Hydrodemolition Expert for Liverpool Port Expansion

Corecut Ltd, a British specialist, is implementing hydrodemolition techniques for the expansion of the Seaforth Passage at the Port of Liverpool. The first British AQUA CUTTER Evolution 710V robot from the hydrodemolition manufacturer Aquajet Systems AB in Sweden has been deployed at the project to accelerate construction work.

Corecut Ltd played a crucial role in the preparatory work for widening the Gladstone Lock entrance and adjacent quays at the Port of Liverpool, operated by Peel Ports. The increasing size of the next generation of cargo ships means that the area around the Liverpool Seaforth Passage and docks, which has remained unchanged since its construction in 1971, needs to be expanded. Navigating some of these ships through the 40 m wide Seaforth Passage is currently compared to 'steering a cocktail stick through a straw', and the additional width will significantly improve turning times within the tidal windows.

The Belfast-based company Farrans Construction received the €9 million contract to carry out the work, which will widen the passage by 20 m to a total of 60 m. Additionally, the Gladstone Lock entrance will be fitted with a new quay wall, and the existing wall will be demolished. The widening works initially required the relocation of power and water lines between the quays on both sides of the Seaforth Passage. Here, Corecut's ability to offer both wire sawing and hydrodemolition services as a subcontractor proved invaluable.

As part of the widening works, the existing conduit must be demolished and a new one built across the passage. The new duct being constructed is a total of 120 m long, consisting of risers on both sides, each 20 m long, a 70 m straight section under the seabed, and another 10 m section at a ninety-degree angle around the horizontal leg of the eastern harbour side. It is made of steel pipes with a diameter of 1,020 mm and contains a 315 mm thick HDPE water pipe, six 33 kV cables, three 11 kV cables, and various port communications, all pre-installed.

Before this, however, the reception points on both sides of the passage had to be cut out and carefully removed to protect the integrity of the existing structure and ensure it can be restored after the installation of the new U-pipe. Pneumatic or mechanical breaking was not an option due to the vibrations involved. Due to the depth of the affected sections and the restricted working area, with ceiling depths of over one metre, ground and wall sawing as well as core drilling were also not feasible. Therefore, a combination of wire sawing and hydrodemolition techniques was proposed, where the Aqua Cutter Evolution 710V, with its extension arms, provides a safe, cost-effective, and time-saving alternative.

Corecut, headquartered in Broxburn, East Lothian, Scotland, has established a solid reputation in diamond drilling, concrete sawing, and controlled demolition. The highly skilled team of over 50 CSCS-qualified staff across the UK has successfully completed thousands of contracts with state-of-the-art equipment. The family business was founded in 1976 by Ewan's father Alistair and is now managed by Ewan and his brother Finlay. They decided late last year to invest in an AQUA CUTTER 710V Evolution Aqua Cutter, ordering it through the British dealer Aquapower Ltd. They quickly recognised the potential of hydrodemolition, seeing it as a natural extension of their service package that complements their drilling and concrete sawing activities.

Corecut was the only company able to offer diamond cutting and hydrodemolition without subcontracting to third parties, a key reason for ordering the Aqua Cutter. The company was able to compete against traditionally manual firms that would have required the construction of an elaborate and expensive scaffold over the water. Corecut proposed using hydrodemolition techniques with the AQUA CUTTER and its extension arm, allowing it to reach 3.5 m over the side of the dock, saving both costs and time on the project.

The 710V Evolution robot is the most versatile hydrodemolition machine on the market, with the flexibility to work horizontally, vertically, and overhead. The unique 3D positioning of the front drive head gives the operator full freedom to efficiently reach all areas without restrictions. Corecut was able to initially move large concrete pieces from both reception points over areas of 3.5 metres wide and 2.5 metres long, and up to 3.5 metres deep. Approximately 260 tonnes of concrete were removed in 14 lifts ranging from five to 34 tonnes, all while the heavily trafficked shipping lane around the work continued normally.

The 710V AQUA CUTTER was then used to remove up to 500 mm of concrete from both end walls, exposing the reinforcement. Overall, Corecut was able to safely and efficiently remove more than 26 m³ of concrete from the two reception points. A significant advantage of the hydrodemolition process is that concrete is removed without damaging the reinforcement, allowing for rapid re-concreting on the exposed reinforcement once the U-pipe structure is in position. Hydrodemolition techniques are known to more than double the lifespan of repairs or coatings compared to removing concrete with jackhammers.

The AQUA CUTTER typically operates at pressures of 1,000 bar to 2,500 bar, but Corecut successfully operated it at 900 bar for this job. The Corecut robot worked remotely and mostly from the top of the dock walls. It cut in a trapezoidal pattern to remove the concrete, with the drive head – which contains no sensors – working at certain points below the waterline. Robotic hydrodemolition was the safest and best-controlled solution for this contract. By using the boom and small hood, we were able to access otherwise unreachable areas without requiring additional temporary works.

Once all preparatory work at the Seaforth Dock is completed, a new quay will be laid, and the existing wall will be demolished. The overall project completion is expected in December 2014.