The first of two drives on the UK’s 8km long, $42.2m Portsmouth Transfer Tunnel is scheduled for completion at the end of February. At the Christmas break, the 4km long Budds Farm drive was reported to be over 75% complete.The second drive, the 4km long Eastney Drive , is now over 50% complete.
Contractor Edmund Nuttall is building the 8km long sewage transfer tunnel using two Lovat TBMs. The 2.8m i.d tunnel has been split into two 4km long drives. Excavation is in opposite directions starting from two 7m diameter intermediate shafts at Kendalls Wharf. The shafts are connected by a 60m NATM tunnel. The transfer tunnel will have fully gasketed, bolted pre-cast concrete segments. The invert level will be between 21m and 29.5m below ground level.
The TBMs will be removed from two reception shafts, one at Budds Farm and one at Eastney. On completion, the Budds Farm TBM will be sent to Cork, Ireland, for use on the 2.6km long, 3m diameter River Lee Siphon Interceptor No 1 by the Nuttall/Ascon JV.
