ENGINEERS IN CONFERENCE.

Shannon News, 10 April 1923, Page 3

ENGINEERS IN CONFERENCE.

VARIOUS MATTERS DISCUSSED. Following is a report by Mr Davies, Otaki Borough ' Engineer, upon the Engineers’ Conference ■ held at Auckland last week:—■

Conference was .opened by; Mr Gunson,* Mayor of Auckland, on Monday, February 19, in the Technical Institute. He referred to the special advantages local authorities would receive by such gatherings. Local Governments, he said, were more than ever dependent upon the professional man, and Councils recognised that.if the best must be obtained engineers should be given an opportunity to compare experiences. He was delighted to see such a large attendance and to know that representatives were there from far north to the south of the South Island. He wished all a pleasant and profitable stay whilst in Auckland, and assured them of every facility in inspecting .'the many works of the City Council. .Mr Gunson’s remarks ' were heartily applauded, and on completion the President of the Society thanked him for the welcome on behalf of the members. The usual business w T as then proceeded with, viz., minutes, appointment of officers, balance-sheet, etc. After the.. ordinary business had been dispensed with, the. reading of papers commenced. The following is not a complete list' of. papers read, but are the most important'from the standpoint of County and' Borough Councils.

(1) The economical Te-loca J tion and ihipr.ovemenhpf, existing roads by alteration in grades and alignments. (2) Notes on road location: (3) Street paving by Trinidad asphalt.

(4) Tar-macadam treatment of roads. (5) Bituminus and tar-treated roads. (6) Road culverts. (7) County engineering as relating 1 o roads.

(8) Roads in the province of Quebec. (9) Sullivan-service reservoir (Dunedin water-supply).

(10) Los Angelos, water-supply undertaking. (11) Water supply (notes on). . (12) Algae in water. (13) -Pipe line secondary stresses. (14) Standardisation. (15) Notes on the' centralised fuel power-house, complementary to hydroelectric energy. ' The President’s address was taken first. This dealt with the coal supply of New Zealand. Graphs were given Showing-the •increase in- amount' ' won from the mines since 1886 to the. present year. This increase amounted to about. 25 per cent., every 10 years, such increase agreeing with, the previous experience of older countries. Tables were then given of the Government geological surveys of coal fields in New Zealand. From these (after allowing for the assumed' rate of increase) the probable life of. the coal supply in Ncw s Zealand was deduced, which is estimated at about 60 years. The visitor’s next object was to suggest means of conserving this supply. In -Ncw Zealand the consumption per head of population was about .2J tons (Great Britain 4J tons) exclusive of bunker-coal for ships. This consumption is analysed as follows: —. Railway 15 per cent. Coastal Steamers 5 per cent. Factories, Trams, Engineering, Bricks, Cement, etc.3o per cent Domestic 40 per cent:.; Less ..10 per cent. The writer' wen t on to explain that with development all classes would increase, though the 40 per cent, for domestic purposes could be decreased by the use of hydro-electricity. The total coal (estimated) in New Zealand was as follows: Proved 449,000,000 ton§, Estimated (Geological Dept.) 1,407,000,000 tons. By the present method of mining not more than 50 per cent, of coal could be mined owing to the large arches left for supporting the roof. There was also a very large waste through the small coal not being marketable. This had been made into briquettes in some countries, and if proceeded with a great saving could be affected. The use of this coal for power generating purposes had also

not been fully exhausted. The extent to which hydro-electricity should be installed,. along with the use of gas for heating purposes, was fully considered in the address.

The first paper taken (marked 15 on above list) was really a criticism of the Government in proceeding with the Arapuni hydro-electric works until the demand for this load had grown to such an extent (or was in sight) to ensure that such a scheme would pay. Mr Brown proposed to instal a steam generating plant at Huntley. The writer (Mr Brown) contended that, the capital cost could be kept down by installing sufficient power to meet the demand and increasing units as required. This could be readily done by erecting steam plants in the heart of the coal fields where fuel was cheap. The. advantage of utilising some of the waste coal as indicated ,in the President's address

would- also be met.i The paper was supported by several engineers. Mr Birk (chief electrical engineer) gave a very detailed reply, with figures to show that the optimism of the Government was justified, and that the Arapuni scheme would pay after the first year. Particulars had been taken of every small hydro plant in the North Island, which would be used as “demand creating units,” and in many eases (as in Wellington and Christchurch) steam and hydro plants would be used as “stand-by units” in the event of temporary failure of the main scheme. Mr Crookes and other engineers of the Auckland Power Board, supported the Government proceedings at once with the main scheme, and proved that within a few years Auckland city would require up to 30,000 h.p. The total output of Arapuni scheme is 150,000 h.p.

The chief items for discussion, however, were road-making and preservation of same. All classes were discussed, viz., concrete, macadam, earth, tar-mac-adam, grouting, and tar-painting, the type to be chosen being a question of economics, depending upon population, traffic, and grades of roads. Several experiments hg,d been taken showing the saving in power effected over a period of 40 miles by tar-treated and macadam road, and from this data the cost per mile a council would be justified in spending (w r ith a given traffic) was deduced. In a short summary of the conference this data cannot be given, though papers and discussion thereon will be printed later, and issued to eaeh member of the institute.

Among the works visited was the Nihipotu dam, which will be the chief water supply for the city of Auckland, situated about 18 miles out of Auckland. It is now almost complete, but has taken about 7 years to build. Other works visited were the concrete and laying of tar-macadam roads within the city, also a visit to the street works of the Tamaki West Road Board. This Board has recently let a contract for of tar work to be 18 feet. The method employed is what is termed the penetration method, and consists of scarifying the road surface, then laying four inches of metal, rolling it without a binder, and immediately after, spraying tar on to penetrate through the crevices. At this spraying the amount of tar used is equal to 11' gallons per square yard. After further rolling, more tar is supplied and carried over with fine chips of metal, thus making a sealed surface. Other important -works inspected -was the Auckland Electric Works (now in course of erection), and the harbour extension. On Saturday the conference finished, and was generally considered to have been one of the most successful.

On- Saturday Mr Davies travelled on to Rotorua. Sunday was spent in looking around Whaka and Rotorua, where hot springs, geysers, spout baths, quaky ground, and hot mud-pots are evident. Whaka is well-known as a Native town, though the hot springs make it. a particularly weird place, especially at night. Rotorua, however, is well-known as a very pleasant town, with its wide streets and beautiful gardens. When leaving Rotorua on Tuesday morning the party were informed that the first elections for Mayor and Council would be held that day, the Government having approved of the formation of a Borough to consist of two representatives from the Government and four Coun-’ cillors to be elected with a Mayor. VTauinaranui was reached ..by 7 a.m., whore the journey was broken, principally to inspect a stone-crusher offered for sale by that Council. The Chairman bf Works’ Committee and engineer took Mr Davies over the crushing plant and street works, also the hydroelectric plant, now in course of construction from the Wanganui river. This borough, with a population of less than 2,500, has recently carried loans total-

ling £96,000 £60,000 for electrical machinery with mains, and £36,000 for street improvement. They have a bed of shingle similar in many respects to Otaki. A stone : crushing plant has been erected complete with screens and bins for collecting various sizes of metal, from sand to 2i-inch. They have also purchased a steam roller and scarifier • along with a steam self-tipping wagon for carting the metal from bins to the streets. The amount spent on the above street-plant amounts. to approximately £SOOO. The cost per yard of metal crushed, equals to an average of 8s 6d> according to the amount put through per day, but the best effect of such a plant is noticed on the roads. They are able to place the right size of metal with binding, and later consolidating with roller, using a plentiful supply of water.