Almost a month after the Wollangambe River spill, Centennial Coal has not cleaned up its mess, according to concerned environmental groups.
Colong Foundation for Wilderness spokesman, Keith Muir, said tonnes of finely crushed coal from a mine tailings dump at Centennial Coal's Clarence Colliery near Lithgow, collapsed into the Wollangambe River which flows into the Blue Mountains World Heritage Area on July 2.
But Mr Muir said "the company responsible has still not begun a clean-up operation that was ordered by NSW Environment Protection Authority".
"We demand the company take effective immediate action to remediate the river and ensure the damage caused by this spill does not spread further," he said.
But an EPA spokeswoman says the EPA in collaboration with the National Parks and Wildlife Service (NPWS) is requiring the company to undertake trials to establish the best approach to cleaning up the material in the river.
The EPA issued a clean-up notice on July 3 requiring the pollution be removed by July 7.
In a media statement last Thursday, Centennial Coal's executive general manager Katie Brassil said Centennial was in full compliance with the EPA's notice and "doing all it can to work with regulators to ensure an appropriate and timely clean up".
"Repairs to the holding cell wall were completed on July 13 and clean up activities continue to progress well."
She said from the day of the incident Centennial "engaged a specialist team to oversee the clean up and over three hundred metres of the impacted area, closest to the Wollangambe, being cleaned up by hand".
"The next stage, with EPA approval, includes the introduction of machinery on Clarence's mining lease closest to the holding cell wall, to assist. The clean up timing for the Wollangambe River is being discussed with a variety of state agencies and ... will commence shortly".
Nature Conservation Council CEO Kate Smolski believes the company's "inaction" had "allowed tonnes of finely crushed coal to move eight kilometres down this wild river".
"If immediate action is not taken, these pollutants will soon enter the spectacular Wollangambe canyon in the Blue Mountains World Heritage Area where any remedial action will be vastly more difficult and expensive," she added.
But NSW Environment Protection Authority spokeswoman Liza Cassidy said to date Centennial was in full compliance. The area was very sensitive and difficult to access and machinery might not be a possible option.
"The EPA is focusing on preventing any further stuff ... but we've got moving water and if it's 8kms down the river it would not surprise me."
EPA south director, Gary Whytcross, said that the "quick response by the EPA in directing the company to install 22 silt fences had worked to prevent any further material entering the Wollangambe".
The spilt material on the hillside between the emplacement and the river was being "progressively cleaned up".
Last Friday the EPA approved further clean-up activity of the remaining material in the drainage line immediately down slope of the emplacement.
"The breach in the coal reject emplacement has been fixed, the material in the hillside is being cleaned up, and most of the material in the river has been located.
"This is a very sensitive environment which is difficult to access due to the natural terrain, making clean-up efforts challenging and requiring carefully planning.
Mr Whytcross said the EPA had sought the scientific advice of Office of Environment Heritage "to ensure we have the best knowledge available to guide the clean-up of the river".
Mr Muir said those using the canyon for recreational purposes were angry about the operation.
"I find this situation remarkable, and very disturbing. To allow this well-loved and wild river in a World Heritage Area to suffer this serious acute injury without Centennial Coal responding. Canyoners and locals are very angry about this response. The Wollangambe River must be cleaned up and Centennial Coal must answer for its inaction to date."
Blue Mountains National Parks has made a decision not to close the park following the spill but is "monitoring the situation".
"There is no current public safety risk associated with the clean-up. We may close a section of Blue Mountains National Park if the clean-up method warranted it - that is helicopter operations to lift coal bags out of the park," regional manager Alan Henderson said.
The EPA's investigation into the cause of the incident is continuing.