Portland Port deep water berth finished ahead of schedule

Knights Brown has overcome a demanding programme to complete the construction of a 250m deep water berth at Portland Port in Dorset ahead of schedule.

The work is part of a £25M scheme at Portland Port, a commercial port located on the UK's south coast, which involves replacing an existing deep water berth with a new, extended one.

The new deep water berth allows the port to simultaneously accommodate two 350m long cruise ships, the first pair of which have already arrived in port.

Construction company Knights Brown was appointed as managing contractor for the scheme, while Ramboll was appointed to carry out the design work as principal designer. The piling contract was awarded to Red 7 Marine.

The works, which got underway last autumn, also included a 75m extension to the solid quay face of the port’s current primary cruise berth, the outer coaling pier. In addition, the project will create an additional 15,000m2 of quay space to extend the total available area to 21,000m2.

The principal operations included demolishing the original deep water berth and dolphin; constructing a 410m combi pile wall comprising 136, 1.4m diameter, 24m long tubular steel piles separated by sheet piles; and anchoring each tubular pile with 32m long tie rods to a sheet pile anchor wall.

On top of the piles, 25t precast concrete units were installed to act as permanent formwork for the in-situ capping beam, which comprised more than 2,000m3 of structural concrete.

Construction also involved crushing and transporting off road 400,000t of locally sourced quarry waste to create a granular fill material to bring the extended quay area to level.

The project also went ahead under an alternative procurement route after competitive tenders exceeded the funds available.

The alternative procurement arrangement saw Portland Port adopt a unique form of contract that relied on collaboration between all parties. Having chosen to work with Knights Brown to develop the approach, Portland Port agreed to carry the major project risks and directly procure high value materials and subcontract packages.

Knights Brown’s role as managing contractor was to adopt appropriate mitigation methods that would minimise the port’s exposure. These measures allowed the project to be brought in line with the budgetary restraints without compromising the scope of works.

Knights Brown managing director Kevin Valentine said: “Our intention was to find a way to deliver the full scope of what was wanted within the timescale and budget available. This has been achieved through true collaboration and cooperation, at quite astonishing speed.”

Before starting on site, Knights Brown worked closely with Ramboll to ensure buildability and maximise value engineering opportunities.

A key driver of the design process was to allow rapid construction. Consequently, off site fabrication was prioritised as a means of meeting programme, while also limiting works that had to be carried out over water and avoiding tidal activities.

Knights Brown has said that the precast capping beam was an important contributing factor as it eliminated the need for shuttering and was designed to allow prefabrication of the steel reinforcement.

Another important productivity gain was achieved with Red 7 Marine, which together with specialist engineers designed a pair of bespoke piling gates to speed up installation of the combi pile wall through improved accuracy and tolerance.

Want to read more? Subscribe to GE’s enewsletters and follow us on Twitter and LinkedIn