UST Program - Leak Prevention - Frequently Asked Question #1

Question: When performing post-installation enhanced leak detection (ELD), using the Enhanced Tracer Tight® test method, what portions of the underground storage tank (UST) system need to be inoculated?

Answer: The intent of the post-installation ELD requirement is to replace the traditional 0.1 gallon/hour (gal/hr) tank and line tightness test with the more sensitive (0.005 gal/hr) post-installation ELD test. As stated in Health and Safety Code, Chapter 6.7, section 25290.2(i), "Before the underground storage tank is placed in use, the underground storage tank shall be tested after installation using one of the following methods to demonstrate that the tank is product tight." Therefore, for UST systems installed on or after July 1, 2003, the post-installation test method must be able to evaluate the primary tank and piping to 0.005 gal/hr. However, we recommend owners/operators have a separate inoculation of the secondary piping to evaluate its tightness to the same standard, which would thereby demonstrate the secondary containment also meets the required “product tight” standard. This will be essential for systems installed on or after July 1, 2004, which have a vacuum, pressure, or hydrostatic (VPH) continuous monitoring system. Having the secondary containment be vapor-tight will enhance the efficiency of the VPH continuous monitoring system.

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