Department of Environmental Quality (DEQ)Vapor Intrusion Update
Since the DEQ significantly lowered the risk-based concentrations (RBCs) for naphthalene, many heating oil cleanup projects have required increased risk assessment and/or engineering controls to address vapor intrusion for naphthalene and total petroleum hydrocarbons. An increased number of cleanup projects with contamination over 2,500 ppm have required soil gas sampling to eliminate the vapor intrusion exposure pathway. In their February 2010 Contractors Bulletin, the DEQ’s Heating Oil Tank Program has updated the RBC table to include RBCs for heating oil constituents in soil and groundwater for the Vapor Intrusion into Buildings exposure pathway. Also, the DEQ is requiring work plans and the completion of a work plan checklist (see page 4 of the July 2009 Contractor Bulletin) prior to conducting soil vapor sampling. Look for DEQ to announce vapor intrusion guidance training in the coming weeks.
The full text of the DEQ’s February 2010 Contractor’s Bulletin can be found Here