Extended Team

Peter Mock, PhD, PG, PH, President and Principal Scientist at Peter Mock Groundwater Consulting, Inc. (PMGC) since 1997. Mr. Mock work specializes in numerical simulations of flow and transport with extensive experience collecting and interpreting basic geologic, hydrologic and chemical data. Projects of note in his resume include regional simulations of the Irvine Sub-basin in southern California, of the carbonate system of southeastern Nevada, and of the N and D Aquifers of northeastern Arizona, as well as Remedial Investigations of several federal Superfund Sites, including Tucson International Airport, Phoenix-Goodyear Airport, Indian Bend Wash, San Gabriel Valley, Montrose-Del Amo and MCAS El Toro. Peter has also worked on subsidence, artificial recharge, and dewatering projects, and on the adjudication of water rights on the Gila River Watershed. He was a Neutral Expert for groundwater modeling on the Guadalupe Oil Field Meditation and oversaw the remediation of two multi-million-gallon jet fuel spills beneath an airport property. Mr. Mock has spoken at numerous conferences on water resources and environmental science and has given short courses on aquifer test analysis and numerical modeling. Mr. Mock earned his Bachelor of Science in Hydrology and PhD in Hydrology with a minor in Applied Mathematics at University of Arizona and worked at Arizona Department of Water Resources and at CH2M Hill prior to launching PMGC.

Jill Ryer-Powder, PhD, DABT, Principal Health Scientist at Environmental Health Decisions, provides expertise in the fields of toxicology, human health risk assessment, and product hazard evaluation. She brings more than 25 years of experience in litigation support, risk assessment, Proposition 65 evaluation, and occupational toxicology to human health hazard and evaluation projects. In her position, Dr. Ryer-Powder is responsible for strategic preparation, project management, and evaluation of chemical toxicity for risk assessment and product hazard evaluation projects. She is also involved in the investigation and analysis of legal and regulatory issues and controversial claims regarding chemical causation of diseases in humans. Her solid technical background, coupled with her frequent involvement in risk and hazard evaluation projects, gives her a broad perspective on the technical, economic and regulatory considerations for human health hazard evaluation work.

Dr. Ryer-Powder was a pioneer in the development of safe exposure levels for petroleum fuels and ammonia. She has extensively researched the toxicological issues surrounding human exposures to petroleum hydrocarbons, ammonia, and chlorinated hydrocarbons. In her experience in evaluating potential hazards from chemicals, she has worked extensively with USEPA Region IX, Cal/EPA Department of Toxic Substances Control, Los Angeles Regional Water Quality Control Board, San Diego Regional Water Quality Control Board, and Orange County Health Care Agency. Negotiations have involved presentation and approval of health risk assessments, health-based cleanup levels, and the setting of safe levels of exposure in the occupational and public arena.

Dr. Ryer-Powder has managed and performed more than 100 health risk assessments for local and national clients. Her site experience includes Preliminary Endangerment Assessment risk assessments, Proposition 65 evaluations, federal and state Superfund sites, Manufactured Gas Plant sites, RCRA sites, and Brownfields sites. She has prepared hundreds of Material Safety Data Sheets (MSDSs) and product labels for consumer and industrial products, including petroleum fuels, solvents, metals, fertilizers, pesticides, adhesives, and fabric protectors. She has worked with trade associations, private industry, and regulatory agencies to develop safe exposure levels to petroleum products and ammonia. She has presented results of risk assessments in public meetings. She has also provided expert testimony in cases involving exposure to metals, solvents, and petroleum hydrocarbons. Dr. Ryer-Powder has lectured on several occasions on the subject of risk assessment to students in the University of California system.

She received her Bachelor Degree in Nutrition from Cornell University, her PhD in Toxicology from Rutgers University, and did post-doctoral work at University of Southern California/Children’s Hospital of Los Angeles.

David Johnson, MS, PG, Principal Owner of DMJ Consulting Group, has 30 years of program management experience in the fields of environmental remedial investigation (RI/FS), environmental and hazardous waste management, Phase I/Phase II site investigations, construction oversight, groundwater monitoring and hydrogeology, municipal water resources, regulatory agency interaction and site closure strategies, water quality assessments, and groundwater resource development. Experience includes project management, planning, staffing, training, budgeting and oversight of field construction operations, regulatory agency interaction, budget tracking and management, well design/specification (large-capacity public supply wells and monitoring wells), construction/specification management and contractor oversight, soil, groundwater and soil vapor sampling, Westbay® well design and sampling, well development, use of various sampling pumps and equipment, health risk evaluation, indoor air sampling, borehole logging and stratigraphy, groundwater monitoring programs, borehole geophysics, aquifer pump testing and hydrogeologic characterization.

Mr. Johnson earned a Bachelor of Science degree in Geology from Humboldt State University, California, and a Master of Science in Geology with emphasis in Hydrogeology and Engineering Geology at California State University, Los Angeles. He maintains Professional Geologist licenses in California, Washington, Illinois and Wisconsin. Mr. Johnson is also Adjunct Professor of Physical Sciences at Citrus College in Glendora, California. Mr. Johnson teaches courses in physical geography, geology, Geographical Information Systems (GIS) and oceanography.

John McCabe, CSP, QEP, CEM, President and MEHS Consulting, has over 30 years of experience in national and international Environmental Health and Safety (EHS) programs, including multi-media regulatory compliance, serving clients in manufacturing, oil and gas, biotech/pharmaceutical/medical device, aerospace, electronics, government, and construction fields, including in a litigation context. He has managed EHS teams and services for large consulting organizations and in private industry, including for Workers Compensation Claims, Accident Investigation, H&S Compliance Program Development, Emergency Response, and Environmental Regulatory Compliance Audits.

Mr. McCabe earned his Bachelor of Science degree in Biology from California State University, San Diego and his Master of Science in Environmental Engineering from University of Southern California. He holds the following registrations: Certified Safety Professional (CSP), Qualified Environmental Professional (QES), and Certified Energy Manager (CEM).

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