Illinois Storage Tanks: UST and AST Rules, Registration, and Fund

Illinois storage tank regulations are enforced by three agencies at once: the Office of the State Fire Marshal handles permits, registration, and technical standards; the Illinois Environmental Protection Agency runs cleanup and site remediation; and the U.S. EPA sets federal baseline standards and spill prevention rules. Underground tanks answer primarily to 41 Illinois Administrative Code Parts 174, 175, and 176 and 35 Illinois Administrative Code Parts 731 and 734, while aboveground tanks fall under the Gasoline Storage Act and 41 Illinois Administrative Code Part 180. Civil penalties reach $100,000 per violation, plus up to $25,000 for each day a violation continues.1Illinois General Assembly. Illinois Code 415 ILCS 5/42 – Civil Penalties

Which Agency Handles What

The jurisdictional split trips up owners more than any single technical rule. Send permit applications, tank registrations, and installation notifications to the OSFM. Send release notifications and cleanup documents through the Illinois EPA after first calling the Illinois Emergency Management Agency. The Illinois EPA also administers the Underground Storage Tank Fund.2Illinois Environmental Protection Agency. Leaking Underground Storage Tanks

Federal rules run in parallel. The U.S. EPA sets baseline UST performance standards through 40 CFR Part 280 and imposes Spill Prevention, Control, and Countermeasure plan requirements on oil storage facilities that meet certain thresholds. On the aboveground side, the OSFM controls installation and dispensing under the Gasoline Storage Act.3Illinois General Assembly. Illinois Code 430 ILCS 15 – Gasoline Storage Act

Underground Storage Tank Standards

Every newly installed or replaced underground tank in Illinois must be double-wall construction with interstitial monitoring, meaning a sensor between the inner and outer walls that flags a leak before anything reaches the soil. This has been the standard for tank permits issued since February 1, 2008.4Office of the Illinois State Fire Marshal. Technical Requirements for Underground Storage Tanks – 41 Illinois Administrative Code Part 175

Since May 2, 2023, any tank installation or replacement also requires replacing all existing single-wall piping with double-wall piping for the full length of the product line. The only exception is European suction systems. If you are budgeting a tank swap, price the piping upgrade at the same time.

Motor fuel dispensing facilities need a current OSFM permit, evidenced by a green decal, and cannot open until they pass an on-site OSFM inspection. Falling out of compliance can result in a red tag on your tanks, which prohibits any further operation or fuel deliveries until the problem is fixed.

A tank can remain out of service for up to five years from the date of last use, provided it meets current performance standards (spill and overfill equipment excepted). After five years, the owner has to return it to active use or permanently close it.

Aboveground Storage Tank Standards

Any bulk AST over 110 gallons requires an OSFM application and field inspection before it can be filled. The OSFM distinguishes between bulk storage tanks (not dispensing directly into vehicles) and dispensing tanks, with separate rules for each.5Office of the Illinois State Fire Marshal. Aboveground Storage Tanks (AST)

Capacity limits vary by facility type:

  • Commercial, industrial, or government facilities: a maximum of two aboveground tanks, up to 2,500 gallons each, for flammable or combustible liquids.
  • Agricultural operations: up to four tanks per facility at 2,500 gallons each, with total storage of any single fuel type capped at 5,000 gallons.
  • Construction sites: up to two dispensing tanks, 2,500 gallons each.
  • Mining and coal-fired power plants: tanks for off-road diesel equipment can hold up to 12,000 gallons but must sit at least 50 feet from property lines, buildings, and other storage tanks.

All tanks must be steel construction, vapor tight, and kept at least 30 feet from any building. Gravity discharge is prohibited in most scenarios. Tanks need a UL- or FM-listed pumping device and clear marking with the product name and a “FLAMMABLE — KEEP FIRE AND FLAME AWAY” warning in letters at least four inches high.6Legal Information Institute. Illinois Administrative Code Title 41, Section 180.20 – Aboveground Storage – Dispensing

Registration and Notification

UST registration goes through the OSFM, not the Illinois EPA. Owners submit electronic notification forms for each facility, listing the street address for both the owner and the facility location. A separate form is required for each site if you own tanks at multiple locations.7Legal Information Institute. Illinois Administrative Code Title 41, Section 176.440 – Notification Requirements

For newly installed USTs, the notification form doubles as a compliance certification. The owner must certify that the tank meets current installation, cathodic protection, release detection, and financial responsibility rules. Any change to information on file — including a change in ownership — must be reported to the OSFM within 30 days. New owners complete the notification form and provide the Property Identification Number for the facility along with proof of legal ownership such as a deed or lease.

For ASTs, installation or relocation applications go through the OSFM Technical Services Division. The OSFM sends back instructions confirming that tanks cannot be filled until an on-site inspection is completed.

Operator Training

Every UST facility needs three classes of trained operators. Class A operators carry ultimate responsibility for regulatory compliance. Class B operators handle day-to-day operations, maintenance, recordkeeping, and repair decisions. Class C operators must be physically on site whenever the UST system is in use or being filled, and they need to know how to respond to spills, releases, and alarms.

Approved training courses remain valid for five years under 41 Illinois Administrative Code Section 176.635. Class A and Class B operators who fail to retrain annually and are then found out of compliance by the OSFM through a Notice of Violation related to release detection, corrosion protection, spill and overfill prevention, or financial responsibility face mandatory retraining that includes both coursework and testing.8Office of the Illinois State Fire Marshal. Operator Training Do not let certifications lapse.

Leak Detection

Federal rules require leak detection monitoring at least once every 30 days. Approved methods include:

  • Interstitial monitoring: sensors between the walls of double-wall tanks and under-dispenser containment areas.
  • Automatic tank gauging: electronic systems that measure product levels and flag discrepancies suggesting a leak.
  • Statistical inventory reconciliation: a third-party service that analyzes delivery and dispensing records to detect losses statistically.
  • Continuous in-tank leak detection: systems that run ongoing checks within the tank itself.
  • Groundwater and vapor monitoring: external methods that test soil vapors or groundwater near the tank.

For tanks holding 2,000 gallons or less, manual tank gauging can satisfy leak detection requirements if all method-specific criteria are met.9U.S. Environmental Protection Agency. Release Detection for Underground Storage Tanks (USTs) – Introduction When piping is removed or replaced at a UST site, Illinois requires investigation of the entire tank system for contamination, not just the immediate work area.

Release Reporting

If a leak or spill occurs, the UST owner or operator must notify the Illinois Emergency Management Agency within 24 hours. IEMA then alerts the Illinois EPA, which takes over cleanup oversight.10Illinois Environmental Protection Agency. Leaking Underground Storage Tank Program Responsibility and Liability This notification is not optional in a financial sense either: costs incurred before notifying IEMA are not eligible for reimbursement from the Underground Storage Tank Fund.11Illinois General Assembly. Illinois Code 415 ILCS 5/57.9 Any tank owner planning to seek reimbursement must also submit a site investigation budget to the Illinois EPA before beginning investigation work.

The Underground Storage Tank Fund

Illinois operates a fund that reimburses eligible tank owners for cleanup costs after a petroleum release. It is financed by a $0.003 per-gallon motor fuel tax and a $0.008 per-gallon environmental impact fee, both currently set to expire in 2030.12Illinois Environmental Protection Agency. Illinois Underground Storage Tank Fund Guide

To be eligible, all of the following must be true:

  • The release involved petroleum-based fuel, aviation fuel, heating oil, kerosene, or used motor oil refined from crude oil.
  • The tank was registered with the OSFM and all fees were paid.
  • The owner is not the U.S. government, and the fuel is not exempt from the Motor Fuel Tax.
  • IEMA was notified of the confirmed release before cleanup costs were incurred.
  • Costs have not already been covered by private insurance or a court order.

Farm and residential heating oil tanks are not eligible.

The fund covers cleanup costs above a deductible that depends on when the release was reported. For releases reported on or after June 8, 2010, the deductible is $5,000. Releases reported before that date carry a $10,000 deductible, with higher deductibles of $15,000, $50,000, or $100,000 applying in certain cases based on when the tanks were originally registered and when the state received notice of the release. To access the fund, the owner first obtains an Eligibility and Deductible Application from the OSFM, which sets both eligibility and the deductible amount.

Financial Responsibility

Federal regulations require petroleum UST owners to demonstrate they can cover the costs of a release. The per-occurrence amount depends on facility type:

  • Petroleum marketing facilities or facilities handling more than 10,000 gallons per month: $1 million per occurrence.
  • All other petroleum UST owners: $500,000 per occurrence.

Annual aggregate requirements are $1 million for owners of 1 to 100 tanks and $2 million for owners of 101 or more tanks.13GovInfo. 40 CFR 280.93 – Amount and Scope of Required Financial Responsibility Review your aggregate assurance whenever you acquire or install additional tanks.

Acceptable mechanisms include insurance policies, surety bonds, letters of credit, trust funds, or state fund coverage. Illinois tank owners who register with the OSFM and pay required fees can use the Underground Storage Tank Fund as their financial assurance mechanism for corrective action costs. The fund does not cover third-party liability claims, so separate coverage may still be necessary for bodily injury or property damage.

Federal SPCC Plans

Facilities that store oil in Illinois may also need a federal Spill Prevention, Control, and Countermeasure plan on top of state UST and AST requirements. The SPCC rule applies if the facility meets all three of these conditions: it is not transportation-related; it could reasonably discharge oil into navigable waters or adjoining shorelines; and it exceeds a storage capacity threshold of more than 1,320 gallons of aggregate aboveground oil storage or more than 42,000 gallons of completely buried oil storage.14U.S. Environmental Protection Agency. SPCC Rule Applicability Only containers of 55 gallons or more count toward the threshold.15U.S. Environmental Protection Agency. Oil-Filled Equipment Capacity Less Than 55 Gallons

Most SPCC plans need to be certified by a licensed Professional Engineer. A self-certification option exists for “qualified facilities” under 40 CFR 112.6, which generally applies to smaller operations meeting specific capacity and spill-history criteria.16U.S. Environmental Protection Agency. PE Certification and Applying PEs Seal

Which Tanks Are Exempt

Not every tank triggers the full weight of Illinois UST regulations. Systems excluded from 35 Illinois Administrative Code Part 731 include:

  • Tanks with a capacity of 110 gallons or less.
  • Equipment or machinery containing regulated substances for operational purposes, such as hydraulic lift tanks or electrical equipment tanks.
  • Wastewater treatment tanks regulated under Section 12(f) of the Illinois Environmental Protection Act.
  • Tanks holding hazardous waste (covered by separate RCRA requirements).
  • Tanks containing only minimal concentrations of regulated substances.
  • Emergency spill or overflow containment systems that are emptied promptly after use.
17Legal Information Institute. Illinois Administrative Code Title 35, Section 731.110 – Applicability

Federally, farm or residential tanks of 1,100 gallons or less used to store motor fuel for noncommercial purposes are excluded from 40 CFR Part 280. Tanks used to store heating oil for consumptive use on the premises where stored are also excluded from the federal UST definition.18eCFR. 40 CFR Part 280 – Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks

Illinois draws its own line on heating oil. Under state law, a “heating oil underground storage tank” means a tank used exclusively to store heating oil for consumptive use on the premises and serving other than a farm or residential unit. Those tanks remain subject to Part 731. A heating oil tank at a commercial building is covered; a heating oil tank at a house or farm is not.

Penalties

Under 415 ILCS 5/42, general violations of the Illinois Environmental Protection Act — storage tank violations included — carry civil penalties of up to $100,000 per violation, plus up to $25,000 for each day the violation continues. Hazardous waste (RCRA program) violations reach up to $50,000 per day.19Illinois General Assembly. Illinois Code 415 ILCS 5/42 – Civil Penalties

Beyond fines, the OSFM can revoke a facility’s motor fuel dispensing permit and issue a red tag on tanks, shutting down operations until compliance is restored. The Illinois EPA can issue compliance orders requiring immediate corrective action. Cleanup costs frequently run into hundreds of thousands of dollars regardless of whether penalties are also imposed.

The daily penalty provisions compound the damage quickly. A tank owner who ignores a violation notice for 30 days could face $750,000 in continuing penalties on top of the initial $100,000, before cleanup costs enter the picture. Documented maintenance, prompt corrective action, and a clean compliance history are what Illinois regulators and courts weigh when setting penalty amounts, so keeping dated inspection logs, repair receipts, and monitoring records is worth more than any argument made after the fact.