pukekohe wastewater treatment plant

Temporary design in this sense is the ultimate balancing act of quick design turnaround, safety, reliability, ease of installation and removal, and cost.

Throughout 2016 ACH provided temporary works design support to the upgrade of the Pukekohe Wastewater Treatment Plant. Engineering design was required throughout the construction process to support the huge excavation (over 2,000m3) in which the new wastewater pump station and storage tanks would be located. This included temporary shoring to hold up the 9m high walls of the excavation and maintain support for 100 and 300 tonne cranes above. The area was located in soft soils and adjacent to a stream, so consideration had to be directed to the effects of ground water and constructability with the temporary supports in place. Temporary design in this sense is the ultimate balancing act of quick design turnaround, safety, reliability, ease of installation and removal, and cost.

The last time this treatment plant had been given an upgrade was back in 2009. Prior to which the plant was pumping wastewater into large ponds spread out over an area of 34.8 hectares, with the only treatment being a series of rotary aerators. The system posed some health risks to maintenance staff, was slow, inefficient in terms of land use and was prone to odour.

The 2009 upgrade subsequently stirred up excitement, with the newer system being heralded as “a state-of-the-art treatment plant that caters for business and residential growth and reduces environmental impact”. This initial upgrade increased capacity, efficiency and performance through increasing the treatment capacity and reducing the footprint to only 3.5 hectares. The plant became odour-free, safe and efficient.

Since the 2009 upgrade, the plant has been targeted again for this current upgrade in order to cope with Auckland’s rapid population growth. Watercare, who manages the upgrade, spent time discussing the planned project with local stakeholders, iwi, and community groups to ensure the best option was put forward for the community. This pre-consent process resulted in consents being sought for a longer term outcome, which will rehabilitate a wetland and improve water quality in a Waikato River tributary. ACH are very happy to be part of such a positive outcome for the future of our community.