1. (1) Application. All new and existing aboveground storage tanks shall be inspected in accordance with this section.

2. (2) Inspection of field-erected metallic aboveground storage tanks.

   1. (a) Metallic aboveground storage tanks within the scope of API 653 shall be inspected in accordance with API 653.
   2. (b) Initial inspections shall be conducted as required in Table 93.440.

   3. (c)

      1. 1. The agency conducting an API 653 inspection shall report all applicable information from the inspection on an API 653 tank inspection summary form supplied by the department.

         Note: TR-WM-119-API 653 Tank Inspection Summary is available from the Bureau of Weights and Measures, P. O. Box 8911, Madison, WI 53708-8911, or at telephone (608) 224-4942, or from the Bureau’s Web site at https://datcp.wi.gov/Pages/Programs_Services/PetroleumHazStorageTanksForms.aspx.

      2. 2. A copy of the API 653 tank inspection summary shall be provided to the tank owner or operator along with the complete API 653 inspection report.
   4. (d) The tank owner or operator shall have the API 653 inspection summary on site and available for inspection within 30 days after receiving it from the agency that performed the inspection.

   5. (e) For tanks undergoing a transition from storing an unregulated substance to storing a regulated substance, any inspection in Table 93.440 that has not occurred shall be performed before putting the regulated substance into the tank. For the purposes of this paragraph, the service date is the date the tank was initially placed into service after construction.

      Table 93.440

      Inspection Type and Schedule

      - See PDF for table

3. (3) Inspection of shop-built metallic aboveground storage tanks.

   1. (a)

      1. 1. The owner or operator of all shop-built metallic aboveground fixed storage tanks shall have the tanks inspected in accordance with STI SP001, except as provided in subd. 2.

      2. 2.

         1. a. An alternate inspection procedure that provides equivalent environmental and fire safety protection may be used if accepted in writing by the department, or if developed by the certifying engineer for a facility in accordance with the federal spill prevention control and countermeasure regulations in 40 CFR 112.

         2. c. This paragraph does not apply to heating oil tanks or to tanks at farms and construction projects.

            Note: STI SP001 requires monthly and annual inspections and requires maintaining records of these inspections. For almost all ASTs that have a capacity of 5,000 gallons or less, these inspections are only required to be visual. For most tanks that have a capacity of more than 5,000 gallons, the requirements include, but are not limited to, having a certified inspection every 20 years, consisting of a visual exam and spot, ultrasonic examination, with no requirement for an integrity pressure test. STI SP001 includes optional checklists that may be used for the required record keeping. These checklists and a compendium that contains further guidance for these inspections are available from the Bureau of Weights and Measures, P. O. Box 8911, Madison, WI 53708-8911, or at telephone (608) 224-4942, or from the Bureau’s Web site at https://datcp.wi.gov/Pages/Programs_Services/PetroleumHazStorageTanksForms.aspx.

            Note: Tanks that are not required by this paragraph to have periodic inspections may otherwise be required to have periodic inspections, by the federal Spill Prevention Control and Countermeasure regulations in 40 CFR 112.

            Note: Heating oil tanks and tanks at farms and construction projects are subject to the requirements in NFPA 31 or 30A under ss. ATCP 93.310 and 93.630, respectively.

   2. (b)

      1. 1. The inspection schedule required in par. (a) shall be based on the tank’s time in service.
      2. 2. Monthly inspections may be omitted for seasonal-use tanks during periods when the tank does not contain a regulated substance.

   3. (c) If product is found within a tank’s interstitial space during an inspection under this subsection, delivery of product into the tank shall be immediately suspended, and either of the following actions shall be taken within 10 business days:

      1. 1. A vacuum or pressure test shall be performed in accordance with the manufacturer’s recommendations.

      2. 2. The tank shall be closed in accordance with s. ATCP 93.460.

         Note: See sub. (5) for further requirements for corrective action.

4. (4) Inspection of nonmetallic aboveground storage tanks.

   1. (a) The owner or operator of all nonmetallic aboveground storage tanks — including concrete, tile−lined, fiber−reinforced plastic, and homogeneous plastic tanks — that have a capacity of 5,000 gallons or more shall have the tanks inspected in accordance with all of the following:

      1. 1. ‘Monthly inspection.’

         1. a. At least monthly there shall be a visual inspection of the tank exterior, pipe connections and secondary containment, for signs of leakage, physical damage, and environmentally induced degradation.
         2. b. Any product or water present in the secondary containment shall be removed.

      2. 2. ‘Annual inspection.’

         1. a. At least annually there shall be a visual inspection of tank supports and foundation for signs of physical damage and chemically or environmentally induced degradation.
         2. b. At least annually there shall be a test of the functionality of the tank venting system, if so equipped.
      3. 3. ‘Qualifications for inspection.’ The monthly and annual inspections shall be done by owners, contractors or operations personnel, who are knowledgeable of the facility operations, the tank construction and operation, and the characteristics of the product stored.
      4. 4. ‘Every 5 years.’ At least every 5 years, there shall be an external and internal examination of tank and pipe connections for physical or chemical damage or environmentally induced degradation, conducted by personnel trained and experienced in examining the specific tank construction type.
   2. (b) HIR FTV RP 2007, In-service Inspection of Aboveground Atmospheric Fiberglass Reinforced Plastic Tanks and Vessels, may be used as an alternative to the sub. (4) (a) requirements for fiberglass reinforced plastic tanks.

5. (5) Corrective action.

   1. (a) If a suspected or obvious release is encountered during the inspections under this section, a tank-system site assessment shall be conducted in accordance with s. ATCP 93.465 before the tank is returned to service.

   2. (b) All corrective actions, including repairs that are indicated by the inspections under this section, shall be completed before the tank system is returned to service.

      Note: Under s. ATCP 93.400 (11) (a) 1., (b) 1., and (c) 9., records of the inspections that are required under this section must be maintained at the storage-tank site for at least either three years or the interval between inspections, whichever is longer.

History

History: CR 17-092: cr. Register October 2019 No. 766, eff. 11-1-19; CR 24-034: r. (3) (a) 2. b., am. (4) (a) (intro.) Register October 2025 No. 838, eff. 11-1-25.