Thursday, November 17, 2022

 
 
Shaping the face of N.Z.
The Ministry of Works and Development, adviser to the Government on the design, construction and planning of all public works, probably is the country’s biggest “scene shaper.”

Its work involves roading, power, irrigation, public buildings, town and country planning and many other fields. Consequently, nearly every New Zealander is affected by the department's activities.

The ministry’s head office is in Wellington but for operational purposes the country is split up into seven districts and several special-purpose power projects like the Upper Waitaki hydro development. The largest district in the country is the Christchurch district, covering an area of the South Island bounded by Kaikoura to the Waitaki River on the east coast and Karamea to Jackson’s Bay in the west.

The size of the district makes for great climatic variations, from high rainfall coastal areas to arid conditions in the east, with mountainous country in between. It is not unusual when travelling by car from the West Coast to Christchurch to encounter heavy rainfall, snow and then blazing sunshine all in the space of three hours. Such varying conditions bring with them many problems in engineering and construction work.

The public probably sees the ministry’s men most often as they work on roads, although this is only one aspect of the department’s responsibilities.

Last year, the Christchurch district spent $8.9 million on maintenance and improvements to the State highway system. The department acts as agent for the National Roads Board.

Irrigation is another major activity where the department is responsible for the maintenance and operation of five major schemes. A major new scheme on the Waiau plains is currently being planned.

Town and country planning affects most people at some time in their lives, and this legislation is administered by the department. Much of the work is advisory and involves co-operation and coordination with local authorities in the preparation and administration of their district schemes. But there are many other important activities involving regional development, coastal reserves, advice on planning and lately the proposed new town at Rolleston.

Another activity involves the design and construction of major public buildings, such as the Christchurch police station, law courts, schools, and university buildings.

The James Hight library building at Ilam, recently commended by the New Zealand Institute of Architects, is an example of what the ministry can achieve.

But the department is not always commended. It is often criticised, particularly in areas like property acquisition.

No-one likes to have their property acquired for a public work, but it is an unfortunate fact that where such works are essential in the national interest, someone will be hurt.
 
 
Many problems for engineers
The Christchurch district of the Ministry of Works and Development, covering Canterbury and Westland, poses many problems for civil engineers.

The six engineers and 12 draughtsmen of the district design engineer’s section provide a structural design service to the highways, irrigation, public health and hydrological survey sections.

Most of the section’s work is concerned with bridge design, and the wide range of topography from the Canterbury plains over the Southern Alps to the coastal strip of Westland presents quite a contrast in bridge sites — wide, braided river channels, deep gorges and steep, swiftly flowing rivers draining areas of high rainfall.

The early bridge engineers did not, understandably, build bridges suitable for present traffic needs. They generally chose the most favourable, and consequently economical, sites. Now that locations have to be changed to fit in with road alignments designed to satisfy modern traffic requirements, sites are often less suitable from a bridging viewpoint, resulting inevitably in higher costs.

An interesting insight into development over the years can be seen in the bridging programme. Canterbury has always been well-populated and consequently has been relatively well served with bridges. The bridging needs of the West Coast, however, did not receive such high priority in the past, apparently on account of the fairly sparse settlement there. Now the designers are finding themselves involved in an extensive programme to strengthen and replace older bridges on the West Coast while at the same time designing overbridges and underpasses for the Christchurch motorway.
 
Staff of 1500
The Christchurch district office of the Ministry of Works and Development employs more than 1500 people. They are divided into staff and “wage workers.”
 
There are 662 staff in Christchurch, 99 in Greymouth, 110 in Timaru and 59 in Westport.

“Wage workers” number 329 in Christchurch, 117 in Greymouth, 77 in Timaru and 91 in Westport.

There are also 80 people engaged in special employment schemes designed to maintain full employment.
 
 
 
Irrigation a great benefit
About 90,000 hectares of the Canterbury Plains have benefited from irrigation schemes constructed by the Ministry of Works and Development since the 1930s.

Most of this land is supplied with water from the Rangitata diversion race, which has its intake at the Rangitata Gorge and carries up to 1000 cusecs 42 miles across the top of the plains to the Rakaia River at Highbank.

There, the river is 300 feet below the plains. Water that has not been diverted to irrigation passes through the Highbank power station to generate electricity.

The three schemes supplied with water from the Rangitata are Mayfield-Hinds (35,000 ha), the Valetta Farm Settlement (7000 ha) and Ashburton-Lyndhurst (26,000 ha).

Two smaller schemes are the Redcliffs (2000 ha), which has its intake on the Waitaki River, and the Levels Plains (5000 ha), which takes water from the Opihi River.

Another scheme, Morven-Glenavy (12,000 ha), which has its intake on the Waitaki River below the Redcliffs scheme, is nearing completion. Water has been available to parts of the scheme for two seasons and will be available to the whole area in 1976.

A new project, the Waiau Plains scheme, was given approval in principle earlier this year and is under investigation. It is hoped that full approval for the scheme will be given later this year.

The irrigation schemes are operated and maintained by Ministry of Works and Development racemen who see that water is delivered to the farms in rotation to meet farmers’ requirements.
 
 
Roads a Key to Prosperity
Roading is the backbone around which the prosperity of the country has been built. When there is a holdup or collapse, their importance to the nation’s economic and social life is brought home with a jolt.

The Christchurch district office of the Ministry of Works and Development is responsible for nearly 1500 kilometres (916 miles) of national State Highway and about 1000 kilometres (628 miles) of provincial State highway in its district.

The office has the job of carrying out the policies of the National Roads Board and also services the board’s district roads councils, each of which is headed by the district commissioner of works.

The office investigates proposals for new roading and is responsible for arranging standards for things like highway alignment, sealing widths and speed values.

Another responsibility is the arranging of any restrictions needed on State Highways, like speed limits, parking restrictions and bus stops.

The office also issues permits for overweight loads to use the State Highway system. Permits are only granted for loads which cannot be broken down into smaller packages.

Up to the beginning of July this year, 183 permits for single journeys and 52 continuous permits had been issued.

Cranes, motor scrapers, traction engines (with rubber-tyred axles) and heavy plant carried on transporters are the kinds of items that would require a permit.

In addition, the office carries out overall supervision of highway maintenance and construction work and runs a traffic counting information service which provides important data for planning.

The district highway engineer (Mr J. G. Sullivan) is in charge of roading. Construction and maintenance work is the responsibility of the four resident engineers at Christchurch, Timaru, Greymouth and Westport.

The Christchurch office would like to see the sealing of all State Highways in the district. About 71 kilometres (44 miles) are unsealed, much of it on State Highway 70, which runs inland between Kaikoura and Culverden and carries a low volume of traffic.

Although the office is primarily concerned with State Highways, it is also involved with local authority roads. An example of this is a study being carried out into the needs of logging traffic with the new chipboard mill at Rangiora.

Finance for roading work comes from the National Roads Board. Funds can also come from the “roads vote”, which is under the control of the Minister of Works and Development and is used for the development of roads in remote or difficult areas.

During the 1975-76 financial year, more than $6 million will be spent on State Highways in the Christchurch district.

A further $5.25 million will be paid in subsidies to local authorities.
 
M.O.W. has watch on environment
The environment is a prime consideration of the Ministry of Works and Development, which has a staff responsible for scrutinising its own plans as well as those of other departments.

Planning officers are concerned with the overall public interest when works, including State highways, buildings and other major projects, are being conceived.

The ministry also studies all district planning schemes prepared by local authorities under the Town and Country Planning Act. If it considers that there is a need for additional public works it can recommend appropriate action to the minister.

If it identifies a weakness in a district scheme or some matter apparently contrary to the public interest, the ministry can recommend that an objection be lodged.

Apart from this more formal role of study and possible objection, the ministry is able to offer environmental advice and a landscape design service at all stages of public works planning.
 
Waitaki—a huge power reservoir for N.Z.
In terms of cost and generating capacity, the Upper Waitaki power development is the largest hydro scheme ever undertaken in New Zealand. It will not be surpassed until the Clutha project gets under way.

The Waitaki River, third in New Zealand in flow rates behind the Clutha and Waiau, rises in the Southern Alps. It draws on a vast catchment dominated visually by Mount Cook and other peaks.

The $300 million Upper Waitaki project is located on the vast inland plain known as the Mackenzie Country.

The middle reaches of the Waitaki River have already had their hydro-electricity generating potential tapped, first with the Waitaki dam near Kurow and, in more recent times, by the Benmore and Aviemore projects.

Now the second-third of the catchment’s hydro potential is being harnessed, leaving only the last 45 miles between Waitaki dam and the sea to be possibly used at a future date.

The three glacier-created and glacier-fed headwater lakes of Tekapo, Pukaki and Ohau break the monotony of thousands of acres of parched tussock land. In sourcing the Waitaki River they each disperse through outlet rivers taking their individual names.

Apart from one small power station completed on the Tekapo River more than 20 years ago, the generating power of these rivers has until now not been harnessed until they each flowed into Lake Benmore to boost water storage behind the large earth dam.

In the new project, however, the river flows will pass through four new stations before reaching Benmore.

Huge earth dams will span two of the river valleys and, by the time the project is finished more than 100 million cubic yards of earth will have been moved.

The first stage in the Upper Waitaki power development involves the diversion of the Lake Tekapo outflow from its natural course down the Tekapo River valley.

The existing Tekapo A power station stands only one mile from the lake, powered by water led through a . hillside tunnel. Since 1951, the water from Tekapo A’s tailrace has reentered the Tekapo River and passed on to Benmore.

By late 1976, however, the Ministry of Works and Development will have finished construction of a 16 mile canal which will couple up to the power station’s tailrace.

Taking its name from its source lake, the Tekapo power canal strikes out almost at right angles to the normal river channel and will carry the flow into Lake Pukaki instead of Benmore.

Civil engineers engaged on the project have calculated that the canal would be large enough to have the inter-island ferry Aramoana motor down its path.

It terminates on a plateau high above Lake Pukaki and the water then has a vertical fall of 500 feet passing through twin steel penstocks for more than a  mile before it rushes through the first new power station in the project, Tekapo B, and then out into the lake. At this stage two of the headwater lakes will have been united.

Tekapo B will have two generators each producing 80,000 kilowatts to give a total capacity for the station of 160,000 kilowatts.

The natural outlet from Lake Pukaki is already controlled to hold storage for the Benmore, Aviemore and Waitaki power stations but a new dam under construction will double the capacity of the lake.

A massive concrete spillway is under construction to pass flood flows into the Pukaki riverbed.

From the western side of the new dam, another canal strikes out to carry the combined flow of lakes Tekapo and Pukaki to the next power station in the scheme.

The Pukaki canal will extend for some eight miles to the northern bank of the Ohau River and containing both Pukaki and Tekapo water, it will pass nearly four times the flow of the 16-miles Tekapo canal.

Peak flow capacity is to be 15,500 cusecs, or nearly six million gallons a minute. Width from berm to berm is 262 feet and the depth of water will be 33 feet. It too is built from natural materials. In comparison to the one-ship earlier canal, the Pukaki canal on completion will be able to accommodate both the Aramoano and its sister-ship, Aranui side by side.

Just before it reaches the powerhouse site, the Pukaki canal is joined by yet another canal, this one carrying the outflow from Lake Ohau.

Their confluence, 1700 feet above sea level, is a historic landmark for here the Waitaki’s three headwater lakes will merge into one united flow. At present they do hot meet until Benmore.

The combined canal flow passes through a giant concrete intake structure, and then crashes down through four, 19 feet diameter steel penstocks to the Ohau A powerhouse. From the end of the canal it has a vertical fall, or head, of 194 feet.

The Ohau A powerhouse is tucked into the north bank of the Ohau River valley. To locate it there a massive earthmoving exercise has seen 2.25 million cubic yards of glacial spoil excavated from the site.

The largest of the four new stations, Ohau A, will have a peak generating potential of 264,000 kilowatts, from four generators.

The water will be expelled from Ohau A into a new lake to be created by the construction of a dam across the Ohau River valley.

Lake Ruataniwha, just to the south of Twizel, will have an area of some 850 acres and, although its creation is still some years away, landscape staff and ecological authorities are already working on the establishment of a lake-shore environment complete with wildlife habitats, recreational areas and boat launching ramps.

From the Ruataniwha dam, water will be led through another natural material canal to the Ohau B power-station and then to Ohau C, virtually on the shore of Lake Benmore. Stations Ohau B and Ohau C are being built to a common design, each with a generating capacity of 212,000 kilowatts.

In terms of total power! output, the completed; Upper Waitaki project will; ultimately provide sufficient electricity to fill Auckland's projected requirements for 1975. If the present demands of Christchurch, Wellington, Dunedin, Hamilton and a few other cities were aggregated, they would not be able to use all the Upper Waitaki output. 




Tu Tangata, Issue 7, 1 August 1982, Unnumbered Page