Vapor Intrusion and Indoor Air Evaluation

By:

Metropolitan Civil Engineering and Environmental Remediation Services

The presence of volatile chemicals in contaminated soil or ground water offers the potential for chemical vapors to migrate through subsurface soils and/or preferential pathways (such as underground utilities) thereby impacting the indoor air quality of area buildings. Vapor intrusion refers to this migration of volatile chemicals from the subsurface into overlying buildings. The accumulation of these volatile vapors in buildings can result in significant safety and health concerns.

It is recommended that the user periodically refer to the NJDEP Vapor Intrusion web site ( http://www.nj.gov/dep/srp/guidance/vaporintrusion/) for the latest information on the vapor intrusion pathway. The Department will update the screening level tables included in the document soon after new toxicity factor information becomes available from USEPA Region III. Region III currently updates their Risk Based Concentration (RBC) Table twice a year (April and October).

The Department will also update the guidance document as the state of the science advances in the evaluation of the vapor intrusion pathway. Updates to the document and the associated tables will be highlighted in the “What’s New” section of the NJDEP Web site.

To properly evaluate vapor intrusion a thorough evaluation of the building's ventilation system and subsurface conditions needs to be conducted by a knowledgeable professional in accordance with state and federal established procedures.

The evaluation process typically includes a thorough building chemical inventory, the advancement of soil gas probes and the collection of soil gas samples. When indoor air quality problems are identified they can normally be resolved through the modification/installation of a properly designed ventilation system.

Metropolitan is well experienced with U.S. EPA and State vapor intrusion investigation techniques. We have completed numerous vapor intrusion and indoor air quality studies at commercial and residential properties. We have the experience to identify and resolve indoor vapor intrusion problems and the practical know-how to resolve indoor quality issues in an efficient and cost effective manner.