Control and Management of Acid Mine Drainage

Background

Acid mine drainage (AMD) is the outflow of acidic water from mining sites. AMD is caused by large-scale earth disturbances characteristic of mining and other large construction activities, usually within rocks containing an abundance of sulfide minerals. The acidic leachate can drain from many sources, including waste rock piles, tailings ponds and following the flooding of abandoned underground mine collieries.

Various aspects of the generation and dispersal of acid mine drainage (modified from Tutu et al., 2008)

Program Objectives

The overall objective of this program is to develop new scientific knowledge on the prevention, control and management of acid mine drainage at former mining sites. Specific project objectives include:

Assess the performance of engineered cover systems installed at mine waste rock piles;
Develop numerical models to predict the long-term performance of cover systems during future climatic extremes; and
Evaluate and optimize mine water management approaches at treatment plants.

Research Methods

Field Investigations

Field investigations are being conducted at the Sydney Coalfield in Nova Scotia, Canada. A number of waste rock piles overlain with different engineered cover systems are being periodically monitored using advanced site monitoring instrumentation. In addition, two mine water treatment plants are located within the coalfield and ongoing work is assessing the performance of these plants and investigating new strategies to optimize their performance and operational costs.

Design, installation and performance monitoring of engineered cover systems at mine waste rock piles

Laboratory experiments

Kinetic experiments have been performed on mine waste rock samples extracted from the WRPs using leaching columns and humidity cells. These experiments will help determine the metal leaching rates and help better inform numerical models on predicting the rates with which the WRPs are seeping key AMD components. Furthermore, a AMD analysis laboratory has been developed at a mine water treatment plant to allow real-time monitoring of plant performance during treatment of extracted mine water.

Experimental apparatus of metal leaching columns and modified acidity titration

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Numerical groundwater and contaminant transport modeling

Contaminant transport models are being developed to investigate the long-term performance of engineered cover systems, including the impacts from large storm events and climate change.

Contaminant transport simulations to predict the long-term evolution of AMD at a waste rock pile

Program Output

Journal Papers (2017 - 2020)

Ramasamy, M., Power, C. (2019) Evolution of acid mine drainage from a coal waste rock pile reclaimed with a simple soil cover. Hydrology, 6(4), 83.

Ramasamy, M., Power, C., Mkandawire, M. (2018) Numerical prediction of the long-term evolution of acid mine drainage at a waste rock pile site remediated with a HDPE-lined cover system. Journal of Contaminant Hydrology, 216, 10-26.

Power, C., Ramasamy, M., Mkandawire, M. (2018) Performance assessment of a single-layer moisture store-and-release cover system at a mine waste rock pile in a seasonally humid region (Nova Scotia, Canada). Environmental Monitoring and Assessment, 190(4), 186.

Power, C., Ramasamy, M., MacAskill, D. MacPhee, J., Shea, J. Mayich, D., Baechler, F., Mkandawire, M. (2017) Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada). Environmental Science and Pollution Research, 24(34), 26744-26762. doi: 10.1007/s11356-017-0288-4

Selected Conference Publications

Merritt, P., Power, C. (2020) Evaluation and Optimization of Mine Water Treatment in the Sydney Coalfield, Nova Scotia, Canada. 55th Central Canadian Symposium on Water Quality Research, Canadian Association on Water Quality (CAWQ), February 20, 2020, Toronto, Ontario, Canada.

Power, C. (2020) In Situ Performance Monitoring of Engineered Cover Systems at Mine Waste Rock Dumps. 55th Central Canadian Symposium on Water Quality Research, Canadian Association on Water Quality (CAWQ), February 20, 2020, Toronto, Ontario, Canada.

Power, C., Tavana, H., Ramasamy, M. (2019) Field performance of engineered HDPE-lined cover systems over acid-generating mine waste rock piles. American Geophysical Union (AGU) Fall Meeting 2019, San Francisco, United States.

Power, C., Ramasamy, M., MacAskill, D., Mkandawire, M. (2015) Geochemical assessment of reclaimed mine waste rock piles in the Sydney Coalfield. CLRA – Atlantic Reclamation Conference, 20-21 October 2015, Fredericton, New Brunswick, Canada.

Ramasamy, M., Power, C., MacAskill, D., Mkandawire, M. (2015) Variably saturated flow modeling of soil cover systems on Lingan waste rock pile. CLRA – Atlantic Reclamation Conference, 20-21 October 2015, Fredericton, New Brunswick, Canada.

Ramasamy, M., Power, C., Mkandawire, M. (2015) Diversion of steady state modeling from actual hydro-geodynamics in flooded mines of the Sydney Coalfield. International Conference on Renewable Energy and Sustainable Environment (RESE – 2015), 3-5 August 2015, Pollachi, Tamilnadu, India.