In 1992, groundsmen at Wilson Park noticed a strong chemical smell at the grounds and saw a black tarry substance oozing from the ground. They also noticed that irrigation fittings were dissolving under the ground and that they were getting skin rashes. Park users also sensed something strange about the park. After sport, local children noticed a black sticky substance on their legs and hands and parents became concerned.
The Park was then fenced off and the pollution investigated by the custodian, Auburn Council. A huge pollutant mass was identified under the surface of the park and the clean-up process began.
Today the park looks clean and green, much like it was during the 1930s when it was a golf course. What did happen at Wilson Park and what was the land like before it became a tarry chemical waste dump?
History
Wilson Park looking east across the park in 2001
Wilson Park was originally part of the Blaxland Estate. In 1879, the estate was successfully offered to the Government and the site was used for market gardening, with substantial mangrove wetlands and mud flats bordering the Parramatta River. The riverfront was eventually reclaimed and in the 1930s, the newly expanded site became part of the Carnarvon Golf Club. During World War II the Department of Defence, who ran the adjoining Newington Naval Armaments Depot, occupied the land. After the war and a subsequent period of disuse, the site was taken over by Petroleum and Chemical Corporation of Australia Limited (PACCAL) and a new town gas plant was constructed. PACCAL leased the site from the NSW Government in 1953 and a year later began producing town gas by the thermal cracking of crude oil. Other products created included solvents and tar, both of which were needed in rapidly expanding post war Sydney. Whilst the new products provided tarred roads and gas to cook with, the production process also created massive air pollution, and neighbouring suburbs like Ermington were severely affected. During PACCAL's 20 years of production, air pollution was very visible. Another form of pollution was also created but the public could not readily see it. Four tonnes of tar sludge waste was created each day and dumped in two open ponds in the north eastern corner of the site.
By the mid 1970s, waste disposal became a real problem as there were no more suitable ponds for on-site disposal and very limited opportunities existed for the off-site disposal of the corrosive and odorous chemical waste. Public pressure too, was mounting as Dorothy Packer's campaign bore fruit and a new pollution regulator, the State Pollution Control Commission was proceeding towards another prosecution of PACCAL for breaches of the Clean Air Act. The Company had already committed approximately 50 such breaches and was facing competition from the natural gas being piped over from South Australia. In the light of these pressures, PACCAL ceased operations in 1974 and began to decommission the site.
The main issue with the decommissioning was knowing what to do with the tar ponds. A large amount of the material in the ponds was transported to the landfill at nearby North Newington. Some of the sludge was mixed with crushed sandstone and spread as a levelling agent over the north western quarter of the site. The major proportion of sludge was left onsite, at the direction of the relevant authorities, and covered with imported fill before being capped with one metre of clay.
The site failed to sell at a public auction in 1977 and lay vacant until 1988 when Auburn Council was made trustee of the site and officially opened the new Wilson Park. The park comprised three soccer fields and a passive recreation area, BBQ and children's play area, foreshore walking path and amenities blocks. The new sports park was welcomed enthusiastically by the community who were short of public open space and keen on outdoor sports like soccer, hockey and netball. It was well patronised and all seemed well for four years. However, in 1992, the chemical waste legacy was realised when groundsmen Brian Simpson and Barry Dryborough saw evidence of pollution at Wilson Park. They reported a strong chemical smell near the Parramatta River, the presence of a black tarry material oozing to the surface of the playing fields and the rupturing of plastic irrigation fittings under the ground.
Auburn Council investigated the problem and immediately closed Wilson Park. Studies were carried out and the presence of pollution confirmed. The park was fenced, closed to the public and the playground and BBQ equipment removed. Further studies confirmed the presence of chemicals in the location of the former tar ponds; the mass of contamination was estimated at 230,000 tonnes.
Science and the Wilson Park Clean-up
The State Government and Auburn Council worked together to fund the clean up of Wilson Park which adjoined the Sydney Olympic site and was very close to the proposed Olympic Village. In 1996 the Olympic Coordination Authority (OCA) announced that it would fund the completion of the remediation works and the clean up commenced.
Although the remediation of Wilson Park was undertaken by a team of engineers and remediation experts, the underlying philosophy of the remediation strategy was based on the observation of groundsmen, Simpson and Dryborough.
Both men had been farmers in England and were keen on cricket. They took special care of the pitch and kept it well watered, well fertilised and regularly cut. When the tar pollution surfaced on the grounds, Brian and Barry noticed that the pitch seemed to show less contamination than other areas of the park. They spoke with site chemist and keen home gardener David Sheumack, and together they resolved these confounding results.
Results from the Cricket Pitch
It appeared that where intensive agricultural practices had been carried out by park groundsmen, natural populations of soil-born micro-organisms increased. In particular, those organisms which liked to feed on the pollutants in the fertile topsoil greatly increased in number and this meant that the pollution degraded more rapidly than normal. David Sheumack recognised the value of these observations. In essence, Brian and Barry had unknowingly applied modern bio-remediation principals to the land under their care and set in train the state-of-the-art clean-up of the site.
Science Saves the Day
The field observations by the groundsmen were followed by scientific research that confirmed their findings on the cricket pitch. David Sheumack proposed the hypothesis that enhanced bioremediation was occurring in areas with optimal fertile conditions. His hypothesis, if correct, could greatly assist the remediation strategy and in 1999, following a specially funded project, David was able to demonstrate the presence of BTEX degrading microorganisms and determine optimal conditions for their proliferation. He also worked on the bioremediation of the contaminated leachate that was captured from the buried tar ponds and as a result, on-site bioremediation was initiated, saving many thousands of dollars in off-site treatment fees.
Bioremediation ponds (top), installation of the cut off wall (middle) and looking east across the park today (bottom)
The clean up of Wilson Park was more than bioremediation of contaminants in soil and water. In the main it was an engineering project with a "biological" stage completing the work. The engineering work was completed in two stages.
The first stage stopped flow of polluted groundwater to Parramatta River by the installation of a clay cut-off wall. Hydraulic gradients controlled ground water flow to two pump pits, which transferred the leachate to the on-site pond for the bioremediation process. This occurred in 1997 and also included the recovery of contaminated material from the foreshore of the Parramatta River. All the contaminated material was then consolidated in two large mounds which were established over the former PACCAL tar ponds. The second stage of the park clean-up included creation of additional bioremediation ponds, capping the mounds covering the tar pits, installation of the clay cut-off wall to completely encircle the tar pits, installation of a sheet pile wall to bedrock and installation of a series of wells to control hydraulic gradients.
The Wilson Park site currently generates approximately 20,000 litres of contaminated groundwater per day. The water is typically contaminated with PAHs, Phenols, BTEX and Grease & Oil. The contaminated water is stored within collection sumps prior to being discharged into a series of three treatment ponds. As the water cycles through the ponds, it is bioremediated. The water in the final treatment pond is tested to identify the appropriate disposal method. Optimal conditions of these ponds were determined in a research project managed by the Ecology Programs.
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