Tasmania 1918-1945 Water (Hydroelectric) Power

Introduction

Around the start of the 20th Century, there were world-wide developments in the use of water power to generate electricity, and in the industrial uses of electricity, including electric metallurgy. The commercial importance of cheap reliable electricity was becoming obvious. In Tasmania several small hydro-electric schemes had been commissioned at Waratah and Launceston prior to 1900. In the new century Professor Mc Cauley from the University worked out the power potential of the Great Lake in the central highlands, and promoted its development.

Hydro Electric Era begins

There were various commercial proposals and negotiations for hydro-electric developments in Tasmania. A private company floated in London secured a concession over the Great Lake region, and began work on a power station at Waddamana. However the company ran into financial difficulties arising from transport costs and delays due to bad weather. The State Government agreed to buy the uncompleted project, and in 1914 the new Hydro-Electric Department took over completion of the power station and transmission lines. This marked the beginning of the Government policy of encouraging intensive industrial development based on cheap hydro-electric power. and the start of the ‘Hydro-Electric Era’.

In 1916 a contract with the Electrolytic Zinc Company was signed, described by the Department’s Director as “the precursor to a revolution in the industrial life of the State”. The works were constructed at Risdon on the western bank of the Derwent, five miles above Hobart, with deep water frontage and wharf accommodation for large ships, as well as connection to the Tasmanian railway system. After developing the treatment of zinc concentrates through the experimental and semi-commercial stages, the large plant went into full operation by 1922. Slab zinc and associated by-products were produced, using concentrates from Broken Hill and Rosebery.

At Queenstown the Mt Lyell Mining Company had independently proceeded with its own hydro-electric installation, using the water power available at Lake Margaret, seven miles from the works. This was completed in 1914. Electricity was then used to replace steam power in the works. Until 1928 the end product was blister copper, which was sent to Port Kembla for refining. From 1928 on the blister copper was electrolytic Z-ally refined on site in the Company’s new plant.

Following the initial power station at Waddamana, the Department further developed the Great Lake Scheme. The water supply of Great Lake was augmented by construction of diversion works on the Ouse River. The storage capacity of the lake was greatly increased by construction of a multiple arched dam at Miena, where the outflow was controlled to the Shannon River and the Waddamana canal system. The Shannon Power Station was constructed in 1929.

Hydro Electric Commission

The Hydro-Electric Commission (HEC) was established under the HEC Act 1929, and took over the responsibilities of the previous Department. The Act also vested in the HEC control of “all waters in lakes, falls, rivers and streams”. The HEC proceeded to plan the Upper Derwent Scheme, diverting water from below the river source at Lake St Clair to a canal leading to Tarraleah Power Station.

The state election in 1934 was very significant. The Labor Party was elected, with A.G. Ogilvie as Premier. This was the start of 35 years of unbroken Labor Government, with the Party winning 10 elections in a row. Ogilvie was one of the few political leaders in the 1930’s who went against the orthodox economic thinking of the time. He sharply increased public spending, borrowed more money, and expanded the role of government. Construction of the Upper Derwent Scheme was an important election commitment. The HEC pushed ahead, using a large workforce in arduous conditions. The Tarraleah Power Station, the first stage of the Scheme, was opened in 1938. This was a ‘run of the river’ station, diverting water from the Derwent, just below its source at Lake St Clair, to a canal system leading to the station.

Following the Zinc Works, in the 1920’s other industries were attracted to Tasmania by the availability of cheap hydro-electric power. These included carbide manufacture, chocolate making, and textile mills. In the 1930’s the Qgilvie Government facilitated the establishment of two large paper mills, located at Burnie and Boyer.

As well as funding the HEC works, the Government increased the workforce of the Public Works Department to carry out an expanded road and bridge construction programme. This included the replacement of the Bridgewater Bridge and construction of the Hobart Floating Arch Bridge. The principal designer of these two innovative structures was PWD engineer A. W. Knight. He was appointed Chief Engineer of the PWD in 1939 and then HEC Commissioner in 1946.

During the Second World War, Tasmanian mines, textile mills, and food processors worked overtime to meet wartime demand. Munitions factories were established, wooden boats built, and high precision optical lenses manufactured. To provide increased peak capacity, the Waddamana B Power Station was constructed. The fourth and last machine in this went into operation in 1949.

Construction of the second stage of the Upper Derwent Scheme (later called the Tarraleah-Butler’s Gorge Power Development) was much slowed by the shortage of manpower during and immediately after the War. It was not fully completed till 1959, The works involved Clark Dam in Butlers Gorge below Lake St Clair, Butlers Gorge Power Station, and a second canal to the existing Tarraleah Power Station.

The HEC continued to construct nearly all its works in the post-war period using its own day labour workforce. This expanded rapidly, helped in the late 1940’s by a sudden influx of displaced men from Europe’s refugee camps. By 1962 the HEC construction force numbered some 1,750 staff and award workers. Only specialised works such as tunnels were built by contract.

The 1944 strategic decision by the Commonwealth Government to build an aluminium smelter at Bell Bay at the mouth of the Tamar greatly increased anticipated power demand. This led to the Trevallyn Power Development, with a dam on the South Esk River in suburban Launceston. The power station went into service in 1955. In the same year the aluminium smelter operated by the Australian Aluminium Production Commission commenced production. Subsequently a ferro-manganese plant was built at Bell Bay for a subsidiary of Broken Hill Co. This commenced production in 1962.

Well before completion at Tarraleah. work started on building the Tungatinah – Lake Echo Power Development, involving dams on the Nive and Dee Rivers, tributaries of the Derwent. Following this, further power developments down the Derwent were progressively built. Of particular engineering interest, the Catagunya Dam completed in 1962, was an innovative prestressed concrete dam anchored on dolerite rock. At the time it was only the second major work of its kind anywhere in the world, and at 165 feet nearly twice as high as the first, located in Scotland.

The final power development down the lower Derwent was at Meadowbank above New Norfolk, and just above the tidal limit. This development became operational in 1968.

A prolonged drought in the late 1960’s, necessitating power cuts, underlined the need for expansion using water catchments elsewhere in the State. The next major development harnessed the rivers flowing north. Six power stations were built on the Mersy, Forth and Wilmot Rivers.

Water from the Great Lake was diverted northwards and down a vertical shaft to the underground Poatina Power Station 500 feet below ground level. The storage capacity of Great Lake was increased by construction of the Miena Dam.

Author: Ted Pitman