Client: APA Concrete repairs
Contractor: MMC Diving Services
Duration: 14 days
Date posted: 11-03-2019
With HMNB Portsmouth awaiting for the arrival of the new £3bn, 65,000-tonne aircraft carrier HMS Prince of Wales, extensive preparations are underway at the naval base.
The existing berth requires "FSU's" (Fender Support Units) to keep the vessel off the jetty and in the pre-dredged berth pocket. These FSU's are required to go up and down with the tide, and due to the sheer size of these units, the jetty is having some structural modifications to enable it to house them.
MMC were contracted by APA Concrete Repairs Ltd to undertake the removal of the old 65 tonne concrete pile caps, x8 in total had to be cut out of the jetty to make room for larger piles and the new pre-cast pile caps. These were cut off underwater using a custom built diamond wire jig. Once these were lifted clear from the water, an underwater hydraulic concrete cutting chainsaw was used to remove x4 large concrete nib blocks from within the jetty. These existing nibs were then cleaned up and prepared ready for the new concrete fascias by our team of divers.
Divers were then positioned in a diver man riding cage which was ratchet strapped in position around the base of the existing pile below the nib. Cleaning up works were undertaken using a hydraulic chainsaw to cut out the large areas of grouting and removing the old nib using underwater hydraulic breakers BR67 and pneumatic CP9.
