Mobilizing for Deep Rock Tunnel Connector start Dec 2012
Desiree Willis, Robbins Technical Writer
- Arrival of the cutterhead in Indianapolis, USA, marks the start of assembly on site of the Robbins main beam TBM that will launch early in the new year (2013) for the city's Deep Rock Tunnel Connector (DRTC) project.
- The arrival at the staging site of the 6.2m (20.2ft) cutterhead was timed with a ceremony attended by the city's mayor and local officials to mark the assembly progress of the large main beam Robbins TBM. Once launched from the 76m (250ft) deep shaft, the machine will embark on a 12.2km (7.5-mile) long wastewater CSO tunnel for the Shea/Kiewit JV.
- The contractor-owned Robbins machine was refurbished and redesigned at the Cleveland, Ohio, and Mt. Pleasant, Pennsylvania, facilities following its most recent excavation for the New York City Second Avenue Subway.
- A new world record daily advance in the 6m-7m diameter range of 124.7m is claimed by Robbins on the Deep Rock Tunnel Connector project in Indianapolis.
- The record rate occurred on June 12, 2013. The substantially refurbished and redesigned 6.2m diameter Robbins Main Beam TBM, owned by the Shea/Kiewit contractor JV, is a veteran machine originally built in 1976. It has since has been rebuilt multiple times, and was last used on New York City's Central Subway.
- The TBM was launched in early 2013 and began its excavation in limestone and dolomite rock. Muck removal is being achieved with a Robbins continuous conveyor system including both horizontal and vertical belts hauling muck up a 76m-deep shaft.
- Jennfier Mentink, for the client, Citizen's Energy Group, told TunnelTalk that progress on the 12.2km drive had reached 5,626m as at July 19. The best weekly advance recorded to date is 231m, the best monthly advance rate 515m. She added that Black & Veatch design of the deep tunnel CSO extension along the White River and Fall Creek is now 60% complete. "We are on target to call qualifiers for tunnel construction of that extension in late 2015," said Mentink.
Indy TBM claims record daily advance 23 Jul 2013
Desiree Willis, Robbins Technical Writer
- Its latest rebuild was complex, according to Dave Girard, Senior Engineer for J.F. Shea Construction: "We retrofitted a machine built in 1976 with the latest technology - in particular, variable frequency drive motors." Other new components include the back-loading cutterhead with 19in disc cutters and rescue chamber.
- Despite the complexities of the redesign, the machine is scheduled to be launched in early 2013, proceeding towards the Belmont Wastewater Treatment Plant in what is expected to be a geology consisting of competent limestone and dolomite rock. Robbins continuous conveyors, including a horizontal and vertical conveyor, will aid in muck removal during the long drive.
- Once complete, the tunnel will be lined with unreinforced concrete, making the finished diameter 5.5m (18 ft). Cleaner water is the ultimate goal of the city's new DRTC, which will include in its scope four shorter tunnels that will be added on afterwards.
- The DRTC will convey up to 2.1 million m3 (550 million gal) of combined sewer overflows daily to the Southport Advanced Water Treatment Plant. By 2025 the network of five tunnels will total over 40km (25 miles), and will reduce wastewater overflow into the White River, Fall Creek, Pogues Run and Pleasant Run waterways by 95% or more.
- The City received nine tightly competitive bids for the DRTC CSO project from most of the top US tunneling contractors, and a few internationals. All of the bids were below the Engineer's Estimate of about US$280 million, with the Shea/Kiewit JV submitting the apparent low bid of $180.2 million.
- Construction inspection will be carried out by Aecom, which also holds the design contract for the DRTC. Black & Veatch is designing future deep tunnel CSO extensions along the White River and Fall Creek. Additional storage tunnels will also extend along the Pleasant Run and Pogues Run waterways.
Slim spead in Indianapolis' CSO tunnel bids - TunnelTalk, August 2011
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