Stewart Smith, M.S. Hydrologist


Mr. Smith joined Hydro Geo Chem in 1989 as a Hydrogeologist. His responsibilities include management of site characterization and remediation activities, numerical assessment of landfill gas generation and design of LFG collection and control systems, design of soil and groundwater remediation systems, collection and interpretation of chemical and hydrogeologic data, use of numerical models for remedial design and as predictive and interpretive tools, and preparation of interpretive reports. Project management duties have included representation of clients to and negotiation with controlling regulatory agencies.





B.S. (Geosciences), University of Arizona, Tucson, Arizona, 1980.
M.S. (Hydrology), University of Arizona, Tucson, Arizona, 1989.


• Management of a groundwater remediation project at an Albuquerque, NM landfill site. Project elements include estimation of landfill gas generation rates, design of a soil vapor extraction (SVE) system to remove VOC from soils underlying the landfill that act as a continuing source to groundwater, and design of a groundwater pump and treat system. Includes field measurement of soil and aquifer properties to support the design of the SVE and groundwater treatment system, and evaluation of other remedial alternatives.

• Numerical modeling of the decomposition of municipal solid waste under both aerobic and anaerobic conditions. Model results were used to support the design of an in-situ pilot aerobic treatment system for a closed City of Tucson landfill and to predict long term methane generation rates for untreated landfills.

• Numerical modeling of a baro-pneumatic landfill gas generation rate measurement technique to support a patent application. Patent is pending. Use of the technique to estimate landfill gas generation rates in landfills located in Tucson, AZ, Albuquerque, NM, and Livermore, CA.

• Design of deep soil vapor extraction (SVE) systems for protection of groundwater beneath three Tucson, AZ landfills. Systems were configured to maximize removal of deep vadose zone volatile organic compounds (VOC) that have acted as a source to groundwater while minimizing air intrusion into the overlying landfill. The design process included the use of three-dimensional numerical gas flow and transport models that utilized estimates of soil properties derived from field air permeability tests.

• Management of an SVE design study at a U.S. Environmental Protection Agency Superfund site located near Gary, Indiana. Work included performance of a pilot test, design of an SVE remedial system for the site using numerical models, and preparation of a design report. The effects of biodegradation resulting from SVE operation were included in the evaluation. The system is currently operating within design parameters.

• Analysis of multi-depth soil gas data collected at a municipal landfill in Tucson, Arizona. Work included supervision of field activities and development of numerical flow and transport models that incorporate groundwater and soil gas data as an aid to understanding past history and current and potential future impacts of VOCs on groundwater.


Member, National Groundwater Association


Member, Phi Kappa Phi (Honorary Society).


General Physics Corporation Short Course, "Bioremediation Engineering" November 1992.

Air and Waste Management Association Seminar, "Bioventing and Vapor Extraction: Uses and Application in Remediation Operations", April 1992.

OSHA 40-Hr Health and Safety Training for Hazardous Waste Site Activities, September 1989. 8-Hr Refreshers, Annually.


Bentley, H.W. and S.J. Smith. 1998. Soil Vapor Extraction of Chlorinated VOCs in the Vicinity of a Landfill Equipped with a Landfill Gas Control System. Presentation at the 1998 Arizona Hydrological Society Eleventh Annual Symposium. September 23 to 26, 1998. Abstract with Proceedings.

Bentley, H.W., J. Tang, S.J. Smith, D. Samorano, R.G. Arnold. 1998. Analysis of Remedial Options for Chlorinated VOCs at Harrison Landfill. In: Bioremediation and Phytoremediation, Chlorinated and Recalcitrant Compounds. The First International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Monterey, California, May 18 to 21, 1998. pp. 21-26

Ward, J.J. and S.J. Smith. 1998. Arid Zone Landfills: What Do Investigation and Modeling of Containment Migration Reveal About Transport Mechanisms? Presentation at the 1998 Arizona Hydrological Society Eleventh Annual Symposium. September 23 to 26, 1998. Abstract with Proceedings.

Smith, S.J., J. Pepe, and G.R. Walter. 1995. The Effect of Variable Injection Rates on Air Sparging Patterns in Heterogeneous, Porous Media. Presented at the First International Symposium on In-Situ Air Sparging for Site Remediation. Las Vegas, Nevada.

Smith, S. and G. Walter. 1993. Numerical Modeling of "Raining" Soil Vapor Extraction Wells for a Hypothetical Alluvial Aquifer. Presented at Rocky Mountain Ground Water Conference - Ground Water Technology and Tasks in the 90's, Albuquerque, New Mexico, 1993.

Walter, G.R., R.D. Philip, and S.J. Smith. 1993. Chicken/Egg Arguments in the Establishment of Soil Cleanup Standards. Presented at Hazmacon '93, San Jose, California.


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