Expansion of Driefontein WwTW


Project Details

Client Johannesburg Water
Location City of Johannesburg, Gauteng
Project Value R220 million
Completed 2013

Project Description

The Driefontein Wastewater Treatment Works is operated by Johannesburg Water, and services the northern suburbs of Roodepoort, Muldersdrift, Mogale and Rietfontein.

In the past, the wastewater flow to the Works was restricted by the urban edge, which placed a constraint on residential and commercial development in the drainage basin.

The existing Wastewater Treatment Works had a nominal treatment capacity of 25 Mℓ/day and was retrofitted to 30 Mℓ/day by upgrading and replacement of existing infrastructure. The proposed urban development in the drainage area requires a further 50 Mℓ/day treatment capacity.

Scope of Services

Process, hydraulic and civil design, tender documentation and construction monitoring for a 50 Mℓ/d expansion of the Driefontein Wastewater Treatment Works:

  • New combined inlet works with screens and vortex degritters for a flow of 80 Ml/d
  • New combined primary settling tanks and primary sludge screening installation
  • Conversion of the existing primary settling tanks to VFA fermenters
  • New combined balancing tank for 80 Ml/d inflow
  • Two 25 Ml/d biological reactors, one of which will be constructed under this project and the second one as a future project
  • New secondary settling tanks for the first 25 Ml/d module
  • New disinfection installation for 80 Ml/d
  • New combined sludge screening and pre-thickening (gravity belt thickener) installation
  • All associated services, roads and stormwater infrastructure

Special Features and Challenges

  • Limited space available for the expansion, and challenging topography of the site
  • Tying in of the new combined inlet works, primary settling tanks and balancing tank with the existing module.