THE TUNNELLERS.

Auckland Star, Volume LIX, Issue 76, 30 March 1928, Page 8

THE TUNNELLERS.

DRILLS, FUSES AND BANGS. SEWERING VOLCANIC AREAS. UNUSUAL DISCOVERIES MADE.

When expert tunnellers set out with popper drills and gelignite to blast their way through difficult country themselves into the undertaking with a zest that is born of the spirit of adventure. They are determined to shift things, but they do not know what will turn up.

Tunnellers now working in the Mount Albert and Mount Eden boroughs consider that they are dealing with country which is as challenging as any to be found in Xew Zealand. It is so because of the unusual formation and the wide variety of physical features. If there are difficulties—well, difficulties exist to be overcome.

An interesting cut has just been carried through the old cabbage tree swamp block at Edendale under contract from the Mount Albert Council, and it is extended to the eastern boundary of the borough at Parrish Road. In all. the length of the contract is 69 chains. From Parrish Road a similar cut is being made by the Mount Eden Council along the western boundary of its borough as far as Balmoral Road, then along that road as far as Henley Road. This will remedy the flooding which has been caused in winter time at the Dominion Road terminus. From the respective borough engineers. Messrs. J. Rogers and E. W. Begbie, it was learnt that all drainage contracts in hand are progressing well, and that further contracts are to be let as occasions require. Both boroughs are carrying through a system of drainage for stonnwater and sewerage, the water to pass out through screens at Meola Creek and the latter to join with the mams of the Metropolitan Drainage

The secretary of the Metropolitan Drainage Board (M r . H. H. Wat kins) stated that a comprehensive scheme is now being carried through by the board for the regrading and cleaning of the Meola Creek outlets. As part of this - ® 77ft trench « being cut ne ™ the Mount Albert Grammar School. The system is for the board to put in the mains and for the connate to carry out reticulation in their own boroughs. What the Gelignite Discloses. ! From the viewpoint of the layman it is of interest to note some of the discoveries which from time to time have been made in the course of tunnellmg in Auckland. In the cabbage tree swamp block recently the workmen traced a lengthy seam of fine white earth such as is said to be of value for the manufacture. of explosives and for

other commercial purposes. To a Pressman who drew his attention to the matter, Professor J. .A. Bartrum said that this deposit is known as "infusorial earth," and that it has been formed in the pools of clear water which originally existed in the volcanic areas. He said that the earth probably has a similar value to that of pumice for furnace laying, but that as it is found more or less extensively as a marine deposit it is not likely to be in great demand. There are few more reliable authori- [ ties on the working of volcanic areas than Sir. J. Williamson, a contractor who has carried through many undertakings for the Mount Eden Borough Council. He was met with on a contract in Oaklands Road, and to the inquiring Pressman he pointed out a variety of exhibits in subterranean parts—hard blue rock, stone honeycombed by volcanic action, scoria both rough and fine, papa rock, clay and sandstone. The greatest depth experienced in stone was 50ft. That was in Brentwood Avenue, near the Dominion Road bridge. "We found hard blue stone all the way 18 chains of it," said Mr. Williamson] and the deeper we went the harder it got. Work like that is not verv payin«» for contractors. °

Signs of Old Riverbed. In contrast, the greatest depth in clay and sandstone was about 70ft, under Mount Eden Road, at the junction with Woodside Road. The tunnel there was through sandstone, very wet, and needing a lot of timbering. "We met a stream of water there," said Mr. Williamson, "which needed a two-inch pipe running all the while to get it away." Asked if he had found any signs of riverbed formation, Mr. Williamson said l there were distinct signs of such in a tunnel at Woodside Road, near the Mount Eden terminus. "The ground," he remarked, "was very wet and marshy. We found old logs from trees, and at a depth of about 40ft kauri logs and some pieces of kauri gum. This is the only place in Mount Eden where I have known kauri gum to be excavated." . T Mr. Williamson was a member of the «ew Zealand Tunnelling Corps, that rather wonderful organisation which delighted to do things in its own way but never failed to "get there." He says that tunnelling to-day cannot be compared with the work in France The conditions are so different. "Tools used now, he added, "are much the same as those used in, say, 1900, except that the compressor and popper drill have taken the place of the hammer and drill. Jow we fire more blasts and use more gehgmte, but we save a lot in labour. Tunnelling experience in war time did not add to general knowledge for use in. civilian life."

Axe Nerve* Affected? .When one watches men working down at a depth in all kinds of difficult county* list ® n ® to the rat-tat-tat of the drills and hears the frequent explosions, the query naturally arises as to whether; "® rve ® health are greatly affected. Mr- Williamson says they are not affected any more than by other forms ol- manual work. In fact, men prefer

tunnelling because it is less monotonon. This contractor has a high the labour engaged on the Mount sewerage works. He says it is as mmi. if not better, than before the war. ",Bi% borough sees that the men on contracts are properly looked after, and men an more settled. * Spg "The relations between masterTtiiS men," added Mr. Williamson, to be much more friendly than farnwrty, and the officials of the Labourers* UraniKj seem to do the best they can for tbiT",' men without causing friction. Tn ; fApfe the workers to-day are more 11 IfW. than I have ever known them to be.* <*4