Construction company Liviero reports that it is fast-tracking the implementation of parts of a R231-million contract at Rand Water’s Panfontein water treatment residue disposal site, near Vereeniging.

The expansion of the sludge disposal site and modifications to the supernatant pipeline began in August. But Liviero says the first delivery target needs to be accelerated because additional capacity is urgently required, as all the existing drying ponds are filled to capacity.

The company has committed to handing over ten ponds in September to assist with Rand Water’s Panfontein capacity requirements, explains Liviero CEO Neil Cloete.

Liviero’s project at Panfontein entails removing existing sludge and drainage pipes and installing new sludge pipes and water guns, as well as a new drainage system, including concrete channels and sand flumes. Associated steel sludge delivery pipelines, subsurface drains and fittings will also be installed.

In addition, the contractor will raise the pond walls by 4 m in 20 drying ponds. The ponds will be lined with 1.5 mm high-density polyethylene (HDPE) lining. The subsurface drains will drain into a 1 km trapezoidal concrete channel.

A total of one-million cubic metres of commercial filling sand was imported for the wall construction and 825 000 m2 of HDPE lining and geotextile will be installed, along with 19 km of steel sludge pipes and 68 km of subsoil drainage.

Between 500 t and 1 300 t of dry sludge is produced each day during Rand Water’s purification process. The dry sludge is removed from the sedimentation tanks containing thin slurry. The tanks contain 3% dry sludge.

The sludge is then pumped to Rand Water’s sludge disposal site, at Panfontein, where it is dosed with an organic flocculent in gravity thickening plants to aid the separation of the solids from the liquid. The thickened sludge is pumped onto drying beds, where it is dried through evaporation, and the clear supernatant fluid is drawn off and returned to the purification system.