Located in Mpumalanga, the Kusile Power Station project consists of a power station precinct, power station buildings, administrative buildings( control buildings and buildings for medical and security purposes), roads, and a high-voltage yard. The associated infrastructure will include a coal stockyard; coal and ash conveyors; water-supply pipelines; temporary electricity supply during construction; water and wastewater treatment facilities; ash disposal systems; a railway line; limestone offloading facilities; access roads( including haul roads); dams for water storage; and a railway siding and / or a railway line for the transportation of the limestone supply. In February 2011, Esor Franki was awarded the P26 Terrace Underground Facilities contract at the Kusile Power Station in Ogies, Mpumalanga, which consisted of all the interface piping between the bulk supply systems and the terminations to the buildings on the power block, and was mobilised to site in March 2011. The entire contract comprises the installation of drainage systems and high-pressure fire and water supply piping in a range of diameters from 150mm to 630mm for pressure lines, and up to 2 500mm for bulk stormwater lines. The total meterage to be installed in the contract period is in the order of 50km of networked pipe. The balance of the contract comprises the installation of two HDPElined holding recycle dams and 10km of in situ concrete networked cable and pipe tunnels. It is the Esor Construction part of the contract that this article covers.

Esor’ s scope of work

Alex Keevy, contracts director at Esor Construction, explains the scope of work undertaken by the company.“ Most of our work is underground, and consists of piping and large-diameter concrete drainage works, up to 2 500mm. Also included in our scope of work is 11km of underground, cast in situ cabling trenches, which vary in size and depth, but on average are about 9m 2, in which thousands of kilometres of electrical cabling is housed. Some of these trenches are up to 10m below GL,” he adds. Esor handled the HDPE piping for potable water and also the piping for fire water.

Included in the above surface drainage works are open V-drains, which are built around the perimeter of the coal stockyard that feeds coal to the six units.

The volume of water coming out of the coal stockyards amounts to thousands of litres, as not only must the stockpile be dampened down daily to prevent spontaneous combustion of the coal, but rainfall must also be drained away to the stockyard dams. Keevy describes how the stockyard itself is lined with concrete and is tapered from the centre to the edges to facilitate efficient draining, which is further enhanced by an intricate drainage network below the concrete slab that feeds the water into the V-drains and ultimately into

14- CEC February 2018

The Civil Engineering Contractor February 2018 | Page 16