In the U.S., Affholder has begun tunnelling on Sacramento’s Bradshaw Interceptor Sewer Section 8 in good fashion with approximately 213m excavated in under a month following the launch of their refurbished Lovat TBM in late March.
The US$19.3M project is being carried out for the Sacramento Regional County Sanitation District and the 2.4km of 3.07m diameter tunnel will be used to convey wastewater from the northeast of Sacramento County to a regional wastewater treatment plant.
The Lovat MP121RL/PJ Series 8600 machine will excavate through firm to hard sandy clay, silty clay and clayey silt with trace gravel and cobbles at an average depth of 10.6m beneath major roadways. A member of the project team told T&TI that the primary lining in the tunnel consists of steel ring beams with timber lagging. Final support will be by way of a 1.82m diameter reinforced concrete pipe.
A total of 11 shafts will be sunk on the project, two are complete and planning for the remaining nine is underway said T&TI’s source. The primary lining for the shafts, which vary between 11m and 4.3m, is ring beams and timber lagging as per the tunnel. Manhole risers 1.52m i.d. will eventually be built at the shaft locations to the street surface.
With two possible areas of contaminated land being traversed by the tunnel, employees had to be “hazwopper trained”. This involves communicating the possible hazards to the workers of the dangers associated with the contaminated soil and training them in how to mitigate any risks.
Construction was started on 15 November last year and is scheduled to be complete by the end of May 2006.
