ICC Underground Storage Tank (UST) Decommissioning
Test Study Guide 2025/2026 Accurate Questions and
Verified Correct Solutions with Rationales || 100%
Guaranteed Pass <Latest Version>
Section 1: Regulations and Definitions (Questions 1-20)
1. What is the primary federal regulation governing Underground Storage Tanks (USTs) in the
United States?
A. Clean Water Act (CWA)
B. Resource Conservation and Recovery Act (RCRA)
C. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
D. Safe Drinking Water Act (SDWA)
Answer: B. Resource Conservation and Recovery Act (RCRA)
• Rationale: RCRA Subtitle I specifically regulates USTs storing petroleum or hazardous
substances. The EPA's UST regulations (40 CFR Part 280) are established under the
authority of RCRA.
2. According to the federal UST regulations, which of the following is typically EXEMPT from
UST requirements?
A. A 4,000-gallon tank storing diesel fuel at a truck stop.
B. A 1,100-gallon tank storing used oil at an auto repair shop.
C. A 500-gallon residential heating oil tank in a basement.
D. A 10,000-gallon tank storing gasoline at a retail station.
Answer: C. A 500-gallon residential heating oil tank in a basement.
• Rationale: Federal UST regulations (40 CFR 280.12) exempt tanks used for storing
heating oil for consumptive use on the premises where stored.
3. The term "decommissioning" of a UST system can refer to:
A. Closure-in-place only.
B. Permanent closure only.
C. Temporary closure only.
D. Both temporary and permanent closure.
,Answer: D. Both temporary and permanent closure.
• Rationale: Decommissioning is a broad term encompassing the processes of either
temporarily taking a UST out of service (temporary closure) or permanently removing it
from service (permanent closure, which includes removal or closure-in-place).
4. What is the maximum period a UST can remain in temporary closure without requiring
permanent closure actions under federal law?
A. 3 months
B. 12 months
C. 24 months
D. There is no time limit if corrosion protection is maintained.
Answer: B. 12 months
• Rationale: After 12 months of temporary closure, the UST system must be permanently
closed unless the owner/operator meets specific requirements for extended temporary
closure, such as maintaining corrosion protection and leak detection.
5. A "Site Assessment" is required by federal regulation after the permanent closure of any
UST that has:
A. Been in service for more than 10 years.
B. A capacity of over 1,000 gallons.
C. Stored a regulated substance.
D. A record of any past release.
Answer: C. Stored a regulated substance.
• Rationale: 40 CFR 280.72 mandates that a site assessment be conducted at all UST
systems permanently closed after previously storing a regulated substance, to check for
any release that may have occurred.
6. Who is typically the "Implementing Agency" (IA) for UST regulations?
A. The local fire department.
B. The UST owner or operator.
C. The EPA or a state agency with approved program.
D. The tank installation contractor.
Answer: C. The EPA or a state agency with approved program.
• Rationale: The Implementing Agency is the governmental body with regulatory
authority. Most states have state programs approved by EPA to enforce the UST
regulations.
,7. The purpose of the "30-day notification" is to inform the implementing agency of:
A. The discovery of a suspected release.
B. The intent to permanently close or change-in-service a UST system.
C. The results of a site assessment.
D. The completion of tank installation.
Answer: B. The intent to permanently close or change-in-service a UST system.
• Rationale: Federal regulation (40 CFR 280.71) requires owners/operators to notify the
implementing agency at least 30 days before permanently closing or changing the
service of a UST.
8. Which of the following would be considered a "Change-in-Service"?
A. Removing a gasoline tank from the ground.
B. Filling a diesel tank with inert sand.
C. Converting a gasoline tank to store diesel fuel.
D. Temporarily taking a tank out of operation for 6 months.
Answer: C. Converting a gasoline tank to store diesel fuel.
• Rationale: A change-in-service occurs when the stored substance is changed. Since both
gasoline and diesel are regulated substances, this is a change-in-service, not a
permanent closure. The tank must be assessed and cleaned before the change.
9. The "Zone of Engineering Control" refers to:
A. The entire property where the UST is located.
B. An area where contamination is allowed to remain under specific controls.
C. The excavation zone immediately surrounding the UST.
D. The area within a secondary containment structure.
Answer: B. An area where contamination is allowed to remain under specific controls.
• Rationale: This is a term often used in state-level regulations for closure-in-place, where
contaminated soil is left in place under a legally enforceable instrument that restricts
land use and requires monitoring.
10. Liability for contamination from a UST release typically falls upon:
A. The current property owner only.
B. The current UST owner/operator only.
C. Any past or present owner/operator who contributed to the release.
D. The decommissioning contractor.
text
, **Answer: C. Any past or present owner/operator who contributed to the release.**
* **Rationale:** Under laws like CERCLA (Superfund), liability is "strict, joint, and several,"
meaning any responsible party can be held liable for the entire cleanup cost, regardless of their
degree of fault.
11. The definition of an Underground Storage Tank (UST) includes which of the following
criteria?
A. It must be entirely buried.
B. At least 10 percent of its volume must be below ground.
C. It must be located in a vault.
D. It must have a capacity greater than 1,100 gallons.
text
**Answer: B. At least 10 percent of its volume must be below ground.**
* **Rationale:** The federal definition (40 CFR 280.12) specifies that a tank is "underground"
if 10% or more of its combined volume (including pipes) is beneath the surface of the ground.
12. A "regulated substance" includes:
A. Only petroleum products like gasoline and diesel.
B. Only hazardous substances as defined by CERCLA.
C. Petroleum and CERCLA hazardous substances, excluding certain exempted materials.
D. Any liquid stored in an underground container.
text
**Answer: C. Petroleum and CERCLA hazardous substances, excluding certain exempted
materials.**
* **Rationale:** The UST regulations cover a broad range of substances, specifically petroleum
and hazardous substances defined under CERCLA, with specific exemptions listed in 40 CFR
280.12.
13. Temporary closure requires the owner/operator to:
A. Continue operation and maintenance of corrosion protection.
B. Continue operation and maintenance of leak detection.
C. Leave the tanks empty and vented.
D. Both A and B.
text
**Answer: D. Both A and B.**
Test Study Guide 2025/2026 Accurate Questions and
Verified Correct Solutions with Rationales || 100%
Guaranteed Pass <Latest Version>
Section 1: Regulations and Definitions (Questions 1-20)
1. What is the primary federal regulation governing Underground Storage Tanks (USTs) in the
United States?
A. Clean Water Act (CWA)
B. Resource Conservation and Recovery Act (RCRA)
C. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
D. Safe Drinking Water Act (SDWA)
Answer: B. Resource Conservation and Recovery Act (RCRA)
• Rationale: RCRA Subtitle I specifically regulates USTs storing petroleum or hazardous
substances. The EPA's UST regulations (40 CFR Part 280) are established under the
authority of RCRA.
2. According to the federal UST regulations, which of the following is typically EXEMPT from
UST requirements?
A. A 4,000-gallon tank storing diesel fuel at a truck stop.
B. A 1,100-gallon tank storing used oil at an auto repair shop.
C. A 500-gallon residential heating oil tank in a basement.
D. A 10,000-gallon tank storing gasoline at a retail station.
Answer: C. A 500-gallon residential heating oil tank in a basement.
• Rationale: Federal UST regulations (40 CFR 280.12) exempt tanks used for storing
heating oil for consumptive use on the premises where stored.
3. The term "decommissioning" of a UST system can refer to:
A. Closure-in-place only.
B. Permanent closure only.
C. Temporary closure only.
D. Both temporary and permanent closure.
,Answer: D. Both temporary and permanent closure.
• Rationale: Decommissioning is a broad term encompassing the processes of either
temporarily taking a UST out of service (temporary closure) or permanently removing it
from service (permanent closure, which includes removal or closure-in-place).
4. What is the maximum period a UST can remain in temporary closure without requiring
permanent closure actions under federal law?
A. 3 months
B. 12 months
C. 24 months
D. There is no time limit if corrosion protection is maintained.
Answer: B. 12 months
• Rationale: After 12 months of temporary closure, the UST system must be permanently
closed unless the owner/operator meets specific requirements for extended temporary
closure, such as maintaining corrosion protection and leak detection.
5. A "Site Assessment" is required by federal regulation after the permanent closure of any
UST that has:
A. Been in service for more than 10 years.
B. A capacity of over 1,000 gallons.
C. Stored a regulated substance.
D. A record of any past release.
Answer: C. Stored a regulated substance.
• Rationale: 40 CFR 280.72 mandates that a site assessment be conducted at all UST
systems permanently closed after previously storing a regulated substance, to check for
any release that may have occurred.
6. Who is typically the "Implementing Agency" (IA) for UST regulations?
A. The local fire department.
B. The UST owner or operator.
C. The EPA or a state agency with approved program.
D. The tank installation contractor.
Answer: C. The EPA or a state agency with approved program.
• Rationale: The Implementing Agency is the governmental body with regulatory
authority. Most states have state programs approved by EPA to enforce the UST
regulations.
,7. The purpose of the "30-day notification" is to inform the implementing agency of:
A. The discovery of a suspected release.
B. The intent to permanently close or change-in-service a UST system.
C. The results of a site assessment.
D. The completion of tank installation.
Answer: B. The intent to permanently close or change-in-service a UST system.
• Rationale: Federal regulation (40 CFR 280.71) requires owners/operators to notify the
implementing agency at least 30 days before permanently closing or changing the
service of a UST.
8. Which of the following would be considered a "Change-in-Service"?
A. Removing a gasoline tank from the ground.
B. Filling a diesel tank with inert sand.
C. Converting a gasoline tank to store diesel fuel.
D. Temporarily taking a tank out of operation for 6 months.
Answer: C. Converting a gasoline tank to store diesel fuel.
• Rationale: A change-in-service occurs when the stored substance is changed. Since both
gasoline and diesel are regulated substances, this is a change-in-service, not a
permanent closure. The tank must be assessed and cleaned before the change.
9. The "Zone of Engineering Control" refers to:
A. The entire property where the UST is located.
B. An area where contamination is allowed to remain under specific controls.
C. The excavation zone immediately surrounding the UST.
D. The area within a secondary containment structure.
Answer: B. An area where contamination is allowed to remain under specific controls.
• Rationale: This is a term often used in state-level regulations for closure-in-place, where
contaminated soil is left in place under a legally enforceable instrument that restricts
land use and requires monitoring.
10. Liability for contamination from a UST release typically falls upon:
A. The current property owner only.
B. The current UST owner/operator only.
C. Any past or present owner/operator who contributed to the release.
D. The decommissioning contractor.
text
, **Answer: C. Any past or present owner/operator who contributed to the release.**
* **Rationale:** Under laws like CERCLA (Superfund), liability is "strict, joint, and several,"
meaning any responsible party can be held liable for the entire cleanup cost, regardless of their
degree of fault.
11. The definition of an Underground Storage Tank (UST) includes which of the following
criteria?
A. It must be entirely buried.
B. At least 10 percent of its volume must be below ground.
C. It must be located in a vault.
D. It must have a capacity greater than 1,100 gallons.
text
**Answer: B. At least 10 percent of its volume must be below ground.**
* **Rationale:** The federal definition (40 CFR 280.12) specifies that a tank is "underground"
if 10% or more of its combined volume (including pipes) is beneath the surface of the ground.
12. A "regulated substance" includes:
A. Only petroleum products like gasoline and diesel.
B. Only hazardous substances as defined by CERCLA.
C. Petroleum and CERCLA hazardous substances, excluding certain exempted materials.
D. Any liquid stored in an underground container.
text
**Answer: C. Petroleum and CERCLA hazardous substances, excluding certain exempted
materials.**
* **Rationale:** The UST regulations cover a broad range of substances, specifically petroleum
and hazardous substances defined under CERCLA, with specific exemptions listed in 40 CFR
280.12.
13. Temporary closure requires the owner/operator to:
A. Continue operation and maintenance of corrosion protection.
B. Continue operation and maintenance of leak detection.
C. Leave the tanks empty and vented.
D. Both A and B.
text
**Answer: D. Both A and B.**
