The south waste rock dump at Mine Doyon, Cadillac, Québec has been generating
acidic drainage since 1985, two years after the dump was started. Acid generation
increased steadily from 1985 to 1988 and since 1988 the dump has been generating
strong acidic drainage which is presently collected and treated with lime.
Between 1991 and 1994 the south dump has been the subject of extensive
investigations and studies carried out through the MEND Prediction Committee
primarily by Groupe de Recherche en Géologie de l’Ingénieur (GREGI), Université
Laval, Sainte-Foy, Québec. The results of these studies have been issued in a series
of ten reports. The site investigations included tasks such as drilling and sampling of
the rock dump materials; piezometer, lysimeter and thermocouple installations;
sampling of acidic drainage, groundwater and pore water; collection of gas samples
within the dump; collection of microbiological specimens; measurement of surface
temperatures and temperature profiles in the dump; and collection of climatic and
hydrologic data. The laboratory and analytical studies carried out included
characterization of the physico-chemical and mechanical properties of the different
types of waste rock; water chemistry analyses including rapid chemical techniques to
monitor acid mine drainage; hydrology and water budget studies; geotechnical and
hydrological studies including evaluation of dry barriers; extensive studies of
mineralogy and geochemical processes; microbiological enumeration and diversity
studies; and predictive modeling of acid mine drainage processes including heat
transfer analysis. One of the more important objectives of the studies at the south
dump was to measure physical and chemical properties of an actual waste dump and
to identify key processes contributing to the generation of acid mine drainage.
The MEND Prediction Committee arranged for a peer review of the studies carried out
at the south dump by a designated group of expert consultants (Peer Review Team).
The peer review was carried out under five separate technical components identified
as (i) hydrology, (ii) geotechnical and hydrogeology, (iii) geochemistry and
mineralogy, (iv) microbiology and (v) predictive modeling. The Peer Review Team
made a technical and scientific review of the ten reports provided by the MEND
Prediction Committee with particular reference to providing a critique of strong and
weak points, identifying new information and understanding developed from the studies
and suggesting areas for future work. This report provides the peer review commentary
on the Mine Doyon study.
The overall conclusion of the peer review is that the Mine Doyon study has provided a
new understanding of some specific technical issues and represents a thorough and
exceptionally well documented case study. The peer review also identified a number of
inconsistencies and occasional technical errors in the reports which should be
corrected. The inconsistencies occur mainly in the earlier reports which were issued
without the benefit of the complete study results, also budget and time constraints were
a contributing factor.
