$300 million scheme for Hyder Welsh Water comprising 2.6 km of 2.44 m-diameter tunnels, 3.5 km of 1.95 m, and 3.7 km of 1.6 m in waterbearing mudstone, siltstone and sandstone using Herrenknecht EPB for the large diameter and AVN 2000D and AVN 1600D pipejacked machines for the smaller diameters. 20 access shafts ranging in internal diameter from 6.1 m to 7.62 m with precast concrete linings supplied by Tarmac Charcon and a 20 m-diameter, 40 m-deep pumping station. Shaftwork commenced December, 1997. Partnering agreement involves Welsh Water, Hyder Consulting, Laing Civil Engineering, Van Oord, and Byzack, with the latter handling the tunnelling. Completion 1999. June 1998.
