PADEP’s New (and Improved) Vapor Intrusion Guidance

August 1, 2017

Are you buying a property in the city? Have you been informed that the property is being sold at a reduced rate, but were not given a reason why? Is it possible that there was a release from a facility near your property? Depending on the concentrations and site conditions, volatile substances in the subsurface could potentially result in vapor-phase intrusion of these substances into inhabited buildings at a level that poses a threat to human health.

PADEP’s updated Vapor Intrusion (VI) Guidance, entitled “Land Recycling Program Technical Guidance Manual (TGM) for Vapor Intrusion into Buildings from Groundwater and Soil under Act 2,” became effective January 18, 2017. The TGM provides guidance for implementing the Pennsylvania Code Chapter 250 regulations (Pennsylvania’s Voluntary Cleanup Program, commonly known as Act 2). As a property owner (referred to as “remediator” in the TGM), you will be expected to implement the new VI Guidance in order to satisfy the requirements of Act 2 for any Act 2 reports submitted after January 18,2017.

The VI Guidance outlines significant changes to the process for addressing VI that include new/clarified key terms and more options to comply with the Act 2 Statewide Health and Site-Specific Standards. Some benefits of the new VI Guidance include separate approaches for petroleum versus non-petroleum constituents, additional alternative assessment options (near-source and sub-slab soil gas screenings), and details regarding addressing VI under the Act 2 Site-Specific Standard.

In general, the VI assessment process under the new VI Guidance initially includes development of a Conceptual Site Model (CSM) and delineation of concentrations of soil and groundwater constituents, followed by screening of potential VI sources via identification of preferential pathways and application of proximity distances as described in the TGM.

Mitigation (elimination of the complete pathway between the contamination source and the receptor) may be used at any time during the process, and it can be used in lieu of a complete evaluation of the VI pathway.

The remediator chooses from the following options if potential VI sources are identified: (1) alternative VI assessment options (near-source soil gas screening, sub-slab soil gas screening, indoor air screening, or VI modeling); (2) mitigation with an Environmental Covenant; (3) remediation and re-evaluation of the VI pathway; or (4) selection of the Act 2 Site-Specific Standard.

Some of the new/clarified terminology in the VI Guidance that may be important to consider during your building design phase and/or when evaluating existing on-site buildings include Potential VI Source, Preferential Pathway, External Preferential Pathway, Significant Foundation Opening (SFO), Point of Application (POA), and Proximity Distance.

Preferential pathways considered in consort with POA and proximity distance as it relates to the horizontal and vertical location of the potential VI source could be utilized to address potential VI when siting and designing future buildings at the site. When identified, SFOs in existing buildings at the site could be sealed to inhibit vapor entry. Depending on your proposed plans, mitigation may be a more favorable option for your particular scenario with regards to schedule.


PADEP’s new VI Guidance provides a more-detailed process for satisfying Act 2 requirements and additional options for addressing VI to those who wish to obtain a release of environmental liability from the PADEP. Understanding how to apply the process and evaluate options could possibly save you time and/or money.

Please contact Jennifer A. Ewing, P.G., ( or Mary A. King, P.G., ( at 800-365-2324 if you have any questions about the new VI Guidance and how it may influence an upcoming project, or about Act 2 in general.

About the Author

Jennifer A. Ewing, P.G.

Jennifer A. Ewing, P.G., is a Senior Project Manager in CEC's Environmental Engineering and Sciences Practice at our Pittsburgh headquarters office. She is a certified Asbestos Inspector.

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