UST Technical Compendium: New/Upgraded UST Systems

These interpretations and guidance are based on the 1988 UST regulation.

EPA revised the UST regulations in July 2015. Some of the information in this compendium may no longer apply because of those revisions.

  • Question 1: Removed. Superseded.
  • Question 2: Removed. Superseded.
  • Question 3: If a tank was installed during the interim prohibition, with galvanized piping installed with cathodic protection, but there were no "corrosion experts" on the staff of the installers, would the tank system still meet the requirements to do tank tightness testing every five year rather than the annual testing?
    Answer: Yes, if the cathodic protection is being monitored and meets the criteria for cathodic protection.  This should be sufficient for purposes of systems protected prior to December 22, 1988.  The tank system must also have spill and overfill controls to qualify for the five-year tank testing plan.  Also, the piping must be monitored for releases like any other piping. 
    [There is no additional material included for this answer]
  • Question 4: An owner/operator has an STI-P3 tank with fiberglass piping and a steel pump. As currently designed, the pump is in contact with the backfill. Because of this contact, does the pump have to be cathodically protected?
    Answer: This owner/operator has three options: (1) isolate the pump from the backfill; (2) cathodically protect the pump; or (3) get a "corrosion expert" to certify that, given the individual circumstances, cathodic protection is not needed. The corrosion expert would document this certification in a letter sent to the owner/operator, who would then keep copy in the office files. 
    [There is no additional material included for this answer]
  • Question 5: The technical regulations require owners/operators to check their cathodic protection within six months after a tank is installed, then every three years thereafter. For tanks already installed as of December 22, 1988, do owners/operators have to check the cathodic protection within six months after the regulations become effective, or does he/she have three years to make the first inspection?
    Answer: For tanks already installed, owners/operators must begin adhering to the three-year inspection requirements. They would have to conduct an inspection within three years after the final rule's effective date--December 22, 1991--to qualify as a "protected UST system." 
    [There is no additional material included for this answer]
  • Question 6: Do the national codes or the final rule deal with the size of the overfill catch basin--are there specific requirements for minimum volumes?
    Answer: No limits are established by national codes or in the final regulations concerning the size of the catch basins that must be used. Because these basins are for small spill containment, they should be able to contain volumes of at least one to two gallons. The standard size on the market is five gallons.
    [There is no additional material included for this answer]
  • Question 7: Can owners/operators test their own cathodic protection systems using the Steel Tank Institute's "PP4" cathodic protection testing apparatus? 
    [May 6, 1993 letter to Region V from Ms. Beth Lockwood of Minnesota (PDF) (122 pp, 761 K)]
    Answer: Yes, owners/operators can test their cathodic protection systems using the "PP4" tank testing apparatus and meet 40 CFR 280.31(b). This is because the PP4 test system was developed by corrosion experts, and the user can simply and easily verify that the cathodic protection system is operating properly without extensive knowledge about the dynamics of corrosion or corrosion protection. 
    [October 27, 1993 letter to Mr. Phillips of Region V (PDF) (122 pp, 761 K)]
  • Question 8: In 1992, the Steel Tank Institute (STI) requested that EPA relax the frequency requirements for ongoing cathodic protection monitoring, required under 40 CFR 280.31(b)(1), of "sti-P3" USTs from within 6 months of installation and at least every 3 years thereafter to at the time of installation and subsequently only after any disturbance of the tank excavation.
    Answer: After careful review, the Agency has decided not to take any action at this time to relax the frequency requirements for cathodic protection monitoring of sti-P3 tanks. 
    [June 8, 1994 memorandum to John Barnes of STI (PDF) (122 pp, 761 K)]
    [Notice of Data Availability (PDF) (122 pp, 761 K) - attachment to June 8, 1994 memorandum]
    [Summary of Comments and EPA Responses (PDF) (122 pp, 761 K) - attachment to June 8, 1994 memorandum]
  • Question 9: What are the monitoring/inspection requirements when using the combination of internal lining and cathodic protection (CP) as a corrosion upgrade option?
    Answer: There are three scenarios that might occur when using this corrosion upgrade option. They are:
    1. Applying internal lining and CP at the same time. 
    2. Applying CP to an UST with an internal lining. 
    3. Applying an internal lining to an UST with CP.
    For all options, the CP system needs to be monitored in accordance with 40 CFR Part 280.31. Periodic inspections of the lined tank are not required if the integrity of the UST was ensured prior to the addition of CP. Because integrity assessment is part of the industry lining codes, this will be the case in scenarios 1 and 3, but not necessarily 2. For example, if CP is added to an UST that was lined 5 years ago, but the integrity of the UST was not ensured prior to adding the CP, then periodic inspections of the lined tank are required. 
    [December 4, 1995 memorandum to State and Regional Program Managers (PDF) (122 pp, 761 K)]
  • Question 10: What is EPA's guidance regarding the assessment of the integrity of older bare steel USTs before the application of cathodic protection, under 280.21(b)(2)(iv)? In particular, what did EPA advise regarding ASTM Emergency Standard ES 40 (valid Nov.15, 1994-Nov.15, 1996)?
    Answer: In guidance dated May 18, 1995 and Sept. 14, 1995, EPA recommended that implementing agencies find that the combination of ES 40 and certain monthly leak detection monitoring constitutes a method that prevents releases in a manner that is no less protective than that specified in the regulations at 280.21(b)(2)(i-iii). In guidance dated Oct. 21, 1996, EPA recognized that ES 40 would expire, and recommended that implementing agencies continue to follow their current policies until further guidance was issued, and that they not change to a policy relying only on leak detection for integrity assessment. 
    [May 18, 1995 memorandum to State and Regional Program Managers (PDF) (122 pp, 761 K)]
    [September 14, 1995 memorandum to State and Regional Program Managers (PDF) (122 pp, 761 K)]
    [October 21, 1996 memorandum to State and Regional Program Managers (PDF) (122 pp, 761 K)]
  • Question 11: Removed. Superseded.
  • Question 12: Removed. Superseded.
  • Question 13: Removed. Superseded.
     
  • Question 14: Do ACT-100 and, where accepted by implementing agencies (see NUS Question 12), ACT-100-U tank technologies with anodes attached for supplemental corrosion protection have to be periodically monitored according to 280.31?
    Answer: EPA does not believe that periodic cathodic protection monitoring is required for these tanks because they meet new tank standards without the addition of anodes.  Therefore, EPA recommends that implementing agencies determine the following:
    Periodic monitoring of cathodic protection systems is not required in the following cases:
    1. When factory installed anodes are included with a new ACT-100 or ACT-100-U installation.
    2. When field installed anodes are included with a new ACT-100 or ACT-100-U installation.
    Note: In cases where cathodic protection is retrofitted to a previously installed ACT-100 or ACT-100-U tank, cathodic protection monitoring is required because the status of the cladding cannot be determined.   This memorandum supersedes the information contained in a previous regulatory interpretation regarding CP monitoring requirements for clad steel tanks dated July 18, 1991.
    [February 23, 1999 memorandum to State and Regional Program Managers (PDF) (122 pp, 761 K)]
  • Question 15: What is EPA's guidance regarding the new recommended practice for inspecting internally-lined tanks by Ken Wilcox Associates, Inc. (KWA)?
    Answer: After careful review of the KWA recommended practice, comparison to existing lining inspection standards, and review of the federal regulations, EPA believes that the KWA recommended practice meets the requirements necessary for conducting inspections of internally-lined tanks as required in the federal regulations at 40 CFR 280.21(b).  In addition, EPA recommends that states review the recommended practice to determine if it meets their lining inspection requirements, if applicable under state law.  EPA recognizes that states may decide not to allow use of the KWA recommended practice for the periodic inspection of internally-lined tanks under state law.
    [November 8, 1999 Memorandum to State and Regional Program managers (PDF)(122 pp, 761 K)]
    [Attachment 1 - KWA Recommended Practice (PDF)(20 pp, 426 K) ]
    [Attachment 2 - Comparison (PDF)(122 pp, 761 K)]

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Last updated on March 13, 2026