NMPP TANKSBunding walls used on the tanks for the prevention of leakages and spillages
The NMPP project is Trans-net’s largest-ever single capital investment project and entails the construction of a pipeline between Durban and Jameson Park, in Heidelberg, Gauteng.
It will be used to transport petrol, diesel and aviation fuel from refineries in Durban, as well as imports of refined petroleum products for the new storage facilities at Island View in the Port of Durban, where Terminal 1 of the NMPP project is under construction.
The 24-inch-diameter pipeline covers 550 km from Island View to an inland fuel terminal, Terminal 2, which is under construction at Jameson Park.
Construction firm Group Five was awarded the contract to build the pipeline pump stations and the two terminals under the engineering, procurement and construction management joint venture team, which comprises civil engineering firms Arup and Worley Parsons.
Group Five Civil Engineering site agent Mirek Paczynski says about 50% of the R700-million civil engineering requirements of the Terminal 2 contract has been completed.
Civil works, involving 800 site workers, were started in 2010 for completion in 2013.
“The civils contract calls for concrete foundations, concrete ‘bunding’ walls – containment walls that will prevent possible leaks and spillages from the tanks reaching the environment in the event of a disaster – and charcoal-pigmented concrete slabs between the steel tanks and bunding walls,” he notes.
Concrete foundations are being provided for four petrol and four diesel tanks, each 36 m in diameter and 20 m high, and for two intermix tanks containing a mixture of fuels, each 21 m in diameter and 20 m high.
The tank foundation ring beams, for which a fly ash concrete mix is being used, are 1.2 m high and 500 mm thick. Transnet specified a concrete strength requirement of 35 MPa.
The bunding walls are 300 mm thick and 3 m high. The concrete slab surfaces within the bunded area, containing two jet fuel tanks, cover 6 072 m2. Slab surfaces around the petrol and diesel tanks cover 10 560 m2 for each of the two bunded areas.
Paczynski says Chryso’s Cryplon fibres form an important part of the concrete mix for these reinforcing slab surfaces to prevent plastic shrinkage and cracking and add toughness and impact resistance to the slabs.
“Reinforcement of the concrete was generally achieved solely through the addition of the Chryso fibres to the mix, except for thicker slab areas where mesh reinforcement was also required,” he states.
He notes that the use of fibre reinforcement has increasingly become a specification because of the rising costs and periodic shortage of mesh or steel products.
Fibres in the mix improve initial dispersion and bond the concrete.
Other advantages of the Chryso Cryplon fibres include a reduction of plastic settlement, a reduction in bleeding and a reduction in water and chemical permeability.
Chryso is also the national distributor of speciality chemicals company Lanxess’s Bayferrox pigmentation, which is being used to add the charcoal colouring to the concrete slabs in the bunded areas.