The final phase of pre-construction required for the installation of the mechanical, electrical and instrumentation works at the Outeniqua Wastewater Treatment Works Upgrade is currently under way with significant progress to date
Several structures were completed in 2019 and included the new concrete structure 10 Ml/d biological reactor, a blower and electrical motor control centre housing facility as well as other site and flow control structures to prepare for the switch over and flow splitting between the existing and new facilities. The contract includes an odour control facility at the inlet works to contain and treat odours originating from this part of the treatment works.
A number of construction activities are currently taking place on site and are mostly civil engineering construction activities in preparation for the awaited mechanical and electrical equipment:
- A crane has been installed in the blower room for the handing of the equipment during installation and for maintenance purposes
- Road construction is under way to create access to the new reactor
- Various cable trenches have been excavated for the upgrading of the electrical system
- The cone-shaped structure around the centre column in the settling tank has been constructed to prepare for the rotating bridge installation on the tank
- Excavation is taking place around the inlet works for the indoors skips handling facility, odour control facility and a rock catcher septage receiving structure
The majority of the mechanical and electrical designs have now been approved and orders have been placed for equipment. The delivery of the imported items to site is expected by the end of September 2021. Local suppliers are busy with off-site manufacturing of steel structures to house some of the mechanical equipment. A wide range of equipment to be installed includes; 3 blower units to provide air for the fine bubble aeration system, 10 mixers, 2 Archimedean screw pumps, 4 vertical shaft surface aerators, 3 perforated mechanical screens, 1 hydro conveyor, 2 screenings washers, 1 septage unit, an odour control system and a chlorine gas scrubber plus various minor items. Various pumps, actuated valves and sluice gates are also required.
The existing carousel reactor on site is also due for an upgrade as part of this project and will predominantly involve the replacement of the aged aerators in the reactor with larger aerators to provide additional capacity. This work is scheduled to begin once the assessment of the 30 year old concrete and reinforcement steel has been finalised. The assessment will provide input on the strengthening of the existing structure to handle the additional loading of the heavier new aerators. Current indications are that the new plant will be operational by mid-2022 with all construction completed in early 2023.