Environmental legislation and advances in tailings disposal technology in North America and Europe

Synopsis

California has traditionally led North America in the development and enforcement of environmental legislation. In 1984, the so-called “Sub-Chapter 15” regulations governing discharge of wastes to land was promulgated into law, with prescriptive standard requirements for containment of all mining related wastes. The legislation was based on the primary objective of protection of underlying groundwater and no significant impact on downstream beneficial water usage. While the overall requirements of Sub-chapter 15 appropriately achieve this objective, the prescriptive standards are sometimes inappropriate, and impose unnecessary constraints on the design of waste containment systems. This limitation has been recognised, and current trends in the USA and Canada are focusing on site specific objectives and containment systems.

The development of sub-aerial tailings disposal systems in North America over the last 10 years has played a major role in providing a cost-effective method of achieving or exceeding environmental protection standards. In California, the Jamestown Mine, a 6000 tpd gold mining operation and the first mine to be permitted under the new “Sub-chapter 15” regulations, has a sub-aerial tailings management system permitted as an engineered alternative to prescriptive standards. The facility is designed to achieve a fully drained, stable mass of tailings suitable for immediate reclamation on completion of operations, with separate storage of all process liquids and precipitation. The same design concepts have been proposed for a potential gold processing plant in northern Greece.

In the U.K., environmental legislation has historically developed piecemeal in response particularly to public pressure and to research developments. The Environmental Protection Act recently enacted is intended to draw previous regulations and legislative acts together and to provide a unified approach to all matters concerning environmental pollution. This legislation has, to an extent, been influenced by EC Directives and by the lead given by North America.

In some fields, however, particularly in mining, there has been a joint approach by both Governmental bodies and industrial concerns. The Aberfan disaster, for instance, led to stringent mine waste disposal legislation with regard to safety and stability, though, environmental and pollution regulations were not included. Current environmental legislation seeks to correct this, though local planning agreements and conscientious mine operators have often pre-empted statutory enforcement. Some tailings disposal projects in the UK have therefore been in the van in using state of the art technology to achieve safe and efficient tailings disposal and to minimise environmental pollution.

This paper outlines current North American legislation governing the disposal of mineral processing wastes, including the requirements for tighter controls and total containments, and compares these to European practice. The development and application of sub-aerial tailings disposal technology, particularly with respect to total containment/zero release, is described with case histories and operating experience in North America, the United Kingdom and Europe.