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Sewage

Obayashi and Atlanta-based minority contractor MassAna Construction is the lowest bidder among the five teams who made an offer to build the Clear Creek and North Avenue tunnels, that will drain areas north of downtown Atlanta, and a pumping station. The JV offered a $210.2 million bid, 22% lower than the two closest competing bids of USD267.9 million and USD270 million. Contract signing planned on 30th March, 2004 with Atlanta's Department of Watershed Management. Two 8.2 m-diameter tunnels, each about 6.4 km in length, will be bored using two hard rock TBMs. Mucking-out with conveyor belts. The North Avenue tunnel would run south to north, beginning west of the college and ending at the R.M. Clayton Water Reclamation Center in northwest Atlanta. The Clean Creek tunnel will run east to west. The tunnels would intersect near the college and flow north to the R.M. Clayton pumping station. Construction to begin late next year. More details in E-News Weekly 13/2004. Visit www.ci.atlanta.ga.us/government/watershed.aspx and www.obayashi.co.jp/english 13/04.Obayashi and MassAna Construction ordered two Herrenknecht hard rock TBMs to excavate Atlanta's west area CSO storage tunnels. The 800-ton 91 m-long TBMs are open-style main beam machines, equipped with a 8,235 mm-diameter cutting head. The total installed main drive power is 3,200 kW, the thrust force is approximately 18,000 kN and the expected average compressive strength is 175 MPa. Geology made of fine to medium grained gneiss. Continuous conveyor for mucking-out. Cast in situ concrete lining. Machines to arrive in June 2005 for expected tunnelling start in July/August 2005.Contract A includes the 6,405 m 7.32 m finished diameter Clear Creek tunnel excavated by TBM in deep rock, 244 m of drill/blast excavated 3.35 m-diameter tunnel, one 4 m-diameter flow intake shaft structure and two 12.2 m-diameter shafts. Contract B includes the North Avenue tunnel and pumping station, consisting of a 7,140 m 7.32 m finished diameter deep rock tunnel, two 12.2 m-diameter shafts, a submersible type pumping station and one 7.32 m-diameter emergency overflow shaft and channel. Subscribe to E-News Weekly 13/2004. Visit www.herrenknecht.com 30/04.



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