Dr. Walker has more than 31 years of consulting and research experience specializing in mine waste hydrogeochemistry and contaminated site assessment and remediation. His experience includes project management and liaison, development of management and closure plans for tailings and mine rock and execution of conventional and advanced characterization studies. He has extensive experience in the hydrogeochemical and mineralogical characterization of mine tailings, waste rock, sediments, soils and dust to identify and interpret long-term metal stability, mobility and environmental availability and routinely applies this knowledge to developing water quality estimates for mine sites from planning through closure. Dr. Walker utilizes advanced knowledge on arsenic geochemistry and mineralogy developed through his research to manage complex arsenic mobility issues in the environment. He has also applied his hydrogeological and geochemical skills to the characterization, management and remediation of organic chemicals and metals in groundwater at commercial and industrial sites.