EDF Energy contracted Fugro Seacore to manage and undertake a nearshore site investigation in the Bristol Channel off Hinkley Point in Somerset. The energy provider is to build a third nuclear reactor, Hinkley C, at Hinkley Point and the site investigation was required to facilitate tunnel and shaft designs for two cooling water intakes and a single outfall.
Fugro Seacore acted as principal contractor for the complete nearshore package and directed several marine vessels including its largest jack-up, Excalibur and two survey vessels to complete the geophysical surveys, sampling and in-situ testing. A total of 23 boreholes were drilled to various depths between 35m-70m into the mudstones and limestones using the wireline Geobor S system on Excalibur. Down-hole testing included Lugeon Tests (Packer Tests), optical and acoustic logging and PS logging. Ground conditions on site allowed for excellent core recovery, which was frequently 100%. Part way through the investigation Fugro Seacore was able to recommend additional works to provide an increased understanding of the site to ultimately benefit the tunnel design process.
Operations were completed during the months of October and November 2009 in some of the worst weather for several years. The benefits of Excalibur’s size, both in terms of operability and onboard accommodation proved invaluablefor completing the investigation in the timescales required by the Client.