Analyst Proposes Theory For Deaths In Well

Press, Volume XCVIII, Issue 28869, 14 April 1959, Page 16

Analyst Proposes Theory For Deaths In Well

(New Zeaiana Press Association)

INVERCARGILL, April 13. Evidence concerning the accident which claimed four victims in Queen’s Park. Invercargill, on January 20 was heard before the District Coroner (Mr W. Grieve) in the Coroner’s Court at Invercargill today. One inquest, that into the death of Peter Brookland, a waterworks employee, was completed, a. 1 evidence was heard in the other three inquests, which will be completed tomorrow morning. A verdict was returned that Brookland died of anoxia, as a result of descending a deep well in which the air at the time contained an extremely low ’ concentration of oxygen, not sufficient to support life for more than a few minutes.

The other three victims of the tragedy were John Tapu Wilson, a waterworks employee; William Henry Little, a reserves department employee, and Thomas Terence McCambridge, a fireman. Analyst’s Evidence

Donald Frederick Nelson, acting Government Analyst at the Dominion Laboratory, Dunedin, told the Court that he took air samples from the No. 11 bore, where the accident occurcd, on the morning of January 21. On January 26 he carried out further analyses of the air in No. 11 bore, and also of the air in bores Nos. 10, 12 and one. A S2arch was made for carbon monoxide, hydrogen sulphide and methane, but these gases could not be detected. The January analysis of the air in No. 11 bore showed the gas was essentially nitrogen, with 3.7 per cent, carbon dioxide and little, if any, oxygen.

Air was approximately one part oxygen, which was essential for life, and four parts of nitrogen, an inert gas, said Mr Nelson. An atmosphere consisting essentially of nitrogen and devoid of oxygen would rapidly bring about unconsciousness and death if the victim was not quickly removed.

The presence of carbon dioxide would increase the rate of breathing and hasten death. To find the source of this lethal atmosphere in the bore, water samples were taken from bores 11 and 12 on March 25. Before the water was sampled the air was analysed. The oxygen content in No. 11 at that time was about two-thirds of the oxygen content of normal air, while the composition of the air in No. 12 was substantially normal. Analysis of the water in No. 11 bore showed that the sample contained considerably more carbon dioxide, about one-eighth the oxygen, and nearly three times the nitrogen of distilled water in contact with air.

Because of the sampling difficulties at No. 11, resulting from the pump failing every few seconds and the suspended sand and turbulence caused by pumping, it was probable that the gas content of the water was higher than shown in the analysis, said Mr Nelson. .

In a well the pressure due to the head of the water would increase the solubility of the gases, he said. From these figures it might be deduced that the lethal nitrogen in No. 11 bore came from the water. Conditions of still, warm weather might result in the nitrogen rising in the bore as a plug, rather than mixing with the air and diffusing away, said Mr Nelson. “Breathing” Another possible explanation for the nitrogen in the well would be “barometric breathing.” When the pressure rose air would be forced into the porous strata surrounding the well, and while there could lose its oxygen dus to lignite or iron in the strata. With a fall in barometric pressure this air, depleted in oxygen, would move back into the well shaft. To the Coroner, Mr Nelson said the most effective way of purifying the atmosphere in a well would be to pump air into the level where men were working, with a compressor. Alfred John Bertrand Canning, senior inspector of health at Ihvercargill, said the only appropriate reference on the department’s files to an incident of this kind concerned a death in a manhole in the United States. The general conclusion in thst case, after exhaustive investigations, was that the proportion of oxygen in manholes in low, swampy areas could be expected to be less than that in the atmosphere, and might drop to dangerously low levels.