As President, Dr. Tonkin manages or advises on a variety of projects. He specializes in data synthesis and modeling to guide groundwater, surface water, soil and contamination studies, for public, private, and legal clients. This includes planning sampling and monitoring programs; collaborating with other experts; developing and applying models; and presenting to stakeholders.

Dr. Tonkin received his PhD on the topic of model calibration and uncertainty analysis under Dr. John Doherty and has instructed on these and other topics.

EDUCATION
  • PhD, Civil Engineering, University of Queensland, Australia, 2009
  • MSc, Hydrogeology, University of Birmingham, UK, 1994
  • BSc, Applied Geology, University of Birmingham, UK, 1993
AREAS OF EXPERTISE
  • Groundwater Remedy Design
  • Groundwater Flow and Contaminant Transport Simulation
  • Environmental Data Analysis and Interpretation
  • Modeling Project Design and Management
  • Water Resource Evaluations
  • Model Calibration and Uncertainty Analysis
AWARDS AND HONORS
  • Co-Inventor of U.S. Patent No. 10,371,860 (issued Aug. 6, 2019), entitled “Simultaneous Multi-Event Universal Kriging Methods for Spatio-Temporal Data Analysis and Mapping”: 2019
  • ITRC Industry Recognition Award (co-recipient) – MTBE and other Fuel Oxygenates Team: 2005
  • NGWA Outstanding Groundwater Remediation Project Award (co-recipient): 2004
  • ENTEC Award for MS Program and Thesis: 1994
  • British National Environmental Research Council (NERC) MS scholarship: 1993
  • Individual Structural Geological Mapping Award: 1993
  • Royal Air Force Flight Training Scholarship: 1988
APPOINTMENTS AND COMMITTEES
  • 2021–present: Groundwater Resources Association of California (GRAC) GRACast Subcommittee
  • 2013–2022: MODFLOW-and-More Conference Organizing Committee: CO School of Mines, Princeton
  • 2018, 2019: Groundwater Journal, Guest Editor
  • 2005–2010: Interagency Steering Committee on Multimedia Environmental Models (ISCMEM)
  • 2002–2006: Interstate Technology and Regulatory Council (ITRC) MTBE Team
PROFESSIONAL SOCIETIES
  • National Ground Water Association (NGWA)
  • Geological Society of America (GSA)
  • Groundwater Resources Association of California (GRAC)
  • American Geophysical Union (AGU)
REPRESENTATIVE PROJECTS
OTIS AFB MMR Fate-and-Transport Analysis, Modeling, and Remedy Design2024-12-13T18:15:56+00:00
Otis AFB MMR TCE Concentration Plumes

OTIS AFB MMR Fate-and-Transport Analysis, Modeling, and Remedy Design

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Former Halliburton Manufacturing Facility2024-12-10T20:06:06+00:00
Hydraulic Gradients with Time

Former Halliburton Manufacturing Facility

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Fate and Transport Modeling of Fuel Additives2024-12-06T22:52:40+00:00
NYSDEC Figure

Fate and Transport Modeling of Fuel Additives

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Aquifer Parameter Tool (Texture2Par) Development2024-12-06T22:38:50+00:00
Texture2Par SVSIM Examples

Aquifer Parameter Tool (Texture2Par) Development

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Hanford Natural Resources Damage Assessment Upwelling Study2024-11-21T23:16:25+00:00

Hanford Natural Resources Damage Assessment Upwelling Study

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Hanford Site: Groundwater Modeling2024-11-21T18:15:38+00:00
Hanford Groundwater Model figure

Hanford Site: Groundwater Modeling

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West Lake Landfill Site2024-11-21T17:46:08+00:00
West Lake Landfill Site RIM Figure

West Lake Landfill Site

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EPA Region 5 Hydrogeological Synthesis and Numerical Modeling Support2024-11-21T17:33:12+00:00
Map of SSP&A's current and past projects for EPA Region 5

EPA Region 5 Hydrogeological Synthesis and Numerical Modeling Support

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Managed Aquifer Recharge Geochemical Evaluations in Basalts2024-11-21T17:28:39+00:00
Columbia River Gorge

Managed Aquifer Recharge Geochemical Evaluations in Basalts

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Hanford Site Statistics and PHREEQC Geochemical Model2024-11-21T17:09:28+00:00

Hanford Site Statistics and PHREEQC Geochemical Model

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PUBLICATIONS & PRESENTATIONS

  • DiFilippo, E., M. Tonkin and W. Huber, 2023. Use of Censored Multiple Regression to Interpret Temporal Environmental Data and Assess Remedy Progress. Groundwater, vol 61, no. 6: 846-864. doi: 10.1111/gwat.13315

  • Wyatt, K., M. Beck, and M. Tonkin, 2022. Advanced Geostatistics to Optimize the Sampling Approach for Contaminated Soil Investigations and Remediations. Platform presentation at Battelle’s Twelfth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. May.

  • Muffels, C., S. Panday, C. Andrews, M. Tonkin, and A. Spiliotopoulos, 2022. Simulating Groundwater Interaction with a Surface Water Network using Connected Linear Networks. Groundwater. doi: 10.1111/gwat.13202

  • Tonkin, M.J., and M. Chowdhury, 2022. Groundwater Modeling to Support Site Characterization and Remediation in Field Sampling Methods for Remedial Investigations. 3rd Edition.

  • Tonkin, M.J., and Chowdhury, M., 2021. Monitoring Network Analysis for Integrated Central Plateau Decision Making (at the DOE Hanford Site). Invited Presentation at REMPLEX, the 2021 Global Summit on Environmental Remediation, November.

  • Tonkin, M.J., M. Hill, R.M. Maxwell, and C. Zheng, 2020. Groundwater Modeling and Beyond: MODFLOW-and-More. 2019 Special Issue. Ground Water, v. 58, no. 3, pp. 325-326, doi: 10.1111/gwat.12999.

  • Spiliotopoulos A., E.L. DiFilippo, P. Khambhammettu, D. Hayes, M.J. Tonkin, M. Hartman, K. Ivarson, and J. Hulstrom, 2019. Web-Assisted Methods and Tools for Efficient Remedy Design and System Performance Evaluation at Hanford. Presentation at the Waste Management Conference, Phoenix, AZ, March 7, 2019. Received “Superior” paper and “WM2019 Papers of Note Winner” awards. OSTI #23003084

  • DiFilippo E.L., M.J. Tonkin, A. Spiliotopoulos, W. Huber, and V. Rohay, 2019. Evaluating Environmental Remediation Performance at Radwaste Sites Using Multiple, Censored Regression Analysis. Presentation at the Waste Management Conference, Phoenix, AZ, March 7, 2019. IAEA #52043413

  • Maxwell, R.M., A. Navarre – Sitchler, and M. Tonkin, 2018. Forward: Modeling for Sustainability and Adaptation. Ground Water, v. 56, no. 4, pp. 515-516, doi: 10.1111/gwat.12795.

  • Bedekar, V., E.D. Morway, C.D. Langevin, and M. Tonkin, 2016. MT3D-USGS Version 1: A U.S. Geological Survey Release of MT3DMS Updated with New and Expanded Transport Capabilities for Use with MODFLOW. U.S. Geological Survey Techniques and Methods Report #6-A53, Reston, VA. 69 p.

  • Tonkin, M.J., J. Kennel, W. Huber, and J. Lambie, 2015. Multi-Event Universal Kriging (MEUK), Advances in Water Resources, v. 87, pp. 92–105, January. doi: 10.1016/j.advwatres.2015.11.001

  • Royer, P. D., M.J. Tonkin, and T. Hammond, 2014. Conjunctive Water Use in Confined Basalt Aquifers: An Evaluation Using Geochemistry, a Numerical Model, and Historical Water Levels. Journal of the American Water Resources Association (JAWRA), v. 50, No. 4, pp. 963–976, August. doi: 10.1111/jawr.12151

  • Tonkin, M.J., J. Kennel, W. Huber, and J.A. Lambie, 2013. Hybrid Analytic Element Universal Kriging Interpolation Technique Built in the Open Source R Environment. Presentation at the American Geophysical Union, Fall Meeting 2013, Abstract #H52E-03.

  • Tonkin, M. and Z. Tajani, 2012. Piecewise-Continuous Boundaries Using the MODFLOW FHB and MT3DMS HSS Packages. Ground Water, v. 50, no. 2, pp. 296-300. doi: 10.1111/j.1745-6584.2011.00811.x

  • Bedekar, V., C. Neville, and M. Tonkin, 2012. Source Screening Module for Contaminant Transport Analysis Through Vadose and Saturated Zones. Ground Water, v. 50, pp. 954–958. doi:10.1111/j.1745-6584.2012.00954.x

  • Ma, R., C. Zheng, J. Zachara, and M. Tonkin, 2012. Utility of Bromide and Heat Tracers for Aquifer Characterization Affected by Highly Transient Flow Conditions. Water Resources Research, v. 48, #8. doi: 10.1029/2011WR011281

  • Bedekar, V., R.G. Niswonger, K. Kipp, S. Panday, and M. Tonkin, 2011. Approaches to the Simulation of Unconfined Flow and Perched Groundwater Flow in MODFLOW. Ground Water, v. 50, no. 2, pp. 187-198. doi: 10.1111/j.1745-6584.2012.00811.x

  • Ma, R., C. Zheng, M. Tonkin, and J. Zachara, 2011. Importance of Considering Intraborehole Flow in Solute Transport Modeling under Highly Dynamic Flow Conditions. Journal of Contaminant Hydrology, v. 123, Issues 1-2, April 1, 2011, pp. 11-19.

  • Spiliotopoulos, A., R. Shannon, M.J. Tonkin, and L.C. Swanson, 2011. Evaluation of Temporal Variations in Hydraulic Capture due to Changing Flow Patterns Using Mapping and Modeling Techniques. Presentation at MODFLOW and More 2011, Colorado School of Mines, Golden, CO. OSTI #1011435

  • Bedekar, V., M.J. Tonkin, and A. Spiliotopoulos, 2011. Implementation of a Contaminant Treatment System (CTS) Module in MT3DMS. Presentation at MODFLOW and More 2011, Colorado School of Mines, Golden, CO.

  • Khambhammettu, P., M.J. Tonkin, and A. Spiliotopoulos, 2011. FIELDGEN_D – A Modified 2D Field Generator for Deterministic and Stochastic Groundwater Modeling. Presentation at MODFLOW and More 2011, Colorado School of Mines, Golden, CO.

  • Shannon, R., A. Spiliotopoulos, and M.J. Tonkin, 2011. Estimating Contaminant Migration Pathways Using a Time Sequence of Water Level Maps and Particle Tracking. Presentation at the 2011 Ground Water Summit and 2011 Ground Water Protection Council Spring Meeting. National Ground Water Association, Baltimore, MD.

  • Smoot, J.L., F.H. Biebesheimer, J.A. Eluskie, T. Simpkin, M.J. Tonkin, and A. Spiliotopoulos, 2011. Groundwater Remediation at the 100-HR-3 Operable Unit, Hanford Site, Washington. Presentation at the Waste Management Conference, Phoenix, AZ. February 27– March 3, 2011. OSTI # 1004613

  • Hunt, R., J. Luchette, W. Schreuder, J. Rumbaugh, J. Doherty, M. Tonkin, and D. Rumbaugh, 2010. Using a Cloud to Replenish Parched Groundwater Modeling Efforts. Ground Water, v. 48, no. 3, pp. 360-365.

  • Spiliotopoulos, A., M.J. Tonkin, D. Shrimpton, J. Blount, T. Simpkin, and J. Hanson, 2010. Groundwater Modeling in Support of Remedial Process Optimization: Implementing a Developing Conceptual Site Model into Comparative Remedy Analyses. Presentation at the Waste Management Conference, Phoenix, AZ, March 7-11, 2010.

  • Tonkin, M.J. (Editor), 2010. PEST Conference Proceedings. Potomac, MD, November 2009. Available at www.LULU.com.

  • Zheng, C., J. Weaver, and M. Tonkin, 2010. MT3DMS, A Modular Three-dimensional Multispecies Transport Model: User Guide to the Hydrocarbon Spill Source (HSS) Package. Prepared for U.S. Environmental Protection Agency, Athens, GA.

  • Tonkin, M., and J. Doherty, 2010. Citation and Acceptance of the 2009 M. King Hubbert Award. Ground Water (published online). January 2010.

  • Tonkin, M., S. Dadi, and R. Shannon, 2009. Collection and Mapping of Water Levels to Assist in the Evaluation of Groundwater Pump-and-Treat Remedy Performance. SGW-42305 (Rev. 0). Prepared for the US Department of Energy, Richland, WA, September 2009.

  • Karanovic, M., M. Tonkin, and D. Wilson, 2009. KT3D_H20: A Program for Kriging Water-Level Data Using Hydrologic Drift Terms. Ground Water, v. 45, no. 4, pp. 580-586, July/August. doi: 10.1111/j.1745-6584.2009.00565.x

  • Tonkin, M. J., 2009. Efficient Calibration and Predictive Error Analysis for Highly-Parameterized Models Combining Tikhonov and Subspace Regularization Techniques. Doctoral Thesis, University of Queensland, Australia.

  • Weaver, J., J. Zhang, M. Tonkin, and R.J. Charbeneau, 2009. Modeling the Transport of Ethanol Fuel Blends with the Combined HSSM and MT3D Models. Presentation at the 21st Annual National Tanks Conference and Expo, Sacramento, CA, March 30 – April 01, 2009.

  • Tonkin, M., and J. Doherty, 2009. Calibration-Constrained Monte Carlo Analysis of Highly-Parameterized Models Using Subspace Techniques. Water Resources Research, v. 45. W00B10. doi: 10.1029/2007WR006678

  • Spiliotopoulos, A., M. Karanovic, and S.P. Larson, 2008. Development of Transient Flow Models for the Solomon River Basin. Presentation at MODFLOW and More 2008, Colorado School of Mines, Golden, CO.

  • Tonkin, M., C. Arola, and D. Miller, 2007. Decision-Level Modeling within a Feasibility-Study Process: An Application at the Hanford Site. Presentation at the Association of Engineering and Environmental Geologists 50th Anniversary, Los Angeles, CA, September 26-28, 2007.

  • Tonkin, M., and J. Doherty, 2007. An Efficient Calibration-Constrained Monte Carlo Technique for Evaluating Model Predictive Uncertainty. in Proceedings of an International Conference on Calibration and Reliability in Groundwater Modeling: Credibility of Modeling (ModelCARE2007), Copenhagen, Denmark, September 2007. IAHS Publication 320.

  • Hunt, R., J. Doherty, and M. Tonkin, 2007. Are Models Too Simple? Arguments for Increased Parameterization. Ground Water, v. 45, no. 3, pp. 254-262.

  • Tonkin, M., J. Doherty, and C. Moore, 2007. Efficient Non-Linear Predictive Error Variance for Highly Parameterized Models: Water Resources Research, v. 43. W07429. doi: 10.1029/2006WR005348

  • Tonkin, M., C. Tiedeman, D. Ely, and M. Hill, 2007. OPR-PPR, a Computer Program for Assessing Data Importance to Model Predictions Using Linear Statistics, Constructed Using the JUPITER API. Prepared in Cooperation with the U.S. Department of Energy. Techniques and Methods 6-E2. U.S. Geological Survey.

  • Muffels, C., H. Zhang, J. Doherty, R. Hunt, M. Anderson, and M. Tonkin, 2006. Incorporating PROPACK into PEST to Estimate the Model Resolution Matrix for Large Groundwater Flow Models. Presentation at the American Geophysical Union (AGU) Fall Meeting, Moscone Center, San Francisco, CA, December 2006.

  • Muffels, C., J. Doherty, M. Anderson, R. Hunt, T. Clemo, and M. Tonkin, 2006. LSQR and Tikhonov Regularization in the Calibration of a Complex MODFLOW Model. Presentation at the Geological Society of America Annual Meeting, Philadelphia, PA, October 2006.

  • Muffels, C., M. Tonkin, H. Zhang, M. Anderson, and T. Clemo, 2006. Application of LSQR to Calibration of a MODFLOW Model: A Synthetic Study. in Proceedings of MODFLOW and More 2006, Managing Ground-Water Systems, International Ground Water Modeling Center, Colorado School of Mines Golden, CO, May 2006, v. 1, pp. 283-287.

  • Tonkin, M., M. Karanovic, A. Hughes, and C. Jackson, 2006. New and Contrasting Approaches to Local Grid Refinement. in Proceedings of MODFLOW and More 2006, Managing Ground-Water Systems, International Ground Water Modeling Center, Colorado School of Mines Golden, CO, May 2006, v. 2, pp. 601-605.

  • Tonkin, M., and J. Doherty, 2005. A Hybrid Regularized Inversion Methodology for Highly Parameterized Environmental Models. Water Resources Research, v. 41, no. 10, October. W10412. doi: 10.1029/2005WR003995

  • Tonkin, M., and M. Becker, 2005. Environmental Insite: A Software Package for Ground Water Data Visualization. Ground Water, v. 43, no. 4, pp. 466-470. Software Spotlight.

  • Tonkin, M.J., 2005. Model Analysis Using the JUPITER API. Presentation at the Annual Public Meeting of the Interagency Steering Committee on Multimedia Environmental Models (ISCMEM), American Geophysical Union (AGU), Washington, DC, August 2005.

  • Tonkin, M., J. Weaver, C. Zheng, C. Muffels, and J. Rumbaugh, 2005. Coupled Free and Dissolved Phase Transport: New Simulation Capabilities and Parameter Inversion. in Proceedings of the 2005 National Ground Water Association (NGWA) Conference on MTBE and Perchlorate, Assessment, Remediation, and Public Policy, San Francisco, CA, May 2005.

  • Muffels, C., M. Tonkin, J. Haas, and D. Trego, 2005. Predictive and Post-Audit Mass Flux Estimates. in Proceedings of the National Ground Water Association (NGWA) Ground Water Summit, San Antonio, TX, April 2005.

  • Tonkin, M. (as Contributing author to Interstate Technology & Regulatory Council (ITRC) MTBE and Other Fuel Oxygenates Team), 2005. Overview of Groundwater Remediation Technologies for MTBE and TBA. February 2005.

  • Neville, C. and M. Tonkin, 2004. Modeling Multi-Aquifer Wells with MODFLOW. Ground Water, v. 42, no. 6, pp. 910-919.

  • Tonkin, M. and C. Muffels, 2004. Assessing Hydraulic Capture through Combined Analytic Elements and Interpolation. EPA Groundwater Forum, Sacramento, CA, October 2004.

  • Tonkin, M., S. Larson, and C. Muffels, 2004. Assessment of Hydraulic Capture through Interpolation of Measured Water Level Data. Presentation at the Conference on Accelerating Site Closeout, Improving Performance, and Reducing Costs through Optimization: Environmental Protection Agency, Federal Remediation Technology Roundtable, Dallas, TX, June 2004.

  • Tonkin, M., T. Clemo, and J. Doherty, 2003. Computationally Efficient Regularized Inversion for Highly Parameterized MODFLOW Models. in Proceedings of MODFLOW and More 2003: Understanding through Modeling, International Ground Water Modeling Center, Colorado School of Mines, Golden, CO, September 16, 2003, v. 2, pp. 595-599.

  • Tonkin, M., M. Hill, and J. Doherty, 2003. Modflow-2000, The U.S. Geological Survey Modular Ground-Water Model – Documentation of Mod-Predict for Predictions, Prediction Sensitivity Analysis, and Enhanced Analysis of Model Fit. Prepared in Cooperation with the U.S. Department of Energy. U.S. Geological Survey Open-File Report 03-385.

  • Lolcama, J., H. Cohen, and M. Tonkin, 2002. Deep Karst Conduits, Flooding, and Sinkholes: Lessons for the Aggregates Industry. Engineering Geology, v. 65, no. 2-3, pp.151-157.

  • Tonkin, M., and S. Larson, 2002. Kriging Water Levels with a Regional-Linear and Point-Logarithmic Drift. Ground Water, v. 40, no. 2, pp. 185-193.

  • Neville, C., and M. Tonkin, 2001. Representation of Multi-Aquifer Wells in MODFLOW. in Proceedings of MODFLOW 2001 and Other Modeling Odysseys, International Groundwater Modeling Center, Colorado School of Mines, Golden, CO, September 2001, v. 1, pp. 51-59.

  • Cohen, H., M. Tonkin, and C. Neville, 2000. Determination of Hydraulic Conductivity Distribution in a Heterogeneous Glacial Sand Aquifer: Correlation between Estimates Based on Impeller Flow Meter Data and Grain Size Distributions. Society for Sedimentary Geology/International Association of Sedimentologists Research Conference: Environmental Sedimentology: Hydrogeology of Sedimentary Aquifers, Santa Fe, NM, September 24-27, 2000.

DEPOSITION & TESTIMONY EXPERIENCE

DEPOSITIONS

  • 2022 – Goleta Water District v. Slippery Rock Ranch, LLC. Superior Court of the State of California. No. 1487005. March 18.

  • 2022 – Goleta Water District v. Slippery Rock Ranch, LLC. Superior Court of the State of California. No. 1487005. March 12.

  • 2021 – Goleta Water District v. Slippery Rock Ranch, LLC. Superior Court of the State of California. No. 1487005. August 31 – September 1.

  • 2021 – Goleta Water District v. Slippery Rock Ranch, LLC. Superior Court of the State of California. No. 1487005. April 28.

  • 2019 – Goleta Water District v. Slippery Rock Ranch, LLC. Superior Court of the State of California. No. 1487005. September 16 – 17.

  • 2018 – State of New York v. United Gas Corp., et al. December 11 – 12.

  • 2016 – Waverley View Investors, LLC. vs. United States of America. United States Court of Federal Claims. No. 15-371L. December 15.

  • 2016 – Samantha Hall vs. Conoco, Inc. et al. United States District Court for the Western District of Oklahoma. No. 14-CV-670-HE. March 3.

  • 2014 – Jerilyn K. Allen et al. vs. ExxonMobil Corporation. Circuit Court of the State of Maryland, County of Baltimore No. C-11-8536. April 4.

  • 2011 – State of New York vs. 913 Portion Road Realty Corp, et al. Supreme Court of the State of New York. No. 26495-M. July 29.

  • 2008 – Jeff Alban et al. vs. ExxonMobil Corporation et al. Circuit Court of the State of Maryland, County of Baltimore. No. 03-C-06-010932. February 6.

TESTIMONY

  • 2017 – Waverley View Investors, LLC. vs. United States of America. United States Court of Federal Claims. Case No. 15-371L. May 15.

  • 2017 – White Bear Lake Restoration Association, ex rel, State of Minnesota vs. Minnesota Department of Natural Resources and Thomas J. Landwehr in his Capacity as Commissioner of the Minnesota Department of Natural Resources. State of Minnesota Second Judicial District Court, County of Ramsey. Case No. 62-CV-13-2414. March 23.

  • 2017 – Waverley View Investors, LLC. vs. United States of America. United States Court of Federal Claims. Case No. 15-371L. January 18.