LAKE COLERIDGE.

Press, Volume LXI, Issue 18403, 9 June 1925, Page 10

LAKE COLERIDGE.

RECORD OVERLOAD.

Tuesday last, the 2nd inst., was as regards weather conditions, a day similar to yesterday; rain fell, and darkness set in early in the afternoon. This state of things in conjunction with the overlapping of the industrial, lighting, and heating loads sent the maximum recorded at the Lake Coleridge power-house up to 14,060 k.w., representing an overload of 2060 k.w., 'or an overload equal to over one-sixth of the nominal generating capacity of the plant. This peak load was recorded during the half hour, i p.m. to 4.30 p.m., and is the highest maximum recorded at the power-house. The peak load recorded at the Addington substation on the same day, between 4.30 p.m. and 5 p.m., also outstripped anv previous figures and was 11,340 k.w., or 660 k.w. below the total nominal generating capacity of the lake power station.

Mr R. G. MacGibbou, .Resident Electrical Engineer, told a reporter yesterday that the generators had stood up well to this big overload and were reported to be O.K. In view of this overload arrangements had been made by the "Department with the Tramway Board for the Board to bring into operation part of its stand-by plant for one hour, between 4 p.m. and 5 p.m. on days when the weather conditions are similar 'to those experienced on the 2nd inste and yesterday. The Board's plant is capable of generating 1500 k.w., and the-arrangement made is that 500 k.w. should be available under the conditions mentioned.' Mr Mac Gibbon added that ho did not anticipate that the lo°bd of tho 2nd inst. would bo exceeded this winter. It was noteworthy that tho highest peak load experienced this winter was recorded within four days'of last winter's highest? maximum, which was recorded on May 29th, 1924, and'was 13,180 k.w.,'the highest peak load which had been recorded till that date.

EXTENSION OF POWER STATION. PROGRESS OF WORK DURING ' '' a MAY. The report for May regarding the progress of the different works in connexion with the extension of the Lake Coleridge power station states that tho weather; during the month waj» favourable. At the end of the month thero was a total of 23G men employed, ns follows:—Officers, 7; artisans, 23 j labourers, 65; tunnel contract, 118; powcr-houso contract, 17; and cartago contract, 6. Steel Caisson. —On May 10th tho bottom length (sft 3in) of tho intake cylinder successfully launched and was floated into position at the head of the temporary trestle. The placing of concrete in the annular space between tho inner and outer shells 'of tho cylinder was put in hand, and at tho end of the month the level of tho concrete "was 15ft above the culling edge of tho ,cylindor. Thejflrst sft of con-* creto was placed under' water, the mixture used being:! part cement, \\ part sand, and 3 parts shingle: the shingle' was placed by means of 6-inch pipes leading to the base of tho cylinder. After placing the first sft of concrete under water it was possible to pump out the water and .place the remainder of the concrete in dry; The mixturo was deduced t~o I—2—4,'; and it. is proposed to use this, mixture to complete the. work. Tho cylinder had a marked inclination to develop a list towards the centr.o of the lake; but this was to bo expected on account of the. inclination of the lake bed at the point where tho cylinder is being sunk. It was overcome by manipulating the top loading, to ' suit, placing concrete in tho shorn ■Bide first, and by means of wire ropos between the cylinder and the shore. A sft length of cylinder was taken along tho trestle and placed on top of the section that was floated out. To date the' cylinder has been sunk only 2ft. The excavation down to rock level, by I moans of an orange-peel grab, will bo | commenced immediately. It is propoßod to excavate the rock portion without compressed aid if possible, by keeping the cylinder reasonably dry by means of a ten-inch centrifugal pump. A bulkhead has been manufactured and an air-lock in case it is found necessary to do tho sinking by compressed air. ' An experiment carried out with a four-inch centrifugal pump when the cylinder was embedded only 2ft below the lake bed gave promising indications of being able to I cope with the water by pumping, as ' the four-inch pump was capable of causing a difference of level of Cft between the inside and tho outside of the cylinder. Subaqueous Tunnel.—This tunnel has now been excavated to a length of 16 lineal feet, and tho walls have been for a length of 135 ft from the gate ' shaft towards the cylinder. The quality of the rock through which the tunnel is beiag driven varies considerably in hardness, but only a slight.seepage of water has been encountered so far. It is proposed to stop driving this' tunnel within about' 20ft of the cylinder, and to commence work upon placing of concrete invert and concrete lining of the gate shaft. T inhel Contract.—The following progress has been made during the month: Lineal Lineal feet for feet 'to Excavation—. - month. date. Intake end to centre shaft 132 1098J Centre shaft to intake end 49| 94J Centre shaft to outlet end 66 107 Outlet end to centre shaft 198' 1518J . Lineal Lineal feet for feet to Concrete lining— month. da'e. Intake end to centre ehaft 99 1041J Centre shaft to intake end 33 60 Centre shaft to outlet end 33 59 . Outlet" end to centre shaft 181J 1317* The contractors have considerably increased the number of men employed and better progress with the tunnel ;can be looked forward to in the future. | Surge Chamber. —During the month 290 yards of concrete were placed in the surge chamber. The concrete is now placed to a level approximately 10ft | above the top of the haunches. The three air vent pipes have been placed in position, and a total of 50ft of tunnel pipes leading out of the 'chamber have been connected in posi-* tion. Work is being restricted owing to the difficultyxof getting shingle from the K'akaia River. Pipe Line. —The pipe line contractors 'made an appearance upon the work during the • month; anchor blocks will be completed as the pipe line is erected. Power-house » Extension. —During the month the walls of the power-hou*e exterior were brought from the level "of the top window beam (1212.50 ft) to the under side of the cornice and parapet (1217.50 ft); 25i cubic , yards of con.crete were placed during the month. Boxing for roof beams and ceiling has' been fixed; 'all window-frames (with the exception* of eight which have not yet arrived on the job) have been fixed in position; reveals, sills and interior walla from the generator floor level up to tho crane runway have been plastered. Tail and Kace Extension and Weir Basins. —Two shifts have been working (Continued at foot of next column.) '

on the drag line excavator. To date 6500 cubic yards of material have been shifted; 2500 cubic yards had to be handled twice in order to deposit clear of excavation.. ,