GISBORNE WATERWORKS

Timaru Herald, Volume XIC, Issue 13422, 21 October 1907, Page 7

GISBORNE WATERWORKS

Tin? reticulation of GisborneV'water supply was completed last week. It consumed \24 { miles of .pipes; 13 miles of which are.4 inch, 6 miles of 6 inch, and shorter lengths of 3, 8. 9, 10, and 12 inch pipes. 500 fire ' plugs, 192 valves and 850 house (services were fitted by the contractors; 45 tons of lead were. used in joining the mains and pipes. The. work of laying the main from the headworks to the borough was rendered unusually difficult through its having to be laid under two rivers. The contractor,'Mr Gordon, told the Gisborne "Herald" that there would have been no trouble at all, had the crossings been made with flange joints and rubber washers, but the lead joints were far from elastic, and took a lot of handling,;. The crossings are cornpoised of cast iron on the slopes, with a. si eel piping on the river bottom. Mr Gordon went on to explain jji detail the method with was adopted and the precautions that were observed to avoid mishap. After the pipe had been let down ■•successfully into the dredged out channel the pressure was .applied, . and a serious-' leak was , discovered. . The repairs could only be effected by a diver, and a, force pump was used to drive air into the pipes to ascertain the leakage by air bubbleis. Owing to the large amount of silt, the task was, exceedingly difficult, but after three days' actual work the defect was overcome. The same process was adopted in laying the main across the Taruheru, but "to the astonishment of the contractors- the application of the airpressure test?'proved that the job leaked from end to end. This, it was subseqriently discovered, was .'caused', by the lifting of'the'"pipe'"'whilst "subjected to pressure, and a remedy was soon, effected. When the final test' t:bok place, however, more trouble arose. -The specified test • was 300 Ibs, and the pressure had been • attained on the town end of the pipe, whilst the gauge on the Whataupoko side registered 2961b5. Asked what the .working pressure would be, Mr Gordon said' itwould not go above 1601bs at the outside. The inspector, Mr Hay,. was unsatisfied, and ordered the additional 61bs .to be. put" on, when, without warning, a blow-out resembling the noise of a shot from a confirm, took place in the river. To repair the damage; a coffer .darn had to be built, the .water 'pumped out, and the broken pipe replaced. It was a cast iron pipe which went, Mr Gordon added. The steel pipes, he.-was certain, would never blow out, as they had been submitted to a. 6001b pressure before leaving Wanganui. Upon the final testing of the section, every thing went off without mishap.