CONSTRUCTION
McVeigh's Weir
In 1947, a weir was constructed
at McVeigh's upstream of Walsh's Creek to supply the Upper Yarra and O'Shannassy Aqueducts, then the reservoir construction
work was undertaken with day labour in three stages:
Ancillary works
These
involved an electricity sub-station for power from Warburton to the dam site, a modern works store, compressor building, equipment
repair shop, rail-head siding at La La, Warburton, reconstruction of the Wood's Point Road from Warburton (realigning, forming
and sealing, undertaken by the Country Roads Board), and accommodation for the employees involving two-men huts for 250 employees,
eight workmen's cottages and staff quarters, a mess building for 200 men, and a township water supply system and sewerage
treatment works. The threat of fires in the thickly-forested site led to the formation of a fire-fighting unit, construction
of firebreaks and access tracks, and installation of fire hydrants in the works and township areas.
River Yarra Diversion
A tunnel 2,600 feet long and 20 feet diameter was constructed through
the mountain side on the north abutment of the dam, carrying water to Doctors Creek then back to the Yarra River. Work commenced
in April 1949, and was completed in 1952 by driving both ends simultaneously, and the rock placed on the downstream zone of
the dam wall. The same miners were also employed to drive the tunnel through Mt Little Joe near Warburton. The diversion tunnel
was sealed with concrete plugs and two large valves in August 1957, and the river was trapped for the first time with two
68 inch steel pipes providing an outlet for minor flood waters direct to the Yarra River.
The
Dam
The first embankment material of the dam was put in place in 1951, and the construction was completed
in 1957 with 7.5 million cubic yards of earth and rock fill. The construction involved a reinforced concrete wall to cut off
any seepage across the foundation bedrock, projecting 10-15 feet into the impervious earth fill. This, together with a grout
curtain ensured that seepage did not undermine the earthfill structure. The core of the dam was red clay, and the outer layer
rock fill. As the clay was dumped from the borrow pits, it was spread by bulldozers then rolled by tractors. Each layer was
rolled 20 times. In 1955 seven 40-ton Euclid bottom-dump trucks were acquired, and a power shovel excavated over a million
cubic yards of soil for the spillway.
The Township
This was constructed to
provide all amenities to attract workers to such a remote and inhospitable site. Three quarters of the workers lived on site,
while the rest were bussed in daily from down the valley. At its peak, the project employed 1,300 workers with a population
in the township of 1,000 (about one third were wives and children). The Board provided a primary school, kindergarten and
health clinic, a large co-operative store, and a post office. There were weekly cinema shows, concerts and dances held in
the mess hall, as well as sports grounds. Initially, the labour force suffered a 300-400% turnover, but stabilised during
the course of the construction project.
Labour Force
Many single men
were attracted to the site, particularly migrants from Yugoslavia, Albania, England, Scotland, Ireland and Italy. Italians
disembarking at Princes Pier were even recruited as they stepped off the ships, those from farming backgrounds being favoured
for the work. Some of the new arrivals were unable to speak much English, and apparently workers wore numbers to identify
themselves.
Despite the mixture of nationalities at the temporary township, however, there was little conflict, and
Dingle and Rasmussen have called it "a conspicuously successful piece of social engineering". Indeed, workers cultivated a
particular pride in "our dam", and held what was known as "the Upper Yarra Star", with ex-Upper Yarra employees reputedly
being "given first preference on other jobs". Annual reunions of workers are still held today.
The bulk of the work
was undertaken using day labour. By mid 1950, 900 men were engaged on the project including 80 "New Australians", and those
involved in driving the tunnel, logging or stone-crushing received incentive payments. All materials for the construction
and township had to be brought in, and tools and tents were apparently in short supply.
Plant
and Equipment
The Upper Yarra project employed large modern plant in comparison with earlier dams, including
40-ton Euclid bottom-dump trucks, a power shovel to excavate the spillway.
Tunnels
Other
works included the expansion of the Upper Yarra Aqueduct to double its capacity (the sides were raised by 2 feet), and driving
the Mt Little Joe tunnel as part of the Upper Yarra-Silvan conduit. The tunnel was completed in 1950, involving blasting a
tunnel for 6,200 feet and eleven and a half feet in diameter, down to a depth of 510 feet through granite and homfels, using
pneumatic drills.
Commissioning
The completion of the Upper Yarra dam in 1957 coincided with the
centenary of Melbourne's water supply system, beginning with the building of the Yan Yean Reservoir in 1857.
