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UST Program – Leak Prevention – Frequently Asked Question #16

UST Program - Leak Prevention - Frequently Asked Question #16

Question: Is the low-level containment sump testing an acceptable method of secondary containment testing in California?

Answer: No.

State Water Board staff have received numerous inquiries regarding the updated Petroleum Equipment Institute Recommended Practices (RP) 1200-19, section 6.6, specifically regarding the recently included low-level containment sump testing (LLST). LLST as described in RP 1200-19 requires sump sensors to shut off turbines or dispensers (positive shut down) once activated and additionally requires a sump hydrostatic test by adding approximately 6 inches of water above the sensor activation point. This test would be in lieu of the hydrostatic sump tightness test as described in RP 1200-19, section 6.5.

Underground storage tank (UST) regulations, section 2637(c) detail the requirements for secondary containment testing in California, to include, using a test procedure that demonstrates the system performs at least as well as it did upon installation. Hydrostatically testing sumps above the highest penetration has always been the manufacturer’s standard for installation testing of sumps and under-dispenser containment (UDC). LLST testing, as described the PEI Recommended Practices (RP) 1200-19, is not an equivalent test procedure.

Local guidance LG 160, written in 2001, allowed sump testing of “something less than the entire containment”. LG 160 was superseded by guidance in 2018, removing this allowance and requiring testing equivalent to that performed at installation. Additionally, in 2013 the State Water Resources Control Board (State Water Board) determined testing boots in UDCs could remain in place, allowing easier secondary containment testing of both the pipe and sumps.

Furthermore, data collected by the State Water Board on secondary containment failures identified sumps and UDCs as having the highest failure rates, thereby causing releases to the environment. Not surprisingly, the most common component failures of sumps and UDCs are sump penetrations. Currently, secondary containment testing is being performed on sumps and UDCs that are generally 20 to 35 years old, and proper secondary containment testing is the only means of determining the quality of these aged components.

The State Water Board is aware of service technicians performing the LLST on turbine sumps and bringing the water level only up to the crest of the UST, and thereby testing only one half of the sump/tank top interface. This does not meet California’s secondary containment testing requirements and additionally fails to meet earliest opportunity, since a primary release on the untested side of the sump, if leaking, would never reach the sensor on the opposite side of the sump. UPAs must reject these LLST tests and require secondary containment testing meeting regulatory requirements.


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