Publish Time: 2021-10-22 Origin: google
The project to extend the continuous ash disposal facility (ADF) at Eskom’s Majuba power station has passed its midway point. The project will ensure that waste residue from the boiler furnaces is responsibly stored.
The project’s contractor, Concor, reported being over halfway with extending the continuous ash disposal facility, located near Amersfoort in Mpumalanga. This project will ensure that the coal-fired power plant can continue generating electricity while complying with ever-stricter environmental regulations regarding the responsible storage of waste.
The ash disposal facility project began just before the first COVID-19 lockdown in early 2020. To date, the contractor has handed over Terrace 2A and is in the process of handing over one of the two rehabilitation dams, says Dlamini. The construction of the extensive terraces – which measure 1.2km long by 175 metres wide – began with bulk earthworks, cutting down to a design level before constructing the various layers.
These layers include 100mm of filter sand, followed by a Class 2 geomembrane and two 150mm layers of clay. This is covered by a double-textured 1.5mm HDPE geomembrane, followed by a 300mm coarse ash layer. Each liner terrace, constructed from stabilised ash, is broken down into compartments of 5-metre widths, located every 100 metres.
“Underneath these layers, we are constructing a network of herringbone subsoil drains with a leachate collection system which will flow into a pollution control dam,” Dlamini says. “This will drain into Pollution Control Dam 5.”
Specialist sub-contractors have been used for the all-important lining beneath the dams, as well as the identification of any potential leaks in this lining.
“The excavation and bulk earthworks for the pollution control and rehabilitation dams is followed by the construction of a subsoil drainage layer,” he says. “In addition to the geomembranes and layers of filter sand and impermeable clay, this layering includes 250 mm thick geocells, a ballast layer comprising 300mm thick cement-stabilised sand (8% by mass) and geocells.”
The rehabilitation dams also have penstocks and valve chambers. Enhancing the environmental controls are water perimeter canals around the whole facility to separate and channel clean and dirty water. These are lined with 100mm geocells filled with 30 MPa concrete, controlling the stormwater in the area.“The canals play a vital role in reducing the risk of any washdown from the tailings facility.
Complying with strict environmental regulations means ongoing monitoring on-site, according to Portia Rasakana, Lubocon’s environmental manager at the Majuba project. She highlights waste management as a key focus to avoid any environmental impact, but concerns such as pollution and dust management also receive constant attention.