ICC UST Decommissioning Exam (U2) –
International Code Council | 2025/2026 Actual
Questions and Verified Answers .
INTRODUCTION / EXAM OVERVIEW.
This comprehensive study guide is designed for candidates preparing for the ICC U2 Underground
Storage Tank Decommissioning Certification Exam for the 2025/2026 testing cycle. The ICC U2
credential is recognized nationally and required or accepted by many states for professionals
involved in the safe removal and closure of UST systems.
Critical Update for 2025/2026: Pursuant to California Health and Safety Code Section 25292.05,
all single-walled USTs must be permanently closed by December 31, 2025
. This represents one of the most significant regulatory deadlines in UST history and will be heavily
tested.
Certification Information:
• Certifying Body: International Code Council (ICC)
• Credential: ICC U2 – Underground Storage Tank Decommissioning
• Validity Period: 2 years; renewal requires either passing the exam again or fulfilling state-
specific continuing education requirements
• Regulatory Framework: EPA 40 CFR Part 280 (federal); state-specific codes including
California CCR Title 23, Chapter 16 and H&SC
• Exam Format: Multiple-choice, typically 150-200 questions
• Target Audience: Environmental contractors, UST removal specialists, compliance officers,
site assessors, and regulatory inspectors
Major Content Areas Covered:
• UST System Definitions: UST (tank and connected piping substantially/totally beneath
ground) vs. UST system (tank, piping, ancillary equipment, containment system); exclusions
(vent lines, vapor recovery lines, fill pipes designed not to hold standing fluid)
• Permitting Requirements: Permit must include state UST ID numbers, expiration date,
monitoring requirements – NOT tank manufacturer name and capacity
,• Temporary vs. Permanent Closure: Temporary: ceased operations but will be used within
12 consecutive months; Permanent: indefinite removal or closure; closure-in-place
preferred when removal would damage structures or incur excessive costs
• Notification Timelines: 30-day written notice prior to permanent closure; 24-hour verbal
notice before breaking concrete; federal regulations do not require temporary closure
notice but state agencies often do
• Single-Walled UST Deadline: All single-walled USTs must be permanently closed by
December 31, 2025 (California H&SC 25292.05)
• Release Reporting: Spills >25 gallons reported within 24 hours; spills ≤25 gallons not
contained/cleaned up within 24 hours also reportable
• Initial Abatement Reporting: Within 20 days of confirmed release, submit report
summarizing steps and results
• Record Retention: Tank closure letters: minimum 3 years; tank construction/repair
records: life of tank; monitoring records: 3 years
• Flash Point Classifications: Flammable liquids: <100°F; Combustible liquids: ≥100°F;
Diesel: 126-205°F; Pure ethanol: 61.88°F; Gasoline: Class IB flammable (<73°F, boiling
>100°F)
• Fire Triangle: Oxygen, fuel, source of ignition – all must be present for combustion
• Vapor Hazards: Benzene exposure associated with blood disorders; toluene effects:
tiredness, confusion, weakness, memory loss, nausea
• Purging Requirements: Use educator-type air mover; drop tube remains in place to pick
up vapors from bottom; discharge vapors 12' above grade, 3' above adjacent roof lines, 5'
above canopy projection, 15' from power/ventilation
• Inerting: Remove oxygen using dry ice: 1.5 lbs per 100 gallons capacity; NEVER put dry ice
in drop tube; oxygen levels <5% before closure begins
• LEL Requirements: Do not begin removal until LEL reading below 10%; use combustible
gas indicator (CGI) for testing
• Monitoring Requirements: Continuous monitoring for secondary containment with
audible/visual alarm or flow stop; automatic line leak detectors installed by November 9,
2004; annual testing required
• Spill Container Testing: Every 12 months
• Cathodic Protection: Inspect within 6 months of installation; test every 12 months; CP
tester certification required
, • Secondary Containment: Must contain 150% of largest primary container volume;
continuous monitoring required for all double-wall piping
• Overfill Prevention: Approved methods: automatic shutoff devices, overfill alarms, flapper
valves – NOT spill containers
• Emergency Impact Valve Location: Base of dispenser
• Fiberglass Tank Repair: Small fractures/epoxy repair; fiberglass cloth minimum 12x12
inches; second layer overlap by 1 inch (NOT 5 inches)
SECTION 1: UST SYSTEM DEFINITIONS, REGULATIONS, AND PERMITTING
(Questions 1-25)
Q1: According to H&SC Section 25281(y)(1), what is the correct definition of an underground
storage tank (UST)?
A. Any one or combination of tanks, including pipes connected thereto, that is used for the storage
of hazardous substances and that is substantially or totally beneath the surface of the ground
B. An underground storage tank, connected piping, ancillary equipment, and containment system, if
any
C. A tank that is at 10% below ground surface
D. A tank that is at 10% below ground surface and is not regulated as a hazardous waste tank under
22 CCR
[CORRECT] A. Any one or combination of tanks, including pipes connected thereto, that is used for
the storage of hazardous substances and that is substantially or totally beneath the surface of the
ground
Rationale:
• The statutory definition of a UST focuses on the tank and its connected piping that are
substantially or totally beneath the ground surface. The broader "UST system" includes
additional components.
Q2: According to H&SC Section 25281, what is the correct definition of an underground storage
tank (UST) system?
A. Any one or combination of tanks, including pipes connected thereto, that is used for the storage
of hazardous substances and that is substantially or totally beneath the surface of the ground
, B. An underground storage tank, connected piping, ancillary equipment, and containment system, if
any
C. A tank that is at 10% below ground surface
D. A tank that is at 10% below ground surface and is not regulated as a hazardous waste tank
[CORRECT] B. An underground storage tank, connected piping, ancillary equipment, and
containment system, if any
Rationale:
• The UST system definition is broader than the tank itself, encompassing all connected
components including piping, ancillary equipment, and any containment systems.
Q3: Which of the following statements is true regarding pipes and lines in UST systems?
A. Portions of vent lines, vapor recovery lines, and fill pipes that are beneath the surface of the
ground are "pipe" and therefore part of the underground storage tank system
B. Pipe does not include vent lines, vapor recovery lines, and fill pipes that are designed to prevent,
and do not hold, standing fluid in the pipes or lines
C. Primary containment shall be product tight and compatible with stored product
D. Secondary containment shall be product tight and constructed to prevent structural weakening
[CORRECT] B. Pipe does not include vent lines, vapor recovery lines, and fill pipes that are designed
to prevent, and do not hold, standing fluid in the pipes or lines
Rationale:
• H&SC Section 25290.2 specifically excludes vent lines, vapor recovery lines, and fill pipes
from the definition of "pipe" if they are designed not to hold standing fluid.
Q4: A permit to operate a UST system must have all of the following listed on the permit, EXCEPT:
A. The state UST identification number(s)
B. Name of the tank manufacturer and tank capacity
C. Permit expiration date
D. Monitoring requirements
[CORRECT] B. Name of the tank manufacturer and tank capacity
Rationale:
International Code Council | 2025/2026 Actual
Questions and Verified Answers .
INTRODUCTION / EXAM OVERVIEW.
This comprehensive study guide is designed for candidates preparing for the ICC U2 Underground
Storage Tank Decommissioning Certification Exam for the 2025/2026 testing cycle. The ICC U2
credential is recognized nationally and required or accepted by many states for professionals
involved in the safe removal and closure of UST systems.
Critical Update for 2025/2026: Pursuant to California Health and Safety Code Section 25292.05,
all single-walled USTs must be permanently closed by December 31, 2025
. This represents one of the most significant regulatory deadlines in UST history and will be heavily
tested.
Certification Information:
• Certifying Body: International Code Council (ICC)
• Credential: ICC U2 – Underground Storage Tank Decommissioning
• Validity Period: 2 years; renewal requires either passing the exam again or fulfilling state-
specific continuing education requirements
• Regulatory Framework: EPA 40 CFR Part 280 (federal); state-specific codes including
California CCR Title 23, Chapter 16 and H&SC
• Exam Format: Multiple-choice, typically 150-200 questions
• Target Audience: Environmental contractors, UST removal specialists, compliance officers,
site assessors, and regulatory inspectors
Major Content Areas Covered:
• UST System Definitions: UST (tank and connected piping substantially/totally beneath
ground) vs. UST system (tank, piping, ancillary equipment, containment system); exclusions
(vent lines, vapor recovery lines, fill pipes designed not to hold standing fluid)
• Permitting Requirements: Permit must include state UST ID numbers, expiration date,
monitoring requirements – NOT tank manufacturer name and capacity
,• Temporary vs. Permanent Closure: Temporary: ceased operations but will be used within
12 consecutive months; Permanent: indefinite removal or closure; closure-in-place
preferred when removal would damage structures or incur excessive costs
• Notification Timelines: 30-day written notice prior to permanent closure; 24-hour verbal
notice before breaking concrete; federal regulations do not require temporary closure
notice but state agencies often do
• Single-Walled UST Deadline: All single-walled USTs must be permanently closed by
December 31, 2025 (California H&SC 25292.05)
• Release Reporting: Spills >25 gallons reported within 24 hours; spills ≤25 gallons not
contained/cleaned up within 24 hours also reportable
• Initial Abatement Reporting: Within 20 days of confirmed release, submit report
summarizing steps and results
• Record Retention: Tank closure letters: minimum 3 years; tank construction/repair
records: life of tank; monitoring records: 3 years
• Flash Point Classifications: Flammable liquids: <100°F; Combustible liquids: ≥100°F;
Diesel: 126-205°F; Pure ethanol: 61.88°F; Gasoline: Class IB flammable (<73°F, boiling
>100°F)
• Fire Triangle: Oxygen, fuel, source of ignition – all must be present for combustion
• Vapor Hazards: Benzene exposure associated with blood disorders; toluene effects:
tiredness, confusion, weakness, memory loss, nausea
• Purging Requirements: Use educator-type air mover; drop tube remains in place to pick
up vapors from bottom; discharge vapors 12' above grade, 3' above adjacent roof lines, 5'
above canopy projection, 15' from power/ventilation
• Inerting: Remove oxygen using dry ice: 1.5 lbs per 100 gallons capacity; NEVER put dry ice
in drop tube; oxygen levels <5% before closure begins
• LEL Requirements: Do not begin removal until LEL reading below 10%; use combustible
gas indicator (CGI) for testing
• Monitoring Requirements: Continuous monitoring for secondary containment with
audible/visual alarm or flow stop; automatic line leak detectors installed by November 9,
2004; annual testing required
• Spill Container Testing: Every 12 months
• Cathodic Protection: Inspect within 6 months of installation; test every 12 months; CP
tester certification required
, • Secondary Containment: Must contain 150% of largest primary container volume;
continuous monitoring required for all double-wall piping
• Overfill Prevention: Approved methods: automatic shutoff devices, overfill alarms, flapper
valves – NOT spill containers
• Emergency Impact Valve Location: Base of dispenser
• Fiberglass Tank Repair: Small fractures/epoxy repair; fiberglass cloth minimum 12x12
inches; second layer overlap by 1 inch (NOT 5 inches)
SECTION 1: UST SYSTEM DEFINITIONS, REGULATIONS, AND PERMITTING
(Questions 1-25)
Q1: According to H&SC Section 25281(y)(1), what is the correct definition of an underground
storage tank (UST)?
A. Any one or combination of tanks, including pipes connected thereto, that is used for the storage
of hazardous substances and that is substantially or totally beneath the surface of the ground
B. An underground storage tank, connected piping, ancillary equipment, and containment system, if
any
C. A tank that is at 10% below ground surface
D. A tank that is at 10% below ground surface and is not regulated as a hazardous waste tank under
22 CCR
[CORRECT] A. Any one or combination of tanks, including pipes connected thereto, that is used for
the storage of hazardous substances and that is substantially or totally beneath the surface of the
ground
Rationale:
• The statutory definition of a UST focuses on the tank and its connected piping that are
substantially or totally beneath the ground surface. The broader "UST system" includes
additional components.
Q2: According to H&SC Section 25281, what is the correct definition of an underground storage
tank (UST) system?
A. Any one or combination of tanks, including pipes connected thereto, that is used for the storage
of hazardous substances and that is substantially or totally beneath the surface of the ground
, B. An underground storage tank, connected piping, ancillary equipment, and containment system, if
any
C. A tank that is at 10% below ground surface
D. A tank that is at 10% below ground surface and is not regulated as a hazardous waste tank
[CORRECT] B. An underground storage tank, connected piping, ancillary equipment, and
containment system, if any
Rationale:
• The UST system definition is broader than the tank itself, encompassing all connected
components including piping, ancillary equipment, and any containment systems.
Q3: Which of the following statements is true regarding pipes and lines in UST systems?
A. Portions of vent lines, vapor recovery lines, and fill pipes that are beneath the surface of the
ground are "pipe" and therefore part of the underground storage tank system
B. Pipe does not include vent lines, vapor recovery lines, and fill pipes that are designed to prevent,
and do not hold, standing fluid in the pipes or lines
C. Primary containment shall be product tight and compatible with stored product
D. Secondary containment shall be product tight and constructed to prevent structural weakening
[CORRECT] B. Pipe does not include vent lines, vapor recovery lines, and fill pipes that are designed
to prevent, and do not hold, standing fluid in the pipes or lines
Rationale:
• H&SC Section 25290.2 specifically excludes vent lines, vapor recovery lines, and fill pipes
from the definition of "pipe" if they are designed not to hold standing fluid.
Q4: A permit to operate a UST system must have all of the following listed on the permit, EXCEPT:
A. The state UST identification number(s)
B. Name of the tank manufacturer and tank capacity
C. Permit expiration date
D. Monitoring requirements
[CORRECT] B. Name of the tank manufacturer and tank capacity
Rationale:
