DETAILS OF SCHEME.

Taranaki Daily News, 11 August 1922, Page 7

DETAILS OF SCHEME.

* FEATURES OF THE WORK, SOME STRIKING FIGURES. - • i * i ■ « "S ESTIMATES OF COSTS. ii*. . -2?! ~ I ' DESCRIPTION OF COMPLETE SCHEME. . „ (Known as Seheme No, 1.), ■j.he complete scheme provides for an intake on the Waiwakaiho River in the vicinity of the Junction Road 262J5 feet above the level of the tailwater at the existing power-house, and the conveyance of the water up to a maximum of 200 cubic feet per second by means of a tunnel called No. 1 tunnel, 1805 feet long, into the valley of the Mangamahoe stream. For the construction of a weir across the Waiwakaiho River at the intake to No. 1 tunnel for the purpose of raising the head of water at the tunnel. For the building of a dam 110 feet high and 610 feet long, on the crest, with a reinforced concrete core wall across the Mangamahoe stream to impound the waters of the Mangamai hoe and also the Waiwakaiho in a storage reservoir having an area of 95 acres, and a capacity of fifty million cubic feet, witlj a 15-foot draw off. i For the building of two embankments 1400 feet long on thef, south side of the proposed reservoir to prevent the water overa flowing the adjacent lands. K For the construction of a second tunnel (called No. 2 tunnel), approximately 4010 feet long, to convey the water from the storage reservoir to the forebay overlooking the Powerhouse. The level of this tunnel will be placed so that there! will be a draw off of 15 feet. The scheme provides for the construction of a forebay and surge chamber, also the laying of three Penstock pipes, 5 feeC internal diameter, supported on concrete cradles, together with all necessary expansion joint anchors, etc., and the conveyance of the water from the termination of the 5-feet Penstock pipes by branch pipes to the various units at the Power-house. The scheme involves additions to the Power-house, and a tail-race, and very large additions to the electrical plant. The units, when the full force of the station is in use, are taken as follows: — 2 units of 1500 h.p. each. > 2 units of 3000 h.p. each. The power developed will be 9000 horse-power, on a 45 per cent, load factor. DESCRIPTION OF PARTIAL SCHEME E.2. (Now in course of construction.) Being part of Complete Scheme No. 1. Under this scheme it is proposed to convey 150 cubic feet of water per second to present power-house at the increased elevation of the proposed new forebay to the existing powerhouse, thereby giving an additional 2000 h.p. This scheme includes the No, 1 and 2 Tunnels, being portions of the completed scheme, and conveying the water (viz., 150 eusecs), from one to the other by 3952 feet of open race cut in the hillside and 550 feet of pipes across the Mangamahoe Stream* From the forebay of No. 2 tunnel the water will be carried to the present power-house by means of Penstock pipes. It also includes electrical machinery to deal with the extra 2000 h.p. developed. The race and pipes conveying the, water between the two tunnels, estimated to cost £7535, are not classed as permanent works. The balance of the works form portion of the completed seheme. The construction of partial seheme E.2 is now nearing completion, the only work remaining to be done being:—• Construction of Forehay. Intake Chamber to No. 2 Tunnel. Alterations to water supply. Additions to electrical plant. In some cases the expenditure has exceeded the final estimate of cost. In others the expenditure is less than the estimate. Altogether it is expected that Scheme E2 will be completed somewhat under the estimate. ESTIMATE OF COST OF WORKS IN COURSE OF CONSTRUCTION, . £ Weir .-sj®...-..-.-..-,™ 2,200 No. 1 Tunnel 13,'131 No. 2 Tunnel, Water Race and Forebays, etc. 46,024 Penstock Pipes and Bus Pipes, etc 20,360 Extra Valves .. 1,600 Contingencies, Engineering, etc 11,815 Total Civil Engineering portion , £95,330 Electrical Plant .- 12,300 Change over to 3 phase ... . 5,400 Transmission Lines 12,000 Power House Cottages 2,800 Land purchase and easements .... 14.000 Contingencies, Electrical portion ...I 1,935 First year’s interest, jinking fund 10,900 Cost raising loans, etc, 5.335 Additional contingencies allowed ■ 12,000 £172,000 Allowed for enlarging tunnel forebay & survey, etc. 9,000 Further expenditure anticipated after completion of works for purchase extra turbines and generators, reticulation lines, meters, etc., before whole output can be , disposed of 20,000 Total—Partial scheme estimated cost £201,000 ESTIMATED COST OF COMPLETE SCHEME NO. 1. Dam across Mangamahoe Stream. 110 ft high, 010 ft long 75,000 Two Embankments 1400 ft. long, across the low-lying lands, on south side of reservoir 21.000 2 extra Penstock pipes, valves, bus pipes, etc. 29,000 Contingencies as above 6,250 Extra Turbines and Generators, etc 03,000 First year's interest and sinking fund .... 14,840 Cost raising loan 2.910 Total additional iost £212,000 Cost of Scheme E2, as shown above 201,000 Total estimated cost complete scheme £413,000 Total capital expenditure of present undertaking, excluding extensions 97,994‘ Total capital (.st of undertaking when complete scheme finished £510,994