The Piriaka power station is a hydroelectric power facility in Manawatū-Whanganui in New Zealand which draws water from behind a weir on the Whanganui River near Piriaka and diverts it through a canal and penstock to the Piriaka Power Station, which is located approximately southeast of the town of Taumarunui, via SH4. The power station discharges back into the Whanganui River.
History
Development
Since 1914 the borough of Taumarunui had had a gas plant supplied by the Dreadnought Gas Co. which supplied the town with gas for lighting and cooking but by 1917 the system was beginning to deteriorate.
The passing of the Electric Power Boards Act in 1918 which allowed local authorities to generate and distribute electricity assisted in converting Andrew S. Laird, who had been the mayor of Taumarunui since 1917 into an enthusiastic proponent of electricity generation. While the Taumarunui borough council had intended to wait until after the First World War had finished before pursuing the matter further, Laird was able to convince the council to follow the lead of others in the region such as Ohakune, Raetihi and Te Kuiti in building its own hydroelectric power scheme. As a result, W. J. Gibbs the engineer of the Te Aroha Borough Council was engaged to investigate possible options. However, nothing appears to have resulted from his endeavours. Then in early 1919, the council asked the Minister of Internal Affairs to request Lawrence Birks, the senior electrical engineer in the Public Works Department (PWD) to assess the hydroelectric potential of the Taumarunui area. The government declined the request and suggested that the council employ a private consulting engineer.
Laird became even more supportive of a scheme after while attending a conference of local bodies in Hamilton in February 1919 to consider the development of hydro-electric power in the Auckland region and visiting the Horohara power station. The borough council polled its ratepayers for approval to raise loan to build a power scheme but the motion was defeated by 118 to 80.
Three months later as a result of losing the April 1919 elections Laird was replaced by former mayor, George Steadman and the idea of a power scheme was dropped.
By 1920 despite there being 71 local electrical supply authorities throughout New Zealand. Taumarunui had no electrical supply despite the Public Works Department pointing out that there was potentially a demand of 2,000 hp from combined population of the 9,667 in Taumarunui and the surrounding region, which was more than enough to justify the establishment of an electrical supply authority.
With the reliability of their gas supply system continuing to deteriorate (for instance by January 1919 it was leaking 25,000 to 30,000 cubic feet of gas per month), the borough council decided to investigate the options for switching to electricity. On 5 August 1920 applications (which closed on 6 September 1920) were called for from electrical engineers to undertake the necessary investigations and to provide an estimate of the required cost of a scheme. From the 16 applications the Wellington-based consulting engineers Hay & Vickerman won the contract, with a fee of £100 subsequently being agreed for their preliminary work.
The borough council formally received Hay & Vickerman's report on 18 November 1920. Hay & Vickerman offered four possible hydro-electric power and lighting schemes. The council adopted the engineer's recommended Wanganui River Number 1 proposal, which they estimated would cost £44,000.
Due to the undeveloped and sparsely populated state of the rural area surrounding Hay & Vickerman recommended against establishing a power board.
After the Wanganui River Trust consented to borough council's proposed power scheme, the Whanganui River or Wanganui River as it was then called, Hay & Vickerman applied on behalf of their client for a water power licence, which was granted on 21 February 1924. This licence also granted the borough council the right to distribute electricity with the borough, the town of Manauni, part of Kaitieke County along the sides of the Whanganui River for a mile either side from Kakahi down to the junction of the Onagare and Whanganui Rivers.