FOUNDATION AND Exploration Services recently carried out a site investigation for the redevelopment of Whitby's wastewater system.
FES, working for Yorkshire Water Services and consultant Earth Tech, put down 62 land and marine boreholes, 14 trial pits and carried out cone penetration testing for the scheme, which involves construction of tunnels beneath the harbour, pumping stations, a treatment works and associated sewers.
Boreholes were sunk to depths of between 5m and 30m using cable percussion and rotary techniques.A total of 17 boreholes were drilled in the harbour; 10 from a jack-up platform and seven from scaffold platforms. Insitu measurements, including SPTs, permeability, resistivity and CBR tests, were also carried out and groundwater samples collected.
Soil and water samples were taken to FES' laboratories in Consett and Basingstoke where they underwent a variety of tests including undrained triaxial compression, CBR, compaction and shear box, ring shear, resistivity, compressive strength and point load. Samples were also tested for a range of contaminants.
Gas monitoring standpipes were installed in five of the boreholes and concentrations of H 2S, CO 2and O 2were monitored at regular intervals.