Stockton revisited: The mine and regulatory minefield

Below is the Commissioner's overview of the report. The full report is available in pdf format on the right. Also available as a pdf document is a table detailing the old mining operations which comprise the 111 mining licenses referred to in the report.

Commissioner's overview

Mining on the West Coast of the South Island has long played a major role in New Zealand history. My great-great-grandfather was a gold miner on the coast, although he rather self-importantly called himself a mining engineer. In 1879, the Denniston Incline began operating, carrying coal from the Mount Rochfort Plateau down to the railhead in a bucket suspended on a wire cable. It is said that some wives, having travelled up this terrifying incline, never left the plateau again. In 1908, the strike by the Blackball miners led to the birth of the Labour Party in a pub two years later.

I feel a sense of history, albeit much more recent, in releasing this investigation.

In 1988, the first Parliamentary Commissioner for the Environment, Helen Hughes, became concerned about the environmental conditions in the coal mining licences being transferred to the Coal Corporation, a new state-owned enterprise. In 1992, she expressed her concerns more fully in a report on the environmental management of coal mining. Four years later, the Coal Corporation became Solid Energy NZ Ltd.

In 2005, the second Parliamentary Commissioner for the Environment, Dr Morgan Williams undertook a scoping study on Solid Energy’s environmental management systems and performance. In the resulting report in 2006, he made a commitment to investigate the environmental management of Solid Energy’s mine at Stockton on the West Coast of the South Island.

In 2008, as the third Parliamentary Commissioner for the Environment, I followed up on that commitment. However, this investigation has turned out to be rather more than just a review of the environmental management of one large coal mine. In traversing the ‘minefield’ of the old regulatory regime that still governs many of the mines in this country, I found myself echoing some of Helen Hughes’ concerns seventeen years later.

Stockton mine is the largest coal mine in New Zealand and it is located in an area which presents huge challenges to any environmental manager. The discovery of the endangered giant snail, Powelliphanta augusta, and the subsequent relocation programme, have dominated media coverage about the impact of the mine on the environment. That issue is not recanvassed in this report; rather the focus is on the physical environment as the cradle of the ecosystem.

Average rainfall on the Stockton Plateau exceeds six metres per year. The streams in the area are naturally acidic, and mining exacerbates this because sulfide minerals exposed through mining are oxidised and sulfuric acid is formed. This ‘acid mine drainage’ is one of the most significant environmental effects of coal mining in general, and for Stockton mine in particular. And it is of special interest, since water quality is a major environmental issue in New Zealand.

Given the great concern about climate change and the carbon dioxide emitted through burning coal, I cannot be enthusiastic about coal mining. However, putting these concerns to one side, I am pleased to report that Solid Energy now has a well-established and comprehensive Environmental Management System at Stockton mine to manage the impacts of its mining operations on the surrounding environment. This conclusion is supported by some improved outcomes. Regular monitoring of the Mangatini Stream over two recent years shows a dramatic reduction in the concentration of total suspended solids in the water. Over the same period, the Ngakawau River has become much less acidic, with the average pH rising from 4.4 to 6.2.

Nevertheless, this investigation has drawn my attention to the persistence of the old regulatory regime for mining. Over a hundred mining licences granted prior to the 1991 enactment of the Resource Management Act and the Crown Minerals Act continue to apply until they expire. In one case, this is not until 2062.

There are two sets of issues associated with these old mining licences. The first is that the environmental conditions in, and associated with, the licences were written decades ago and many will be outdated. The second is that enforcement of these conditions is fraught with difficulties and inconsistencies. Stockton mine operates under one of the old mining licences, but just because the environmental management of this one mine has improved markedly, it does not follow that other mines with old licences will be.

In September this year, just as this report was being finalised, the possibility of a more permissive approach to mining on land managed by the Department of Conservation (DoC) was raised by the Minister of Energy and Resources. Anticipating questions about this, we found that of the 111 mining licences granted under the old regime, at least 55 include DoC land, although none of it is land on Schedule 4 of the Crown Minerals Act. However, some of this conservation land may be inadequately protected.

The extent of the environmental damage caused by mining is, of course, dependent on many factors. In general, opencast or strip mines, like Stockton, are more damaging than underground mines. Mines that lead to exposure of sulfide minerals to the air acidify streams and groundwater, and thus environmental damage can extend far beyond mine boundaries. A gold mine that leaves cyanide residues in streams is worse than a quarry that leaves sediment in streams.

Another issue is ‘orphan’ sites, where mines cease operation and are abandoned, leaving remediation costs to be borne by taxpayers and ratepayers. For example, Tui mine on Mount Te Aroha was abandoned in 1975 by Norpac Mining Ltd. Part of its legacy is a large tailings pile; in 1980 the Hauraki Catchment Board had to build a gravel embankment to prevent it slipping down the mountainside. The Ministry for the Environment is now spending nearly ten million dollars on further remediation of Tui mine. Environment Waikato and Matamata-Piako District Council are also contributing resources to dealing with this ‘orphan’ site.

This is a major reason why the greatly improved environmental management of Stockton mine by Solid Energy is not a basis for assuming that there is no problem. Solid Energy may well be acting as a ‘good citizen’ and going beyond the environmental requirements associated with ‘old’ mining licences, but it is a state-owned enterprise in New Zealand for the long haul.
 
Private companies are in a different position, and face different incentives and options such as liquidation. Solid Energy can sell ‘old’ mining licences to private companies and indeed may itself one day be privatised, although the Government has indicated no plans in the short term.

The writing of this report has confirmed for me the complexity of issues that surround mining. Mining of some minerals and other resources will continue to be a part of New Zealand’s future, but we must ensure that it is done with far more sensitivity, discrimination, and good environmental management than it has been done in the past.

As always, I would like to thank the staff who worked on this investigation, especially the tenacious Shaun Killerby. His long memory and interest in history have been particularly valuable.

Dr Jan Wright
Parliamentary Commissioner for the Environment