THE BOROUGH RACE
In 1870, Oamaru was a pioneer town of just 3,000 people.
In the mid-19th century, wool was a much sought after commodity, particularly for military uniforms, and so wealthy families established very big pastoral holdings in North Otago. As there were no trees here, the land was immediately available for grazing sheep on the native grasses. Large flocks were introduced to meet international demand for wool. However the town soon needed some basic facilities before it could grow and become the town we see today, particularly before there was enough permanent wealth here to create our lovely limestone buildings.
The elegance of Victorian Oamaru's limestone buildings is well appreciated, but its 1880 public water supply, being out in the countryside and much less attractive than the white stone buildings, is not. It is however a work of considerable civil engineering competence which has its own elegance; an elegance which derives from its concept, design, execution and use. This use is a very unusual use but one which was central to the development of the town.
Water supply for the town, in 1870, comprised of wells and springs and a small ephemeral stream. Most households collected rainwater off their roofs.
The stream became polluted and muddy and the wells became unreliable. As the town grew, so did fire insurance premiums. A fire brigade with access to a reticulated town water supply became urgently needed.
Two factors influenced council decision-making: the effect of the poor water supply on health, and the cost citizens were forced pay for clean water. A reliable water supply would solve both these issues.
The hills close to and right above town had deep gullies which were suitable as reservoir sites. It was pretty obvious that any of these could, with just an earth dam, provide good water storage at a height above the town which would create a water supply delivering water at over 100psi. How to get water there, however, and where from, soon became one of the defining questions for Victorian Oamaru.
A few options were obvious, and some less obvious. A few ridiculous ones too, were proposed. Pumping from the Waitaki River with steam driven pumps was possible and there was coal nearby, but the cost and maintenance of this technology was daunting for the council. In the end, a gravity water race was decided as the best option. This decision started a complex process of selection and construction.
Commencing with what was, in effect a competition with a prize of £150 for a design, the council eventually appointed an engineering designer. They then commenced the appropriate fund raising, the publication of statutory notices, and tendering.
By 1876 a public water supply and distribution scheme had been designed and land was acquired, legislation passed, and the necessary finance raised on international financial markets in London and Scotland. Over the construction period, funding had to be increased twice to cover the final costs. By 1881 when it was finished, the race had cost £136,000 and servicing the loans bankrupted Oamaru for two decades.
Despite the fact that many of the town's citizens were unconvinced that it would work or was even necessary, this major public work needed careful and competent design.
As well as the physical remnants of the Borough Race which are illustrated on the panel adjacent, Oamaru still has the 70 sheets of original drawings created by the design engineer, Donald McLean. Duplicate copies (for the council and the engineer) are drawn on transparent linen in red and black Indian Ink and washed with water colours. The survey sheets are seminal to the project, and are remarkable. They are beautiful artefacts in their own right.
The Borough Race, as it became called, is a fascinating item of New Zealand's industrial heritage. Not only was it well made and very functional as a town water supply, but also because the design, from the beginning, included 300HP of "spare capacity" to be available for motive power. This provision, required by the council, is what makes the race unique in New Zealand, and probably rare anywhere in the world.
The Borough Race is a long hand-dug channel with a very low gradient and its intake was a long way inland and at elevation. It terminated at a generous reservoir relatively high above town. The race traverses nearly 49 kilometres from its intake on the Waitaki River. It was carried over 19 streams or across substantial gullies encompassing small streams. This was done by constructing wooden trestle box aqueducts.
Six tunnels were driven to penetrate a number of rocky ridges.
To protect supply quality, all along its route, there were comprehensive provisions to divert any small streams, watercourses and natural run-off generally over the race. This was achieved with wooden troughs called overbyes which were small aqueducts in their own right. They carried contaminated water away from the race.
These structures also protected the race from over-filling and over-topping during heavy rain. If uncontrolled run-off entered the race in quantity, it would overload and over top the banks, causing catastrophic erosion. This happened a number of times in the history of the race.
The water in the balance of the race flowed at just walking pace.
The five tunnels have a combined length of 2.7 km and the 19 timber aqueducts have a combined length of 1.4 kilometres.
The tunnels are all still clear and they have a flat floor. Being over two metres high, they could be comfortably walked through to maintain them. They are partly lined with cut limestone and the arched portals are built from bolstered blocks.
The aqueducts are on mixed wooden and limestone (block) piers and they have substantial timbers in their structure. For a water supply, some are quite big. One was very big. A few were rebuilt in the 1940s with concrete piers.
The timber had to be sourced from outside North Otago and was tarred to make it durable. It was mainly kauri - huge planks! All the steelwork was made locally. The aqueducts were originally of rectangular box section roughly two metres by one metre, but all these flumes have been replaced over the years with half round steel.
The fall was calculated to be 1:3964 (although the first four kilometres are steeper and three concrete structures were built to slow the water and break its force in that first section).
Construction work began in 1877. The race design comprises an open channel about two metres wide and one metre deep, pretty much following the hundred metre contour from the intake on the Waitaki River at about 126 metres above sea level to the reservoir at Ardgowan [above the town] where the water level is 97 metres above sea level.
The race was unlined and only puddled or plastered with cement in a few places. At first it leaked, but this eventually stopped as silt built up and the banks became colonised by water plants.
The race was maintained along its whole length by a team of about seven racemen who lived with their families in small houses along it. Their job was to clean and maintain the waterway and the land beside it. Each had a specific ‘beat’ to look after.
Because the race flowed slowly, it didn't naturally flush material down its length. While this was a boon for water quality, it required a team of dedicated racemen to keep it flowing and the banks free of build-up and growth. It was de-watered every Wednesday and the racemen would go into the watercourse to remove plants and contaminants like mussels and waste matter.
Horses and drays were kept at two locations and a centrally located engineering shop and forge was used for maintenance and to create the required hardware. In later years, when the hillsides were more heavily stocked with cattle, the race needed full fencing on both sides for its whole length. This required around 150 kilometres of fencing.
Apart from small take-offs permitted for domestic drinking and stock watering along its length, the intake water was delivered in its entirety to Ardgowan. The race was not used for irrigation of pastoral land, but in the 1960s some irrigation of orchards and berry farms was permitted.
As the water was reticulated right around the business area of the town and because it was over 100psi, it was quickly recognised as being ideal for running electricity generating turbines. The first electricity was generated from the town supply in 1887. It is thought that there might have been up to 100 independent DC generating plants in Oamaru at the peak of the technology.
As soon as it was built, and the very large cast iron mains laid throughout the town, the spare 300HP designed into the race was put to work through water engines, turbines, Pelton wheels and other water motors. One water engine rated at 135HP ran a large Haslam refrigeration compressor for the local freezing works.
The New Zealand Refrigerating Company had an built an abattoir at Eveline (near the outfall of Boundary Creek) in the late 1870s. Carcasses were taken into Oamaru for freezing on board specially provisioned refrigerated sailing ships and then shipped overseas. The ‘frozen meat business’ was seminal to Oamaru's later growth and wealth and is a whole story in itself.
The NZ Refrigerating Company, realising that ships could turn around more frequently (and profitably) if the carcasses could be frozen on land while incoming vessels were in transit, built a freezing chamber and store in Oamaru. The company was however, continually at odds with the council over its massive consumption of water and the rate it paid for it, and eventually its compressors were run on steam.
By about 1895, grain growing had overtaken sheep farming in North Otago, and large flour mills and grain stores on the waterfront dominated business. These too used the mains water supply to run water engines and turbines for motive power.
The first DC power was created using a genuine Pelton designed (patented) wheel connected to a Compton Bipolar generator, just three years after the Pelton wheel was patented in America.
When it was switched on, the Red Lion Flour Mill was lit by 23 electric light globes. Urban myth has it that on that evening Oamaru had more electric lights than London – and we still have the generator here in town!
By 1915 the borough council recognised the potential for reticulated AC electricity to be generated from the water in its supply pipes. It decided to build its own Pelton wheel powered plant running off the water delivered to the reservoir by the Borough Race. Although it took until the middle of WWI in 1917 to see the fruition of this vision, Oamaru became the fourth town in New Zealand to have council-supplied, fully reticulated AC power.
The race was in use for 103 years and was de-commissioned in 1983. Some of the remains of the race are still here and the tunnels and a number of the aqueducts survive. The bywash sluice gates and the fence that kept the stock out over the whole 50km (on both sides) can still be traced. Four of the racemans’ cottages are still lived in today.
Sadly all the easement land is now back in private ownership and the artefacts are slowly slipping into the past.
This water supply is an inspirational an example of Victorian engineering and is an achievement of Oamaru should be very proud.
The artefacts comprising the race are sort of protected by the Historic Places Act which makes it an offence to modify anything both created before 1900, and associated with our heritage. However many of the aqueducts have been demolished, some prior to the Act, and some after. Many of the demolitions can very easily be defended on the grounds of safety. Luckily some of the more remote aqueducts still survive in excellent condition for their age.
The Borough Race is not a listed (historic) item or place and is under-appreciated by the community. Many Oamaru people do not know anything about it and certainly not that it was used to generate electricity so early in New Zealand's electrification history.
However, many of the landowners with histories that intersect the place and the period when the race was operational are well aware of it and its stories, and that it had significant potential right up until the day it was de-commissioned.
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Photo taken in Pukeuri, New Zealand
Misplaced? Suggest new location