About Flo Americas

Andrea (Andie) Gehlhausen, M.Sc., is a principal hydrogeologist with more than 20 years of technical experience managing projects both in the United States and internationally. As a hydrogeologist and geologist, Andie has worked on a wide variety of projects that include hydrogeological conceptual model development, oil field directional drilling technology applied to mine dewatering, technical writing in support of regulatory compliance, groundwater flow and contaminant transport modeling, and extensive on-site field work, including well installation, borehole logging, VWP installation, water quality sampling, and implementation of aquifer pump tests. Project management experience spans small relationship based local projects to fast burn large value complex projects with contract values exceeding $17MM USD. Andrea is currently the Business Manager and Principal Hydrogeologist for Flo Americas and enjoys the opportunity to lead and mentor a dynamic team

Doug Oliver, M.Sc., P.G., is a principal hydrogeologist with more than 30 years of experience, focusing on mining and environmental applications. He has worked on planned and active mines (both underground and open pit), as well as closed/legacy sites for several commodities including copper, lithium, borates, iron ore, nickel, uranium, and gold, in a variety of geographic settings and climates throughout the world ranging from extreme desert environments to the arctic. He has evaluated data and developed conceptual models of hydrogeologic systems and performed and overseen groundwater modeling studies to evaluate impacts from mine dewatering, tailings storage facility seepage, compare alternatives for remediation of contaminated sites, predict future impacts to water quality for planned mine facilities, and evaluated capture zones for groundwater containment systems. He also has extensive experience with technical reviews, including risk reviews, due diligence, pre- and post-investment reviews for water-related aspects of projects.

Sebastian Torrealba, Ph.D., is a principal hydraulic engineer with over 25 years of experience in the global hard rock mining sector. He established himself as a recognized expert in mine surface water management, specializing in stormwater management, erosion, and sediment control design, applying his extensive knowledge to enhance environmental practices within the industry. Sebastian has a proven track record in developing comprehensive site-wide water management plans and stormwater management and design as well as surface water monitoring plans. His expertise extends to creating sophisticated water balance and water quality models using GoldSim® and formulating effective mine closure plans that span from conceptual design to detailed engineering, execution, operation, and post-closure phases.

Cristina Story, M.Sc., G.I.T., is a technical principal hydrogeologist with over 15 years of experience in hydrogeologic field characterization and groundwater modeling. She has led and managed field programs across the U.S., including Arizona, Nevada, and Alaska, as well as internationally in the Philippines, Mexico, Lao PDR, Colombia, and Guatemala. Her expertise is in conceptualizing and developing numerical groundwater models to assess mine dewatering requirements, pit-lake formation, and the environmental impacts of mining activities. Cristina’s technical background includes designing and installing groundwater monitoring systems, implementing underground instrumentation, conducting short- and long-term aquifer testing, and performing geotechnical core logging and field investigations.

Cab Esposito, M.S., is a senior hydrogeologist with more than 10 years of environmental consulting experience, specializing in groundwater resources. Since 2015, Cab has focused on groundwater in California, primarily supporting agricultural and environmental needs to meet complex regulatory requirements. His project work includes site-scale hydrogeologic characterization, development and calibration of regional groundwater flow models, and scenario analyses incorporating climate change projections.

Cab is proficient in the MODFLOW family of codes, with calibration performed using PEST/PEST++ and UCODE and develops custom workflows in R and Python for data integration, remote sensing, and advanced data visualization. He has applied evapotranspiration (ET) estimates from public platforms such as OpenET and implemented other surface energy balance methods to improve water use and recharge assessments. His experience extends beyond California, including mine remediation projects across the United States.

Sam Schoenmann, M.Sc., is a mining hydrogeologist with over seven years of experience in hydrogeologic field characterization, geologic modeling, and groundwater modeling His diverse background spans mining, oil and gas, environmental remediation, and geotechnical investigations, providing him with a well-rounded perspective on subsurface systems. Sam integrates his extensive field experience—including well and vibrating wire piezometer installations, packer and aquifer testing, and groundwater monitoring—with advanced data analysis and numerical modeling. He specializes in developing conceptual hydrogeologic models, processing and interpreting field data, and conducting groundwater flow modeling using MODFLOW and Groundwater Vistas. His expertise also extends to geospatial modeling in Leapfrog 3D, particle tracking with MODPATH, and environmental assessments.

Bailey Mullett, M.Sc., is a hydrogeologist with 2 years of experience in field characterization and hydrogeologic data analysis and data management. She has experience with ArcGIS, Leapfrog, FEFLOW, Python, and MATLAB for analysis of field data and development of hydrogeologic conceptual models. She utilizes programming tools for pre- and post-processing and groundwater model inputs. Bailey has experience with hydrogeologic field characterization, including hydraulic packer testing, vibrating wire piezometer installation, well installation, long-term aquifer testing, and water quality sampling for groundwater and surface water.