Civil Engineering December 2021 | Vol 29 No 11

36 December 2021 Civil Engineering T he Western Cape’s Berg River is the heart of a delicate and important ecological system, relied on and impacted by the communities in the catch- ment. However, pollution in the Berg River catchment has long been a cause of great concern, especially to communities, farmers and industry in the various municipalities of the West Coast and Cape Winelands regions. The cost of pollution in the River includes both economic and social repercus- sions for the agricultural export industry, the risk of disease to downstream water users, and ecological consequences for the sensitive estuary at St Helena Bay. A Berg River Water Quality Task Team was established in 2009 to investigate and propose short- and long-term interven- tions to improve the water quality of the Berg River system. The highest priority recommendation was to expedite the upgrade and improvement of under- performing and overloaded wastewater treatment works (WWTW) in the Berg River catchment. The Wellington WWTW was already overloaded and underequipped to handle the flows and high seasonal loading that it received in 2012, while the capacity con- straint was hampering developments and economic growth within the region. The capacity and processes were insufficient to treat the inflows to the general limit effluent standard. In 2013, Drakenstein Municipality took the strategic and critical decision to upgrade the Wellington WWTW with a modern nutrient removal process and cater for foreseeable growth and expan- sion in the town for the next 25 years. Additional project objectives were to ensure the facility was operator centric and visually aesthetic. The upgrade would also alleviating stress on the nearby Paarl WWTW by diverting some of the Paarl sewer catchment flow to the upgraded Wellington WWTW. Zutari (previously Aurecon) in as- sociation with Lyners Consulting was appointed in 2014 to undertake the plan- ning, design and construction supervision of the proposed upgraded treatment works, and construction began in early 2016. The project was required to upgrade the works to a full biological nutrient removal process with an average dry weather flow capacity of 16 Mℓ/day, from the existing capacity of 6 Mℓ/day. UNIQUE DESIGN ASPECTS The project concept was for a fully automated plant with innovative features, including advanced processing technolo- gies to ensure a high-quality effluent, energy-efficient technologies, robustness, and a smart control system to allow op- erational and maintenance efficiency and better support the plant’s operators. A flexible operating configuration was designed for the biological reactor with the aeration equipment able to provide peak air requirements during the high loading season, while having a good ‘turn-down’ factor to save electricity during normal months. Energy efficiency was enhanced by minimising pumping through the works and adopting energy-efficient technologies such as a fine bubble diffused aeration system in the bioreactor, which is 15% to 20% more energy efficient than traditional technologies. The works can also run effectively on partial backup power for the critical equipment, reducing generator running costs during power disruptions. It was also decided to include primary settling processes, which can reduce up to 30% of the energy requirements on the downstream bioreactor. Furthermore, the works provides non-potable water to various consumers in the town, promoting the municipality’s drought resilience strategy. PROTECTING THE BERG RIVER The upgraded Wellington WWTW is making a valuable contribution to Drakenstein Municipality’s long-term strategy to protect and improve the Berg River, ensure resiliency, and increase capacity for future development in the region. The project serves as a good ex- ample of a smart, sustainable and resilient water infrastructure solution.  SANRAL SA I CE 2021 Nat i onal Awards Category: Techn i cal Excellence FINALIST Technical Excellence category (Sponsored by Maccaferri SA) KEY PLAYERS Client: Drakenstein Municipality Consultant: Zutari Contractors: Stefanutti Stocks & Inenzo Water Reviving our Rivers – Upgrading of the Wellington Wastewater Treatment Works An aerial view of the upgraded Wellington WWTW