LAKE COLERIDGE.

Press, Volume LXI, Issue 18380, 13 May 1925, Page 11

LAKE COLERIDGE.

EXTENSION OF POWER

STATION.

STEEL CAISSON PLACED.IN POSITION.

An important part of the works in connexion with the extension of the Lake Coleridge power station was effected during the week-end in the sinking, into its proper position at the lake end of the subaqueous tunrifel. of the big steel caisson. By means of this caisson tho waters of the lake will oe tapped, and will oo conveyed by ™ ieS '* b ~ aqueous tunnel to the tunnels which deliver the water to tho generating units. Tb» caisson is a double-shelled steel cylinder 25ft in length: the outer shell is 19ft in diameter and the inner, lojft in diameter. It was manufactured by the Dunedin Engineering Company. Favourable weather conditions ou the lake were essential in order that the floating of tho caisson out to the end of the trestle could be effected successfully. A start was made at 6 o dock in tho morning, advantage being taken of tho calm state ot the lake waters. Tho caisson was rolled down the skids and took the water without interruption. A temporary top was placed on the annular (ring-shaped) space at the top; As the space between the inner and outer shells was air-tight the caisson was able to float. By the,courtesy of Mr Murchison, of Lako Coleridge station, his motor-launch was used to tow tne caisson. When it reached the end of tho trestle, the temporary top was taken off and water was'pumped into the space. between tho two shells and the caisson sunk to its correct position. Ihe water was then pumped out and concrete filling was placed in the space between tho two shells. This is the foundation portion, of the caisson ; other sections are to be superimposed on it. The subaqueous tunnel, which will connect with the caisson is at present constricted;to within 100 ft of the caisson. ' The eneinecring staff, naturally, are gratified that, this ticklish bit of work has been so successfully accomplished.