Background and Scheme Details
Since 1998, TrustPower has been investigating how to bring adequate electricity generation to the people on the West Coast. In March 2006 TrustPower filed an application for Resource Consent for the Arnold Power Scheme with the West Coast Regional Council.
The Arnold Hydro scheme evolved out of TrustPower’s original Dobson generation proposal. It is designed to assist the West Coast meet growing electricity demand, free up power for supply elsewhere in New Zealand and improve efficiency through reduced electricity losses from transmission. The Scheme is thus of national significance, with national as well as regional benefits.
The Arnold scheme involves diverting up to 100 cumecs (m3/s) of the current water flowing in the Arnold River via the canal to generate electricity. At a minimum, a 12-cumec flow (m3/s) will remain in the affected reach of the Arnold River. The scheme, including canals and ponds is approximately 12 km in length. The minimum flow regime forms the dominant mitigation measure for river ecology. Intensive monitoring of the river both before and post construction will ensure that the river ecology is protected. In addition, fish passage past the existing Arnold dam will be provided as part of the new scheme, an enhancement over the current situation.
After being used for generation, the water flow enters a regulation pond. The primary release back to the river from the regulation pond will be via an international standard White Water course which, once constructed, will be operated by a community trust. While the White Water course primarily forms a major mitigation measure for the scheme, it provides a new and complementary recreational opportunity for the West Coast and wider community.
The regulation pond allows the White Water course to continue to operate a high proportion of the time even when the scheme is not operating. It also ensures that discharge back to the river does not induce adverse environmental effects through smoothing out flow fluctuations.
Once the new scheme is constructed it is proposed that the existing power station be decommissioned. Most of the structures, however, including the tail race canal and pipe bridge will remain, and could become features in a wider visitor attraction associated with the Arnold River Scenic Reserve and Recreational area.
The scheme was granted Resource Consents by the West Coast Regional Council in November 2008. To see the Resource Consent application click here. These Resource Consents were appealed to the Environment Court by TrustPower (seeking clarification of conditions), one commercial tourism operator, two landowners and a local fisherman. TrustPower reached agreement with three of these appellants before the hearing leaving only TrustPower and the fisherman to proceed to the Environment Court. The Environment Court heard the appeal in March 2010 and released its decision approving the project in November 2010.
TrustPower is now undertaking further geotechnical assessment and detailed technical design, with a report on the scheme expected to go to the TrustPower board of directors in mid - late 2011. All going well construction work could start in late -2012.
During a projected 24-36 month construction and commissioning phase, the project will provide a significant increase in jobs and expenditure for the local economy. The construction work will be labour intensive and require an estimated workforce of up to 200.
The scheme is estimated to cost around $180 – 200 million.
For further information about TrustPower’s planned Arnold Hydroelectric Power Scheme please contact TrustPower Generation Manager Mike Kedian on 0800 87 11 11 extn 0.
