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Monitoring for Vapors in the Soil

How does the release detection method work?

This method samples for either: product vapors in the soil gas surrounding the UST (sometimes called passive monitoring) or presence of a tracer compound introduced into the UST system (sometimes called active monitoring). Leaked petroleum produces vapors that can be detected in the soil gas. Presence of a tracer compound outside of the UST system is an indication of a suspected release. The UST regulation describes several requirements for using this release detection method. For example, this method requires using porous soils in the backfill and locating the monitoring devices in these porous soils near the UST system.

Features of vapor monitoring systems are:

What are the regulatory requirements?

Will it work at your site?

Before installing a vapor monitoring system, a site assessment must be done to determine whether vapor monitoring is appropriate at the site. A site assessment usually includes at least a determination of the groundwater level, background contamination, stored product type, and soil type. This assessment can only be done by a trained professional.

Will you be in compliance?

For USTs installed [on or before 180 days after effective date], owners and operators may use vapor monitoring as their primary method of release detection. When installed and operated according to the manufacturer's specifications and in accordance with the site assessment, vapor monitoring meets the federal release detection requirements. Vapor monitoring can also be used to detect leaks in piping. Operation of the vapor monitoring system at least once each month fulfills federal release detection requirements. USTs installed or replaced after [180 days after effective date] may no longer use vapor monitoring as the primary method of release detection. USTs must be secondarily contained and use interstitial monitoring.

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