State Water Resources Control Board

The purpose of this letter is to answer questions regarding the State Water Resources Control Board's (SWRCB's) new secondary containment testing requirements for USTs. [Cal. Code Regs., tit. 23, § 2637.] As is common with the publication of new regulatory requirements, the regulated community, and local regulators, have expressed concern about how these new requirements can be effectively and uniformly implemented. We will address those concerns in this LG letter by answering the most common questions regarding secondary containment testing that have arisen to date. We intend this letter to be a working document that will be periodically updated as new questions come up and as new information becomes available.

Why is periodic secondary containment testing required?

The purpose of secondary containment testing is to determine whether the secondary containment system is capable of containing a release from the primary containment until the release is detected and cleaned up. [Health & Saf. Code, § 25284.1, subd. (a)(4)(B).]

How should secondary containment systems be tested?

Secondary containment systems must be tested using a procedure to demonstrate that the system performs at least as well as it did when it was installed. [Cal Code Regs., tit. 23, § 2637, subd. (a)(2).] The SWRCB chose this general standard to allow flexibility in testing methods and to encourage the development of new technology. Flexibility is necessary because many secondary containment tests performed at installation, or shortly thereafter, may not be feasible or cost effective once the system has been put into operation. For example, a secondary containment system that was tested at installation using a pressure test might only be testable after installation using a vacuum or hydrostatic test. Similarly, a system that was tested upon installation using an overnight hydrostatic test with a crude level measurement may be tested under the new requirements using a shorter hydrostatic test with a more accurate measurement device. The key is to ensure that the test method demonstrates that the secondary containment system performs at least as well as it did upon installation.

Periodic secondary containment tests must be performed in accordance with the manufacturer’s guidelines or standards. [Cal. Code Regs., tit. 23, § 2637, subd. (a)(2).] If there are no such guidelines or standards, secondary containment systems must be tested using an applicable method specified in an industry code or engineering standard. (Ibid.) If there are no applicable manufacturer's guidelines, industry codes, or engineering standards, a test method approved by a state registered professional engineer must be used. Footnote 2 (Ibid.)

How does secondary containment testing affect the current monitoring plan?

Because the integrity of the UST's secondary containment system may impact the effectiveness of the monitoring system, owners/operators subject to secondary containment testing should submit a modification or amendment to the existing monitoring plan to their local agency for review and approval. (See Cal. Code Regs., tit. 23, § 2632, subd. (b).) The modification/amendment should include the secondary containment test procedure and any information necessary for the local agency to verify compliance with the relevant regulations.

Should the UST system be shut down and/or emptied of product when components of the secondary containment system are being tested?

The testing guidelines established by the manufacturer, industry codes, engineering standards, or state registered professional engineer approving the method, as well as all applicable local rules (i.e. Uniform Fire Code), must be followed. Absent such guidelines, standards, or rules, there is generally no need to shut down the UST system or to remove the product unless there are operational or safety concerns that prevent the system from operating during the secondary containment test. Footnote 3

What is required regarding submittal of test results?

The results of the secondary containment test--whether pass or fail--must be submitted to the local agency within 30 days of the completion of the test. [Cal. Code Regs., tit. 23, § 2637, subd. (a)(4).]

If the secondary containment system fails its periodic test, should the UST system be shut down or emptied of product until the secondary containment system has been repaired?

In most cases, when the secondary containment system fails its periodic test, system shutdown or product removal is not necessary, as a failed test does not necessarily mean there has been a release. Generally, the UST system should be shut down and product removed only when there has been a failure of system components that routinely contain product and when continued operation of the system might result in a release to the environment. Because secondary containment systems do not routinely contain product, it is reasonable to allow continued operation of the UST system for a reasonable time until the repairs are made. We believe a reasonable time within which to repair a secondary containment system is 30 to 120 days, depending on the type and the extent of the system failure, the repairs needed, and the time needed by local agency staff to review a repair permit application. However, if leak detection records, site evaluation, or visual observations are cause for concern about the system’s integrity, product removal or system shut down may be necessary. Footnote 4 Similarly, product removal or system shut down may be necessary in cases where extended time frames are needed to arrange for repairs. However, in both instances, a tank test (tank tightness test or an automatic tank gauge test) and/or a line test (line tightness test or a line leak detector test) may alleviate the concern about continued operation of the system.

It is important that the owner/operator, the contractor submitting repair plans, as well as the local agency approving the repairs, make an effort to expedite the process in order to minimize any risk of release to the environment.

When testing the sumps and dispenser containment, is it required that the entire containment be tested?

For sumps and under dispenser containment boxes not equipped with fail-safe sensors, Footnote 5 the entire secondary containment system must be tested. However, for sumps and under dispenser containment boxes equipped with fail-safe sensors, something less than the entire containment may be tested if consistent with the testing guidelines established by the manufacturer, industry codes, engineering standards, or state registered professional engineer approving the test method. It is important to note that even though testing only part of the secondary containment may be legally sufficient in some cases, we strongly recommend testing the entire secondary containment, as our experience has shown that sensors and pump shutdown mechanisms are subject to tampering and/or malfunction.

Should secondary containment testing be conducted on the fill/vapor riser sumps and spill containment boxes?

Unless required by regulation (as a result of UST overfill design) or by a local agency acting pursuant to its independent authority, an owner/operator need not conduct secondary containment testing of the fill/vapor riser sumps and spill containment boxes. Nevertheless, because these components are designed to temporarily hold product in the event of a spill or overfill, we recommend that UST owners/operators voluntarily perform secondary containment testing on both of these components in order to determine their integrity.

May the local agency require a UST owner/operator to conduct secondary containment testing more frequently than required by the regulations?

Unless the local agency is acting pursuant to its independent authority, it may not require UST owners/operators to conduct secondary containment testing more frequently than required by the state regulations. However, the owner/operator of a UST system may voluntarily conduct a secondary containment test at any time to determine the integrity of the system. If the system fails the test and repairs are necessary, the local agency should be notified and the repair or replacement permit procedures of the local agency should be followed.

If you have questions regarding this letter, please contact Ms. Shahla Farahnak at (916) 341-5668 or Ms. Laura Chaddock at (916) 341-5870.

[ original signed by: ]

Elizabeth L. Haven, Manager
Underground Storage Tank Program

This LG (local guidance) letter is intended to clarify the SWRCB's UST regulations regarding secondary containment testing. Please note that while an agency's interpretation of its regulations is usually entitled to some degree of deference, the courts have the ultimate authority to interpret the state's laws and regulations. In addition, while this letter is meant to provide guidance to those local agencies with authority to implement the UST laws and regulations, some local agencies may have more stringent ordinances or policies which differ from the guidance contained herein. In such instances, the SWRCB recommends that the local agency provide statements to the regulated community to prevent any confusion regarding the applicable requirements.

For example, if the manufacturer's guidelines, industry codes, or engineering standards are not applicable at a site due to site specific conditions, then it may be appropriate to rely on a test method approved by a state registered professional engineer. Similarly, if it is necessary to test multiple components as a combined unit because of the way the UST system was designed, it may be appropriate to use a test method approved by a registered engineer. The California professional engineer’s approval should include information to demonstrate that the test method is no less stringent than the manufacturer’s recommended test procedure for the individual components.

We recognize that, in some instances, testing the secondary containment may require the temporary removal of the system's leak detection sensors. In many cases, this will not be a problem because the contractor will be able to visually monitor for releases during the test. However, in cases where the contractor is not on site during the test, the leak detection sensors should be adjusted, rather than removed, so that they continue to monitor for releases.

If there are any repairs or replacements that need to be made to the secondary containment system, the local agency's applicable permit procedures should be followed.

"Fail-safe" sensors are programmed to shut down the turbine pump if (1) they detect either water or product, or (2) they are disconnected or fail.

UST Program - Local Guidance (LG) 160