Spoil Dumping Not Cause of Disaster

Manawatu Times, Volume 63, Issue 81, 6 April 1938, Page 5

Spoil Dumping Not Cause of Disaster

Expert’s Evidence

NO SIGN THAT STREAM WAS DAMMED

Per Press Association.

WAIROA, Last Night.

The inquests on the Kopuawhaia victims were continued to-day before Mr V. F. Winter, coroner. The evidence to be called to-day was to comprise in the main that of experts. The first witness was Edward Walpole McEnnis, engineer in charge of the railway construction works at Kopuawhara. Daring the taking of the engineer’s evidence the coroner stated that, so far as he was concerned, the dumping of spoil from the tunnel bad nothing to do w r ith the disaster.

Mr McEnr.is said that the camp known as No. 4 was In existence before he went there. It was established in 1930 and comprised roughly 50 huts and tents, together with a cookhouse, bathhouse and carpenters’ shop. It was situated on the right bank of the stream. On the evening of February 18 there were 42 in camp, also two women and two children. The camp was situated on level ground about 12 or i 3 feet above the normal water level. He had never heard of the stream breaking over its banks before. What had been looked upon as serious floods in the past would not mean more than about a four-feet rise In the river. The two camps known as No. 3 .and 5 were situated cri either side of the camp. The road crossed the stream at No. 4 by a bridge approximately 80 feet long. The deck level of the bridge would be approximately level with the camp site. With an average winter flow there would be about eight feet between the water level and the girders, and the width of the stream would be at least 80 feet. The grade of the channel was fairly steep. The country which the stream drained consisted of steep, grassgrown hillsides and fairly narrow valleys. There was a negligible amount of forest. He understood that the deforestation dated back 40 or 50 years. There were four or five rain tributaries. Did Not Cause Concern. During February 18 the rain was Intermittent, being heavier during the evening. He saw the stream at about 4 p.m. It was dirty, with a slight rise, lie awoke about 3 a.m. The rain was then very heavy. When he saw the stream in the evening it did not give him cause for concern. After the flood he saw some girders of the bridge bolted together and weighing over five tons some chains down the river.

He was first advised of the tragedy at about 7.30 in the morning, and sent two assistant engineers to report on conditions there. Search parties were sent out, there being plenty of volunteers. The banks of the stream were scoured; also the are* covered by the flood. Other parties were detailed to make the access roads passable. The upper watershed, on investigation, bore evidence of heavy scouring, heavy slips and scouring occurring throughout the watershed. He estimated that 200,000 yards of material had been scoured away. Heavy logs and timber were scattered over the janks of the stream, some of the logs >eing 30 feet in length and three feet in diameter. 'l'here was heavy silting from the No. 3 camp downwards and ighter silting farther up. He had never ;een driftwood beyond two inches in liameter come down in floods pre/iou§ly. He did not know of any parts >f the river where an obstruction could iccur. Site Safe and Well Chosen. He had heard it said that the dumpig spoil from the No. 6 tunnel might iave caused the disaster, witness added, .’he high-water mark near the tunnel iter the flood disclosed a rise of nine eet. It was higher farther down. If he water had wanted to, it could have jone up another chain. The water .vould not be impounded even then. He considered that the camp was a ,afe one and well chosen. He had never iad any complaints about it. Beyond aying that there had been phenomelal rainfall he could not say what :aused the flood. To Mr. L. W. Willis, who appeared cr the Public Works Department, witless said that the record of the rainiall from 7 p.m. cn February 18 to 5 ).m. on February 19 showed 9.08 inches. The work of boring the tunnel had leen proceeding for about 18 months. ,Vi?en the boring started the spoil was lumped on the boulder bed of the itream, but not in the water. When hey started dumping, the distance .‘rom the road to the running water at he corner where the spoil was dumped «vas approximately 100 feet. The spoil vas dumped to a height of nine feet.

At this stage the coroner said he would like it to be known that he was satisfied that the dumping of spoil had nothing whatever to do with the disaster.

Witness added that the rise in the level of the river at the tunnel was 9 feet, showing that the water took the opportunity of spreading.

No Damning of Stream.

The spoil, witness said, consisted oi sandstone scrapings, with a heavy pro portion of fine material. All but a small percentage of the boulders in the dump would be ground up by the action o: the hard boulders in the riverbed. H< had prepared data of the fall of th« stream half a mile above, and the fal was 52 feet. At a point h&lf-a-mile above the tunnel the maximum discharge was 21,400 cusecs. Calculations showed that the spoil dump would probably disappear in about three months. From his observations there -was nothing to show that there had been any damming in the stream. There were several tributaries running into the stream between No. 4 camp and half a mile above the tunnel, and their combined discharge would be about 7000 cusecs. Witness said that a totara tree was some months ago cut from the camp site and portions were preservei". A section was examined by the orchard instructor from Gisborne, who estimated that the life of the tree was not less than

85 years. It was presumed, therefore, that the age of the ground where the tree grew was considerably in excess of 85 years. During an inspection of the country by air, witness continued, he saw a number of scars on the hills, and many of them were abnormal in size. The bush was felled 50 or 60 years ago and so far as he knew there had been no similar erosion since the bush wa« felled.