The JV of Morgan Est and Farrans (Construction) as holed through on the first, and one of the longest, stretches of the Belfast sewer project with a 4.7m diameter Lovat mixed face EPBM.

Groundwater varied from 22m-31m above the tunnel invert and geology along the 1,290m long section mainly was comprised of two glacial deposits, boulder clay and Malone Sands.

There were also significant areas of bedrock comprised of Sherwood Sandstone, Mercia Mudstone and Upper Permian marls, and the TBM also met vertical doleritic dykes of variable thickness.

Similar geology is expected for the 540 tonne EPBM along the next section of the sewer, which is 2,200m long. In total, the JV will design, build, test and commission approximately 9.4km of tunnels of up to 4m i.d, and the project also includes pipejacks up to 1.8m diameter. The scheme also includes 27 shafts of 7.5m typical diameter and one of 40m diameter.

The client, Northern Ireland Water, is building the tunnel as part of a US$200M upgrade of the city’s 19th Century sewer system. The project is to be completed in 2009 (T&TI, September 2006, p6).

Morgan Est/Farrans JV holes through on Belfast Sewer Morgan Est/Farrans JV holes through on Belfast Sewer