The JV of Kenny/Kiewit/Shea has begun excavation of the final mainline tunnel on the $140.7m Torrence Avenue Leg of the long running TARP pollution and flood control system serving the south east side of Chicago, US. The JV recently completed the 880m south heading of the main line tunnel. Then the 8.9m diameter refurbished Robbins TBM was backed out, partially disassembled, turned, reassembled and walked to the gripper area for mining of the 10.8km long 8.2m i.d. concrete lined northern heading.
Construction of this heading began in August with a temporary conveyor system for the first 110m until a permanent conveyor could be installed. Currently, the best 8h shift and 24h productions are 35.5m and 88.8m respectively. As we went to press, total excavated tunnel length was 706m.
The Torrence Avenue Leg also involves constructing two 1.3km long, 4.9m i.d. concrete lined connecting spur tunnels using a refurbished 5.9m diameter Robbins TBM. The erection chamber for the first spur is complete and the second is under way, with the first run expected to begin imminently.
Also included in the contract is the construction of eight drop shafts from 2.3m to 8.2m diameter; one 8.2m diameter construction shaft; one 10.2m diameter wheelgate shaft; and one access shaft.
Funding for the Torrence Avenue Leg has been supplied by a bond fund from the client, Metropolitan Water Reclamation District of Greater Chicago, and low interest loans from the State Revolving Loan Fund, a federal grant capitalised water pollution control fund.
The contract was awarded in April 1998, with completion scheduled for November 2002.
