2009 image of the old Timaru reservoirs

Not selected for Google Earth or Google Maps [?]

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Bruce Comfort on February 5, 2012

In this 2009 aerial photograph (Off Google Earth) the construction and shapes of the two reservoirs can be most clearly seen. The rectangular reservoir was built in 1878-79 and was lined with basalt. It was extended (vertically) by about 7 metres in 1911 at about the same time as the pentagonal reservoir was built. That reservoir is lined with concrete and the walls of the extension to the No1 reservoir were similarly protected with poured in place concrete. What is amazing (and can be seen in other photographs under this tag - is that all the concrete was solid plastered to a thickness of about 30mm - and to a beautiful flat finish - something that would never be contemplated today where all concrete for utility structures such as these will be off-the-formwork finish.

Bruce Comfort on February 14, 2012

The 1879-1880 (approx) reservoir at the termination of Timaru's public water supply race.

Like many towns in the dry regions of New Zealand, Timaru was forced to create a public water supply system early in its development and before the rating base could fully support the expenditure. Early Timaru obtained its domestic water from drilled/dug wells, but they were generally unreliable and the water table fell below usable height whenever deep droughts struck.

The citizens of Timaru were engaged in a debate over the years of about 1868 to 1874, through their Borough Council and through newspapers (letters to the Editor) seeking the most cost effective way of building a permanent water supply. The centre of Timaru had been burned to the ground in an disastrous fire in December 1868 and it was clear that a reticulated water supply and a fire brigade was an essential for a growing township.

The council eventually decided to pursue a gravity driven water race from the Pareora River - an idea that had been floating around for ages.

Generally too, it seems that the people and the council were sure that the race was not so complex an undertaking that it couldn't be designed "in-house" (the council had a Chief Engineer of its own - Henry Wigg possibly as a result of the need for design of harbour works?) and built by a digger - being a man (or company) with the experience of digging water races for goldfield sluicing.

This is in considerable contrast to the Oamaru Borough Council which was embarking on a water supply project at the same time. They had decided that their supply (water race) was so complex that it was essential that it was designed in detail and by an engineer engaged solely for that task.

I haven't researched this Borough Race as comprehensively as I have the Oamaru Borough Race, however it is clear from the collection of drawings in South Canterbury Museum under the care of Tony Rippin, that when the race was approved, its design (layout and route) was at least the subject of a proper survey by a competent surveyor a John Thomas Thompson. To the extent that the route and elevations were defined, the race was designed. Whether or not he designed the water race structure (cross sections, siphons, aqueducts and tunnels etc.) is unclear because no drawings have been preserved, but it is possible he contributed to the detailed work of the Borough's Chief Engineer, as only a competent surveyor would have been able to transpose information on the feasible route into civil works that could be built at sustainable cost. The "idea" "to bring water from the Pareora River and deliver it to a reservoir in the downlands close to and above town" would probably have been well understood for decades beforehand and well recognised as being generally feasible.

Thompson's "survey design" is encapsulated on [extant] a about four large sheets of plan drawings and one elevation drawing rendered on linen reinforced paper (which is itself unusually thick) These drawings are dirty and somewhat distressed at the edges but very readable and useful. They are inscribed by Thompson and signed by him. They are dated around 1878.

They are in red and black Indian Ink and are colour washed to highlight the features shown. They are very complex with a large number of dimensions - some drawn in font so small that it is hard to visualise what sort of pen was used.

They define the easement (described as a right-of-way which it legally is/can be called) at about a Chain or 22 feet wide) with the general line of the race itself superposed by a central thick black line.

The history of the survey of the race includes this interesting report on the visit of Henry Wigg to see the Chief Surveyor of Canterbury and the Commissioner of Crown Lands in order to get the acquisition of the easements lands which were needed, settled.

Apparently reserved lands along at least a major part of the race had been set aside for some time and fencing along the boundaries of these reserved lands had been erected by adjoining landowners to the traditional "put-and-take" standards which practical men had been using for fencing legal boundaries for centuries - and still do. The fences follow the boundary closely or precisely or a feature of the landscape in the general sense of the boundary where adhering to the defined legal boundary would make it impossible to actually erect a fence.

The need for a two chain wide easement was generally established in New Zealand for such purposes, but Wigg was keen to not have to survey such a prosaic acquisition from scratch and to exactly two chains - there were unsurveyed sections where he acknowledged that a new survey to dimension was possible [his report advises that this is over about five miles] and appropriate, but over the bulk of the race he wanted to argue that a survey of existing fence lines was "good enough"

THE PROPOSED WATER-WORKS.

The following report of the Borough Engineer Mr Wigg was read at last Wednesday evening's meeting of the Borough Council.

4th February, 1878.

  1. In accordance with a resolution of the Council, I proceeded to Christchurch on the 28th ult. in order to consult with the Chief Surveyor as to the best mode of having the land reserved for water-race purposes granted to the Council at the earliest date. I took with me all the plans, sections, field-books, and detailed mathematical reductions of the numerous surveyed lines, and laid the same before the Chief Surveyor. "

  2. Interviews between myself and the Chief Surveyor took place on the 29th and 30th ult., and likewise with the Commissioner of Crown Lands on the latter date; both gentlemen giving to the subject matter much consideration and attention.

  3. The result of these interviews has been as follows: The Chief Surveyor has consented that all the lands reserved for water-race purposes which lie between the reservoir and section 23541 (about 5 miles from Pareora Gorge) are to be granted to the Council, according to the lines as they appear on the Government plans, without requiring me, as was first proposed, to reduce their bearings so as to agree with the lines of true meridian as lately established by the Surveyor-General's department. The Chief Surveyor, however, conceives it necessary that through all the lands which have not been surveyed by the Survey Department, extending from section 23544 to the head of the water-race (a distance of about. 51/2 miles) the lines which are finally to bound the reserve to be granted to the Council, should be laid out on the ground and surveyed on the true meridian, and for this purpose requires them to be connected with the lines of some trig, stations whoso distance and bearings have been recently determined by the officers of the Survey Department.

  4. To this requirement I have consented, subject to the approval of the Council but, in doing so, I have got the important permission that I need not confine the lines of fences to one chain on both side of the centre of the present tortuous race, but may lay out lines which may now, or afterwards, form those of the fences, and be in as long straight lengths as the nature of the ground will permit, which,in so broken a district, I think will be found a matter of great convenience, a saving of considerable trouble, and some extra expense in the fencing which would otherwise occur.

  5. As laying out the fences is a process that may, under any circumstances be gone through, it is far better to deal with this length of about 51/2 miles as early as may be convenient.

  6. When tho survey of the fence lines has been made under the conditions named above, the Chief Surveyor will accept the survey and adopt it as showing the lines defining the land to be granted to the Council, and no further survey of this length of reserve will be necessary for the purpose of passing the land under the Transfer Act so that I recommend the Council to adopt the suggestion of the Chief Surveyor and Commissioner of Crown Lands, the former having undertaken to furnish me with the bearings (from the true meridian) of trig stations in the neighbourhood of the proposed survey.

  7. With this report I lay before the Council, three sheets of drawings of special castings which will be required in conjunction with straight pipes numbered from 2 to 4 drawings in detail of proposed dam at lit ad of race numbered 5 design for the covered reservoir numbered 7 and also a list of the hydrants and valves which will be required for the whole Borough. "

  8. The sewer now being constructed in, the Great South Road is, of necessity, progressing slowly. In consequence of the fineness of the gravel used in the concrete, a longer time to set is required, than when the material is larger and more exposed to the free action of the atmosphere.

I am etc.

Henry Wigg, C.E. Board and Waterworks Engineer. 

In the absence of any existing complete and complex race construction drawings (such as were produced by Donald McLeod for the Oamaru Borough Race) it could be surmised that the contractors Black & Black, were simply commissioned to build the race to a general fixed dimension, with tunnels and aqueducts where set out and of these [there were just a few - two tunnels and possibly three or four smallish aqueducts] to "standard design"

Evidence in the form of existing sections of the race show it was small in cross section - and not unlike a gold miners' race with tunnels just big enough to crawl through (I leave it to the reader to consider how these tunnels were excavated and made durable!) in places it was formed with stonework and plaster and there was one section made in concrete, but over the bulk of its length it appears to have been just a small trench.

Although the race has been filled in in many places in the downlands, it is still quite clear in the Pareora Gorge and can be walked along - on parts of the easement (waterworks reserve) around Evans Crossing, land still in the ownership of the Timaru District Council.

Much of the detailed design of fixtures and fittings and of the reservoirs themselves (quite substantial structures) clearly fell to Henry Wigg who was the Chief Engineer of the Borough of Timaru and a surveyor also.

These items were comprehensively designed, as was a reservoir keepers' cottage and the valve and screen chambers but not everything got built to plan - it's common with civil works of this sort that the designer's dreams get squeezed into the budgetary reality of the day - and anyway, sometimes the things that get put on paper are not the best solution to what is encountered when the shovels hit the dirt.

So, we see in the collection of drawings, a design for the valve tower, valve chamber and connecting bridge of the conventional type, out in the lake, of which Oamaru's Ardgowan Reservoir, Wellington's Lower Karori Reservoir and Dunedin's Ross Creek Reservoir have extant and very good examples.

Timaru's one however was never constructed, and the valve chamber was built into the bund in the centre of the east bund and covered by a prosaic little corrugated iron shed.

Drawings are also there for a second structure, a covered reservoir - with vaulted brick chambers and roof, a huge Gothic structure partly underground and partly above with multiple courses of brick in the walls and an arched roof in three long rectangular sections of brick and concrete. Of course covered reservoirs were being built like this in bigger cities in the world and some may even have been built in New Zealand by this time (1880) but clearly the scale and complexity was outside Timaru's budget and the drawings never translated into civil works.

Just the one open bluestone lined reservoir was built. A second reservoir was not added until 1910-11.

The stone lined reservoir was designed to be 437' long and 127' wide at the top. This is 131 metres x 40 metres and with its sides sloping in to a floor of 116 metres x 20 metres this reservoir held 5,000,000 gallons of water at a depth of 20' (6.4 metres) That is roughly 25 million litres.

So far I have not located any photographs of the reservoir completed and filled with water - hopefully they exist.

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Photo taken in Centennial Park, Otipua Creek 7974, New Zealand

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  • Uploaded on February 5, 2012
  • Attribution-Noncommercial-No Derivative Works
    by Bruce Comfort

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