1. (1) A UST system is out of service if:

   1. (i) the facility owner (or their authorized representative) takes the tank system out of service by submitting an application to the department, in accordance with section 598-1.14(a)(5) of this Part, indicating that the tank system is out of service; or
   2. (ii) the tank system is no longer receiving or dispensing a hazardous substance, unless the tank system is used for standby storage or is part of a closed-loop system. Records explaining why a tank system that no longer receives or dispenses hazardous substance is not out of service, must be retained until the tank system is permanently closed and made part of the spill prevention report. Within 30 days after the tank system becomes out of service, the facility owner (or their authorized representative) must submit an application to the department, in accordance with section 598-1.14(a)(5) of this Part, indicating that the tank system is out of service.

2. (2) Out-of-service UST systems are still subject to all applicable requirements of this Part, with the exception of periodic equipment testing/monitoring/inspections, walkthrough inspections, and leak detection required under sections 598-2.2(c) through (f), and section 598-2.3(a) and (b) of this Subpart if the UST system is empty. (A UST system is considered empty when all hazardous substance has been removed using commonly employed practices so that no more than 2.5 centimeters (one inch) of residue remain in the UST system.)

   1. (i) The suspended requirements of sections 598-2.2(c) through (f), and 598-2.3(a) and (b) of this Subpart must resume in accordance with the original schedule when the UST system is returned to service. However, if the UST system has been out of service such that any of the next periodic testing/monitoring/inspections was not conducted in accordance with the original schedule, the testing/monitoring/inspection must be performed when the UST system is returned to service.
   2. (ii) For UST systems taken out of service due to repairs (in response to a leak), the repair and subsequent testing requirements of section 598-2.2(h) of this Subpart must be successfully completed before the UST system is returned to service.

3. (3) When a UST system is out-of-service for 30 or more days, the UST system must meet the following requirements:

   1. (i) the tank must be emptied so that no more than 2.5 centimeters (one inch) of residue remains. Any hazardous waste that is removed from the tank system must be disposed of in accordance with all applicable State, local and Federal requirements. Tanks must be protected from floatation in accordance with generally accepted engineering practices;
   2. (ii) vent lines must be left open and functioning; and
   3. (iii) all piping, manways, fill ports, gauge openings, vapor returns, pump connections, and ancillary equipment must be capped and secured.

4. (4) UST systems that are out-of-service for more than one year must be permanently closed if the tank system has not been protected from corrosion as required in section 598-2.1(b)(1)(ii)(b) of this Subpart. The department may grant a time extension based on the findings of a site assessment performed by the owner or operator in accordance with subdivision (d) of this section. UST systems that are out-of-service for more than one year must be inspected or tested in accordance with section 598-2.3(c)(1) and (d)(2) of this Subpart and determined to be structurally sound and tight before being returned to service.

   (b) Permanent closure of tank systems.

   To permanently close a tank system, the tank system must be removed from the ground or closed in place in accordance with paragraph (1) of this subdivision or undergo a change-in-service in accordance with paragraph (2) of this subdivision.

5. (1) A tank system must be removed from the ground or closed in-place in accordance with the following:

   1. (i) at least 30 days before permanent closure, the facility owner (or their authorized representative) must notify the department of this action, unless such action is in response to corrective action in accordance with Subpart 6 of this Part;
   2. (ii) the required assessment of the excavation zone under subdivision (d) of this section must be performed after notifying the department in accordance with subparagraph (i) of this paragraph, but before completion of the permanent closure. The resultant report must be submitted to the department within 90 days after permanent closure;
   3. (iii) liquid and sludge must be removed from the tank system. Any removed hazardous waste must be transported and disposed of in accordance with all applicable State, local and Federal requirements;
   4. (iv) the tank must be cleaned and rendered free of hazardous vapors. Provisions must be made for natural breathing of the tank to ensure that the tank remains free of hazardous vapors;
   5. (v) all piping must be disconnected and removed or securely capped or locked out or plugged. Manways must be securely fastened in place;
   6. (vi) tanks must be removed from the ground unless it will be detrimental to a building foundation or other structure. Tanks that are closed in-place must be filled with a solid inert material (such as sand, concrete slurry, synthetic filler, or cellular concrete). If an inert material is used, all voids within the tank must be filled;
   7. (vii) if a tank is to be disposed of, it must be retested for hazardous vapors, rendered vapor free if necessary, cleaned of any residuals or sludge, and punched with holes or otherwise made unfit for storage; and
   8. (viii) all tanks must be protected from floatation caused by flooding or high ground water level in accordance with generally accepted engineering practices;
   9. (ix) within 30 days after permanent closure, the facility owner (or their authorized representative) must submit an application to the department, in accordance with section 598-1.14(a)(6) of this Part, indicating that the UST system has been permanently closed.

6. (2) A tank system must undergo a change-in-service in accordance with the following:

   1. (i) at least 30 days before permanent closure, the facility owner (or their authorized representative) must notify the department of this action, unless such action is in response to corrective action in accordance with Subpart 598-6 of this Part;
   2. (ii) the required assessment of the excavation zone under subdivision (d) of this section must be performed after notifying the department in accordance with subparagraph (i) of this paragraph, but before completion of the permanent closure. The resultant report must be submitted to the department within 90 days after permanent closure;
   3. (iii) liquid and sludge must be removed from the tank system. Any removed hazardous waste must be transported and disposed of in accordance with all applicable State, local and Federal requirements;
   4. (iv) the tank must be cleaned and rendered free of hazardous vapors. Provisions must be made for natural breathing of the tank to ensure that the tank remains free of hazardous vapors;

   5. (v) within 30 days after permanent closure, the facility owner (or their authorized representative) must submit an application to the department, in accordance with section 598-1.14(a)(6) of this Part, indicating that the UST system has been permanently closed.

      (c) Closure of tank systems abandoned prior to August 11, 1994.

      All tanks taken out-of-service, but still in or on the ground, prior to August 11, 1994 must be closed in accordance with the requirements of subdivision (b) of this section.

      (d) Site assessment for permanent closure.

7. (1) The owner or operator must perform a site assessment at the time of permanent closure of any underground tank system. A site assessment may be required of any such tank system that is permanently closed prior to August 11, 1994 if, in the judgment of the department, the tank poses a current or potential threat to human health or the environment. The site assessment must include soil, vapor, or groundwater monitoring in sufficient depth to determine if environmental contamination exists in the vicinity of the tank site.
8. (2) In selecting sample types, sample locations, and measurement methods, the following must be considered: the method of closure, type of backfill, geology, water table contours, aquifer thickness, porosity, background water quality, the nature of the substance known or suspected to have been stored at the facility, and other factors appropriate for identifying the presence of a release.
9. (3) If contaminated soil, vapor, groundwater or free product is discovered, the owner and operator must begin corrective action in accordance with section 598-6.2 of this Part.
10. (4) The site assessment report must be prepared by a qualified engineer or technician. Records of the date of closure and the report must be incorporated or referenced in the spill prevention report and maintained for the life of the facility.

(a) Out-of-service UST systems.