Digester 8 – Lessons Learnt Constructing New Zealand’S Largest Mesophilic Wastewater Digester

To meet the needs of Auckland’s strong regional growth, the digestion facility at Auckland’s Mangere Wastewater Treatment Plant required expansion, and quickly. Effecting this by means of the addition of an eighth mesophilic digester, Watercare Services (Watercare), CH2M Beca and Brian Perry Civil united to design and construct Digester 8, New Zealand’s largest mesophilic wastewater digester.

With its brownfield site, wholly contained within the existing operational plant, the Digest 8 project was challenging. Key issues to be addressed were: the pressing need for augmented digestion capacity; a short construction timeframe; the need for outstanding quality; and the requirement for a unique blend of heavy civil, process, electrical and control, mechanical and commissioning disciplines. This challenge was met through a mix of both traditional and innovative approaches, and a persistent team of engineers from all parties who worked to bring the project to its successful conclusion.