FES were required to construct three cable percussion boreholes up to 35m deep on both landward sides of the bridge, five trial pits up to 3.7m deep, ten 1.2m observation pits, and to complete 15 window sample boreholes up to 4m deep and six cone penetration tests up to 24m deep.

Geoenvironmental data was also obtained for Gifford's EIA report from two 10m boreholes in the western and eastern land approaches, sampled for contamination testing with particular interest on the western side, which crosses a former power station site.

The backwater navigation channel is subject to a 2m tide and a 2 knot current. Using the jack-up platform Coastal Explorer , FES completed six cable percussion boreholes to a maximum depth of 40m and three cone penetration tests to 23m.

Over water, FES also carried out seismic piezocone tests at the locations of the proposed bridge piers and quay walls. Also, 25 seabed vibracores were recovered from the channel for a dredging survey as well as a number of water samples for contamination testing.

MJ Information No: 19520