McConnell Dowell is please to annouce that we have set a new Direct Pipe® world record, for the longest single drive by a micro tunnel boring machine (MTBM) on Watercare’s Snells Algies wastewater pipe and outfall project.

The project team and ‘Piper’ the MTBM set a record of 2021 metres at 3:45 pm on 28 July 2020, surpassing the previous New Zealand record by 92m. ‘Piper’ was adeptly named by students from Snells Beach School, they provided their handprints to decorate the machine with the intent to “help her on her journey”.

As well as the record distance the closed-faced Herrenknecht machine bored through challenging geological conditions, a curved alignment, and was considered an “essential” project during the COVID-19 lockdown making the achievement even more remarkable.

“This record achievement demonstrates the depth of skill and experience we have in our tunnelling teams, as well as our dedication to working through challenges to deliver another world class project for our customer,” says McConnell Dowell Project Manager Brent Whiting

The project is split into three distinct operations involving a trenched dig and lay section, a Direct Pipe® drive, and marine dredging for the final marine pipeline.

Over 4km of DN630 HDPE pipe has been laid through traditional trenched dig and lay, primarily along public roads and the design incorporated six air valves and seven scour valve chambers.

The outfall section consists of 2021m of trenchless installation of a 1220mm OD steel pipe which is linked to the seabed section of 258m of DN 335 HDPE pipeline.

Upon breakthrough, the MTBM was driven into a pre-dredged trench off the coast at Martins Bay. The machine will be separated from the main steel pipe and lifted to the surface using an in-house designed pontoon that will also be used to transport the MTBM to a local harbour where it will be lifted out using a straddle carrier.

This is the first phase of Watercare’s three-stage scheme to supply the Warkworth, Snells Beach and Algies Bay communities with reliable wastewater services to cater for population growth. The scheme will improve water quality in the Mahurangi Harbour and deliver an upgraded wastewater system.