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Ashburton Lyndhurst Irrigation Scheme Stage 2

Methven, New Zealand

Project execution period

December 2013 – July 2017  

Project description

The Ashburton Lyndhurst Irrigation Scheme (ALIS) supplies irrigation water to a local agricultural community consisting of approximately 30,000 hectares in the mid-Canterbury region of New Zealand.

Stage two of the ALIS upgraded the existing open race scheme with a pressurised pipe network including the installation of new telemetry network to enable water to be monitored electronically and remotely.

The project team built on the strong relationship with Ashburton Lyndhurst Irrigation Ltd (ALIL) established through the execution of stage one of the scheme, and was involved in the early project development and concept design works. Monadelphous (formerly Water Infrastructure Group) was awarded the detailed design and construction Contract for stage two in late 2013. The team engaged with land owners to determine their individual requirements, location of property connection points, expectations, and circumstances to develop the concept design and costings.

Contract value

NZ$88 million

Scope of work

The project scope included the design, supply, installation, construction, testing and commissioning of the irrigation scheme.

Detailed design optimised a pressurised irrigation pipe network with a capacity to deliver 11,500 lt/sec to all shareholder locations with only minor pumping requirements.

The construction scope included the procurement, installation and commissioning of 231km of pipelines, four mainline PRV stations, three minor pump stations, 243 property off-takes and automated regulator gates. Monadelphous was responsible for the hydraulic reticulation, structural and mechanical design, plus geotechnical and environmental assessment.

Highlights & achievements
  • Innovative design – taking advantage of the natural fall of the Canterbury Plains to provide pressurised water to the farm gate
  • The use of gravity resulted in significant energy savings (reduced pumping and transmission losses), increased reliability and improved water use efficiency (including a 15% saving in water by eliminating losses of open channel system)
  • The annual energy savings achieved by piping the scheme rather than pumping from races is equivalent to the energy used to power 2,000 homes
  • Buried pipe network allowed shareholders to develop previously inaccessible areas of open race in to productive farm land.
  • Staged delivery approach comprising sectional completion dates over a three-year period enable early revenue from water sales