Impacts of Longwall Coal Mining on the Environment in New South Wales
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IMPACTS OF LONGWALL COAL MINING ON THE ENVIRONMENT IN NEW SOUTH WALES Total Environment Centre PO Box A176 www.tec.org.au Sydney South 1235 Ph: 02 9261 3437 January 2007 Fax: 02 9261 3990 Email: [email protected] CONTENTS 01 OVERVIEW 3 02 BACKGROUND 5 2.1 Definition 5 2.2 The Longwall Mining Industry in New South Wales 6 2.3 Longwall Mines & Production in New South Wales 2.4 Policy Framework for Longwall Mining 6 2.5 Longwall Mining as a Key Threatening Process 7 03 DAMAGE OCCURRING AS A RESULT OF LONGWALL MINING 9 3.1 Damage to the Environment 9 3.2 Southern Coalfield Impacts 11 3.3 Western Coalfield Impacts 13 3.4 Hunter Coalfield Impacts 15 3.5 Newcastle Coalfield Impacts 15 04 LONGWALL MINING IN WATER CATCHMENTS 17 05 OTHER EMERGING THREATS 19 5.1 Longwall Mining near National Parks 19 5.2 Longwall Mining under the Liverpool Plains 19 5.3 Longwall Top Coal Caving 20 06 REMEDIATION & MONITORING 21 6.1 Avoidance 21 6.2 Amelioration 22 6.3 Rehabilitation 22 6.4 Monitoring 23 07 KEY ISSUES AND RECOMMENDATIONS 24 7.1 The Approvals Process 24 7.2 Buffer Zones 26 7.3 Southern Coalfields Inquiry 27 08 APPENDIX – EDO ADVICE 27 EDO Drafting Instructions for Legislation on Longwall Mining 09 REFERENCES 35 We are grateful for the support of John Holt in the production of this report and for the graphic design by Steven Granger. Cover Image: The now dry riverbed of Waratah Rivulet, cracked, uplifted and drained by longwall mining in 2006. The Rivulet comprises nearly 30% of the Woronora Dam catchment. Impacts of Longwall Coal Mining on the Environment in New South Wales Page 1 ABBREVIATIONS ABC Australian Broadcasting Corporation ACARP Australian Coal Association Research Program AMCI American Metals and Coal International BHPB Broken Hill Proprietary Billiton CMA Catchment Management Authority CoI Commission of Inquiry CSIRO Commonwealth Scientific and Industrial Research Organisation DEC Department of Environment and Conservation DIPNR Department of Infrastructure Planning and Natural Resources DLWC Department of Land and Water Conservation DMR Department of Mineral Resources DPI Department of Primary Industry EDO Environmental Defenders Office EIS Environmental Impact Statement EP&A Environmental Planning and Assessment KTP Key Threatening Process LTCC Longwall Top Coal Caving NPA National Parks Association NSW New South Wales SMP Subsidence Management Plan TEC Total Environment Centre Impacts of Longwall Coal Mining on the Environment in New South Wales Page 2 01 OVERVIEW 01 Longwall mining is a form of underground coal By the 1990s, residents who lived along the mining that was introduced to Australia and the Cataract River southwest of Sydney reported large United States from Europe in the early 1960s. It cracks in the riverbed above longwall panels allows mining companies better access and vastly operated by BHP (now BHP Billiton). Along with improved recovery rates than older methods of the cracking, sections of the river downstream underground mining. It also results in far more from the cracking started to dry up, iron oxide dynamic land subsidence than the traditional methods. The effects of mine subsidence upon man-made infrastructure are well known. Native Dog Creek: A large pool that would have been several metres deep and a drought refuge for wildlife, has now been drained by However, subsidence from longwall mining has longwall mining. Note rock debris from destablisation of abutting cliff. had, and continues to have, a dramatic effect upon the natural environment. The practice of longwall mining first came under the spotlight in 1974, when a dispute arose between the then Metropolitan Water Sewerage and Drainage Board and the Department of Mines over the proximity of longwall mining to the city’s water supply dams south of Sydney. An inquiry was established under Justice Reynolds into ‘Coal Mining Under or In the Vicinity of the Stored Waters of the Nepean, Avon, Cordeaux, Cataract and Woronora Reservoirs’. Justice Reynolds made several important findings, which were handed down in 1977, including restriction zones around dam walls and stored water. Reynold’s findings also identified an “angle of draw” at which certain levels of subsidence are likely to occur (Reynolds 1977). In the early 1980s environment groups were alerted to numerous cliff falls on the Newnes Plateau, north of Lithgow, that had occurred as a result of land subsidence due to longwall mining by nearby collieries. It later emerged that Centennial Coal were also pumping 14 megalitres per day (about 14 Olympic swimming pools) of mine effluent into the Wollangambe River, polluting it with a black muck that spread downstream. Impacts of Longwall Coal Mining on the Environment in New South Wales Page 3 pollution stained parts of the river red, methane reopened. In other cases cracking has occurred gas leaked to the surface, fish skeletons were under sandy riverbeds and cannot be detected. In discovered and cliff falls occurred along the steep some cases the mining companies have had to gorges running alongside the river. A 1998 court buy water from the water supply dams to provide judgement found in favour of seven parties who an environmental flow back to the damaged had sued BHP over the damage to the river – the stream – but this is not a sustainable solution (and court decided that 80% of the damage could be wastes water in times of drought). attributed to longwall coal mining. The damage that was occurring to rivers from Widespread cracking and draining of river and longwall mining forced changes in NSW creek beds and underground aquifers, cliff falls, Government policy through a new approvals the draining of rare swamps, fish kills, methane process that was introduced in 2004 (see 2.4, gas bubbling to the surface, iron oxide pollution Policy Framework for Subsidence Management). and the release of wastewater into river systems This required mining companies to submit a continue to occur across four coal mining regions Subsidence Management Plan (SMP) for new of New South Wales as a result of longwall longwall panels they were intending to mine. mining. A very significant number of operations However, there is widespread concern that the take place in the Southern Coalfields in Sydney’s new approvals process is failing to protect the water supply catchment and longwall mining is environment from subsidence damage. also proposed in the Central Coast’s water supply SMP’s are being approved largely without catchment. Longwall mining poses a grave threat amendments that ensure avoidance of to the integrity of rivers and ecological environmental impacts. While becoming more communities in National Parks in the Western accurate in predicting the levels of subsidence, Coalfield, while BHP Billiton’s Caroona project in they offer no accurate assessment of the damage the Gunnedah Basin, currently in the exploration that may occur to rivers and creeks. Current stage, threatens multiple levels of aquifers under government policy responses are to monitor the some of Australia’s richest agricultural land. damage and try to fix it up later with unproven It is not disputed by any authority that subsidence remediation techniques. In cases where a river or due to longwall mining can cause deformation of creek has suffered a loss of flow after mining, the ground surfaces as well as cracking of valley mining company will often try to shift the blame to floors and creeklines. This can affect natural water drought conditions, even though streams in flow regimes and water quality, depending on adjacent valleys are still flowing. such factors as the width of the crack, riverbed There are no protection zones mandated for rivers steepness, the riverbed material and the presence being affected by longwall mining despite of organic matter. Subsidence is known to occur numerous reports by government agencies and up to 3km from a longwall panel. independent bodies recommending such a policy. In turn, these impacts can lead to the alteration of This could simply be implemented through a species habitats and changes to the ecological buffer zone around rivers and streams. The mining function of communities (see Section 2.5, industry continues to resist the concept of a Longwall Mining as a Key threatening Process). protection zone arguing that it is unnecessary and Effects can be temporary or long-term. When that the viability of their longwall mines would be water flows are altered, there can be permanent under threat. effects on the functioning of ecosystems in In November 2006 the Total Environment Centre localised areas, which may be exacerbated in (TEC) instructed The Environmental Defender’s drought conditions. Office (EDO) to prepare drafting instructions for Industry and government have responded to this legislation in relation to longwall mining including situation with monitoring and rehabilitation the establishment of a 1km buffer zone around programs. Although hailed by the industry as rivers and creeks (see Appendix). successful, past remediation efforts have failed. They have included concreting or grouting over cracks in riverbeds. However in many cases the cracks run hundreds of feet deep and have Impacts of Longwall Coal Mining on the Environment in New South Wales Page 4 02 BACKGROUND 02 2.1 Definition 2.2 The Longwall Mining Industry in New South Wales Longwall mining is a form of underground coal mining where ‘panels’ of coal are mined side by Longwall mining in NSW began in 1962. In side separated by narrow ‘pillars’ of rock that act 1983/84 it accounted for 11% of the state’s raw as supports. A long wall panel can be up to 4km coal production. This had increased to 36% by long, 250-400m wide and 1-2m thick. Chocks are 1993/94 and stood at 29% in 2003/04.