Work Round The Clock To Finish Benmore Dam

Press, Volume CIII, Issue 30412, 10 April 1964, Page 1

Work Round The Clock To Finish Benmore Dam

(New Zealand Press Association)

DUNEDIN, April 9.

The construction of the huge earth dam at Benmore, the largest task in the £36 million hydro-electric project, will be completed next month—on time.

Men and machines are working day and night to complete the dam before the end of next month, the official end of the construction season.

The dam will contain almost 28 million tons of material to give a structural height of 360 ft and a crest length of 2700 ft making it one of the largest dams of its type in the world. With a production capacity of 540,000 kilowatts—almost six and a half times the amount of electricity Dunedin uses at peak load—Benmore will produce more electricity from its six generators than any other station in New Zealand. Today, the height of the earth dam was only 20ft below the final level. It was becoming more difficult for machines to work on top of the dam because of the everreducing width as the height increases. The final sft of material will be gravel to give a solid base for the two-lane road which will be built on top. Work On Spillway Work on other phases of the project is also nearing completion. The spillway is in the final stages of construction with work being concentrated at the top and bottom. The 1600 ft spillway channel has been completed except for a deflector block at the bottom. This block, 45ft high, 150 ft wide and 30ft thick, will deflect water from the channel in an arc so that the energy is dissipated without causing erosion. At the top of the spillway, two of the control gates and the sluice gates have still to be completed. Three penstocks, with an internal diameter of more than 17ft and an over-all lengt how 424 ft, which will carry the first water from behind the dam down 271 ft and through the powerhouse, have been completed. The other three are rising slowly up the 35-degree slope of the dam face as further prefabricated concrete sections are added. A start has been made installing equipment in the partially-completed powerhouse, in the control block, and the valve house for the unit which will convert the electricity generated in the station from alternating to

direct current for transmission to the North Island.

Although the first power from Benmore for South Island or North Island consumption will not be provided until April next year, electricity for a series of test transmissions through the conversion equipment which will supply the North Island with electricity through the Cook Strait cable, will be generated much sooner.