Lethal gas level in bore

Press, 29 July 1976, Page 3

Lethal gas level in bore

PA Hamilton A concentration of hydrogen sulphide discovered escaping into the atmosphere near Taupo recently would be enough to kill a person in a matter of minutes. But the high level is not found generally in the tourist townshio. Dr R. B. Glover, one of the D.S.I.R. scientists who carried out tests in Taupo recently, considers a by-law is needed to control the drilling of new bores. He said yesterday that the high gas concentration was found after a driller had complet d a new bore. The driller noticed a strong smell

coming from the steam output and asked for a test. “We were surprised at the outcome of the tests,” Dr Glover said.

A person was able to work in 20 to 30 parts of hydrogen gas per million parts per day. But the scientists discovered the new bore cutlet contained 950 parts.

“A person would not last long under those sorts of conaitions. Something has to be formulated before someone is killed. It’s just a matter ot taking precautions,” Dr Glover said. The bores at most Taupo homes were not emitting such a concentration of the gas.

A danger could occur if a bore pipe were placed below a home thermal pool’s water level. The gas would linger immediately above the water line and could be lethal if inhaled. Dr Glover said that if the gas outlet was high enough above ground level, as new outlets were in Rotorua, the poisonous vapour would be diluted in the air. But most of the Taupo outlets were close to the ground. The D.S.I.R. would test new bores, but did not have enough staff to monitor every weli The Mayor of Taupo (Mr C. S. Currie) does not think the problem is too serious. “It’s got the possibilities of building into something bad. Naturally we are concerned, and we are waiting on reports from the D.S.I.R. and we will act on recommendations made by its scientists.”

Mr Currie said something would have to be done to stop people from using the gas for heating. Taupo Borough councillors will meet early next month to discuss introducing bylaws to control bore outlets. By-laws governing the height of gas-exhaust outlets were introduced in Rotorua nearly two years ago. The minimum height for a new bore exhaust has been set at just over 6.5 metres. “The higher the fumes can be discharged, the less lethal it is. When the fumes mix with the air they are quite safe. The gas is dangerous when released in a confined

space,” the Town Clerk of Rotorua (Mr H. C. Childs) said. His council has asked the D.S.I.R. to make tests to see if some method could be found to filter the geothermal fumes. When the exhaust by-laws were introduced for new bores, it was stipulated that all existing bore exhausts must be adjusted within two years to meet requirements. The heightened exhaust outlets, or new filted systems being investigated would not lessen the smell of the sulphur. Mr Childs said: If you can smell it you’re 0.K., if you can’t, you’re dead.