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<RGC: Project Experience
Norwegian Mine Review
Norway
- Client:
- Norwegian Environmental Protection Agency
- Years of Service:
- 1987 to 1991
- Project Description:
- Norway has a history of mining sulphide ores dating many hundreds of
years. In particular there were numerous underground massive sulphide mines
that operated from the early 1900s through to the 1960s to 1980s. Acid
generation from the tailings and
mine wastes from these mines have released dissolved heavy metal loads,
particularly copper and zinc as well as acidity to the receiving environment for
several decades. In the mid 1980s the Norwegian Environmental Protection
Agency started a program of
mine site investigations and remediation directed specifically at both abandoned
and operating massive sulphide mines. Dr. Andy Robertson was appointed by
the Norwegian State Protection Agency to review the acid mine drainage
conditions at 16 mines and advise on potential remediation measures.
- Services Provided:
- Each of 16 Norwegian mines which had mined massive sulphide ores were
visited, site reconnaissance studies completed, conceptual alternative remedial
measures proposed and a preliminary cost estimate developed for the
alternatives. Based on the results the Norwegian State Protection Agency
pursued negotiations with the Norwegian Department of Mines, Mine Owners
and local communities for the implementation of the appropriate remediation
measures. Dr. Robertson continued to provide consulting review
and advisory services to the Norwegian State Protection Agency and those
responsible for the implementation of the remediation plans. A few of the
remediation plans are described below:
- Kjoli Mine: This underground mine operated from the early 1900s to
the 1940s. Ninety thousand m3 of rock waste with a 15% sulphur sulphide
content was placed on scattered piles on the surface. Metals leaching from the
mine and waste exceeded 2.4 tonnes of copper per year destroying a premier
trout stream for 17 km. In 1981 the waste had been consolidated and a surface
application of lime made in an attempt to control the acidic drainage.
Disturbance of the pile resulted in increases in the
metals leaching to over 10 tonnes of copper per year. An alternatives
evaluation by Dr. Robertson resulted in the recommendation that the waste pile
be re-shaped and covered with a geosynthetic membrane and till cover. This
was installed in 1988 by the Norwegian Department of Mines resulting in a
reduction of copper leaching to tenths of a tones per year. The pile is
instrumental in determining long term oxygen entry and moisture conditions in
the pile.
- Skorowas Mine: The Elkem mine was operated between 1952 and
1987 as an underground mine and produced a highly acid generating mine rock
waste pile of approximately 450,000 m3 placed on the side of a hill above a
small lake. An evaluation of alternatives by Dr. Robertson resulted in the
selection of mine waste removal and re-location below final flooded water level
in the lake as the most cost-effective long term acid generation control solution.
The design of the re-location plan was done by
Miljoplan of Norway, with Dr. Robertson providing review and technical
guidance, for Elkem who performed the relocation in 1988. The re-location
involved partial draining of the lake and the installation of a lake water lining
system to control lake water pH and release during relocation. The submerged
wastes were isolated by till covers and rip-rap protected. The final lake level
was raised by constructing a dam to achieve a more efficient deposit.
Instrumentation in the submerged rock waste and in the lake have demonstrated
that lake water quality objectives have been achieved and long term collection
and treatment of acid mine drainage from the mine wastes are no longer
required.
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