The UK’s first Aqua Cutter Evolution 710V from Aquajet Systems has been put to work by specialist contractor Core Cut Ltd at the Port of Liverpool. It is being used during the widening of the Gladstone Lock entry and nearby quayside as part of the Seaforth Widening project for Peel Ports, who owns the port.
The increasing size of ships calling at the Port of Liverpool has led to the need to expand the area of the Port and the extra width of the passage will improve turnaround times within the tidal window.
Belfast-headquartered Farrans Construction secured the contract to carry out the work which will widen the passage by 20 m (66 ft) to a total of 60 m (197 ft) on completion. It will also see new installed fendering around the Gladstone Lock port entry, the existing wall demolished and a new quay wall constructed.
The widening work first required the re-routing of electrical and water services between the quay areas on either side of the Seaforth Passage. Core Cut’s ability to offer both wire sawing and hydrodemolition services as a sub-contractor proved invaluable. As part of the passage widening works we have to demolish the existing service culvert. As a result a service diversion ‘U-Tube’ is being constructed to replace the existing culvert crossing the passage,” explained Farran’s Section Engineer, Ryan Dillon.
In total, the new ‘U-Tube’ under construction is 120 m (394 ft) long. It consists of the risers at either side which are each 20 m 65.6 ft) long, a 70m (230 ft) straight section under the seabed and a further 10 m (32.8 ft) section at a 60 degree angle around the eastern port side’s horizontal leg.
Fabricated from 1,020mm diameter steel tubes, it will contain a 315 mm HDPE water main, six 33 kV cables, three 11 kV cables and various port comms, all pre-installed as the U-Tube is prefabricated on a separate Quay. This entire U-Tube structure will be transported from the pre-fabrication yard to the Seaforth Passage via a 250 tonne crane barge before being installed to its final position via a three crane lift.
Before this can be done, however, the receiving locations on both sides of the passage have to be cut out and removed in a controlled manner; in order to protect the integrity of the existing structure and ensure it can be reinstated following the installation of the new U-Tube.
“Pneumatic or mechanical breaking wasn’t an option due to the vibrations it would have induced,” explained Core Cut’s operations director Ewan Crocker. “Drilling or hand lancing would also have required the erection of elaborate and expensive scaffolding and the use of man baskets. Due to the depth of the sections involved and the restricted working area – with slab depths in excess of a metre – floor and wall sawing and stitch drilling were also ruled out. We therefore proposed a combination of wire sawing and hydrodemolition techniques employing the Aqua Cutter Evolution 710V with its extension arms as a safe, cost effective and time-saving alternative.”
Corejet, Core Cut’s specialist hydrodemolition division, proposed using hydrodemolition techniques with the Aqua Cutter and its extension arm allowing it to reach 3.5 m (11.5 ft) over the side of the dock to save both costs and time on the project.
The 710V Evolution robot can work horizontally, vertically and on over-head applications and its 3D positioning of the front power head gives the operator full freedom to efficiently reach all areas without limitations. Wire sawing allowed Corejet to initially move large sections of concrete from both the receival locations over areas 3.5 m wide and 2.5 m (8.2 ft) long and also up to 3.5 metres deep. In total some 260 tonnes of concrete was then removed in around 14 lifts ranging from 5 to 34 tonnes as the busy shipping passage operated as normal around the work.
The 710V Aqua Cutter was then brought in to remove up to a depth of 0.5 m (1.7 ft) of concrete from both end walls to expose the rebar. In total Corejet was able to remove more than 26 cubic metres (918 cubic feet) of concrete safely and efficiently from both receival locations.