This month will see the publication of the list of pre-qualified bidders for construction of the estimated $120m Chattahoochee Tunnel as part of the Cobb County Water System in Atlanta, Georgia, US (Nov 98). The tunnel, designed by Engineer Jordan, Jones & Goulding will be approximately 16.3km long with an i.d of 5.3m and will be built at depths of between 39.5m and 115m.
Two TBMs will excavate approximately 15.9km of the tunnel, one from the Circle 75 shaft and one from the Elizabeth Lane Shaft. The TBM driven tunnels will be concrete lined as deemed necessary according to local conditions. A 430m section of the tunnel between Elizabeth Lane and the pump station shafts will be excavated by drill+blast, as will a 2.6m dia., 271m long spur tunnel that will connect an existing inte-rceptor with the new tunnel north of the pump station shaft. All drill+blast tunnel drives will be completely concrete lined.
Also included in the project is the construction of two 9.9m dia. construction shafts, four intake shafts (with associated ventilation shafts) and a 36m diameter pump station shaft. Shaft sinking will use drill+ blast techniques. Intake and ventilation shafts will be drilled through the overburden and raisebored through rock. Construction is scheduled to begin in 2000 and will last three years.
The system is being built for the client, Cobb County Water Systems, to achieve federal government standards of wastewater discharge; comply with a mandatory minimising of phosphorus discharges into lakes; and provide relief for older wastewater treatment plants.
Related Files
Location Map
