Col Maybury at a polluted creek near the Neath Colliery site. Credit:Peter Stoop With 65 abandoned mines and countless coal waste dumps throughout the region, the full extent of the problem is unknown. “There is absolutely nothing that survives in the creek, it's highly toxic,” said Col Maybury, president of Kurri Kurri Landcare. “You've only got to look at it to see how much damage it is causing, and it runs all the way to the Hunter River.” A leading national expert on acid mine drainage Dr Alan Robertson said it was a “huge problem, with no simple solution”. Dr Robertson, managing director of RGS Environmental, said acid mine drainage was recognised as the most significant environmental issue for mines around the world.

“There is a huge effort and cost involved in trying to solve the problem,” he said. “We are learning about it all the time ... and have not found the magic pill as yet.” Environmental and soil scientist Simon Leake said the problem was much greater in the Lower Hunter due to coal in that area having an abnormally high sulphur content. He described the run-off as “very toxic”. No “gilled organisms" could live in it and affected soil would never be "as good as it used to be”, he said.

“What will happen is you will get whole sections of waterways that are dead,” he said. “The water needs to be diluted downstream. "The problem is abandoned mines are very difficult to treat, it's like trying to hold your finger in a dyke. The only real way to treat it is impound the water in a dam and treat it with super-fine lime.” Coal in seams around Newcastle and Wollombi has about 0.35 per cent sulphur while export coal in the Greta seam contains 5.2per cent sulphur. "Waste" coal is much worse. Tailings dumped at dozens of locations around Maitland and Cessnock has recorded sulphur content as high as 10.5 per cent. Most of the toxic mines and coal waste dumps are "orphan sites" – no longer owned by mining companies which are therefore no longer held accountable.

Due to limited state budget funding for remediation, most sites are simply monitored. An Auditor-General's report issued last year found that as ownership of mine sites reverts to the Crown, clean-ups may be the government's “largest category of contamination liability”. “The Office of Environment and Heritage advised that potential liabilities for clean-up under the Derelict Mines Program would be substantial and that the few million dollars allocated annually to this program are substantially inadequate,” the report said. About $2.4 million was allocated in last year's budget. If not rehabilitated, derelict mines can affect human and environmental health, threatening water quality through sediment run-off, metal contamination and acid mine drainage.

A spokeswoman for the Division of Resources and Energy said the seven acid mine drainage sites in the Hunter had been rated as low-to-medium risk. She said higher risk sites were given priority for remediation funding. “The NSW government continues to monitor the situation generally and is aware of the ongoing legacies of former mining practices,” she said. “Today's mines are strictly regulated and lodgment of a security deposit is required to cover rehabilitation costs if the mine owner becomes insolvent.” A Hunter-based company was granted approval in 2006 to clear nearly 3 million tonnes of coal waste from the Cessnock area, a procedure previously thought to be uneconomical.

Hunter Enviro Mining recently applied to the state government for approval to have its licence extended for four years and is awaiting an outcome. It has been clearing chitter (coal reject) from dirt and waste material from sites at Aberdare East and Richmond Main East, with a third project planned to start at Neath. The coal is taken by truck to the former Hebburn No.2 colliery, where saleable coal fines are separated at a washery and the remaining acidic waste pumped into the disused mine shaft. The coal is sold through an agent as “trimming coal” for blending into larger cargoes, with a sale price much less than the typical Newcastle spot price. The Newcastle Herald