In an innovative approach to underwater remediation, Shearwater Marine Services successfully addressed structural voids at the non-operational Kilcreggan Berth at Gourock Ferry Terminal. The eight-week project, valued at £400k under an NEC4 Option A contract, involved an adaptive repair method to accommodate larger-than-expected voids. Shearwater's multidisciplinary dive team, along with specialist subcontractors, employed a combination of underwater grout bags and steel plate shutter to fill the voids with over 100 cubic meters of underwater wet mix grout, ultimately satisfying the client's needs and completing the project on time.
The Kilcreggan Berth, owned by Caledonian Maritime Assets Ltd (CMAL), was found to have structural voids and movement during inspections and monitoring by Shearwater Marine Services and AECOM. CMAL tasked Shearwater with remediating these voids to stabilise the structure.
Initial assessments of the structure revealed that the voids towards the north end of the berth were significantly larger than anticipated. This unexpected finding necessitated a change in the repair method initially proposed. The challenge was to design an approach that could handle the volume of concrete required to fill these larger voids, while also accommodating the unique underwater environment.
In collaboration with AECOM, Shearwater developed a strategy involving a combination of underwater (UW) grout bags and steel plate shuttering. This innovative method was designed to hold the quantities of concrete necessary for the voids. Grout bags were fixed in place with reinforcement bars, and divers filled each void from the outside. Holes were then cored in the apron slab to allow underwater wet mix to be poured into the void.
A plate shutter method was devised for the north end of the structure, complemented with a bag work toe, to accommodate the larger voids. Shearwater used a seven-man dive team with a diverse skill set, including underwater inspection, coded welding, and rigging and slinging, to complete the project.
Over the eight-week duration of the project, Shearwater successfully filled the voids with over 100 cubic meters of underwater wet mix grout. The project was completed on time, with only one day lost due to weather, and to the satisfaction of the client and their on-site representative from AECOM.
Shearwater also effectively managed several specialist subcontractors to overcome challenging sections of the task, including apron slab coring, multicat vessel support for plate and beam placement, and concrete pumping in areas where cranage was restricted due to the close proximity of a railway line.
The Kilcreggan Berth Void Remediation project showcases Shearwater Marine Services' adaptability, technical prowess, and efficient project management skills in overcoming unexpected challenges. The company's ability to devise innovative solutions while maintaining safety and operational efficiency reinforces its reputation as a leader in underwater engineering services.