Approaches for the remediation and risk management of total petroleum hydrocarbons (TPH) contamination vary throughout the United States, and might not consistently address both short- and long-term environmental concerns associated with petroleum contaminant mass.

Petroleum products are complex mixtures consisting of thousands of compounds. Contamination at petroleum release sites is likely to be composed of a mixture of anthropogenic and naturally occurring contaminants, including the original petroleum hydrocarbon compounds, petroleum-related degradation products, fuel additives and, to a limited extent, fuel impurities.

Oftentimes, petroleum cleanup focuses on target constituents such as benzene, toluene, ethylbenzene and xylene (BTEX) and the polycyclic aromatic hydrocarbons (PAHs); however, focusing only on this small group of constituents ignores a potentially significant component of the total petroleum release.

Uncharacterized TPH contamination can result in exposure to soil, groundwater and vapor containing elevated TPH levels. This can lead to public and ecological health concerns, work stoppages, temporary job losses, disruptions to small businesses and economic hardships on communities. A process that allows a more informed understanding of TPH chemistry and use of TPH data to identify potential risks ahead of time is an important part of the solution.

The Interstate Technology and Regulatory Council (ITRC) TPH Risk Evaluation team has developed guidance to assist state regulators and practitioners with evaluating risk and establishing cleanup goals at petroleum release sites.

The ITRC’s TPH Risk Evaluation at Petroleum-Contaminated Sites will help both practitioners and regulators:

  • Characterize TPH (e.g., contaminant delineation and sample location selection) for petroleum release sites.
  • Understand and differentiate petroleum vs. non-petroleum TPH constituents.
  • Understand which analyses are appropriate for which situations.
  • Know the tools that can be used to develop site-specific target levels and/or cleanup goals.
  • Know how to use TPH data for mass-based cleanups and to evaluate risk.
  • Understand how to use TPH data to evaluate risk independent of indicator compounds.
  • Know when the use of silica gel cleanup (SGC) is appropriate.
  • Be able to communicate the risk of TPH to the public.

Methods and techniques for characterizing the risk from petroleum mixtures have improved in varying ways, which has led to a wide range of cleanup values. Updated guidance is now needed to help states understand and evaluate the unique properties of TPH. This enhanced understanding of TPH will assist the development of a consistent methodology for establishing risk-based cleanup levels and for establishing and approving methods for risk-based corrective actions at petroleum-contaminated sites.

 

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As a project manager and risk assessor for Burns & McDonnell, Diana Marquez focuses on helping clients with risk assessment, toxicology, vapor intrusion, and large investigation and remediation projects.