MT. PLEASANT WATERMAIN RENEWALS - CHRISTCHURCH
DURATION
July 2024 – Current
CLIENT
Christchurch City Council
CONSULTANT/DESIGNER
WSP
VALUE
$685,000.00
The Mt Pleasant Watermain Renewal project was a technically challenging infrastructure upgrade, aimed at improving the water distribution network by replacing two existing water supply mains from the Mt Pleasant Pump Station and connecting on St Andrews Hill.
Detailed sequencing of the works was required to be developed, to ensure that the water supply to the Mt Pleasant reservoirs was maintained during the contract.
The work had been a long time in planning, with investigation works completed early 2024 to identify the existing buried utilities, most notably the adjacent high voltage transformer and cables. The engineers surveyed and mapped the existing utilities and designed a suitable 3-dimensional pipe alignment, essentially 'threading the needle' to ensure the new pipeline could get from A to B without any obstructions.
From the 3-dimensional design, the 2x 51m pipelines were broken up into a total of 43 bespoke pipe and bend sections, these were fabricated to exact tolerances and to a pressure rating that was three times the standard pipe rating, due to the increased pressure the pipes were under on the hill. A detailed construction methodology was developed to ensure the installation sequence achieved the required installation tolerances, as there was no ability to bend the steel watermains.
The pipelines were installed vertically up a cliff face which required the design and construction of rockfall mitigation netting and rock anchor bolts to restrain the pipeline. Staff and specialist subcontractors completed this by abseiling and scaling the rock face.
This project was crucial for enhancing the reliability and capacity of the local water supply network, ensuring long-term benefits for the Mt Pleasant community.