Valetta Irrigation Scheme

The Valetta Irrigation Scheme – now part of the MHV Ltd Scheme after an amalgamation with neighbouring Mayfield Hinds Scheme. This was the first major scheme for Aquaduct NZ Ltd. Together with sister company Bosch Irrigation, Aquaduct took on the design, supply and construction for the project. This included 84 km of large bore PE pipe of which 16km is massive 1600mm diameter.

The Valetta Irrigation Scheme is supplied by the open channel from the Rangitata Diversion Race (RDR) to the Valetta district irrigation area of 13,000 hectares at a flow rate of up to 4.5 cumecs.

The pipe system replaced an open race system. This resulted in significant savings by recouping the evaporation and seepage loss of channeled water and allowed 37% percent more area to be irrigated using the same amount of water. It also saved on-farm pumping costs and provides the possibility of electricity generation.

In total Aquaduct supplied pipe to the project in sizes from 1.6 metres diameter down to 200mm. 5,800 tonnes of polyethylene material were used to complete this project which was mostly supplied in pipe lengths of between 100 and 250 metres.
A number of innovations were created for the Valetta project including:
  • On-site extrusion of large bore PE pipe in lengths of up to 240m.
  • Floating pipe out of the factory in long plastic troughs.
  • Towing the long pipes from the factory yard on a series of dollies strapped to the pipe, using the pipe as the draw bar.
  • Trenching with a large modified chain trencher with screening off the output belt to separate the fines from the stones.
  • Vibrating the pipe (rather than the usual practice of compacting the bedding) while pouring in the bedding material to ensure that it is properly distributed around the pipe for perfect support. This not only saves time but adds to safety by eliminating the need for personnel in the trench pushing the bedding material under the pipe.
Distinctives of Valetta are:
  • Farmer cooperative owned and operated
  • Low cost high value scheme
  • Installed in record time with pipe extruded on site
  • Efficient gravity fed design
  • Minimal pumping costs. The only pumps in the system are for backflushing the intake screens
  • 60+ farms
  • 84 kms of pipe, including 16kms of 1600mm diameter
  • SCADA remote controlled individual farm log in
  • Exclusively designed and built by Aquaduct and Bosch Irrigation
  • Power generation potential
Valetta won the Irrigation New Zealand’s Innovation in Irrigation Award for the creation of 84 kms of pipe bringing water under gravity from the Rangitata Diversion Race to 60 farms. With pumping eliminated and power generation planned, the scheme continues to be an economic and environmental winner for its farmers.

In 2017 Valetta combined with Mayfield Hinds and operates as Mayfield Hinds Valetta Water

Manufacture of large bore HDPE pipes onsite

Aquaduct 2020 Ltd


P O Box 17,
Amberley, NZ 7441