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United States, California - us/23

Inland Feeder

    Major scheme to provide 650 million gal/day of water for Southern California. 29 km of 12 ft finished diameter tunnels under construction by Shank/Balfour Beatty in three lots: Arrowhead West (6.2 km), Arrowhead East (9.6 km), and Riverside Badlands (13.2 km). Arrowhead East has advanced 2.55 km using contractors own 5.6 m-diameter TBM and similar machines under erection at Arrowhead West and Riverside Badlands. Extensive grouting programme undertaken to reduce water inflow. Project completion scheduled for December, 2003. Sept 1999.   These tunnels cross both the San Andreas and San Manuel faults. Pre-excavation grouting using microcements was being carried out ahead of the TBMs, and backfill grouting around the carrier pipe in the completed tunnels was planned. However, despite the injection of 1,250 t of cut-off grout, which reduced the water inflow from 1,400 gal/min to 275 gal/min, Arrowhead East tunnel has been closed down after completing 2.5 km of drive. Arrowhead West is also closed for similar reasons, and the Metropolitan Water District of Southern California has replaced the management and is considering options for realignment of both tunnels or their abandonment and replacement by pipeline. Riverside Badlands tunnel is unaffected, but it is reported that the Parsons Brinckerhoff construction management team has been replaced by a team from Hatch Mott McDonald. January 2000.   Shank/Balfour Beatty reports good progress on Riverside Badlands tunnel, the only one of their original three contracts that is still in place, Arrowhead East and West having been terminated due to unforeseen groundwater conditions. An average of 52 m/day is being achieved and the 12.8 km-long x 4.8 m-diameter tunnel is nearly half-complete. Bechtel and Jacobs Associates are redesigning the Arrowhead tunnels for re-bid later this year. Visit www.jacobssf.com and www.balfourbeatty.com June 2000.   MWD prequalifying bidders on the Arrowhead East and West projects in San Bernardino. This project was halted by water intrusion in excess of specs with contractor Shank Balfour Beatty J/V paid for work performed and anticipated profit. Visit www.jacobssf.com December 2000.  The Metropolitan Water District of Southern California has awarded to J.F. Shea Construction a $242.2 million contract to drill two tunnels, stretching a total of 12.5 km, under the San Bernardino National Forest. The Arrowhead west tunnel is 5.8 km, the Arrowhead east tunnel is 6.6 km. Finished diameter of 3.6 m. Geology consisting of gneissic metamorphic rock, quartz monzonite, quartz dioride and several faults and fissures. Two TBMs will be required, the maker has yet to be chosen by the contractor. Bolted and gasketed segmental lining, reinforced concrete cylinder pipe. Portal preparatory work will probably begin as early as 100 days. Tunnelling to begin in about a year and will be completed by the second quarter of 2007. Engineering companies involved are San Francisco-based Jacobs and Associates as designer, and Hatch Mott McDonald as construction managers. Financing with pay-as-you-go capital funds and bonds. Visit www.mwdH2O.com and www.jfshea.com 16/02.Breakthrough took place end of July 2001 on the 12.9 km tunnel beneath the Badlands mountain range in Riverside and San Bernardino counties. 16/02.



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