Science and economics drive TPH changes By CHRISTINE VELICER, ELIZABETH STETZ and LINN GOULD Brownfields/TPH Project Industrial land owners and developers are all too familiar with the cost of cleaning up petroleum releases to levels that are "clean" according to Washington state standards. But the definition of "clean" may soon change. The state Department of Ecology is considering new, risk-based ways of evaluating the potential threat posed by petroleum releases. What's at stake? What is moving Ecology to adopt a new approach to evaluating total petroleum hydrocarbons (TPH)? Two forces -- one scientific and one economic -- are driving the change. First, the science of risk assessment has produced exciting results related to the study of petroleum contamination. Scientists and toxicologists have developed innovative ways of estimating the risk to human health and the environment posed by TPH that provide more realistic, site-specific evaluations of risk. And second, prime industrial land is becoming a scarce commodity, especially in King County. As new and growing companies push into undeveloped "green space," hundreds of prime industrial lots lie vacant, fenced off because of the prohibitive cost of environmental cleanup. Often the key contaminant of concern at these "brownfield" sites is TPH. As an example, a recent study found that 85 percent of the sites in the Duwamish Corridor have TPH impacts. In turn, the corridor represents about 65 percent of the city's industrial land base. Who's involved? Ecology, in conjunction with a broad stakeholder group, is developing the new framework for addressing petroleum impacts in soil and groundwater in Washington state. The involved stakeholders include the city of Seattle, the Port of Seattle, King County, the city of Tukwila, the Environmental Protection Agency, the Duwamish Coalition, the State of Washington Pollution Liability Insurance Agency, the petroleum and aerospace industries, electric utilities and federal facilities. Environmental groups were involved early in building a consensus approach, and may become more active in the current stakeholder group. Also, a consulting team led by Foster Wheeler Environmental Corp. (a major environmental contractor), along with Erda Environmental (a risk assessment/management firm) and Onsite Enterprises (a Redmond-based environmental consulting firm), have been retained to assist in developing the framework for evaluating TPH risks. Soils being spread for bioremediation at a site in Bellingham. Photo by Foster Wheeler Environmetnal The "TPH framework" effort has been going on for several years. Several stakeholder meetings were initially held to develop an understanding of concerns regarding the existing TPH policy and to formulate a shared understanding of the type of factors to be addressed in the framework. In May 1996, Ecology held a Risk Assessment Forum to describe the type of TPH framework that stakeholders were requesting and to again solicit input into the process. Throughout 1997, the stakeholder involvement process has continued, including formation of a Laboratory Advisory Board (LAB), led by Dr. Teri Floyd of Floyd and Snider Inc. The LAB is assisting in the development of new laboratory analytic approaches for TPH. Additionally, throughout 1997, the technical detail of the draft framework has been developed by the stakeholder group and the Foster Wheeler/Erda consulting team. Who will be affected? The new TPH framework will be applicable to all sites in Washington, from service stations to large industrial "brownfields" areas. The extent to which TPH cleanups will be affected will vary, depending upon the fuel type, the age of the release, and the types of exposure to TPH that may occur at a site. TPH will probably have higher cleanup levels than currently specified in the Model Toxics Control Act (MTCA) for some types of situations. This may result in reduced cleanup costs and more rapid site evaluations. However, the cleanup levels for TPH and petroleum constituents under certain exposure situations may be lower than existing MTCA regulations. Several case studies are currently being performed under the new draft TPH framework. The case studies will test the framework's technical accuracy, ease of use, and cost efficiency at actual TPH sites in Eastern and Western Washington. What will the new TPH framework look like? The approach used to develop the TPH framework was designed to protect human health and the environment and to take into account the most advanced scientific knowledge. At the center of the new TPH approach is the recognition that TPH is a complex mixture of hundreds of chemicals, with varying levels of toxicity and environmental mobility. Because toxicity and exposure are considered, the new framework is "risk-based." Risk-based approaches for addressing chemical releases are not new. However, until recently, regulatory programs have typically used other approaches to develop TPH cleanup levels. This is because until recently, the science of risk assessment had not been developed sufficiently to address TPH in a risk-based approach. Using the risk-based approach makes sense because it allows for the development of more scientifically-based and more reasonable cleanup levels. Given the mounting costs of TPH cleanup efforts, it is becoming increasingly important to find alternatives to the TPH cleanup approaches used in the past. Two fundamental concepts will form the backbone of the new framework for TPH: the concept of TPH fractionation, and the concept of tiered risk analysis. TPH fractionation The TPH fractionation approach measures TPH compounds present in the environment and groups them by the number of carbon atoms each TPH compound contains. These "groups" of TPH are called "TPH fractions." The approach assigns a toxicity value and representative chemical migration value for each TPH fraction. These values can then be used to develop a risk-based cleanup level for each fraction. The TPH fractionation concept was introduced in the state of Washington in the Department of Ecology's January 1997 Interim TPH Guidance Document. The Interim TPH Guidance uses a basic carbon fractionation approach and addresses some types of petroleum release situations, but is not comprehensive. For example, the interim guidance does not address in detail ecological effects from TPH releases or exposure pathways related to inhalation of petroleum vapors. The new TPH framework addresses these issues, provides a more comprehensive approach for TPH sites, and incorporates the latest scientific evaluation methods. Tiered risk analysis The tiered approach to TPH risk analysis for human health was first formalized by the American Society for Testing and Materials (ASTM) in 1994. It is endorsed by EPA and has been adopted by many states. This tiered TPH approach will meld nicely with the existing MTCA framework for protection of human health. A comprehensive, tiered TPH approach for protection of land and water resources has not yet been developed by other states, ASTM or federal agencies. Therefore, Washington state's TPH framework will lead the nation in development of a tiered ecological approach for addressing TPH. Overall, the tiered risk analysis approach provides for consistent protection of human health and the environment but also allows for increasingly site-specific approaches to address TPH risks. An important part of the framework is the recognition that risk is related to exposure. Sites can be evaluated based on the presence of complete "exposure pathways," such as soil ingestion and vapor inhalation. Once the complete exposure pathways are identified for a site, then cleanup levels specifically designed to be protective of those pathways can be applied. Lower tiers in the process use default inputs to develop cleanup levels, while higher tiers allow for more site-specific approaches to develop the cleanup levels. At any tier, the presence of complete exposure pathways forms the basis of the evaluation. The Department of Ecology's TPH framework will likely be composed of four tiers, Tiers 0 through 3. At the most basic tiers, a number of conservative default values and worst-case assumptions are used to derive risk-based screening level concentrations. The screening levels are available for a variety of common land uses -- residential, commercial and industrial. These screening levels are considered highly protective of almost all petroleum release situations. If concentrations at a site are less than the screening level values, then no further evaluation is necessary. If concentrations exceed the screening level values, then the decision may be made either to develop a cleanup action plan to achieve the screening levels, or to develop alternate cleanup levels using more refined and site-specific data in a higher tier. The decision to proceed to the next tier may involve a number of considerations. Typical factors to consider include the likelihood of a major reduction in cleanup effort and cost, overall site environmental costs, and the data gathering and evaluation effort required for subsequent tiers. Regardless of the tier, the paramount goal of health and environmental protection will still be maintained. Looking ahead The state's new TPH framework rides on the cutting edge of risk-assessment science. It will replace the existing Interim TPH Policy and the current approach in MTCA. Washington state's adoption of the TPH fractionation approach within a tiered risk-based framework that addresses both human health and environmental risks will be more comprehensive and technically innovative than most other states. Similar (though less comprehensive) TPH approaches in other states, such as Michigan, have produced exciting results. In these states, petroleum cleanup costs have dropped dramatically, allowing for redevelopment of TPH sites while still ensuring health protection. According to Ecology's current timeline, land owners and developers in Washington could have a similar, field-tested approach in place by mid-1998, when MTCA revisions take effect. Christine Velicer is a risk assessment project manager for Foster Wheeler Environmental Corp. in Bellevue. Elizabeth Stetz is an environmental management specialist for the Port of Seattle. Linn Gould is president of Erda Environmental Services Inc. in Seattle.