GEOTECHNICAL CONTRACTOR May Gurney's Site Investigation Division recently carried out a drilling programme on the River Orwell for a proposed extension to the Port of Ipswich.
Client Associated British Ports is planning to build a new quay immediately to the south of Power Station Quay on the eastern bank of the River Orwell. The new structure will be supported on piles and extensive dredging will be carried out, including a 'turning circle' on the opposite side of the river.
May Gurney put down 16 cable tool boreholes between 5m and 26m below existing river bed level. The deeper boreholes provided information for pile design and the shallower holes were used to determine the suitability of the materials for dredging.
Extensive testing at the firm's laboratory helped determine material properties.
The boreholes revealed that the site is underlain by a sequence of Quaternary drift deposits comprising alluvium over river terrace deposits, overlying Cretaceous Upper Chalk.
Work was carried out from a temporary barge in the southern approaches of the river just north of the River Orwell Bridge during December 1999 and January 2000.