If you’re evaluating vapor intrusion at your contaminated cleanup site, you can still use the October 2009 Draft: Guidance for evaluating soil vapor intrusion in Washington State: Investigation and remedial action but Table B-1 in Appendix B of the 2009 guidance is out of date and should not be used.
Since 2016, we've issued three vapor intrusion implementation memos that supersede parts of the 2009 guidance:
In 2019, we updated the toxicity values for calculating indoor air cleanup levels, based on recent toxicological information. You'll find these changes in the 2019 update of Cleanup Levels and Risk Calculation (CLARC). Read about all of CLARC's changes in Latest news.
Model Remedies Coordinator