Sec. 598.10. Closure and change-in-service

(a) Change-in-service.

(1) If the substance stored within a tank system is switched to a hazardous substance or from one hazardous substance to another, then the tank system must be evaluated by a qualified engineer to determine that materials are compatible, pressure and vacuum relief systems are adequate and that the tank system is properly designed and suitable for the change-in-service.

(2) Before any underground tank system is converted from storing a hazardous to a non-hazardous substance, a site assessment must be performed pursuant to subdivision (e) of this section.

(b) Closure of tank systems that are temporarily out-of-service.

(1) Aboveground and underground tank systems that are temporarily out-of-service for 30 or more days must be closed as follows:

(i) All hazardous substances must be removed from the tank system to the lowest drawoff point. 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.

(ii) All manways must be locked or bolted securely and fill lines, gauge openings or pump lines must be capped, locked out or plugged to prevent unauthorized use or practices.

(2) Tank systems which are temporarily out-of-service are subject to registration, leak detection and reporting requirements of Parts 596 and 598 of this Title. Tank systems that are out-of-service for more than one year must be inspected or tested and determined to be structurally sound and tight before being returned to service.

(3) Underground tank systems that are temporarily 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 sections 599.3(d) and 599.8(d) of this Title. The department may grant a time extension based on the findings of a site assessment performed by the owner or operator.

(c) Closure of tank systems that are permanently out-of-service.

(1) Any aboveground or underground tank system that is permanently out-of-service may be used to store a substance which is not a hazardous substance as defined in Part 597 of this Title or must be closed as follows:

(i) liquid and sludge must be removed from the tank system. Any hazardous waste that is removed must be transported and disposed of in accordance with all applicable State, local and Federal requirements;

(ii) 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;

(iii) all piping must be disconnected and removed or securely capped, or locked out or plugged. Manways must be securely fastened in place;

(iv) aboveground tanks must be stenciled with the date of permanent closure;

(v) underground tanks must be removed unless it will be detrimental to a building foundation or other structure. Underground tanks that are abandoned 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;

(vi) all tanks must be protected from floatation caused by flooding or high ground water level in accordance with generally accepted engineering practices; and

(vii) secondary containment systems of permanently closed aboveground tank systems must have drainage for accumulated water or precipitation.

(2) If the tank system is to be used to store a substance not defined as a hazardous substance, the owner or operator must empty and clean the tank system prior to storing the new substance.

(3) Tank systems or facilities which have not been closed pursuant to paragraph (1) or (2) of this subdivision, are subject to all requirements of this Part and Part 596 of this Title including, but not limited to, upgrading, periodic tightness testing, inspection, registration and reporting requirements.

(4) If a tank is to be disposed of as junk, 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.

(d) 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) or (c) of this section.

(e) Site assessment for permanent closure.

(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.

(2) The type of monitoring and number and location of samples must be based on geology, water table contours, aquifer thickness, porosity, background water quality and the substance known or suspected to have been stored at the facility.

(3) If contaminated soil, vapor, groundwater or free product is discovered, the owner and operator must comply with the corrective action requirements of section 598.14 of this Part.

(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.

(f) Reporting of out-of-service tank systems.

The owner of a tank system which is to be permanently closed must notify the department pursuant to the requirements of section 596.2(f) of this Title.