WORK AT ARAPUNI

Rotorua Morning Post, Volume 1, Issue 178, 21 March 1932, Page 7

WORK AT ARAPUNI

RESORATION OF HEADRACE AT HYDRO-ELECTRIC STATION. ILLUMINATIN G FIGURES. « Everything is in readiness at Arapuni to commence the filling of the lake preparatory to resuming the supply of electric power. It is expected that thes tunnel gates will be closed on next Wednesday or Thursday. After that it will take from five t« nine days* depending on whether rain falls or not, to fill the lake. A further period of four or fiye days will be necessary to allow the maehinery to dry out, which means that power should be available before the end of this month, or well before the 'estimated time, April. The subsidiary gate in the tunnel will be installed within a few days. The erection of this was recommended by Professor Hornell, to act as an emergency measure in case of aecidents and to relieve the possibility of strain ori the present gates. The subsidiary gate will be placed roughly midway in the tunnel, which ser'ves tp direct water from the lake into the river's former bed. In order to obviate any likelihood of damaging the structure of the tunnel itself an area on each side of it outside of where the gate is to be installed, has been filled with concrete. As soon as the present gates are closed the tun- ' nel will be pierced at this point and the gate will be installed. • The entrance to the headrace is being dressed with a thin skin of Gunnite (a cement, sand and water mixture forced on to a surface with terrific pressure) to stop moisture getting into the rock.

When the river has been diverted over the headrace and spillway again with the closing of the tunnel it is inevitable that a certain amount of pumice will be borne down stream, but it is not thought that it will have any appreciable derogatory effect on the lower reaches. Logs which were lying in the remains of the buried forests are being blown up so that when the water rises they will not float away and cause trouble at Hora Hora or further down the river. Materials Used. ffn connection with the restoration works, the following quantities, etc., have been dealt with: — Bitumen, tons 1,000 Cement, tons 13,150 Metal, c ylds 46,947 Sand, c. yds 26,851 Steel Sheets, tons 300 Reinforcing Steel, tons 394.26 Exeavation, c. yds 237,039 Drains, feet 11,934 Concrete Slabs, number 94,752 Concrete, c. yds 38,861 Short Holes for grouting, feet 67,137 Long Holes for grouting, ft. 71,213 Drainage Tunnels, feet 10,539 Shafts, feet .... 671 Highest' No. of men employed 853