This $103M tunnel project consisted of a 12 ft. diameter tunnel over 350 ft. below existing ground from the Austin’s Water Treatment Plant No. 4 to the Jollyville Reservoir.
The rock tunnel runs over 35,000 LF and was excavated utilizing three (3) TBMs operating concurrently to excavate the three (3) runs consisting of 20,650 LF, 9,600 LF and 4,750 LF. We designed and manufactured the 12 ft. Main Beam TBM and the other two (2) were provided by The Robbins Company.
The tunnel was lined with 84 inch PCCP and grouted in place. Four (4) shafts were constructed; 40 ft. diameter x 350 ft. deep, 36 ft. diameter x 275 ft. deep, 15 ft. diameter x 210 ft. deep and 31 ft. diameter x 130 ft. deep. Shafts were excavated by drill and blast and mechanical means. Ground conditions consisted of uniform limestone and dolomite rock.