Costain was last month preparing to get underway with a 3.4m diameter TBM drive in soft ground in east London with a Lovat shield for a flood relief scheme.
The contractor is accepted the Lovat EPBM in January to excavate the 3,303m long stormwater sewer for the West Ham Flood Alleviation scheme being built by utility client Thames Water.
Geology along the alignment of the main drive, which has 15m-17m cover to the crown, comprises Woolwich & Readings Beds and the Upnor and Harwich Formations. Groundwater levels are expected to range from 10m-14m over the invert.
The cutterhead of “Theodora” has a maximum torque of 1,830kN, rotation speed of 4.8 rpm and is fitted with chromium carbide coated rippers and scrapers. Its drive is hydraulic with two electric motors and variable displacement pumps.
Lovat will also provide technical assistance and spare parts during the tunnelling stage of the 2.87m i.d. stormwater sewer job.
The project also includes five shafts to be built in the waterbearing ground by both caisson and underpinning methods. In addition, microtunnelling on the scheme will see slurry TBM excavation of approximately 2,500m of 1.2m diameter i.d. bores along with 19 shafts.
The client plans to have the full scheme in the London Borough of Newham completed by the end of 2010.
The TBM (MP132SE) supplied to Costain is Lovat’s 250th shield and becomes the fifth held in stock by the UK contractor, which bought its first machine from the Canadian manufacturer in 1987.
Lovat said it has designed and built TBMs that have completed more than 700 projects since the business began in 1972. In March 2008, Lovat was acquired by Caterpillar (T&TI, April 2008, p13).
