Construction of the third phase of the tunnel project---the Cooper Tunnel---is scheduled to be complete by the end of 2007.

Work began in May 2005 after Charleston Water System awarded a $39 million construction contract to Affholder, Inc.

Crews are building the tunnel by by sinking seven shafts and using two tunnel boring machines (TBMs) to drill the tunnel cavity. The mining is taking place more than 100 feet below ground in the public right-of-way, and will not impact the surface. All surface work will take place at the shaft sites.

It will take an estimated 27 months to construct the new Cooper Tunnel, but duration of construction will vary at each shaft site.

Download map of tunnel system (PDF)

Shaft Sites

The location of the seven shaft sites was dictated by several factors, the most important of which was proximity to shafts of the existing tunnel system.

Once the new tunnel is complete, crews will have to divert the flow of wastewater from the existing drop pipes (where wastewater from shallow sewer lines drops into the tunnel) to the new drop shafts. Locating the new shafts close to the existing shafts will allow the connections to be made with as little disruption as possible.

Construction activity for the new Cooper Tunnel is taking place at the following sites:

• Huger Street at Morrison Drive
  The former Cooper River Bridge construction site
  
• Lee Street at East Bay Street
  
• South Street off East Bay Street
  On State Ports Authority property
  
• Ansonborough Field
  Calhoun and Washington Streets
  
• Market Street (completed summer 2007)
  Between East Bay and Concord Streets
  Site layout map (PDF)
  
• Hazel Parker Ball Field
  East Bay at Adger's Wharf
  Download construction info sheet (PDF)
  
• Water Street - Church Street intersection
  (completed summer 2007)
  Download construction info sheet (PDF)
  Download construction newsletter (PDF)

The construction timeline and type of work is different for each site. Click here to view construction updates.

Protecting neighboring properties

Charleston Water System recognizes the concerns associated with the construction near homes and businesses. For this reason, Charleston Water has contracted with Soil Consultants, Inc. to monitor noise, dust, and vibrations generated by construction activities.

These variables were monitored prior to the start of construction to get an accurate assessment of normal conditions in each area, and the sites will be continuously monitored during construction. The data gathered is being used to help identify instances when the contractor may need to take extra measures to reduce noise, dust generation, etc.

In addition, Soil Consultants has surveyed structures within a defined radius of each shaft site and will repeat the surveys after construction is complete. The purpose of these surveys is to protect both Charleston Water System and property owners in the event of damage claims.

Current monitoring at shaft sites for the Ashley Tunnel construction has shown negligable vibration readings. In fact, normal road traffic generates more vibration than the contractor's work activities.

Community Involvement

An important part of constructing a new tunnel in downtown Charleston is minimizing impacts on surrounding residents and businesses.

Engineers had little control over the location of the construction sites, as the new tunnel shafts must be constructed near existing sewer collection points in order to divert the flow into the new tunnel. As a result, several work sites are located in residential areas. In order to reduce the impact on residents, Charleston Water System held numerous community meetings to get input on the construction plans, and received valuable feedback on issues such as working hours, site layout, fencing, and parking and traffic concerns.

For more information, contact Jenny Hagan, Public Relations Manager at (843) 727-6856.