What lies beneath?
It is surprising what underground infrastructure can reveal as Auckland Council contractors discovered when excavating the partially collapsed stormwater pipe on College Hill for upgrade work. The works were being undertaken following the January flooding.
As Auckland Council’s General Manager Healthy Waters, Craig Mcilroy explains, a piece of the city’s construction history was uncovered.
“When trenching in August close to the junction of College Hill and Beaumont Street we uncovered a 19th century double brick lined drainage tunnel, constructed before the city’s foreshore began at what is now Victoria Park.
“After discussions with Heritage NZ it was agreed we could carefully remove the damaged section of the drain to enable the installation of line.”
The tunnel’s bluestone base with double-lined brick above has been largely preserved except for where it clashes with the new pipe being installed.
Pipes being installed are a significant advance in sustainable concrete production. The 2.5 metre pipes with a 600mm internal diameter are made of low carbon concrete that achieves a 22 per cent reduction in emissions compared with a traditional concrete pipe.
Hynd’s Group Sustainability Manager Dr Jackson MacFarlane says the development of these pipes is an important milestone in their sustainability journey.
“By using these pipes for the project, we were able to avoid over 4.4 tons of CO2eq emissions.
“Auckland Council have set an ambitious embodied carbon reduction target and we’re proud to support them.”
The is the first time Healthy Waters have used low carbon pipes, which are manufactured by using supplementary cementitious materials (SCMs) such as fly ash and blast-furnace slag as a substitute for traditional cement, the most carbon intensive element of concrete.
Auckland Council has identified concrete used in its construction projects, along with diesel from machinery and vehicles, as one of the greatest contributors to its carbon footprint.
Te Tāruke-ā-Tāwhiri: Auckland’s Climate Plan commits Auckland Council to reducing carbon emissions in line with national and international commitments and has set itself a target of a 50 per cent reduction in greenhouse gas emissions by 2023 with a goal of reaching net zero emissions by 2050.
The installation of pipe running from the intersection of Beaumont Street and Victoria Street West to England Street started Monday October 9. The $2.86 million project is expected to be completed in late December.