Delineation of the vapor source for a release is necessary to identify which buildings and properties are within the 100-foot LIZ (Section 4). Volume 6 – Volatilization to the Indoor Air Criteria provides information on the criteria used to define the extent of a vapor source. Additional information on vapor source delineation can be found in Attachment B.3 and additional information on petroleum NAPL evaluation can be found in EGLE’s Volume 4: Investigative approach for Petroleum VIAP and Non-Aqueous Phase Liquid – Petroleum Releases Characterization, Remediation, and Management Guidance.
Note: Buildings and properties outside of the LIZ require no further evaluation. Conduits and utilities outside of the LIZ only require evaluation if they have a vapor source that entered the utility or backfill within the LIZ and are found to be transporting a vapor source beyond the LIZ.
Note: Occupied Buildings that are within the LIZ should proceed to Step 3 even if the delineation of the vapor source is not complete.