CPWL is proposing to develop an Irrigation and Stockwater Scheme in the Springfield/Sheffield area of mid Canterbury by September 2017. This Scheme, referred to as the “Sheffield Scheme” is physically discrete from the remainder of the CPWL Stage 1 and Stage 2 infrastructure and can therefore be developed and operated in isolation.
This standalone scheme will take water from both the Waimakariri and Kowai Rivers to irrigate an area of up to approximately 4,250ha. The proposed design includes a pump station and river intake at the top end of the scheme which will pump up to 2m3/s of water from the Waimakariri River into a 2.15Mm3 storage pond on the corner of Cox’s Road and SH73. In addition to this, gravity fed water will be supplied into the pond via the existing Council Stockwater network from the Kowai River. From the storage pond, water will be reticulated via a network of pipes down the plains in a South East direction delivering water at a minimum pressure of 3.5bar to shareholder farms.
In addition to irrigation water, the Scheme will also provide a reliable supply of stockwater to shareholders and rate-payers (where required by Council) year round. Providing stockwater from the pipe network rather than the existing open channel system will enable the closure (with landowner consent) of a significant portion of the smaller lateral water races fed from the Kowai River. This frees up water for irrigation use (albeit subject to more restrictive flow conditions) which would otherwise have been lost through ground infiltration and evaporation (between 70-95%). No additional water over and above what is already consented from the Kowai River is allowed to be taken from the river. Instead it is by investing in piping infrastructure to improve the efficiency of stockwater delivery in the area that is enabling water to be freed up for irrigation use. Under the existing regime a large amount of water must be taken from the river to ensure sufficient water reaches the extremities of the stockwater network. With a fully enclosed pipe system all water taken is used for its originally intended purpose.
Further still, CPWL is also working with the Council to identify opportunities to provide raw water to the two Rural Water Treatment Plants in the area. This would improve the reliability of the existing system and ensure there is sufficient capacity to keep up with forecast town growth.
The location of the proposed Sheffield Scheme relative to Stage 1 and Stage 2 is shown in the figure below.
In December 2015 CPWL lodged two resource consent applications for the proposed Storage Pond. These applications were publically notified in April 2016 and subsequently closed May 2nd 2016. In total, 39 submissions were received, 4 opposing, 4 neutral and 31 in support. Given the level of support shown for the proposal, CPWL is now working through the submissions and preparing evidence to address and find solutions to points raised in preparation for a hearing which is expected to take place in the coming months.