Jon Rohrer, PG, CHg

Principal Hydrogeologist


Contact Information

Phone: (310) 879-4900


Location: Long Beach, CA

LinkedIn Profile


Litigation Consulting

Litigation Expert Testimony

Contaminant Fate & Transport

Source Identification

Soil and Groundwater Investigation

Regulatory Negotiations

Portfolio Evaluation, Site Prioritization, and Closure


MS, Subsurface Hydrology - University of Arizona

BS, Geological Sciences - Lehigh University

Jon Rohrer, PG, CHg

Principal Hydrogeologist

Mr. Rohrer is a Principal Hydrogeologist with over twenty-five years of experience and is a Professional Geologist and Certified Hydrogeologist. He has a Ms in Subsurface Hydrology from the University of Arizona (1996) and a BS in Geological Sciences from Lehigh University (1993). Mr. Rohrer has provided State and Federal expert testimony on a number of technical topics, including historical operations and chemical usage relating to spills and/or releases to the subsurface; responsible party evaluations; fate and transport of contaminants in soil, soil vapor, and groundwater; the extent, severity, and longevity of groundwater impacts in relation to damage assertions; and technical aspects underlying cost allocation approaches. His clients include small businesses and property owners up through Fortune 500 companies that he has successfully assisted in resolving a range of environmental challenges. Mr. Rohrer has also implemented cost-effective and necessary investigation and remediation actions with buy-in from regulators using defined processes and end-points. For example, Mr. Rohrer assisted a PRP-consortium in acquiring a technical impracticability waiver for groundwater impacts in fractured limestone at a major Superfund Site. Mr. Rohrer has extensive experience with a range of contaminants, regulatory settings, and geological environments, including perchlorate, 1,4-dioxane, and other emerging contaminants.

representative projects

Investigation/Remediation: Mr. Rohrer led all aspects of remedial investigation and design for a major gasoline release, including MTBE in a fractured volcanic aquifer. Due to the success of multiple lines of evidence technical investigation approach, a significant mass of contamination was recovered from deep in the vadose zone, after targeting a volcanic-flow related set of migration pathways.


Regulatory Support/Site Closure: Mr. Rohrer led a technical portfolio analysis and subsequent regulatory interactions that resulted in site closure for eight MTBE-impacted gasoline station sites for a major oil company. This included performing several avenues of technical analysis for existing data to break the cycle of low effectiveness spending and regulatory inertia that was hindering closure of these sites.


PRP Searches: Mr. Rohrer in several cases has either performed detailed records searches for one property or for an area resulting in identification of viable potentially responsible parties. This has involved certified manifest acquisition and non-traditional avenues of research.


NRDA: Mr. Rohrer was the field leader for hydrogeology aspects of a Natural Resource Damage Assessment at a site with millions of gallons of free-product and identified an aqueous discharge point to a local river. The technical work supported a settlement of more than $40MM by the California State Attorney General, Department of Fish and Wildlife, and the California Coastal Commission.


Emergent Contaminants: Worked on numerous of cases involving MTBE, TBA, perchlorate, and 1,4-dioxane in the early stages as each of these contaminants developed as contaminants of concern.

  • Kvaerner Aronson, Inc. vs. Mammoth Mountain Ski Area, Mammoth Mountain Ski Area vs. Kvaerner Aronson, Inc. Emco Wheaton Retail Corporation, et al., Mono County Superior Court.

  • Cambria Community Services District vs. Chevron U.S.A., Inc., Chevron Products Company and ChevronTexaco Corporation, San Luis Obispo County Superior Court.

  • City of Morro Bay Nuisance Abatement Hearings, RE MTBE impacts to groundwater.

  • City of Morro Bay, California Energy Commission Application for Certification (00-AFC-12) Hearings for the Morro Bay Power Plant. January 29, 2002.

  • California Senate Select Committee on Perchlorate Contamination, February 27, 2004.

  • Orange County Water District vs. Northrop Corporation et. al., Orange County Superior Court.

  • Confidential Client, Insurance Review of Reasonableness of Site Investigation and Cleanup Costs, Henderson, NV, 2005.

  • Orange County Water District vs. Sabic Innovative Plastics, LLC et. al., Orange County Superior Court.

  • Nammo Talley v. Allstate, United States District Court, District of Arizona.

  • Alcoa Inc. vs. Alcan Rolled Products-Ravenswood LLC, F/K/A Pechiney Rolled Products LLC, Pechiney Cast Plate Inc., and Century Aluminum Company, U.S. District Court for the District of Delaware.

  • HTL Automotive Inc. vs. 1351 Orizaba Avenue LLC, Los Angeles County Superior Court.