Shank/Balfour Beatty driving 9,286 m-long Arrowhead East aqueduct as part of Inland Feeder project which will require a total of 29 km of tunnels. 5.38 m shielded TBM designed by contractor launched March, 1998 and is working in granite and gneiss erecting 1.2 m-deep rings of four precast segments. Average advance on single-shift working is 18 rings/day with 28 rings maximum. 2 km completed to date. Steel-encased 12 ft internal diameter concrete pipe will be installed later and backgrouted in place. March 1999.
See Inland Feeder us/23 for further updates. Sept 1999.
