40 CFR §280.40–§280.45 · Every 30 days (method-dependent)
Release Detection: Monitoring, Testing, and Records (40 CFR §280.40–.45)
Every regulated petroleum UST must be monitored for releases using an approved method, and the monitoring equipment itself must be tested annually. The cadence depends on the method: most tank monitoring runs at least every 30 days, manual tank gauging runs weekly for the small tanks allowed to use it, and piping requirements depend on piping type and installation date.
Tank monitoring methods and cadence
Approved tank methods include automatic tank gauging, interstitial monitoring (required for tanks installed or replaced after April 11, 2016), statistical inventory reconciliation, groundwater and vapor monitoring, and — for tanks of 1,000 gallons or less meeting size and diameter limits — manual tank gauging. Monitoring must generally be performed at least every 30 days; manual tank gauging requires weekly tests built from two consecutive stick readings at the beginning and end of an undisturbed period, with results compared in gallons to the §280.43(b) standards weekly and as a monthly four-test average.
Piping has its own requirements
Pressurized piping must be equipped with an automatic line leak detector and, depending on installation date, either annual line tightness testing or monthly monitoring (installed on or before April 11, 2016) or interstitial monitoring of secondary containment (installed after that date). Suction piping has parallel requirements on a 3-year tightness cadence, with an exemption for safe-suction configurations that meet all the §280.41(b) criteria.
The annual operability test
Under §280.40(a)(3), electronic and mechanical release-detection components must be tested annually for proper operation: ATGs (test alarm, verify system configuration, test battery backup), probes and sensors (residue, floats, shafts, cables, alarm communication), automatic line leak detectors (tested by simulating a leak), vacuum pumps and pressure gauges (communication with sensors and controller), and hand-held electronic sampling equipment. The §280.45(b)(1) record must list each component tested and whether it met criteria or needed action.
Retention
Monitoring results are generally retained for at least one year; annual operability test results for three years; written performance claims for five years from installation; and tank tightness test results until the next test. Calibration, maintenance, and repair records for release-detection equipment must be kept for at least one year after the work.
Citations
- 40 CFR §280.40–§280.45
Citations verified against 40 CFR Part 280 primary-source text, June 2026. Regulations are amended — always confirm against the current eCFR and your state program before acting.