Case Study: Rampion Interconnector Ground Investigation
Date: 2013 - 2014
BAM Ritchies undertook a ground investigation for an offshore wind farm electrical interconnector.
The onshore cable route starts where the offshore cable route finishes, at landfall between Worthing and Lancing in West Sussex. From landfall the onshore cable route loops around the north of Lancing where it then crosses the River Adur and then trends generally north-northeast to the site of the proposed substation at Bolney The total cable route distance is approximately 26km.
The investigation was commissioned in order to ascertain the geotechnical, geoenvironmental, geological and hydrogeological ground conditions across the site.
The scope of the works included:
- the sinking of both cable percussive and rotary cored exploratory boreholes to determine the general sequence of strata and composition of any made ground and natural ground below
- the installation of 19mm and 50mm standpipes to allow for the monitoring and sampling of groundwater
- machine and hand dug trial pits to determine the general sequence of strata and composition of any made ground and natural ground below, as well as for thermal resistivity testing the production of a factual report on the findings.
- soak-away tests within selected trial pits and variable head tests within selected boreholes to determine the hydrogeological conditions across the site
- Cone Penetration Tests (CPTs) to investigate the general sequence of strata and composition of natural ground at the near-shore
- a Bathymetric and Topographical Survey of part of the River Adur
- Soil Electrical Resistivity Tests at the proposed new substation site at Bolney
- laboratory testing on samples from exploratory holes to determine the engineering and chemical properties of the strata
- the production of a factual report on the findings.
The principle quantities were 25 Cable Percussive boreholes, 31 Rotary Cored boreholes, 18 Dynamic Sample boreholes and 259 Trial Pits along with monitoring and laboratory testing.