Aboveground Storage Tank Systems - Facilities with a Capacity of One Million Gallons or More
This Web page explains the permitting process for large AST facilities and provides documents helpful in the permitting and permit renewal process.
Facilities with one or more regulated ASTs with a total liquid substance storage capacity of one million gallons or more must obtain an individual permit from the MPCA following procedures outlined in Minnesota Rules Chapter 7001.4205-4250. 
The goal of an AST major facility permit is to prevent pollution to waters of the state including surface water and ground water, created by leaks and spills of liquid substances from ASTs, their piping, and piping connections located at the facility. This is accomplished through implementation of appropriate release prevention, detection, and containment measures. Permit requirements are risk-based, use applicable industry standards, and cover safeguards such as tank inspections, tank floor design, visual monitoring, leak detection, overfill prevention, transfer areas, secondary containment areas, and above-ground and underground piping design, testing and inspection.
As of January 2004, there were 82 permitted AST major facilities in Minnesota. Major facilities represent only three percent of all AST facilities in Minnesota, but contain 15 percent of Minnesota’s ASTs and 85 percent of the total liquid storage capacity in the state (more than a billion gallons). These facilities are part of the petroleum refining and marketing, chemical manufacturing and storage, public power, ethanol, mining, sugar beet, soybean processing, and pulp and paper industries.
Permit Process
To begin the permit process, the facility owner completes and submits a 
permit application. There is no fee. Permittees should allow ample time for MPCA review and approval. Public notice of permits occurs only if requested by the permittee, or if the permit is controversial. The permit must be issued prior to construction of a new AST facility with a capacity of million gallons or greater, or prior to putting a new tank into service which will increase total storage capacity to more than a million gallons. Permittees may contact MPCA engineers to discuss appropriate tank and piping design prior to and during the permitting process.
New permits are issued for a period of five to ten years. Permittees may seek modification of a permit by submitting a permit modifications application. MPCA approval is required to construct any new field-erected tank or underground piping segment.
Permittees are required to submit a permit renewal application at least 90 days prior to the permit expiration date, in which case the facility continues to operate under the old permit until the new permit is issued. For current permittees anticipating permit renewal, a fact sheet, Changes to Requirements for Re-issued Permits, is available which describes changes to requirements for reissued permits.
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Major AST Facility Permit Application (t-a3-25) - Major AST Facility Permit Modification Application (t-a3-26)
- Changes to Requirements for Re-issued Permits
Inspecting Field-Erected Tanks
Tanks that are constructed on-site are considered "field-erected tanks." These tanks are generally greater than 50,000 gallons in capacity. AST permits require most field-erected tanks to be internally and externally inspected according to American Petroleum Institute (API) Standard 653. These inspections are critical to identifying corrosion and other maintenance problems that could eventually lead to tank failure.
Inspections must be performed by a person trained and certified by the API (an API 653 authorized inspector). Below is a list of companies that provide API 653 inspection services. MPCA does not endorse any of the companies that appear on this list.
The MPCA has important guidelines for tank owners and tank service contractors who use API 653 (an industry standard) to comply with Minnesota rules. The guidelines cover inspector qualifications, inspection frequency, repairs, reports, and other topics.
Spill Planning and Response
Facilities with hazardous substance or petroleum ASTs with greater than 10,000 gallons capacity are required to have a spill plan addressing release prevention and spill response. Spill response and planning guidance material is available from the MPCA’s Emergency Response Team.
Reporting Leaks and Spills
AST owners are required to report a leak or spill of more than five gallons of petroleum or any amount of a hazardous substance from any tank or piping. To report a leak or spill, call the Minnesota Duty Officer at 800-422-0798 (Minnesota only) or 651-649-5451.
Leaks and Spills Cleanup
All leaks and spills from ASTs and associated piping must be cleaned up to protect the environment and public health. The Large AST Program oversees cleanup actions conducted by companies with petroleum contamination at AST facilities with a capacity of one million gallons or greater.
Who to Call
If you have questions about facilities with a capacity of one million gallons or greater, please call Sandy Johnson, 651-757-2469, or Tin Tran, 651-757-2789.
