(a) This article defines temporary and permanent underground storage tank closure and describes the nature of activities which shall be accomplished in order to protect water quality in each of these situations.

(b) The temporary closure requirements of section 2671 shall apply to those underground storage tanks in which the storage of hazardous substances has ceased but the underground storage tank will again be used for the storage of hazardous substances within the next 12 consecutive months. At the end of 12 consecutive months during which the tank is temporarily closed, the local agency may approve an extension of the temporary closure period for a maximum additional period of up to 12 months. Owners and operators shall complete a site assessment in accordance with section 2672(d) before an extension may be granted by the local agency. The temporary closure requirements of section 2671 do not apply to underground storage tanks that are empty as a result of the withdrawal of all stored substances during normal operating practice prior to the planned input of additional hazardous substances.

(c) The permanent closure requirements of section 2672 shall apply to those underground storage tanks in which the storage of hazardous substances has ceased and the tanks will not be used, or are not intended for use, for the storage of hazardous substances within the next 12 consecutive months.

(d) The requirements of this article do not apply to those underground storage tanks in which hazardous substances continue to be stored but no input or withdrawals are being made. In these cases, the applicable containment and monitoring requirements of Articles 3 or 4 shall continue to apply.

(e) During the period of time between cessation of hazardous substance storage and actual completion of underground storage tank closure pursuant to section 2671 or 2672, the applicable containment and monitoring requirements of Articles 3 or 4 shall continue to apply. The time period between cessation of hazardous substance storage and application for temporary or permanent tank closure shall not exceed 90 calendar days. Closure shall be completed within a reasonable time period as determined by the local agency.

(f) At least 30 calendar days prior to closure, or within a shorter period of time approved by the local agency, the owner or operator who intends to close a tank shall submit to the local agency for approval, a proposal for compliance with section 2671 or 2672, as appropriate.

(g) Underground storage tanks that have had an unauthorized release do not qualify for temporary closure pursuant to section 2671 until the owner or operator demonstrates to the satisfaction of the local agency that appropriate authorized repairs have been made which make the underground storage tank capable of storing hazardous substances in accordance with the permit issued by the local agency.

(h) Underground storage tanks that have emitted an unauthorized release and that cannot be repaired by authorized methods shall be permanently closed pursuant to requirements of section 2672.

(i) Decommissioned tanks and underground storage tanks, permanently closed on-site by cleaning and filling with an inert solid prior to January 1, 1984, need not comply with the closure requirements in this section unless required by the local agency. However, hazardous substances released from such tanks before or after the closure, shall be reported by the owner pursuant to Article 5 and shall be cleaned up pursuant to section 13304 of the Water Code, Article 11 of these regulations, and any other applicable law or regulations.

(j) A regulated tank shall be subject to the requirements of subsections (d) and (e) of section 2672 before the local agency may grant exempt status to the tank.