MANGAPOIKE DAM & WATER STORAGE AREAS INSPECTED

Gisborne Herald, Volume LXXVII, Issue 23171, 6 February 1950, Page 4

MANGAPOIKE DAM & WATER STORAGE AREAS INSPECTED

HIDDEN in a vast expanse of hills, the Mangapoike water augmentation scheme based 30 miles from Gisborne came before the public's ego yesterday when the projects were inspected by members of the Gisborne Borough Council, officials of the Gisborne Fire Board and interested citizens.

They journeyed to the area in the morning and woe able to obtain a first-hand vnpresssion of the works accomplished and the scope for future development. Moreover, they saw the solution of a water shortage that has been a problem in this centre foi man}i years.

THE chief highlight for the 1 inspection party was the surveying of a storage lake holding 250,000,000 gallons of water and the recently constructed dam. The two are situated at the source of the catchment area of the Mangapoike Stream, while beyond about 10 chains from the developed area is an undeveloped pond capable of holding 300,000,000 gallons, and still another having a potential storage capacity of about 100,000,000 gallons.

The storage areas in the Mangapoike Valley are a few miles from the present source of the town supply in the catchment area known as Waingake. Consisting of 2200 acres of original native bush this catchment area in the Waingake Valley provides an abundance of water in the winter, but not in the summer, and consequently the augmentation scheme was proceeded with. Up to 2000 ft. Ideal weather enabled the greater part of the schemes to be inspected on the spot yesterday. The party consisted of about 50 pepole. The conveyances travelled over a winding route and rose to about 2000 ft. above sea level. Half of the journey was ever a sealed highway, but as the last portion of the metalled road was reached the cars negotiated a portion rising about 1300 ft. in almost four miles. On a clear day Mt. Hikurangi, near Ruatoria, is easily discernible but yesterday’s view was obscured by cloud. The last one mile and a quarter was over a private road, the summit of which reaches 2000 ft. and then slopes down to 1500 ft. —the height of the approach to the dam. From the bed of the storage lake at the roadside end. the concrete dam rises about 40ft. The foundations were laid 20ft. below the surface of the lake. Behind it members of the party noted with satisfaction that the level of the lake was almost to the spillway. It was filled in the flood of May, 1948. Buoyant Waters

Comprising about 58 acres, half • a mile long and taking two miles to walk around it, the lake is different from most storage areas, receiving the full effects of high prevailing winds which never allow the rippling waters to become stationary.

The water from the laxe flows into a pipeline which runs for three miles over a saddle and underneath the road and through a 330 ft. tunnel, then runs down a natural watercourse consisting of a foundation of lime rock which has the effect of aerating the water before it flows into a pond at the intake at Waingake. From there a 15-in. pipeline, too inadequate to give a flow to meet present-day needs, takes the water to town, covering about 18 miles. Generally the line follows the road, but in some country well known for slipping the pipeline is taken overland, with the route being shortened. The conception of the augmentation scheme by the council’s present consulting engineer, Mr. G. F. Clapcott, dates dack to late in the last century.

Mr. Clapcott first became connected with these remote localities while on surveying work in this district. He has not known more ideal storage areas in the country. He has been responsible for many engineering works works in numerous parts of the Dominion, including mining on the West Coast. Mr. Clapcott was absent from this district for many years and returned during the war period.

Additional Ponds Should the necessity arise—and this is not considered likely for many years as it is estimated that the existing schemes are sufficient for a population of up to 25,000—the other two impounding areas can be brought into operation without a great deal of difficulty. They are situatted in old creeks. No. 2 pond is in a handy position to the pipeline and possesses a Though the access route yesterday was in good order, the heavy rains in the district soon make a quagmire of the area. The rainfall in the Waingake region averages about 50in. a year, while at Mangapoike the yearly average over the past three years has been 90in. Manv difficulties stood in the path of the workmen, to whom great quantities of pipes and cement had to be transported

At present between 800,000 and 000.000 gallons of water are drawn each dav from the new lake and about 500,000 gallons a day from the old supplv from the Te Aral Creek, often referred to as the Waingake supply. Great Conception

“You are witnessing a great conception on the part of Mr. Clapcott and one on which full investigations were started nine years ago,” said the Mayor, Mi-. N. 11. Bull, addressing the party from near the weir.

He added that the scheme had been approved bv a number of engineers, some of whom had gained a good deal of prominence, and was regarded as the solution to a water shortage that

GISBORNE BOROUGH COUNCIL'S VISIT!

had been a problem for at least 30 rears. The supply, until the new storage area had been linked up, had come from the Waingake Stream. With this source, quite often in drv seasons the people of Gisborne were in serious dancer of not having enough water for their normal needs. The first duty was the meeting of requirements for ordinary purposes and the project could not be looked upon as an irrigation scheme. Mr. Clapcott, the Mayor commented, had joined the council’s staff as assistant engineer in 1940. but had been closely associated with the country in 1893 He had been asked by the council to find an augmentation water scheme and had thought of the old ponds which he had seen while in the district in the latter year. Long Range Plan

The scheme had been adopted early in 1941. and in June had been commenced with one exception. That had involved a recommendation by someone else that the water should be delivered through a tunnel to the watershed. This idea was excellent, but had been abandoned when difficulty was encountered in driving through solid papa country. The existing development would not onlv meet the present needs but those of future generations, commented Mr. Bull. The installation of a new pipeline td replace the present one and increase the capacity was a necessity, he said. The existing one, built more than 40 years ago, was designed only to last 20 vears. Mr. Bull remarked that the construction of the dam and the bringing into operation of the new impounding area were a big job for a community of the size of Gisborne and it was difficult to realise the difficulties in construction. The men engaged had worked in heavy rains, mud, and over dangerous routes. , The council had taken over about 900 acres of land for the'new waterworks. which included about 300 acres connected with the other two ponds. The time might come when it would be necessary to link up these ponds as the population of Gisborne increased, but the present areas probably would be sufficient to provide for the needs of a population of up to at least 25,000. Engineer Congratulated

When the capacity of the pipeline was increased with a new one fears in regard to the supplv of water would be completely banished. Mr. Bull congratulated Mr. Clapcott, and extended his appreciation to the contractors and to settlers in the locality who had given substantial assistance and had helped to provide access to the new work. The chairman of the Gisborne Fire Board, Mr. B. S. Bree, on behalf of the board, associated it with the compliments paid to Mr. Clapcott who, he said, deserved every one of them. The board, in its role to protect property from the ravages of fire, had been vitally concerned, for the consequences that might arise from a fire getting way were great. The recent decline of the pressure, he was sure, had given the superintendent of the brigade sleepless nights on a number of occasions.

In the first year that his firm had been engaged the area had had a rainfall totalling 112 in., resulting in no easy task, commented Mr. J. G. Marsden, a representative of the principal contractors, who thanked the council for allotting the contract to his firm. Discovery of Scheme

Mr. Clapcott. conveyed his appreciation of the remarks of the speakers. He recalled that he had begun with a flying start when the former Mayor, Mr. D. W. Coleman, had asked him to investigate a supply. To him it had been like going on a goldfield and hitting the paying ground first. When he had been asked to conduct an investigation and had surveyed the efforts made to find a supply he had walked over the top range and confirmed three facts—the form of storage, the rainfall and access.

He acknowledged assistance given to him, particularly that from the settlers and the consideration of the council.

He expressed regret that the contractors had had a number of difficulties, including shortages of cement and adverse weather. The contractors for the scheme were N.Z. Steel Pipe and Tank Company Auckland. The construction of the dam was undertaken under sub-contract by Messrs. I. Whale, Limited, Auckland. while the excavation and laying of the pipeline was carried out by the Gisborne firm of Mclntosh and Brooking.