UST/AST Exams: Storage Tank Systems, Release Detection, and Compliance
Underground and aboveground storage tank exams focus on regulated tank systems: what is regulated, how releases are detected and prevented, and how records prove compliance. Expect questions framed around a facility scenario with a compliance decision.
Concepts you must understand
- Regulatory scope: regulated USTs versus excluded/deferred tanks (capacity thresholds, heating oil at certain consumption levels, farm and residential tanks, septic tanks).
- Release detection methods: automatic tank gauging, interstitial monitoring for double-walled systems, soil vapor monitoring, groundwater monitoring, manual inventory control with tank tightness testing, and statistical inventory reconciliation - each with applicability limits.
- Release prevention: spill containment, overfill prevention, corrosion protection (cathodic protection, coatings, interior lining), and secondary containment.
- Operating requirements: leak detection, recordkeeping retention periods, financial responsibility, operator training, and reporting/closure obligations when a release is suspected.
- AST specifics: secondary containment and inspection requirements differ from USTs; know which rules apply to which tank type.
Traps
- Mixing UST and AST requirements in one option.
- Recordkeeping durations - options swap monthly, annual, and multi-year retention periods.
- Detection method applicability - a method valid for one tank configuration is offered for an incompatible one (e.g., interstitial monitoring on a single-wall tank).
- Suspected release response - the correct answer is to investigate and report per requirements, not to keep operating while monitoring.
Rule of thumb
Match the method to the tank configuration first, then check the recordkeeping requirement. If a question describes a suspected release, the answer involves investigation and notification, not continued operation.
Worked example: A double-walled UST with interstitial monitoring shows liquid in the interstice. The correct action is to treat it as a suspected release: investigate, and notify the implementing agency within the required timeframe, documenting the finding - not to assume the inner tank is intact and continue normal operation.