Associated Event
28th International Conference on Paste, Thickened and Filtered Tailings
14–16 April 2026 InterContinental Lisbon | Lisbon, Portugal
Co-disposal Opportunities for Waste Rock and Tailings Workshop
17 April 2026 | Sesimbra Room, InterContinental Lisbon | Lisbon, Portugal
Workshop overview
This workshop was developed to leverage the important content published in SME’s Tailings Management Handbook: A Life-Cycle Approach, particularly Part 1 Chapter 9: Other Tailings Disposal Methods and Co-disposal of Tailings.
This workshop presents a brief overview and a summary of key technical considerations for the emerging mine waste management technique of co-disposal of waste rock and tailings. The workshop will delve into the theory and application of co-disposal, exploring geotechnical and geochemical characteristics, tailings dewatering, mixing, transport and deposition, and long-term closure benefits. Many versions of co-disposal have been attempted over the years, each with pros and cons – the differences and similarities between options will be discussed and clarified.
The presenters shall discuss the practical considerations for developing and implementing co-disposal as a relatively new technology using select case histories, including a summary of state-of-practice across the mining industry.
This comprehensive approach will cover all necessary aspects to provide a thorough understanding of what co-disposal is, why it can be a valuable tool in your waste management toolbox, and key considerations for design and implementation.
Key learning outcomes
- What are the different versions of co-disposal
- An understanding of geotechnical properties and their impact on co-disposal
- An understanding of dewatering properties and their impact on co-disposal operations, with a focus on pressure filtration and dry stack tailings
- Typical recipes for co-disposal
- Implementation success stories
- Closure benefits and impacts of co-disposal
Who should attend?
- Managers and decision-makers in mining and industrial areas
- Operational, environmental, tailings and maintenance engineers
- Plant designers, and equipment and reagent suppliers
Program*
*Program subject to change.
Presenters
Dr Devin Castendyk
Vice President Geology
WSP, USA
Devin is a global subject matter expert on the geochemistry of pit lakes and commingled waste facilities composed of tailings and waste rock. He has 27 years of experience predicting and monitoring the chemistry and limnology of 55 pit lakes on five continents. He is lead geochemist for three commingled pilot studies by members of the global GeoStable Tailings Consortium. From 2005 to 2015, he was Assistant and Associate Professor of Water Resources at the State University of New York (SUNY) at Oneonta, where he researched oil sands pit lakes in Alberta and coal pit lakes in Pennsylvania, developed the INAP Pit Lakes Database, co-edited the book Mine Pit Lakes: Characteristics, Predictive Modeling, and Sustainability, and contributed to the Global Acid Rock Drainage (GARD) Guide and the End Pit Lake Technical Guidance Document for the Province of Alberta, Canada. Devin became a consultant in 2015 for Hatch Associates followed by Golder Associates and WSP, where he pioneered techniques for aerial drone water sampling from pit lakes, designed and lead field trials on commingled EcoTails in Mexico and Guatemala, and developed an artificial intelligence tool to evaluate the return-on-investment from critical metal recovery from pit lake water. Devin currently co-leads WSP’s global geochemistry practice area network and is an active leader in the mine water geochemistry community; he has developed and chaired conference sessions, taught short courses, served as a journal reviewer, and has been an invited speaker at international mining industry conferences.
Martha Buckwalter-Davis
Senior Geochemist
WSP, Ireland
Martha Buckwalter-Davis is an associate geochemist with WSP (formerly Golder Associates) in Naas, Ireland, and serves as the geochemistry team leader in the UK & Ireland Metals & Mining – Mine Water team. Martha has 15 years’ experience as a consultant to the mining industry in Canada and Europe, with a technical practice focusing on geochemistry of mine waste with respect to metal leaching and acid rock drainage potential. This includes geochemical characterisation and water quality modelling studies, with integration of the findings into waste and water engineering and management for projects at all stages (exploration to closure). She travels regularly to mine sites around the globe for implementation of geochemical studies including sampling and field trial installations.
She has further interest in the applications of geochemistry to aggregates/construction materials, contaminated land, manufacturing, and waste, and holds expertise in European waste legislation and the circular economy. Before locating to Ireland, she completed a master’s degree at Queen’s University, Canada, on the use of automated mineralogy to assess mineralogical controls on the environmental behaviour of mine waste.
Sue Longo
Senior Principal Mechanical Engineer
WSP, Canada
Sue is a principal and senior project manager with over 22 years’ experience in domestic and international mining projects, with a focus on backfill and tailings disposal in the mining, power and oil sand industries. Sue has worked on conceptual, feasibility and detailed engineering design mandates, as well as start-up and commissioning assignments and operation of pilot plants. She has acted as the design and site lead on a multimillion dollar contracted backfill delivery program for a closed uranium and gold mines in Canada.
Ingrid Martinez
Senior Principal Mine Waste Engineer & Mine Closure Specialist
WSP, Canada
Ingrid is a senior principal mine waste engineer and mine closure consultant in WSP’s Mississauga office, Canada, with over 23 years’ experience in mining engineering projects. She is the mine closure practice area network lead at WSP. Ingrid is a registered Professional Engineer in Ontario. Ingrid’s project management and design experience includes national and international projects (North, Central and South America, Caribbean, Asia and Africa). Typical national and international mining projects have involved: sitting studies, geotechnical site investigations, conceptual to detailed design of tailings management facilities (TMFs), dams inspections, dam safety reviews, construction supervision, water management, tailings deposition planning including in-pit disposal, mine waste rock management, mine closure and reclamation plans including cost estimates and risk assessments, capital and operating cost estimates, and TMF reviews and audits. Ingrid’s experience also includes engineer of record roles for TMFs. Ingrid’s first language is Spanish, and she is fluent in English.
Mark Rizzuto
Senior Process Engineer
WSP, Peru
Mark is a senior process engineer based in Lima, Peru with over 15 years’ experience designing pipeline, pump, and process facilities for the mining industry – from concept through execution and start-up. His specialties include tailings transport and dewatering, and process equipment design and selection. Mark is particularly interested in non-conventional mine waste management technologies such as co-disposal and hydraulic dewatered stacking.
Dr Ben Wickland
Senior Principal Geotechnical Engineer
WSP, Canada
Ben has worked in geotechnical and geoenvironmental engineering since 1998. He specialises in mine waste management and holds degrees in civil engineering and biology, with a PhD in mine waste co-disposal. Ben consults from Victoria, British Columbia (Canada) and leads WSP’s mine waste practice area network. Ben’s consulting experience includes design of mine waste facilities, engineer of record roles for facilities in construction, operation, and closure; mine waste alternatives assessments; risk assessments; field and laboratory investigations for site, borrow, and mine waste characterisation.