The proposed 46MW Arnold scheme will generate enough electricity to make the West Coast largely self sufficient, reducing transmission losses and improving security of supply. It will use generators in an 18km canal running from the existing Arnold hydro dam and then returning water to the river. The primary release back to the river from a regulation pond will be via an international standard White Water course, which, once constructed, will be operated by a community trust.

TrustPower will now carry out detailed technical design and geotechnical work prior to presenting its development case to its Board of Directors for approval. That work is expected to be complete within 12 months, allowing construction to potentially begin in 2012. During a projected 18-24 month construction phase, the Arnold project will result in a significant increase in jobs and expenditure for the West Coast economy, as the construction work will be labour intensive and require an estimated workforce of up to 200. The scheme is estimated to cost around $180 – 200M.

The proposed 72MW Wairau scheme will divert water from the Wairau River above the existing 11MW Branch River hydro scheme, though a 49km canal and six generators, before returning the water to the river. The existing 1 Branch River hydro Scheme consists of a 7.2MW power station on the banks of the Wairau River and a 3.8MW station on the Branch River, a tributary of the Wairau.

The Wairau scheme is also designed to improve security of supply and reduce transmission losses as more electricity will be generated locally rather than importing it from other regions. Currently only 16% of Marlborough’s energy is produced locally. The addition of the Wairau scheme will increase this to over 40%, through the addition of the scheme’s generation capacity producing 367GWh per annum.

The scheme includes the provision of two dedicated recreational areas for public use, and estimates of the cost of the project are in the range of $280 – 320M.

The Arnold project will precede Wairau, with detailed geotechnical studies and technical design for the Wairau scheme expected to take up to two years.