Reinforce Geomembrane for Fly Ash Waste Containment

Neoloy® Geocells provides durable, long-term protection for landfill geomembrane and leak detection system.

The Challenge

Eskom’s Kusile new power station near Pretoria and Johannesburg will be the 4th largest coal-fired power station in the world when fully operational. As a bi-product, Kusile also produces hundreds of thousands of tons of coal waste (also referred to as fly ash or coal ash), which requires disposal in protected landfill dumps with enough storage capacity to last 50 to 60 years. As a potential hazardous pollutant to groundwater, the coal waste lagoons are comprised of a system of liners and monitoring systems to prevent seepage into the environment.

A sand layer is an integral part of the containment solution to detect and contain any leaks. However, the sand must be mechanically confined on slopes in order to maintain the integrity of the layer. The solution also required that the bed or ground of the dump be reinforced sufficiently to protect the sand as well as the geomembrane layers from truck traffic.

Conventional Solution

A solution such as reinforced concrete would require expensive transportation of imported materials. In addition, a long-lasting, durable base over sand would need significant maintenance, as protection against pollution must be guaranteed. This would require close monitoring and high cost.

Neoloy Geocells Solution

ESKOM designed a durable composite liner system to ensure the safety of the surrounding ground water for many years to come.This multi-tiered composite liner system for the fly ash dump consisted of seven layers, including a 100 mm sand layer into which, PRS Neoloy Geocells were placed.

Neoloy is a high-performance novel polymeric alloy (NPA) with high stiffness, tensile strength and creep resistance. These parameters enable the Neoloy Geocell to sustain high loads over time without deformation. This guarantees the durability of the protection system for the long lifespan of the landfill.

The cellular confinement properties of Neoloy’s geocells prevent movement of the sand layer during continuous trafficking of heavy vehicles on the ash dump’s access road. Over 1/4 million m2 of Neoloy Geocell 50 m height were used at the site.

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  • Cost-effective – reduces construction and maintenance costs
  • Simple logistics and installation – folded sections easy to ship and fast to install
  • Flexible system – accommodates subgrade movement and prevents cracking
  • Long design life – unique parameters suitable to long-term design life of landfill