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- About ITRC
TPH Risk Evaluation at Petroleum-Contaminated Sites
Complete remediation at petroleum release sites is often infeasible for technical or cost reasons. Many of these sites may be depleted in typical indicator compounds, such as BTEX, but still heavily contaminated in terms of Total Petroleum Hydrocarbons (TPH). In many cases, states have closed such sites with long term strategies involving institutional control mechanisms (ICs). However, TPH contamination at sites closed with ICs can cause problems associated with future redevelopment of the site when conditions change and contractors are directly exposed to petroleum contamination in soil, groundwater, and vapor containing elevated TPH levels. Some common problems encountered include the following scenarios:
These problems can lead to work stoppages, temporary losses of jobs, disruptions to small businesses involved in the project, unrepaired roads and utilities, etc., and impose economic hardships on a community. A process that allows a more informed use of TPH data to identify potential problems ahead of time is an important part of the solution.
The traditional single-compound approach of managing petroleum contaminants does not fully identify short- and long-term potential environmental concerns, creates delays and cost run ups due to residual petroleum contamination encountered during subsurface utility work or redevelopment. States should utilize a risk-based approach to more effectively incorporate TPH data in addition to traditional BTEX data in cleanup and long-term management decisions.
A 2011, Alaska Department of Environmental Conservation (ADEC) survey of all 50 states and Canada found wide variation in RBCA Tier 1 cleanup approaches using TPH cleanup levels
Methods and techniques for characterizing the risk of petroleum mixtures were refined during the period 2004 to 2014 using a variety of methods, which lead to a wide range of cleanup values. Better guidance is needed to help states develop consistent methodology for establishing risk-based cleanup levels and for establishing and approving methods for risk-based corrective actions.
This ITRC project will review, update, and develop guidance on methods and procedures used for evaluating risk and establishing cleanup requirements at TPH contaminated sites. Much if not all of the information required has already been published by states and other entities over the past 20 years (e.g., TPH carbon range chemistry and toxicity, methods to develop weighted toxicity factors and screening levels for different fuel types, models and approaches to develop screening levels for direct exposure, vapor intrusion, drinking water and aquatic toxicity, gross contamination, etc.). The ITRC document would primarily be a compilation of this existing information presented in an easy-to-use manner for regulators and consultants. This document will also incorporate updated TPH information being collected concurrently by the American Petroleum Institute (API).
A comprehensive guidance on making scientific, risk-based decisions at petroleum-contaminated sites will help states develop guidance to address this common class of contaminants.
The following technical areas and regulatory barriers will be addressed by this project:
The 3-year schedule below would be a reasonable approach: