Construction World February 2017

PROJECT PROFILE

RECONSTRUCTION and DEEPENING of Maydon Wharf

The Stefanutti Stocks Axsys Joint Venture (SSA JV) was awarded the contract for the rehabilitation of berths 1-4, 13 and 14 in April 2014, a total of six out of 15 berths at Maydon Wharf, the Port of Durban’s largest break bulk, edible oils and dry bulk handling precinct.

Construction innovation Two integral elements of the project are the anchor piling work and concrete cope beam construction. A first for South Africa, the Müller Verpress Pile (MV-Pile or HP) has been used extensively in Germany, Netherlands and the United States for anchoring large combination-wall systems (both grouted and un-grouted) as an alternative to the traditional dead man anchor solution and is known to be exceptionally economical both in terms of cost and performance. The HP piling rig makes use of an IHC 70 hydraulic piling hammer to drive the piles. The barge is capable of jacking itself out of the water which prevents it from being affected by the waves of passing vessels, the swell in the harbour and also prevents the piling being affected by tidal variations. By operating on a hydraulic platform the rig can be positioned to the millimetre as well as track to three positions per barge movement. The bespoke anchor piling barge is capable of driving the 33 metre long HP piles, while grout is simultaneously pumped at 1 000 kPa from a colloidal mixing plant on land as the pile is being driven. The grout acts as lubricant during driving and once set it bonds to the steel pile and the surrounding substrate increasing the frictional resistance of the anchor, as well as protecting it from the adverse effects of corrosion. A selection of HP piles are tested under tension loading of 450 tons on each berth. The execution of the HP piling can be measured through the results of the test piles which have passed the stringent testing and specification requirements set forth in the contract. The use of HP piles something the Stefanutti Stocks Axsys Joint Venture prides itself in accomplishing successfully as a first in the country. The design of a water tight shutter system for the cope beam construction was of a complex nature and as such, required rigorous analysis. Initially, a detailed concept of a coffer dam was developed. The coffer dam concept was however discarded due to handling issues

Maydon Wharf was developed for the then expansion of the Durban harbour, in particular to meet the needs of the growing Witwatersrand. The berths were built of timber, with berths 1-4 and 13 and 14 later rebuilt using steel sheet piles in the 1950s. Safety is of utmost importance when dealing with timeworn structures which have been in use since the mid-1900s. Constant monitoring of movement of the existing quay wall is taken very seriously to prevent collapse or failure during pile driving, timber pile extraction and excavations taking place in proximity to the old berths. The project is overseen by Transnet Capital Projects and RCE Consultants are the design consultants. Project description As the largest and busiest shipping terminal in Southern Africa, the aged berthing structures require far greater capacity than the original 20 000 DWT vessels it was originally designed for to meet current and future demands. The reconstruction of Maydon Wharf consists of demolishing the existing quay structure, the removal of old timber piles, installing a new steel combination wall with concrete cope beam and back of quay layer works. Included in the scope of works is the deepening of the seabed by some 4 m to achieve a draft of 14,5 m CD, with the placement of scour rock adjacent to the quay wall, preventing washout by the propellers of the vessels. Torrential winds and harsh sea conditions, are just some of the milder challenges faced on the exciting marine construction project. At berth 13 and 14, extremely hard driving conditions were encountered and the issue was further exacerbated by the old quay wall alignment being far worse in condition and envisaged location, resulting in subsequently changes in design alignment. As such, all aspects of the project required exceptional survey accuracy. Once completed, the six berths will be able to handle bigger vessels with drafts of up to 13 metres.

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CONSTRUCTION WORLD FEBRUARY 2017