New Lock Gates for Sutton Harbour

SMS are assisting Taylor & Sons, who are constructing and installing the new gates. The SMS 36m by 9.75m flat top pontoon barge, complete with 20m spud legs fore and aft, is just able to squeeze through the lock yet is large enough to support the 80 ton crane, complete with 43m boom, required to undertake the heavy lifts of the prefabricated gate sections.

This capability enables Cardiff based Taylor & Sons to undertake the majority of the gate construction works in Cardiff and in Falmouth Docks, where Sub Marine Services operates out of the A&P (Falmouth) Ltd complex. The 80 ton IHI hydraulic crawler crane is driven onto the barge in Falmouth Docks, where the gate sections are then loaded on board and the vessel is mobilised to Plymouth.

Upon arrival, the large components of the gates are installed in situ using the crawler crane, followed by welding and final coating works to complete the installation. Work on Phase 1, the Inner Gates began on site in September, with Phase 2 works on the Outer Gates due for completion next month.

In addition to the barge and crane, SMS have provided two teams of divers to the site to fit coffer dams prior to dewatering the gate recesses for the gate installation works and to undertake the fixing and grout sealing of the new gate sills.

The gates were lifted into position and installed with the new gate sills attached to the bottom of the gate skins. Once the first set of gates had been installed they were swung to the closed position and the new sill drilled through and bolted into position. SMS divers then placed some 1,200 litres of Rockbond supplied RB UWM grout beneath the new inner gate sill to prevent any water flow under the gates. The outer gates and sill installation is currently ongoing.

The gate skin/sill assembly and grouting method employed were both developed for this project and are believed to have never been used before.