Section 1773.4 - Tank Testing and Minimum Wall Thickness Requirements(a) Tank wall thickness testing shall be conducted on in-service tanks at intervals not to exceed the following: (1) If the corrosion rate of the tank is not known, at least once every five years.(2) If the corrosion rate of the tank is known, an interval determined from corrosion rate calculations approved by the Supervisor, but not to exceed once every 15 years.(3) Tank wall thickness testing shall be conducted within two years of the effective date of this regulation for tanks that have not had testing within the required interval.(b) Insulated tanks shall have insulation removed to the extent necessary to determine the thickness of the tank walls or roof.(c) The minimum thickness for a tank shell shall be 0.06 inch.(d) In-service tanks shall be internally inspected and tested to determine bottom plate thickness no less than once every 20 years. In-service tanks that have not been internally inspected within the 20 years preceding the effective date of this section must be internally inspected within two years after the effective date of this section. A tank is exempt from this requirement if:(1) The tank is not an environmentally sensitive tank, it is not in an urban area, and it is not located above subsurface freshwater; or(2) The tank has a foundation that is designed and constructed in accordance with the requirements of Section 1773.2(b); or(3) The tank has a properly installed, operating and maintained leak detection system as specified in Section 1773.2(c).(e) The minimum bottom plate thickness shall meet the following criteria: (1) 0.10 inch for tank bottom/foundation design with no means of detection and containment of a bottom leak;(2) 0.05 inch for tank bottom/foundation design with adequate leak detection and containment of a bottom leak;(3) 0.05 inch in conjunction with a reinforced tank bottom lining, greater than 0.05 inch thick.(f) The Supervisor or district deputy may require that a tank that has had a leak resulting in the release of a reportable quantity be tested to verify integrity prior to being put back into service.(g) A tank that is not repaired within 60 days of failing an inspection or test required by this section shall be taken out of service and designated as an Out-of-Service tank. The Supervisor or district deputy may grant one extension of up to 120 days if the operator shows to the satisfaction of the Supervisor or district deputy that there is no significant threat as a result of the extension.(h) Tanks that are not susceptible to corrosion, such as non-metal tanks and tanks with liners, are not subject to the requirement of this section but shall be inspected and tested according to the manufacturer's specifications or as requested by the Supervisor or district deputy.(i) An operator may petition the Supervisor to allow a minimum tank wall or tanks bottom thicknesses that is lower than what is required in subdivisions (c) and (e) of this section. The Supervisor may grant such a petition if he or she is satisfied that based on the design and use of the tank a lower minimum thickness will ensure that the tank will operate as designed and will be capable of safely containing fluid.Cal. Code Regs. Tit. 14, § 1773.4
1. New section filed 12-30-2010; operative 1-29-2011 (Register 2010, No. 53). Note: Authority cited: Sections 3013 and 3270, Public Resources Code. Reference: Sections 3106 and 3270, Public Resources Code.
1. New section filed 12-30-2010; operative 1-29-2011 (Register 2010, No. 53).