towns of Hollywood, Ravenel, and Meggett. It is structurally unsound, and current peak wastewater flows exceed its design capacity, resulting in occasional sanitary sewer overflows in the Byrnes Down and South Windermere areas during heavy rain events. Learn more about the West Ashley Tunnel Project
Click image to view larger version (PDF: 750 KB).
Project Updates for Phase V, West Ashley Tunnel
Information for contractors and vendors
Project Bidding Phase Complete for West Ashley Tunnel
(February 5, 2013)—On December 19, 2012, Charleston Water System publicly opened bids from prequalified contractors for the West Ashley Sewer Tunnel & Influent Pump Station project. Those bids have been evaluated, and the results are shown in the Bid Tabulation Summary (PDF).
Charleston Water System's Board of Commissioners has authorized staff to award a construction contract to the lowest responsive bidder, Southland Renda JV, a joint venture between Southland Contracting and Oscar Renda Contracting. Read press release.
Information for neighborhoods and property owners near construction sites
(February 5, 2013)—Construction on the West Ashley Sewer Tunnel Project is expected to begin
in March 2013. Most construction activity will take place at three major work sites:
- CWS property at the intersection of Albemarle Road and Croghan Spur Road
- A site off Albemarle Road near Porter Gaud School
- CWS's Plum Island Wastewater Treatment Plant
The project also includes other sewer-related improvements. Charleston Water System will continue to contact neighborhood groups and property owners near all of the project construction sites to provide information about what to expect during the project and answer questions.
For more information, download the project fact sheets listed below or contact Jenny Craft, CWS Communications Manager.
Project Fact Sheets