Birdsall-Dreiss Distinguished Lecturer

David Blowes teaches in the Department of Earth Sciences at the University of Waterloo, where he has held the Canada Research Chair in Groundwater Remediation since 2001. He is a member of the Waterloo Institute for Groundwater Research. He received his B.Sc. in earth sciences from the University of Waterloo, then went on to complete M.Sc. and Ph.D. studies specializing in hydrogeology and aqueous geochemistry at the same institution. In 1991, he joined the University of Waterloo faculty, and now holds the rank of professor. He teaches courses on groundwater geochemistry and hydrogeology. His research focuses on the release and transport of dissolved metals from mine wastes, transport of dissolved metals and nutrients in aquifers, and remediation of groundwater contaminated by dissolved metals and nutrients. He has published over 100 professional papers and presented more than 100 professional talks, and has co-edited three volumes on the environmental effects of sulfide mineral oxidation in mine wastes. He has participated in review panels for the Natural Sciences and Engineering Research Council of Canada and for government agencies in Canada, the United States, Australia, and Europe. He has also acted as a consultant for private companies and government agencies.

To request a visit to your institution, contact David Blowes, Department of Earth Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada, +1-519-888-4878, . The Hydrogeology Division is particularly interested in including liberal arts colleges in the itinerary. The Division will pay transportation expenses; the host institution will provide local accommodations.

Lecture Topics

Permeable Reactive Barriers for Treating Groundwater Contaminated by Dissolved Metals

In situ techniques for treating contaminated groundwater have evolved rapidly over the past decade. Permeable reactive barriers were among the first of these new approaches and now are applied widely. Permeable reactive barriers are installed by excavating a portion of the contaminated aquifer and replacing the aquifer materials with a reactive material tailored to treat the target contaminants. More than 150 reactive barriers have been installed since the initial installations in the mid-1990s. These barriers treat a variety of contaminants, including dissolved metals, nutrients, mine drainage, halogenated hydrocarbons, and petroleum derivatives. Reactive barriers designed to treat dissolved metals rely on removing the metal from the water and retaining it in the reactive mixture through precipitation or adsorption reactions. Most frequently, metal retention is achieved by changing the oxidation state of the metal and precipitating a secondary mineral that is sparingly soluble under the conditions that prevail in the barrier.

During this presentation, I will focus on the development of reactive barrier systems for treating dissolved metals, describing the steps from bench-scale testing to full-scale implementation. The presentation will include the results of laboratory testing, conducted to assess the properties of reactive materials, field installations, long-term monitoring, and the development and application of reactive transport models, used to understand the interaction of physical and chemical processes within reactive barriers and to predict their long-term performance. I will describe our continuing efforts to understand, refine, and extend the limitations of this developing technology.

Predicting, Preventing, and Remediating Acidic Drainage from Sulfide-Bearing Mines and Mine Wastes

The generation of acid mine drainage and the accompanying release of high concentrations of dissolved metals plague mining districts throughout the world. Without adequate control, acidic, metal-laden drainage devastates river courses and contaminates aquifers. Acidic drainage results from the biologically mediated oxidation of sulfide minerals in mine workings and mine wastes, and the transport of the reaction products along groundwater and surface water flowpaths. Over the past two decades, our understanding of the complex interactions between hydrogeology, microbiology, geochemistry, and mineralogy has advanced significantly. At the same time, reactive transport models have evolved rapidly to a high level of sophistication, providing a framework for integrating these highly coupled processes. Combining reactive transport modeling with the results of detailed field and laboratory studies provides an unprecedented ability to predict the potential impacts of mining activities and mine-waste disposal facilities prior to closure. Our improved understanding of the causes of acidic drainage has led to the development of new approaches to mine-waste disposal, including the segregation and selective disposal of sulfide minerals in subaqueous repositories or in cemented paste backfill and codisposing sulfide wastes with organic carbon to prevent sulfide oxidation and to promote sulfate reduction and secondary sulfide precipitation. At sites where acidic drainage persists, new and often passive approaches for remediating contaminated surface water and groundwater are providing new opportunities to protect water resources.

This presentation describes conceptual models of the hydrogeochemical evolution of mine wastes and illustrates these conceptual models with examples from minesites throughout the world. I will describe approaches that can be used to understand and model the predominant physical and biogeochemical processes that control the extent and duration of contaminant release and provide examples of new techniques that are being developed to protect water resources from future contamination and to restore groundwater and surface water quality.

David Blowes of the University of Waterloo has been selected as the 2006 Birdsall-Dreiss Distinguished Lecturer.

This lecture series is sponsored by the GSA Hydrogeology Division and funded by the GSA Foundation.

At the request of interested institutions, he will present one of the two lectures described here.

For more information on Birsall-Dreiss Lecturers, visit the GSA Hydrogeology Division Web site.