HYDRO-ELECTRO SCHEME.

Gisborne Times, Volume XXX, Issue 3415, 5 January 1912, Page 2

HYDRO-ELECTRO SCHEME.

LAKE COLERIDGE WORKS

[per press association./] CHRISTCHURCH, January 4. Tenders are to be invited at once for a supply olf machinery for the Lake Coleridge liydro-eiectrie scheme, and for the pipe-line which will convey water from the lake to the turbines. The Government recently called for tenders for the construction! of a tunnel 7100 ft long to convey water from Lake Coleridge through the hill to the Rakaia River, but only one Tender was receded, and at the end- of this week contractors will be again invited' to submit prices for the work. The tunnel is to have a mean grade of 1 in 1060, and its top at the lake end will be 12ft below the mean lake level. Its internal size, is to be Bft. by Sft in width, with semi-elliptical arch. It is to bo lined throughout with concrete lining, New Zealand cement being specified. The tunel will convey the lake water into the outlet works, where it will enter a pipe-line 2700 ft long,leading to the turbines- The pipes are to be of varying.. thickness up to five-eighths of an inch, according to the pressure, which gradually increases as the power-house is approached. There will be. a total fall of nearly 500 ft from the lake level to the turbines, enabling the. water to be delivered at a pressure of 2101 b to the square inch. -The test pressures lor pipes range up to 4001 b to the square inch.

Art present one or two pipe lines are specified, but at some future- date a third one will be .installed, and the tunnel is to be made, big enough to. cope with the supply then required. The initial machinery to be ordered consists of three Francis reaction 'turbines of 2150 brake horse-power, each deve oped at 500 revolutions per minute, send one pelton impulse turbine, developing 22 ohorse-ipower, to he used for driving the exciters. The main turbines will be. coupled direct to the generators, which are also to be ordered 1 at once, and the total eapacitv of the ]) ar.t will be 4500 Kilowatts, representing 6000 horse-power. The power-house and other structural features are designed so as to easily extend the capacity to 12,000 horsepower, where six genera tore will he recpiired. Specifications for the powcr-hojuse are not yet ready, as the requirements of the machinery will first have to be settled, but the general plan has been decided; in fact, so far as the electrical engineer’s department is concerned it has put the Coleridge scheme into final shape, and it is only necessary now for the machinery contractors to get to work- 'lender’s will be opened in the next three months, and the specified t ine for Uolivery at Lyttelton is within ten months of acceptance. The machinery specified is) cif a type in world-wide use, pud there are no' exclusive features in design which would result, ini restricted tondoring. Eight cottages for the powerhouse employees are to he eonMnicict. immediately, tenders for this work closing on January 31st.