Stefanutti Stocks Coastal is nearing practical completion of the civils works contract – undertaken for the Drakenstein Municipality – for the upgrade and extension of the Wellington Waste-Water Treatment Works (WWTW) that will operate at a new hydraulic capacity of 16Ml/day (average dry weather flow). This is an increase of 10Ml/day from the previous capacity of 6Ml/day. The facility will be able to provide a full biological nutrient removal facility, allowing the removal of nitrogen, including phosphate.
An aerial photograph of the two adjacent sides of the Paarl Waste-Water
The upgrade and extension to the existing WWTW comprised the following scope of works:
Construction of various process units and pipelines, including:
- New elevated inlet works;
- Two 15-metre diameter primary settling tanks (PSTs);
- Two 30-metre diameter secondary settling tanks (SSTs);
- Biological reactor, aerobic digester and anoxic thickener;
- UV closed-vessel disinfection and wash-water pump station;
- Sludge recycling and waste pump stations;
- Main sludge pump station and sludge rising pipeline to Paarl;
- Irrigation pipeline to golf course;
- Gravity sewer main to Pentz pump station;
- Emergency overfl ow pond, fl ow division and collection chamber and interconnecting pipework; and
- Ancillary structures, encompassing various small concrete structures including fl ow division and collection chambers.
Construction of various buildings, including:
- Two-storey administration building which houses offices on the ground floor, and a control room and mini lab on the first floor;
- Blower room housing the Motor Control Centre (MCC);
- Small power, electronics and HVAC for all new buildings;
- Emergency generator building; and
- Medium voltage (MV) building.
Also included in the scope was the construction of the storm water piping network and new internal roads; flow diversions, decommissioning and demolishing of older process units; modifying existing structures, including raising the internal launder walls of the existing SSTs; refurbishing three 15-metre diameter PSTs, the effluent outfall channel to the Berg River as well as existing buildings; and the installation of fibre-optical data cable, streetlighting and landscaping.
The upgrade of the Paarl Wastewater Treatment Works: Phase 1 (Emergency Works) was also awarded to Stefanutti Stocks Coastal and permitted as a large variation order (VO). “The upgrade was executed with remarkable success, largely due to the thorough planning by our newly promoted site agent, Jan-Hendrik Schreuder,” says John Woodburn, Stefanutti Stocks Coastal contracts director.
The Wellington contract took place on a brownfield site and Stefanutti Stocks encountered numerous unforeseen challenges, which required immediate attention and solutions. “The new WWTW was being constructed between the structures of the existing WWTW and sometimes ‘on-top’ of the old one, which had to continue operating at all times,” says Schreuder. Other unique and interesting aspects of the project included that most of the work has been done without the use of major subcontractors, and that the work undertaken facilitated the combination of old processes with new hydraulic and instrumentation processes.
“Stefanutti Stocks Coastal has an impressive portfolio of water sector projects and we were able to utilise our thorough understanding of the waste-water treatment process to the benefit of the project,” says Woodburn. “The project also provided a platform for our young engineers to grow as well as demonstrate their abilities.”