UST/AST Exams
What this domain tests
This domain covers regulated storage tank inspection: federal underground storage tank requirements under 40 CFR Part 280, with state programs approved under Part 281, and aboveground tank practice under NFPA 30/30A, API 653, and STI SP001, alongside SPCC planning under 40 CFR 112.
UST core rules under Part 280
- Release prevention rests on three elements: spill prevention such as a catchment basin at the fill point, overfill prevention such as automatic shutoff, a high-level alarm, or flow restriction, and corrosion protection through coated steel with cathodic protection or non-metallic construction.
- Release detection must suit the tank and piping type. Options include automatic tank gauging with leak detection, interstitial monitoring, statistical inventory reconciliation, and manual inventory control combined with periodic tank tightness testing.
- A suspected release must be reported to the implementing agency within 24 hours. A confirmed release triggers investigation, corrective action, and in some cases closure.
- Owners and operators must demonstrate financial responsibility for the applicable category.
AST core rules
API 653 governs in-service inspection intervals and minimum shell thickness for field-erected tanks. STI SP001 provides a tiered schedule for shop-built tanks, running from monthly walkthroughs through annual and periodic inspections. Flammable liquid service also brings secondary containment and overfill protection requirements, plus SPCC plan review and inspection records.
Worked example
A single-wall steel UST installed in 1988 has spill and overfill devices but no corrosion protection and no release detection. Under 40 CFR 280.21 the owner has two lawful paths: upgrade to the standards for new systems by adding corrosion protection and release detection, or close the tank under Subpart G. Adding release detection alone does not cure the missing corrosion protection, and taking no action is not an option.
Traps that cost marks
- Treating leak detection as a substitute for corrosion protection; they are separate pillars.
- Applying API 653 to every shop-built tank rather than the STI SP001 tiers.
- Reporting a suspected release in days rather than hours.
- Confusing Part 280 technical standards with Part 281 state program approval.