St Mary’s Bay Outfall

A new 2km long pipeline improving water quality by providing for increasing demand on the sewer system and reducing stormwater discharges.

PE pipe assembly by Solo at St. Mary's Bay Outfall

Introduction

In 2020, McConnell Dowell began digging the first of three shafts to accommodate their latest Tunnel Boring Machine to build a new 2km long, 1800mm diameter stormwater storage pipeline. The pipeline will meet an increasing demand on the sewer system as Auckland’s population grows. It will also significantly reduce combined wastewater and stormwater discharges and by improving water quality, will make local beaches safer for people and wildlife.

Challenge

Solo has been engaged to assemble a 460m long PE pipe and marine outfall.

The solution

Due to its length the pipe will first be welded together into one long string at Kaiaua in the Coromandel and then towed behind a barge for 90km to Auckland. Once there, Solo will weld together the giant (13m x 7m) final outfall Wye section on a barge at sea before it is bolted to the pipe and sunk into position. Divers will then make the final connection.