When contacted by Stantec in January 2021 to help develop a solution for the Porirua Wastewater Treatment Plant, the team at Brian Perry Civil (BPC) knew they could help. BPC was engaged through Early Contractor Involvement for our client Wellington Water through their CAPEX panel. The team reviewed the permanent works design concepts and flagged the potential requirement for expensive and extensive temporary overpumping. BPC proposed the novel idea and a different approach to the temporary works required. By establishing a bypass of the treatment plant inlet works, supported by a semi-permanent step screen, a viable solution was developed. This solution generated a 16% cost saving, a significant achievement for Wellington Water, Porirua City Council, and their stakeholders.

Works commenced onsite in November 2021. The project was delivered efficiently and the team adapted to meet design changes and the requirements of working in an operational treatment plant. Working collaboratively with plant operator Veolia, the BPC team maintained open communication while also assisting with small repairs around the plant. Works were completed in April 2023.

Since the bypass step screen was installed there have been no untreated discharges into Tītahi Bay, as the bypass system was sized to the new hydraulic flow requirement.

Awards

1. Civil Contractors NZ Wellington Wairarapa Winner - Projects with a value over $2million
2. Civil Contractors NZ National Highly Commended - Category 3: Projects between $5m and $20m