The Underground Storage Tank (UST) regulations are the EPA rules that require owners and operators of underground tanks storing petroleum or hazardous substances to prevent, detect and clean up leaks. Found in 40 CFR Part 280, they cover tank and piping design, release detection, spill and overfill prevention, corrosion protection, walkthrough inspections, periodic testing, trained Class A, B and C operators, release reporting, closure and financial responsibility.
Leaking USTs are a leading source of groundwater contamination, and petroleum releases can create fire and vapor hazards in nearby buildings. Fuel stations, fleet fueling sites, utilities, airports and facilities with underground emergency generator tanks all face UST obligations. Most UST programs are run by states with EPA approval, and many state rules are stricter than the federal baseline described here.
What Are the Underground Storage Tank Regulations?
EPA first issued the UST technical standards in 1988 under Subtitle I of RCRA and revised them significantly in 2015. The rules are at 40 CFR Part 280, and EPA's underground storage tanks page provides guidance. The 2015 revisions added secondary containment for new and replaced tanks and piping, operator training, periodic walkthrough inspections, testing of spill and overfill equipment and containment sumps, and release detection for emergency generator tanks, with most requirements phased in by October 13, 2018.
A UST system is a tank and its connected underground piping that has 10 percent or more of its combined volume beneath the surface of the ground and stores a regulated substance, such as gasoline, diesel, used oil or a CERCLA hazardous substance.
Who Must Comply?
Owners and operators of regulated UST systems must comply. Several tanks are excluded from the federal definition, including:
- Farm or residential tanks of 1,100 gallons or less storing motor fuel for noncommercial purposes
- Tanks storing heating oil consumed on the premises where it is stored
- Septic tanks, storm water and wastewater collection systems
- Tanks in an underground area such as a basement or tunnel that sit on or above the floor
- Tanks of 110 gallons or less
Some systems, such as field-constructed tanks and airport hydrant systems, have modified requirements. States may regulate tanks that the federal rule excludes.
Key Requirements
Installation and notification (280.20 and 280.22)
New tanks and piping must be protected from corrosion and, for systems installed after April 11, 2016, must be secondarily contained with interstitial monitoring. Owners must notify the implementing agency within 30 days of bringing a UST system into use, and new owners must also notify.
Spill and overfill prevention (280.20(c))
UST systems must have spill prevention equipment, such as a spill bucket, and overfill prevention equipment, such as an automatic shutoff, flow restrictor or high-level alarm. Owners must make sure the volume available in the tank is greater than the volume being delivered and that the transfer is monitored.
Corrosion protection (280.31)
Cathodic protection systems must be tested by a qualified tester within 6 months of installation and at least every 3 years after that. Impressed current systems must be inspected every 60 days to confirm they are running.
Compatibility (280.32)
Owners must notify the implementing agency at least 30 days before switching to a regulated substance containing more than 10 percent ethanol or more than 20 percent biodiesel, and show the system is compatible.
Release detection (Subpart D)
- Tanks: monitored at least every 30 days using a method such as automatic tank gauging, interstitial monitoring or statistical inventory reconciliation. Tanks installed after April 11, 2016 must use interstitial monitoring. Tank tightness testing combined with monthly inventory control is allowed only for a limited period after installation.
- Pressurized piping: an automatic line leak detector plus either an annual line tightness test or monthly monitoring.
- Suction piping: a line tightness test at least every 3 years or monthly monitoring, unless it meets design criteria that make release detection unnecessary.
- Annual equipment test: under 280.40(a)(3), release detection equipment, including automatic tank gauges, probes and sensors, line leak detectors and vacuum pumps, must be tested for proper operation at least annually.
Walkthrough Inspections and Periodic Testing
Walkthrough inspections (280.36)
- Every 30 days: check spill prevention equipment for damage, remove liquid or debris and check for a release, and check release detection equipment to confirm it is operating with no alarms or unusual conditions and that records are reviewed and current. Spill equipment at tanks receiving deliveries less often than every 30 days may be checked before each delivery.
- Annually: check containment sumps for damage, leaks and liquid or debris, and check hand-held release detection equipment, such as tank gauge sticks and groundwater bailers, for operability.
Walkthrough records must be kept for one year.
Spill, overfill and sump testing (280.35)
- Spill prevention equipment must be tested at least every 3 years, unless it is double-walled and the interstitial space is monitored during the 30-day walkthroughs.
- Containment sumps used for interstitial monitoring of piping must be tested at least every 3 years, with the same double-walled exception.
- Overfill prevention equipment must be inspected at least every 3 years to make sure it activates at the correct level.
Records of these tests and inspections must be kept for three years.
Operator Training (Subpart J)
Each facility must designate at least one Class A and one Class B operator, and every person who meets the Class C definition must be designated as a Class C operator.
- Class A: broad knowledge of the UST requirements to make informed compliance decisions.
- Class B: day-to-day operation and maintenance and recordkeeping for the UST systems.
- Class C: employees who respond to alarms and emergencies, such as cashiers and attendants, trained to take appropriate action and notify authorities.
New Class A and B operators must be trained within 30 days of assuming duties, and Class C operators before assuming duties. Class A and B operators at a facility found out of compliance must be retrained within 30 days, unless they take annual refresher training or the agency waives retraining. Training records must be kept as long as the operator is designated.
Releases, Closure and Financial Responsibility
- Reporting: suspected releases must be reported to the implementing agency within 24 hours, or another period the agency sets. Petroleum spills and overfills over 25 gallons, or that cause a sheen on surface water, must also be reported within 24 hours.
- Temporary closure: systems closed for 3 months or more must keep vent lines open and cap other lines. Systems closed more than 12 months that do not meet new or upgraded standards must be permanently closed unless the agency grants an extension.
- Permanent closure: owners must notify the agency at least 30 days before permanent closure or a change in service.
- Financial responsibility: owners must show they can pay for cleanup and third-party damages, with per-occurrence amounts of $1 million for petroleum marketers and facilities handling more than 10,000 gallons a month, or $500,000 for others, and annual aggregate amounts of $1 million or $2 million depending on the number of tanks.
Penalties and Enforcement
EPA and state UST programs enforce Part 280 through inspections, which federal law generally requires at least once every three years. Violations can lead to civil penalties per tank per day, adjusted annually for inflation, and states can prohibit fuel deliveries to noncompliant tanks. Common findings include missing walkthrough records, failed or untested spill buckets, unanswered alarms and lapsed release detection.
Common Compliance Mistakes
- Skipping 30-day walkthroughs or not recording them
- Ignoring or clearing release detection alarms without investigation
- Letting the annual release detection equipment test or 3-year tests lapse
- No designated or trained Class C operators on each shift
- Liquid and debris left in spill buckets and sumps
- Forgetting the 30-day notice before storing higher ethanol or biodiesel blends
How to Comply: Step by Step
- Inventory your systems. List each tank and piping run with installation dates, materials, release detection methods and state registration.
- Confirm your state rules. Check the state program for stricter or additional requirements.
- Designate and train operators. Assign Class A, B and C operators and keep training records.
- Schedule walkthroughs. Set 30-day and annual inspection checklists and assign them.
- Calendar periodic tests. Track annual equipment tests, 3-year spill, sump and overfill checks, and cathodic protection tests.
- Respond to alarms. Write procedures for investigating alarms and reporting suspected releases within 24 hours.
- Keep records. Retain release detection, walkthrough, test and training records for the required periods.
How SMS360 Helps
SMS360's Audits & Inspections module provides mobile checklists for 30-day and annual UST walkthroughs with photos and dated records. Training Management tracks Class A, B and C operator training, and Compliance Management schedules reminders for annual and 3-year tests. Facilities can manage related programs such as the SPCC rule and used oil management alongside their tanks.
Frequently Asked Questions
How often must UST walkthrough inspections be done?
Every 30 days for spill prevention and release detection equipment, and annually for containment sumps and hand-held release detection equipment. Records are kept for one year.
How often must spill buckets be tested?
At least every 3 years, unless the spill bucket is double-walled and its interstitial space is checked during the 30-day walkthroughs.
What is a Class C operator?
An employee, such as a cashier or attendant, who is typically on site and responds to alarms, spills and emergencies. Class C operators must be trained before assuming those duties.
Do emergency generator tanks need release detection?
Yes. The 2015 revisions removed the earlier deferral, and regulated emergency generator USTs have needed release detection since October 13, 2018.
