Petroleum Compounds Added to New York’s Soil Vapor/Indoor Air Decision Matrices

Earlier this year, the New York State Department of Health (NYSDOH) assigned 13 volatile petroleum compounds to three new Soil Vapor/Indoor Air Decision Matrices, which are a companion to the October 2006 Guidance for Evaluating Soil Vapor Intrusion in the State of New York (aka SVI Guidance). With the addition of these new compounds, the need for soil vapor intrusion (SVI) monitoring and mitigation measures will be triggered at sites that previously would not have been subject to them under the former decision matrices. These updates may affect properties impacted by former or current petroleum use such as automotive dealerships, garages, gas stations, etc.

NYSDOH has provided the following tables to summarize the Soil Vapor/Indoor Air Matrices (Matrices A, B, and C) released in 2017 and the new ones (Matrices D, E, and F):

The factors considered by NYSDOH when generating decision matrices are described in Section 3.4 of the 2006 SVI Guidance. Note that NYSDOH publishes updates to the SVI Guidance on its website. You can find a list of all previous updates and changes here.

Why Is SVI Important?

SVI is the transport of chemical vapors from contaminated soil and groundwater into the indoor air of buildings. The purpose of mitigating these vapors is to prevent them from accumulating in an indoor space so they do not reach levels that put occupants at risk.

To test for SVI, indoor air samples and sub-slab vapor samples are collected concurrently in the lowest level of a building. The sampling results are then evaluated against the NYSDOH decision matrices listed above to assess exposure and determine what level of environmental action, if any, is required to properly mitigate potential SVI risks at a site (SVI mitigation typically involves installation of a sub-slab depressurization system). The actions recommended in the decision matrices are as follows:

• No further action
• Identify source(s) or resample or mitigate
• Monitor
• Mitigate (typically involves installation of a sub-slab depressurization system)

When it comes to dealing with subsurface contamination, the remedial tasks can seem intimidating. Walden is here to help you every step of the way with an experienced team of professionals ready to handle any of your SVI needs. For more information about SVI, sub-slab depressurization systems, or your indoor air quality needs, contact Walden today at 516-271-1948.