The Mangorei Power Station is a hydroelectric power facility near Mangorei in Taranaki in New Zealand which makes use of water from the Waiwhakaiho River (which is often written as Waiwakaiho) and the Mangamahoe Stream catchments.
History
Initial development
Of the first 14 publicly available electricity supplies in New Zealand, seven were in the province of Taranaki. Most of these were hydroelectric schemes, utilizing the seasonally consistent water supply provided by Mount Taranaki’s many streams. This development was driven by the demand for electric lighting by both town and rural dwellers plus farmers wishing to power their new electric shearing sheds, milking machines and separator.
In the late 19th century the New Plymouth Borough Council decided to investigate its options for constructing a hydro-electric power station to supply the town with electricity as well as providing a water supply. The nearby Waiwhakaiho River was identified as a suitable source of water. In 1898 a completion was held to design a scheme. The completion was judged by respected engineer Richard Liron Mestayer (1843 - 1921).
The council decided not to proceed with any of the schemes put forward and instead engaged Mestayer in 1901 to design his own scheme, which was subsequently accepted.
His design called for an intake on the Waiwhakaiho River from which water was conveyed to a powerhouse first by a tunnel that passed under the Mangamahoe Stream to a forebay on the hill, from which a diameter steel penstock conveyed the water down to a manifold outside of the station from where the water was split to supply two turbines.
Construction begins
Mestayer's design was accepted, which lead to a construction contract being issued on 13 July 1903 to McWilliams and Andrews to build the scheme. The tunnel was dug from the outlet, from a side drive about 16 chains (322 metres) from the outlet, and from a deep shaft about 21 chains (422 metres) from the outlet. From the side drive and also from the shaft the tunnel was driven in both directions. The alignment of the tunnel was laid out on the surface by Sladden & Palmer, Civil Engineers and Surveyors, and then transferred to the bottom of the shaft by means of heavy plumb bobs suspended from the top by very fine wires, with the plumb bobs themselves hanging in buckets of water to dampen their movement. The line thus transferred was produced in both directions by means of a theodolite. The line was marked inside the tunnel by iron spikes driven into the roof, and from which plumb bobs were suspended to guide the excavation. The levels were transferred from, the surface to the bottom of the shaft using a long steel tape, and then maintained as the work progressed by means of an engineer's level.
The power scheme received a licence from the government to generate electricity on 24 February 1905, and was completed in late 1905.
The first electricity was received in New Plymouth in January 1906, with 120 street lamps and the town hall being lit. By the end of the year the power station which operated from dusk to midnight was supplying 41 customers. By 1907 demand had increased with the power station supplying 126 customers and 230 by 1912.
The power station originally had two turbines each driving a 45 kW single-phase generator. To meet increasing demand the station was enlarged under the supervision of borough engineer A.H. Kendall to accommodate an additional 150 hp turbine driving a 90 kW single-phase generator, which entered service in December 1907.