Staff Directory

Terry Tolan’s professional experience has focused on working in the Pacific Northwest and serving as a leading expert on the geology, hydrogeology, and structural geology of the Columbia River Basalt Group (CRBG) and suprabasalt sediments in the Columbia Plateau, northwest Oregon, and southwest Washington. He is an author or co-author of more than 60 professional publications and geologic maps about the CRBG, including development of mappable, regional stratigraphic subunits for the Grande Ronde Basalt and Frenchman Springs Member of the Wanapum Basalt. Terry has been applying his knowledge of the geology and hydrogeology of the CRBG and suprabasalt sediments to a wide range of groundwater projects for agricultural, industrial, municipal, governmental, and Tribal clients. These projects have ranged from regional-scale three-dimensional characterization and modeling of the suprabasalt sediment/CRBG aquifer systems to local-scale characterization and analysis of the suprabasalt sediment/CRBG aquifer systems to support groundwater development and aquifer storage and recover feasibility and pilot testing. Terry’s technical expertise also extends into CRBG well/well-field design, well construction oversight, and CRBG aquifer testing and analysis. He has developed and refined unique methods and techniques to prepare, geologically log, and analyze CRBG drill cuttings collected from wells to provide subsurface stratigraphic, structural, and hydrogeologic control. These methods and techniques allow him not only to identify individual CRBG units with a high degree of certainty, but also allow for the identification and characterization of internal flow structures within individual CRBG flows. His unique expertise in geologically logging CRBG drill cuttings has been recognized by the US Geological Survey and state agencies and he has been awarded several sole-source contracts to geologically log CRBG drill cuttings and conduct workshops.