Which option describes interstitial monitoring?

• A. Sensors Installed In Containment Sumps
• B. Soil Vapor Monitoring
• C. Groundwater Monitoring
• D. Impervious Liner With A Well

Answer: (A)

Interstitial monitoring focuses on the space between the tank’s primary containment and its secondary barrier. The standard way to do this is by placing sensors in the containment sump, so any leaked liquid that enters the interstitial space is detected immediately. This direct monitoring of the interstitial area provides early and reliable indication of a leak, which is why sensors installed in containment sumps best describe interstitial monitoring.

Soil vapor monitoring, groundwater monitoring, and liner-based monitoring with a well assess other media or routes (soil gases, groundwater, or liner integrity) rather than the interstitial space between containment barriers.