Key contacts
Jeffrey Di Stasi, PE, is a Branch Manager at Keller North America.
Jeff oversees Keller’s operations across New York and northern New Jersey. He has more than 25 years of experience in geotechnical specialty construction, including ground improvement, grouting, and geostructural applications. In his current role, he is responsible for branch performance, including oversight of engineering, estimating, operations, and project management. In 2026, Jeffrey was inducted into The Moles, one of North America's most prestigious heavy construction organizations.
Jeff holds a Bachelor of Science in Civil Engineering from Lafayette College and a Master of Science in Civil Engineering from the University of Massachusetts Amherst.
Paul Schmall, Ph.D., PE, is Vice President of Business Development at Keller North America.
He has more than 35 years of experience in geotechnical engineering and underground construction, with expertise in groundwater control, dewatering, grouting, ground freezing, tunneling, dam construction and rehabilitation, and forensic investigations of geotechnical failures related to groundwater.
Paul holds a Bachelor of Science in Civil Engineering from Bucknell University and a Ph.D. in Geotechnical Engineering from the University of Nottingham. He is a co-author of the third edition of Construction Dewatering and Groundwater Control and served as President of The Moles, one of North America's leading heavy construction organizations.
Joseph Sopko, PhD, PE is Director, Ground Freezing at Keller North America.
Joe Sopko received his BSc, MSc, and PhD in Civil Engineering from Michigan State University. He has more than 40 years of experience in all aspects of design and laboratory testing programs related to underground construction projects. He develops business opportunities related to geotechnical construction, specifically ground freezing and groundwater control, and routinely provides on-site project management and quality control programs. He has designed and managed ground freezing projects worldwide, including forming laboratory-frozen soil testing programs, numerical modeling, and on site quality control and assurance. He has completed over 100 projects, including deep shafts, tunnel adits, cross passages, and emergency TBM recoveries.
Dr. Sopko specializes in ground freezing for civil and mining projects worldwide. He is also an adjunct professor at Michigan State University. He served with the U.S. Air Force as an engineering officer in Afghanistan and Operation Deep Freeze in Antarctica.
Robert Marra is an Area Manager at Keller North America.
IRobert leads Keller’s Water Treatment division and manages groundwater treatment projects throughout North America. He specializes in the design, construction, operation, and management of temporary and permanent groundwater treatment systems for construction dewatering, environmental remediation, industrial facilities, and infrastructure projects. His technical expertise includes air stripping, liquid-phase carbon adsorption, oil/water separation, filtration, ion exchange, coagulation, flocculation, chemical precipitation, ultraviolet oxidation, groundwater recovery systems, PFAS treatment applications, and in-situ remediation technologies.
Since joining Keller in 2019, Robert has advanced through project engineering and project management roles, ultimately leading the water treatment business and overseeing project delivery, client development, operations, and technical strategy. He earned a Bachelor of Science in Environmental Science from Kutztown University of Pennsylvania.
John Balla is a Senior Project Manager at Keller North America.
John leads water treatment, groundwater remediation, and dewatering projects throughout the Northeast and across the United States. With more than 35 years of experience in the water and wastewater industry, John specializes in the design, implementation, and management of temporary and permanent groundwater treatment systems, environmental remediation projects, construction dewatering operations, and PFAS treatment technologies. Prior to joining Keller, he held executive leadership, business development, operations management, and technical sales roles within the environmental and water treatment industries, including nearly two decades leading groundwater treatment and equipment rental operations.
In his current role, John oversees project delivery, treatment system design, permitting support, client development, and operational management for complex groundwater treatment projects. He earned a Bachelor of Science in Mechanical Engineering from Virginia Tech and an MBA in Industrial Management from Fairleigh Dickinson University.
Leigh Finn is a Project Manager at Keller North America.
Leigh specializes in the design, estimation, and delivery of groundwater extraction and treatment systems for construction dewatering, environmental remediation, and drinking water applications. With more than 23 years of industry experience, Leigh has expertise in groundwater treatment technologies including air stripping, liquid and vapor phase carbon absorption, oil/water separation, filtration, ion exchange, chemical treatment, and ultraviolet oxidation systems. She has managed complex environmental and remediation projects throughout New York and New Jersey, serving as a technical leader in the design and implementation of groundwater treatment systems.
Leigh earned a Bachelor of Arts in Geology from Colgate University and played a key role in the planning and installation of the first zero-valent iron (ZVI) permeable reactive barrier at a brownfield site in New Jersey.
Matthew DeGregoris is an Area Manager for Dewatering at Keller North America.
Matthew leads groundwater control and dewatering operations throughout the Northeast, including New York, New Jersey, Connecticut, Pennsylvania, and New England. He has more than 25 years of industry experience and has been with Keller since 2000, progressing through roles including Accountant, Project Administrator, Assistant Project Manager, Project Manager, Division Manager, and Area Manager. Matthew specializes in construction dewatering and groundwater control systems, with expertise in wellpoint, deep well, and ejector well systems, as well as landfill gas extraction well drilling.
Matthew holds a BS in Business Administration from Montclair State University in Montclair, NJ.
Greg Landry, PE, LEED AP, is Chief Engineer – Dewatering at Keller North America.
Greg has over 20 years of geotechnical contracting experience with a specific emphasis on construction dewatering. His current responsibilities include supervising the engineering team and other professionals who perform design and analysis, cost estimation and proposal preparation, client interface, and implementing QA/QC programs for Keller’s dewatering services. Greg has a deep background in designing innovative dewatering solutions for various dams, levees, and coal ash ponds across a range of geologic conditions, depths, configurations, and project objectives.
He holds a M. Eng.Sc., Groundwater Studies, from the University of New South Wales, in Sydney, Australia and a B.A.Sc., Civil Engineering from the University of Waterloo in Ontario, Canada. Licensed as a Professional Engineer in New Jersey, he has authored and co-authored numerous technical papers and has been the Co-instructor for ASCE’s annual short course ‘Construction Dewatering and Groundwater Control - Design and Application,’ since 2009.