Instrumentation and monitoring of an engineered soil cover system for mine waste rock

Abstract

The ability of the soil cover system at the Equity Silver Mine to limit oxygen and water fluxes to underlying waste rock was evaluated using a detailed instrumentation program. Field instrumentation was installed to monitor temperature, gaseous oxygen, and gaseous carbon dioxide in the waste rock piles. Lysimeters were constructed at the base of the soil cover system to monitor infiltration across the soil cover. Sensors to measure matric suction, soil temperature, and water content were installed. An automated weather station was also installed to monitor climate conditions at the mine site. The field data indicates that the lower compacted layer maintained a high degree of saturation (i.e., 90% or higher) during 3 years of data collection (August 1992 to August 1995). This is a positive result, since the lower compacted layer was designed as an oxygen limiting barrier. The average measured infiltration from lysimeters placed at the base of the soil cover system was 5% of precipitation (from October 1992 to August 1993). The measured matric suction data indicates that the hydraulic gradient within the soil cover system is predominantly upward except for relatively short periods of heavy rainfall and snow melt in late fall and early spring.Key words: waste rock, soil cover, instrumentation, monitoring, unsaturated soil, soil-water characteristic curve.

Design of a Dry Cover Pilot Test for Acid Mine Drainage Abatement in Southern Brazil. I: Materials Characterization and Numerical Modeling

“…The performance of a dry cover depends both on the characteristics of the materials used and on climatic conditions. Several researchers have studied dry covers with different configurations and materials (including Barbour 1990;Nicholson et al 1989;O'Kane 1996;Skousen 2000;Swanson 1995;Yanful et al 1993). …”

Indirect Measurement of Suction

“…Over the years, the performance of the thermal conductivity sensor has been improved. Thermal conductivity sensors have been used in the laboratory as well as in the field (Fredlund and Wong 1989;Oloo and Fredlund 1995;O'Kane et al 1998;Marjerison et al 2001;Zhang et al 2001;Nichol et al 2003). Currently, thermal conductivity sensors are available commercially (e.g.…”

A numerical study of soil cover performance

“…Two-and threelayer soil covers were constructed over acid-generating waste rock at Rum Jungle Mine in Australia (Harries and Ritchie, 1987), Heath Steele Mine site in New Brunswick (Yanful et al, 1993a, b), Equity Silver Mine site in British Columbia (O'Kane et al, 1998) and Bersbo mine in Sweden (Lundgren, 1997). Test plots of a three-layer soil cover were constructed on acid-generating tailings at the decommissioned Waite Amulet site near Rouyn-Noranda, Que´bec in 1990 and monitored over a 3-year period (Yanful and St-Arnaud, 1991;Yanful et al, 1994).…”