Hammering on

When completed, the world’s biggest container vessels will be able to dock and discharge at the UK’s largest container port. Owners Hutchison Port Holdings appointed Costain in May 2008 to undertake the first phase of this major contract. The Port of Felixstowe expansion is of great strategic importance in the European market and is critical to secure additional deep-water capacity for the UK market. The second phase of the redevelopment has not yet been committed but will be built to meet market demand. Overall, 1.3km of quay will be built and served by 13 new ship-to-shore gantry cranes. The first phase included piling for the new quay wall and the dredging of aggregate materials to be used as infill material behind the wall while further dredging alongside the quay will increase the depth to 16m initially. The facility has been designed to allow the depth to be increased to 18m should that be required in the future. The total amount of dredged material is expected to be in the region of three million cubic meters. Following the clearance of old buildings and warehouses, piling began in mid-January last year when the first consignment of tubular steel piles supplied by Corus and fabricated in Holland was delivered by sea and unloaded directly onto the construction site. Altogether 277 piles have been installed to form the main quay and return walls. The piles have a diameter of 2.56m, a length of 38m and weigh approximately 47 tonnes. To drive these huge piles, Costain hired two BSP piling hammers, CG300 models, from BPH, a division of Balfour Beatty Civil Engineering, which were joined by a further BSP unit, a CG240, hired from Ipswich-based Watson & Hillhouse for piling on the land-side of the project. Because of the sheer size of the piles BSP designed a special pile sleeve, approximately 3m square, which has a slot on both sides to fit over a pile and accept the clutches welded on the sides of the pile. To further illustrate the size of the piles used the hammers’ drive caps have a mass of 10 tonnes and are 2.6m in diameter. The CG300 has been designed by BSP to operate from pilling rig leaders or crane suspended and is suitable to drive a wide variety of bearing piles. On the Felixstowe quay project Costain used piling gates, supported from temporary piles, to hold the piles in position while being driven into the seabed in batches to correspond to the number of piles between fender positions. Ground conditions below the seabed comprise various layers of silty clays and chalk. A barge mounted crane lifted each pile into place which was then checked for vertical and positional alignment. Once in position a vibratory hammer was initially used to drive the piles as far as possible into the seabed. The two crane suspended CG300 hammers, each with 20 tonnes ram weights then took over to drive the piles to the required depth of almost 35m. The 14 tonnes ram weight BSP CG240 was used to drive 1.62m diameter piles required for the rail track foundations of the ship-to-shore cranes. Commenting on Costain’s use of the BSP hammers at Felixstowe, David Redhead, BSP managing director, says: “I am obviously pleased that Costain selected our hammers for driving the huge piles involved for this redevelopment contract especially when Felixstowe is virtually on our doorstep. Our CG hammer range are being used on various civil engineering projects around the world and have a proven track record in reliability and performance as well as their ability to drive exceptionally large piles. At Felixstowe the three hammers performed well up to expectations and piling for the new quay will be completed on schedule despite an unforeseen technical problem at the outset of the piling phase.” BSP has been designing and manufacturing piling hammers for over 100 years from the early steam powered units through to air, diesel and the latest hydraulic models. The three hammers used on the Felixstowe site were powered by hydro pack units. The range of CG hammers are equally suitable for driving bearing piles from piling rig leaders and include hinged type back guides to allow quicker installation onto the leader. A detachable trip can be supplied to allow the hammer to follow the pile without the need to continually pay out the hammer rope. Fitted with a remote control panel, the CG range is capable of delivering an infinitely variable stroke and blow rate. This enables precise delivery of energy to the pile allowing the contractor to maximise production, avoid pile damage and problems of pile runaway. A major feature of the hammers is the design of the hydraulic actuator which makes a significant contribution to the overall performance, which, for a given blow rate and energy transference, results in less fuel consumption and reduced exhaust emissions. Using a manifold control valve the CG range can be connected into existing power supply from a hydraulic piling rig or crawler crane base. Following completion of the piling phase for the quay the piles are topped off with pre-cast concrete beams to form the surface of the quay onto which rails will be placed to accommodate the ship-to-shore gantry cranes. The beams range from 23 tonnes up to 62 tonnes and will be manufactured on-site.