Oregon
Risk-Based Concentrations (RBCs)
Oregon Risk-Based Concentrations (RBCs)
The Oregon Department of Environmental Quality (DEQ) publishes Risk-Based Concentrations (RBCs) for chemicals, to help determine whether the concentrations found at a site could pose a risk. They go with its guidance titled Risk Based Decision Making for the Remediation of Contaminated Sites. DEQ says Oregon environmental cleanup law and regulations require a risk-based approach for assessing and managing environmental contamination.
In a Phase I ESA
ASTM E1527-21 does not name cleanup or screening levels among its standard record sources. They are the yardstick for the sample results in a DEQ file, and for judging what an old closure was measured against. Six details shape how to read a number.
- DEQ's value comes first, then EPA's. DEQ says that for Oregon sites the DEQ RBCs should be used, and that if a chemical does not have a DEQ RBC, the EPA regional screening level should be used. It says the two are calculated by equivalent methods but can differ for some substances.
- The generic table shows the lower of two values. DEQ says its PDF table of RBCs shows the lower of the non-carcinogenic and carcinogenic values, and that the PDF tables should be used unless site-specific calculations are being performed. It also posts a table abridged for the Tank Program and the Heating Oil Tank Program.
- An approved screening is not reopened by a new table. In the schedule it gave with its May 2018 update, DEQ says approved screenings and risk assessments typically do not require reassessment unless a new decision is requested or required and that decision needs the support of a current evaluation. A closure rests on the table of its day, so note the date.
- Soil no longer screens out vapor intrusion. DEQ says it no longer uses soil RBCs to screen out risk from vapor intrusion, because soil data does not reliably predict that risk, and that its updated values mean lower soil vapor and groundwater screening levels. Its 2025 vapor intrusion guidance is the first update since 2010 and covers environmental cleanup, leaking underground storage tank and heating oil tank sites. For an older closure, check how the vapor pathway was screened.
- Petroleum has generic values for only some products. DEQ says the only generic total petroleum hydrocarbon RBCs are for gasoline, diesel or heating oil, and transformer mineral insulating oil. For other petroleum products the choice is the soil matrix cleanup level or site-specific values, and the generic diesel values cannot be used for lube oil, No. 6 fuel oil or other heavy products.
- A non-detect can stand in for a value. Some RBCs fall below what laboratories can report. DEQ says it will usually accept non-detection based on the best commercially available technology as sufficient evidence that a compound is not present, though not always, where site history gives reason to believe it could be.
What the record shows
DEQ keeps an update history on its page. The entries that change how an older number reads:
| Date | What DEQ says changed |
|---|---|
| November 2011 | Infant exposure through breastfeeding added for long-term exposure pathways; new toxicity values for trichloroethylene; significantly lower values for hexavalent chromium |
| June 2012 | New toxicity values for tetrachloroethene |
| November 2015 | Updated exposure parameter values; skin contact added to tapwater exposure; chemical classes such as polycyclic aromatic hydrocarbons and PCBs each evaluated as a single hazardous substance |
| May 2018 | Updated toxicity factor for benzo[a]pyrene, which DEQ says generally makes screening levels higher by about a factor of 7; corrected soil leaching to groundwater values that the 2015 table listed incorrectly |
| June 2023 | RBCs for vapor intrusion from soil removed; values for vapor intrusion from soil vapor and groundwater calculated in a separate spreadsheet |
| November 2023 | The PDF table corrected for cyanide |
| March 2024 and March 2025 | Annual updates to the vapor intrusion RBCs |
DEQ says it updates RBCs periodically when EPA makes substantive updates to its screening tables. PFAS are a recent addition to what the cleanup program can address; see PFAS in Cleanup.
Where to read the rule and the numbers
DEQ's Risk Based Decision Making for the Remediation of Contaminated Sites page links the guidance, the generic and abridged tables, the vapor intrusion tables and the spreadsheets for site-specific values. This handbook does not carry the numbers. DEQ cites Oregon Revised Statute 465.315 for the risk-based cleanup standards, Oregon Administrative Rules 340-122-0100 through 340-122-0115 for releases of hazardous substances including petroleum, and 340-122-0205 through 340-122-0260 for petroleum releases from regulated underground storage tanks. Questions on vapor intrusion go to VIWorkgroup@deq.oregon.gov.
Getting the file
The pages read name no file of their own for these values. For the screening or risk assessment at one site, the route is described on the Your DEQ Online and public records requests page.
Sources
Oregon Department of Environmental Quality pages, read October 7, 2026, no modified date shown: