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Oregon Department of Environmental Quality

Land Quality 


Environmental Cleanup
Hazardous Waste
Solid Waste

Risk-Based Decision Making for the Remediation of Petroleum-Contaminated Sites


DEQ originally developed the guidance document, “Risk-Based Decision Making for the Remediation of Petroleum-Contaminated Sites” in September 1999 and has updated it periodically. Significant updates expanded the original guidance document in 2003 to cover hazardous substance cleanups as well as petroleum-contaminated sites. Since then, DEQ made other revisions to the risk-based concentrations spreadsheet to bring it up to date with current risk assessment practices. These revisions are summarized in the Revision history.

The 2003 guidance document and subsequent revised spreadsheets can be used for both:

  • Cleanup of petroleum releases from regulated underground storage tanks under Oregon cleanup rules for Leaking Petroleum Underground Storage Tank Systems (Oregon Administrative Rules 340-122-0205 through 340-122-0260)
  • Releases of hazardous substances including petroleum under the state’s hazardous substance remedial action rules (OAR 340-122-0100 through 340-122-0115).

This guidance provides a consistent, streamlined decision-making process for evaluating risk posed to human health and the environment. Use of the guidance is optional. Responsible parties and DEQ may use other models or approaches to evaluate site risk; these options may be more appropriate for individual sites. Alternative approaches must also meet risk-based cleanup standards specified in Oregon statute 465.315.

DEQ continues to update and revise this and related guidance and associated spreadsheets. In 2010 DEQ released two related guidance documents: 1) Guidance for Assessing and Remediating Vapor Intrusion in Buildings (March 2010) and 2) Human Health Risk Assessment Guidance (October 2010). Both documents contain elements that supersede the risk-based decision making guidance for evaluation of vapor intrusion problems or assessment of risk from bioaccumulative contaminants to infants. In 2009, DEQ amended equations in Appendix B of the document. Accordingly, Appendix B of the document remains outdated and does not represent current methodology as described by the U.S. Environmental Protection Agency in 2009, and as implemented in current versions of DEQ’s spreadsheets. Updated equations used in the 2011 version of DEQ’s spreadsheet are in Appendix C of DEQ’s Human Health Risk Assessment Guidance.

Guidance Document and Spreadsheets

In addition to the written guidance document, DEQ's environmental cleanup and tanks section periodically updates two spreadsheets used to calculate generic risked-based concentrations. DEQ provides these spreadsheets to interested parties mainly as reference documents that contain:

  • Environmental cleanup and tanks section generic risk-based concentrations; and
  • Default exposure factors, chemical data and toxicological data used to calculate generic risk-based concentrations.

The default exposure factors, chemical data and toxicological data in these spreadsheets can be modified, where appropriate, to calculate site-specific risk-based cleanup levels.

Copies of the Risk-Based Decision Making guidance document and spreadsheets can be obtained by downloading them from the links below. DEQ offers these spreadsheets for informational and calculation use and without official authorization or support.

DEQ offers these Excel spreadsheets as reference documents for calculating site-specific risk-based cleanup levels. Note that the spreadsheets must be run in both cancer and non-cancer modes to derive all the lowest risk-based concentrations that appear in the PDF tables above. You must have Microsoft Excel 2007 or a newer version, and it must be set to "enable macros" for the spreadsheets to open properly.

Frequently Asked Questions

Revision History

[print version]


For more information about DEQ's Land Quality programs, visit the DEQ contact page.

Oregon Department of Environmental Quality
Headquarters: 811 SW Sixth Ave., Portland, OR 97204-1390
Phone: 503-229-5696 or toll free in Oregon 1-800-452-4011
Oregon Telecommunications Relay Service: 1-800-735-2900  FAX: 503-229-6124

The Oregon Department of Environmental Quality is a regulatory agency authorized to protect Oregon's environment by
the State of Oregon and the Environmental Protection Agency.

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