A massive fracture running up the hillside. Credit:Darren Pateman Damage was cause by unplanned subsidence from longwall mining by West Wallsend Colliery that is mining beneath 23 per cent of the conservation area. Fairfax Media can also reveal that in June this year a waterway was accidentally grouted by workers carrying out remediation works in the reserve. A spokesman for the Office of Environment and Heritage confirmed grouting material, used to fill mine subsidence cracks and holes, leaked into a ''drainage line'' and the colliery had been ordered to ''clean up the site''. The Newcastle Herald found another large depressed part of land in the reserve where all the trees had died.

Grouting in one of the cracks. Credit:Darren Pateman Vast sections of the reserve are cordoned off, with 24-hour security guards monitoring two access points along Archery Road. It is understood the damage was first detected in the popular bushwalking and mountain bike riding area in October last year during regular inspections by mine staff of the subsidence zone above the longwall operation. Part of a collapsed hillside at Mt Sugarloaf. Credit:Darren Pateman A spokesman for the mine said the damage was reported ''immediately to authorities''.

He said the subsidence impacted on an escarpment 160 metres above the mine. ''West Wallsend Colliery continues to work with relevant authorities to maintain public safety, provide appropriate remediation of mining impacts and operate in a responsible manner,'' he said. The underground mine has been operating in the Wakefield area since 1969. ''Occasionally, surface cracking and rock falls occur as a result of underground mining,'' the mine spokesman said. ''Because of this, we develop subsidence management plans that are approved by all relevant authorities, to appropriately manage and remediate affected areas.''

Fairfax Media found several large cracks running across walking trails and subsidence holes throughout the easily accessible area. Environmentalists and bushwalking groups were outraged at the destruction yesterday and called for immediate intervention by the Environment Minister, Robyn Parker. Ms Parker did not respond to questions from Fairfax Media yesterday. National Parks Association Hunter president Ian Donovan described the damage as ''completely unacceptable''. ''This would be totally unacceptable in an urban environment, but it appears to be acceptable at least to mining companies, in a state conservation area,'' he said.

''This is depriving people of enjoyment of the conservation area, let alone to impacts on a highly sensitive area of the range.'' The Office of Environment and Heritage spokesman said the department was notified of the ''greater than predicted subsidence even'' on October 2 last year. He said the majority of the conservation area was open to the public and urged visitors to remain on formed tracks for safety. A review is underway of the colliery's safety management plan prepared as part of the mine approval. The spokesman said the largest subsidence event was 120 metres long and approximately 17 metres wide, with remediation being co-ordinated by the mine.

Adjoining land owner Robert Bignell, who raised the issue of large sections of the reserve being cordoned off with Ms Parker earlier this year, said he was ''disgusted''. ''I was given assurances by the minister in writing that everything was fine and there was not a problem,'' he said. ''As a daily bushwalker in the park, I can't believe the damage that has been caused. It's an outrage and something needs to be done about it.'' West Wallsend Colliery community consultative committee chair and Lake Macquarie councillor Wendy Harrison said she was unaware of the scale of the damage. Ms Harrison said mine representatives had informed the committee of a subsidence event some time ago.

''We were told there was an issue and that it was all under control,'' she said. ''I will be raising this at the next meeting and seeking further information.'' In 2011 state officials from the environment department raised concerns that the mine could damage creeks in the conservation area and urged Xstrata, now Glencore, to avoid mining areas at a low depth in the government-owned conservation area. In a submission to the planning department, the environment department warned subsidence could threaten wildlife and ecosystems. In a report to the planning department, Xstrata said cracking was only possible in an 84-hectare area, less than 11 per cent of the mining area.

The coal company predicted subsidence falls of up to 2.5 metres above its workings. Sugarloaf State Conservation Area was created in 2007 and covers 3937 hectares. Surveys have found the reserve supports 16 threatened species including the spotted-tailed quoll, the brown treecreeper, black-chinned honeyeater and the east-coast freetail-bat. The spotted-tailed quoll, also known as the tiger quoll, is critically endangered and considered the highest priority for conservation in the reserve. According to NSW Environment and Heritage state conservation areas are reserved to ''protect and conserve significant or representative ecosystems, landforms, natural phenomena or places of cultural significance''. Surveys have found the Sugarloaf State Conservation Area is home to 216 species.

It is considered to have ''high fauna diversity'' partially due to the presence of spotted gum, one of only a few eucalypts that grow near the coast and is winter flowering. ''As a result large numbers of animals make use of it as a winter food resource,'' the department website states. The reserve is also part of an ''important ecological linkage for movement of many species between the dry western environments and those found along the coast''. A small population of koalas live in the area and the regionally rare Stephens' banded snake. Some of the larger gullies support rainforest species, including the regent bowerbird and noisy pitta.

Massive chasms defeat efforts to fill with concrete By Darren Pateman Newcastle Herald chief photographer On the journey towards Mount Sugarloaf I had no idea what to expect. As we turned off Archery Road and drove north on Sugarloaf Range Road we came to an area where a concrete machine had been set up. Black pipes ran down the hill and concrete was strewn across the work site.

We followed the piping and came across numerous cracks running through the landscape, filled in with grouting. Slowly they became bigger. Crevices sliced through what used to be a waterfall, cutting off big slabs so any water trickling down led into dark depths. They've tried to fill in many of the holes, but some of them are just too deep. Seeing the creek bed had shocked us but it paled into insignificance when we followed more trails of destruction further south and over a hill.

I don't really have words to describe what we stumbled upon. The land had just given way, it was a massive chasm, like a construction site, like a bulldozer had driven through it. The sight blew us away and the amount of destruction was astonishing. It was quite eerie, imagining how the earth would have trembled and groaned when it collapsed. Once again the cracks disappeared off the edge of a cliff and continued, we could only guess how much further they travelled.