By Toni Williams
The 67km long Rangitata Diversion Race (RDR) may have started from humble beginnings, with workers using picks, shovels and wooden wheelbarrows in its development at Klondyke, Mid Canterbury in 1937.
But it has gone on to supply water to the district’s plains and helping to generate great social and economic benefits to Mid Cantabrians; from the people on the land, to those in its towns and villages.
The engineering feat of its development was celebrated last week by the Mid Canterbury RDR community; those connected to the system such as farmer and RDR Management Ltd (RDRML) chair Richard Wilson, irrigation scheme representatives, members of the engineering fraternity and other invited guests including ‘RDR Kid’ Viv Barrett, 87, (who, at age five, lived with his family in the RDR camp at Ealing as his father Jim, was the first RDR raceman).
Speakers included Mr Wilson, Environment Canterbury’s David Caygill, Institution of Professional Engineers New Zealand (IPENZ) Dr Terry Heiler and Engineering New Zealand heritage adviser Cindy Jemmett.
RDRML interim chief executive officer Tony McCormick said the celebration was the result of discussions between RDR Management Ltd (RDRML), including former CEO Ben Curry (also in attendance), and IPENZ who agreed the RDR project needed better acknowledgement.
An official information board detailing its history and its “engineering wizardry” was unveiled at the Rangitata River intake at the top of Klondyke Terrace during the celebration.
The RDR, completed in 1945, runs from the intake on the Rangitata River to a discharge site at Highbank on the Rakaia River.
Mr Wilson said the RDR was an icon which was built and had “served the community very, very well”.
“As a farmer who has spent all my life within the schemes (MHV and ALIL), I feel that the RDR is part of my river, the Rangitata, because it’s an incredible part of its social economy and everything that has come out of this district.”
“The economic backbone of our community is anchored in our ability to use water for irrigation and electricity generation and also in the future may help it enhance our environmental environment through MAR (managed aquifer recharge systems).”
“It is a great testament to the designers (from its origins with flat irrigation, to spray, pivot and in the future to variable rate irrigation) the RDR still runs the same way and fills the same purpose it was built for,” he said.
“Mid Canterbury’s economic prosperity is linked to the ability to use our plentiful water resource, and without the RDR running across the top, we would be very hamstrung to be able to get the water from (the intake) and to all the farms and the communities it serves. With a reliable water source communities flourish.”
ECan’s David Caygill was the former minister of finance, who signed the transfer documents from the crown to the local community back on October 1, 1990.
“I was proud to be part of that transfer, I was confident that it was the right thing for the Government to be doing.”
It was an example of a project which was better to be administered locally or privately rather than publicly, he said.
“I think it has been…when I think what this project has contributed to the community, I am well satisfied.”
IPENZ Terry Heiler said the RDR designers back in 1935 – 37 were dealing with complex hydrologic issues which were, even now, studied using complex computer models.
“…but these guys got it right. They got the hydrology right, as proven by 75 years of operation.”
Dr Heiler spoke of the size of the gorge project and the use of a diversion of water via gravel weirs and its difference to a bridge with heritage status.
“The RDR is a system, a complete system that starts here at the river and reaches right into the financial and wellbeing health of the Ashburton River,” he said.
“It was the biggest and the boldest move that was made in a country coming out of depression and looking forward to World War. It was a bold move to realise the potential of the trans-Rangitata desert that no-one else could farm in the years leading up to the year the water was available in 1945.”
Dr Heiler said in the 1920s the only thing the land produced well was rabbits and nor’westers.
“In those early days, this concept was in itself of international importance, to envisage the diversion of an alpine river from a vicious gorge carrying high bedload, the transporting and distribution of it across the plains, the crossing of 12 rivers – all of them equally difficult – the inclusion of hydro-electric power generation at the same time – which in itself was a very new thing,” Dr Heiler said.
The race was initially celebrated in 1990 under the Engineering New Zealand’s heritage project.
It was listed as one of 69 worthy examples of New Zealand engineers which helped to shape the communities of the nation. Those heritage projects are now under going a review.