Fugro Seacore (FSCL) was contacted by Besix-Kier back in July 2006 to supply pile top drilling equipment to help with installing piles on a large contract in Milford Haven. The piles were part of the work to extend an existing jetty ready for the arrival of large LNG tankers to the new storage facility being built at the new South Hook LNG Terminal. FSCL mobilised their T3 Pile Top Drill in November 2006.
The process was a complex one which involved the contractor grouting concrete tapered plugs into the bottom of 1067mm O.D. piles and then driving them through the varying layers of overburden into the mudstone bedrock. The concrete plug method was established to clear the path of expected construction debris in the overburden from previous works, which was up to 18m deep. The T3 was then placed on top of the pile, the concrete plug and any overburden removed, using the reverse circulation technique, then a rock socket was drilled beneath the toe. Once the socket was complete, the drill string was removed, a steel cage lowered into the socket and this was then concreted in using FSCL’s drill string as a tremmie. All the piles in question were raking piles with angles varying from 1 in 3 to 1 in 5.
Two drilling contractors were on the site installing marine piles and by early summer in 2007 progress was slow, due to inclement weather conditions in the first half of the year and slow progress by the second contractor. Besix made a decision to remove the other contractors and bring in a second FSCL pile top drill, the Wirth B5. Pile installations were successfully completed in February 2008, with Fugro Seacore commended by the client for its professional approach, expertise and equipment reliability.