Southern Valleys' Irrigation


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Southern Valleys' Irrigation

The Southern Valleys' Irrigation Scheme (SVIS) will be shut down during winter each year (approximately 1 June to 31 August, subject to seasonal variation). This is necessary to avoid additional power charges during winter months. Council will use this period to complete any outstanding maintenance. Council will consider operating the scheme during winter if there is sufficient demand. Persons wanting to take water during winter or the shoulder season should apply in writing. The rate to supply water in this period will be by negotiation.

If you have any questions regarding the shutdown, please contact either Stephen Rooney or Leighton Neal on phone: 03 520 7400.

Scheme description

The Southern Valleys' Irrigation Scheme (SVIS) was constructed to provide irrigation water to horticultural, farming and rural residential properties over an area of approximately 4,500 ha to the south of Renwick. Water is sourced from the Wairau River immediately below the confluence with the Waihopai River. The water flows from the river into a settlement pond and then via a new water race into Ruakanakana Creek.

The main intake pump station is located alongside Ruakanakana Creek at the end of Hammond Road. A secondary intake pump station is provided at the end of Fareham Lane, supplying water to properties in Fareham Lane and Guernsey Road, at the western end of the scheme. The Hammond Road intake pump station pumps the river water from Ruakanakana Creek into the piped reticulation scheme, which includes four booster pump stations.

Water is delivered to properties as per the Terms and Conditions for Supply of Irrigation Water (see above). In summary, pressurised water is available to each property in the scheme. Each property is entitled to a summer application rate of 0.208 l/s/ha (18 m³/ha/day), or the equivalent of 1.8 mm per day. Water delivery to each property is metered and regulated to control the flow rate. There is a minimum 40 m head downstream of flowmeters.

The Hammond Road intake pump station is required to deliver from 0 to 1,000 l/s at 75 m head over the main summer irrigation period, using four identical 280 kW submersible pumps (each capable of 250 l/s at 75 m head) with two operating on variable speed drive (VSD) and two on fixed speed, plus two smaller VSD 75 kW submersible pumps to pump at low flows. These small pumps will be required to operate in the winter and pressurise the system to 105 m head over a flow range of 0 to at least 50 l/s.

Submersible pumps have been selected primarily because of the low noise emission and suitability to pump river water. This pump station includes a 3 mm manual screen and settling chamber which is expected to remove all particles greater than 1 mm and 90% of particles greater than 0.2 mm.

The four booster pump stations will be required to deliver water through in-line submersible pumps at a range of duties, 0 to 122 l/s at 75 m head, 0 to 135 l/s at 92 m head, 0 to 135 l/s at 85 m head and 0 to 172 l/s at 32 m head over the main summer irrigation period, with all pumps operating on VSD. Paynters Road pump station has 2 x 45 kW pumps; all others have 2 x 90 kW. They will be bypassed and not operate in the winter when system pressurisation is achieved by the two 75 kW submersible pumps at the main intake pump station in Hammond Road.

They each use two identical inline submersible pumps mounted horizontally inside a stainless steel pressure casing, installed in a below-ground concrete pit beside the road. Where two pumps are required, they will operate in parallel, with each pump capable of delivering 50% of the duty flow.