StacksVerified U.S. regulatory reference

40 CFR §280.42

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Owners and operators of hazardous substance UST systems must provide containment that meets the following requirements and monitor these systems using § 280.43(g) at least every 30 days:
  1. (a)Secondary containment systems must be designed, constructed, and installed to:
    1. (1)Contain regulated substances leaked from the primary containment until they are detected and removed;
    2. (2)Prevent the release of regulated substances to the environment at any time during the operational life of the UST system; and
    3. (3)Be checked for evidence of a release at least every 30 days.
  2. (b)Double walled tanks must be designed, constructed, and installed to:
    1. (1)Contain a leak from any portion of the inner tank within the outer wall; and
    2. (2)Detect the failure of the inner wall.
  3. (c)External liners (including vaults) must be designed, constructed, and installed to:
    1. (1)Contain 100 percent of the capacity of the largest tank within its boundary;
    2. (2)Prevent the interference of precipitation or groundwater intrusion with the ability to contain or detect a release of regulated substances; and
    3. (3)Surround the tank completely (i.e., it is capable of preventing lateral as well as vertical migration of regulated substances).
  4. (d)Underground piping must be equipped with secondary containment that satisfies the requirements of this section (e.g., trench liners, double walled pipe). In addition, underground piping that conveys regulated substances under pressure must be equipped with an automatic line leak detector in accordance with § 280.44(a).
  5. (e)For hazardous substance UST systems installed on or before October 13, 2015 other methods of release detection may be used if owners and operators:
    1. (1)Demonstrate to the implementing agency that an alternate method can detect a release of the stored substance as effectively as any of the methods allowed in § 280.43(b) through (i) can detect a release of petroleum;
    2. (2)Provide information to the implementing agency on effective corrective action technologies, health risks, and chemical and physical properties of the stored substance, and the characteristics of the UST site; and,
    3. (3)Obtain approval from the implementing agency to use the alternate release detection method before the installation and operation of the new UST system.