Quarrying & Mining Magazine
Feature

When the rivers run over

The year 2010 was recognised as one of the worst on record for natural disasters across the globe, not least for flooding in Australia. Jim Hankins, managing director of Rivergum Industries and chairman of the Sydney sub-branch of the IQA, looks at a plucky Aussie sand producer that braved the impact of a flood disaster and rebounded back to business.

GUNDAGAI IS A HISTORICAL town, approximately halfway between Melbourne and Sydney, on the Hume Highway. It was recognised as a good location for crossing the Murrumbidgee River by our pioneering ancestors.

The town also has a colourful history of bush rangers, a gold rush, and the infamous dog on the tuckerbox (see story below). As of mid-2010, Gundagai had not experienced flooding of the Murrumbidgee River for some years.

Rain fell in the various catchment areas upstream of Gundagai in late 2010. A “below minor” (these terms are related to the height of the river) flood peak of the Murrumbidgee River was reached in early September, at Gundagai.

Heavy rain fell in the catchment area in October and a “minor” flood was experienced with the river height peaking at just over seven metres. After heavy rains during November the Murrumbidgee reached a “major” flood peak of 10.2 metres at Gundagai at the start of December.

A quarry in its path

Tegra Australia is a family owned quarry and concrete business based in southern NSW and manufactures quality aggregates, sands, soils, river stones, river pebbles as well as pre-mixed concrete.

Tegra operates four quarries, seven concrete plants and has two mobile batch plants. Two quarries – Jugiong and Gundagai – are four kilometres from the Hume Highway and both are ‘surrounded’ by bends of the Murrumbidgee River.

Tegra installed a wash plant at its Gundagai quarry six years ago. This operation uses a 30-tonne excavator and a 30-tonne dump truck.

The truck loads a feeder, which sends material to a scalping screen, with a 50mm aperture. The oversize is sold as river rock or is crushed and screened to appropriate sizes. The throughs of the scalping screen are fed to a triple deck inclined screen, with apertures of 20mm, 10mm and 5mm – the minus 5mm goes to a sand screw. Tegra can make a range of natural aggregates and washed sand from its primary feed. Alternatively, with a portable crusher, it is able to crush the oversize and make a similar range of crushed aggregates and wash the crusher dust to make manufactured sand.

Tegra has an older fixed crushing and screening circuit at Jugiong, along with a cyclone sand plant, as well as a fine sand plant (cyclone). This site can produce similar products to Gundagai.

On the 3 December, 2010, with rain continuing to fall and the river rising, Tegra was formally advised of releases from the Burrinjuck Dam on the river with the final amount being 48,000 megalitres. The quarry personnel moved the mobile equipment to appropriate-height ground based on the advice of water releases and forecasts by the Bureau of Meteorology, but left the submersible pumps as they were.

Unbeknown to any of the locals, a landslide occurred on the road to Burrinjuck Dam, leading to a loss of communications. As well, gauges that could be monitored via the internet were knocked out.

Ultimately, 184,000 megalitres of water was released from Burrinjuck Dam. Both of Tegra’s quarry operations alongside the river were virtually encircled by the existing riverbed. When the flood waters came, the river claimed back its former riverbed. The flood waters rose quickly and sliced through both properties, wiping out machinery, work areas, contaminating stockpiles and in some instances, washing stockpiles completely away.

In the final “wash up”, Tegra lost a fine sand plant (sump, pump, cyclone plus tower and skid) at Jugiong, and the retaining wall and feeder were wiped out at Gundagai. Three diesel pumps, a 33,000 litre fuel tank, 1100 volt power lines, pole and transformer were also lost at both sites. Jugiong was “out of action” for a week; Gundagai did not operate for six weeks. Gundagai had several stockpiles that had been certified ready for use. While they could not access them, the silt meant they had to wash the material again. This amounted to 60,000 tonnes of contamination, while approximately 10,000 tonnes were simply washed away. Jugiong lost 30,000 tonnes of product, with another 30,000 tonnes contaminated.

As with so many other communities, businesses and industries, Tegra Australia went back to work, cleaned up what it could, recovered what it could and carried on.

With some juggling, Tegra was able to supply its own internal concrete demands. Today, other than the odd high water mark, it would be difficult to know either quarry had been affected by the flood.

Gundagai was not too badly affected by the flood, having had many terrible floods in its past. The local farmers lost stock and a lot of fencing, but no lives were lost in the area.

Flood mitigation

The NSW Office of Water conducted a review of water management during the floods, which was released in August 2011 and is available on >www.water.nsw.gov.au

Six different agencies have responsibility for water management, in addition to those in the ACT (the Murrumbidgee flows through the ACT). The Bureau of Meteorology forecasts were inaccurate in certain areas, as well as miscommunication by the authorities releasing water from the dams. The landslide at Burrinjuck Dam is referenced in the review.

As a result of the review, it is now publicly acknowledged that there are conflicting interests in the field of water management. Where electricity is generated, the primary concern is typically electricity. Where irrigation is carried out, the primary concern is irrigation and hence retaining water within dams, at capacity. Flood mitigation can be caught between these conflicting responsibilities or become a distant third priority. When the Murrumbidgee passes through Gundagai, it has catchment areas across a range of areas. These areas are controlled by a range of agencies, as well being under the influence of Mother Nature!

This is not to comment on, discriminate against or judge the actions of the various bureaucratic bodies responsible for water management. The author merely wishes to point out the complexities involved in water management, and its effects on flood mitigation. Please note, the highest recorded rainfall fell in these areas in the lead up to the flood. 

Gundagai, the Dog on the Tucker Box, and the quarry industry

While Gundagai is famous for the Dog on the Tucker Box, there is a connection to the quarrying industry.

Frank Rusconi, a local stone mason extraordinaire and quarry owner, who championed the cause of Australian cut stones, particularly marble, was responsible for the construction of the Dog on the Tucker Box, including cutting the marble base it sits on.

Subsequent to this, Rusconi spent 28 years building his Marble Miracle (pictured). The building took over 20,000 pieces of hand-crafted marble and is now housed in the Information and Tourist Centre at Gundagai.

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