The New Jersey Department of Environmental Protection (NJDEP) recently announced the availability of a revision to the Vapor Intrusion Technical Guidance (Version 4.1, January 2018). This document was last updated in August 2016. Revisions to the technical guidance include:
Description of steps taken if the groundwater table is within contact with the building slab, and triggers to conduct a Vapor Intrusion (VI) investigation if Volatile Organic Compounds (VOCs) or Light Non-Aqueous Phase Liquid (LNAPL) are detected in wet basements or sumps.
Clarification is provided on gaining legal access to a building for VI sampling. Lack of access is not an acceptable reason for delaying sampling on accessible properties and legal action to obtain access must be taken.
Definition and clarification of “exterior soil gas samples”, collected from more than 10 feet away from a building, versus “near-slab soil gas samples”.
Language has been added related to the inclusion of the VI pathway in the fate-and-transport description when establishing groundwater Classification Exception Areas (CEAs).
In situations where indoor air samples are not collected due to operational use of the same investigative compounds, the VI pathway for this specific building should be identified as “indeterminate”.
Active gasoline service stations must still be investigated even if the investigated contaminant is in use at the station. Indoor air samples may be delayed (indeterminate status) until a future change in use.
Step-out VI sampling must include buildings within 100 feet of the impacted building irrespective of the contaminant involved, and must be conducted within 60 days for an Immediate Environmental Concern (IEC) condition and 150 days for a Vapor Concern (VC) condition.
Monitoring and maintenance includes annually inspecting buildings that have an indeterminate status to determine potential changes in use.
The Vapor Intrusion Mitigation Monitoring & Maintenance Checklist has been updated.
The updated guidance document can be found at www.nj.gov/dep/srp/guidance/.
For additional information on this topic, contact:
Chris Valligny, LSRP
Rick Shoyer, LSRP
Senior Project Consultant