Aboveground storage tank facilities with a capacity of one million gallons or more

Large Storage Tank FacilityFacilities 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 and their associated equipment. 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 October 2015, there were 77 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% 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.

The owner of a proposed new facility, or an existing facility with small ASTs, intending to construct one or more aboveground storage tanks which would bring the total regulated liquid storage capacity of all tanks at the site to one million gallons or greater, must apply for an AST Major Facility permit. There is no permit application fee.

The application must be submitted and the permit issued prior to initiating construction of any AST which would increase total storage capacity to over 1 million gallons at the facility. AST “construction” is defined to include foundation and containment structures such as a ring walls and dikes, and piping, because MPCA application review includes the adequacy of design of the proposed tanks and associated structures to protect the environment. The AST program recommends that facility contact the program staff to discuss appropriate tank and piping design prior to the permitting process.

Permittees planning for AST construction should allow ample time for MPCA review and approval. The MPCA’s goal is to issue permits within 90 days. Public notice of AST Major Facility permits occurs only if requested by the permittee, or if the permit is controversial. The standard term of an AST permit is 10 years.

A permittee may renew an expiring AST permit by submitting a permit reissuance application at least 90 days prior to the expiration date. If the MPCA receives a permit reissuance application by this date and has not reissued the permit by the expiration date, the permittee may continue to operate the ASTs under the permit after the expiration date. For a summary of changes to requirements in reissued permits:

AST Major Facility permits identify certain actions, such as constructing a new field-erected tank or changing the substance stored in a tank, which require MPCA approval in the form of a permit modification. A permittee may also request to modify other terms and conditions of their permit.

Beginning October 6, 2015, the initial request for modification of an AST permit issued prior to that date will be processed by the MPCA as a permit reissuance, using the new online application service. In addition to identifying the requested change to their current permit, permittees will need to submit complete information for all tanks at the facility. The reissuance process may take longer that the current modification process, so facilities are encouraged to plan ahead when the need for a modification can be anticipated. If the request is for construction of a new field-erected tank or underground piping segment, the application must be submitted and the permit issued prior to initiating construction, including foundation work.

If a proposed or existing facility intends to construct a single AST with a capacity of 1 million gallons or greater storing liquid hazardous materials, or several tanks totaling this amount, the facility is required to first notify the Environmental Review (ER) program using the ER Pre-Screening form, in order to determine whether an Environmental Assessment Worksheet (EAW) for the project is required. The company should submit their online AST application and attach a completed copy of the ER Pre-Screening form. Construction of the tank(s), including foundation work, may not be initiated until it is determined that there is no need for an EAW, or the EAW process has been completed, and the AST permit has been issued.

More information about the Environmental Review and Pre-screening Form can found on the Environmental Review webpage

To use the new MPCA e-Service or online service for AST permitting applications:

  • First create an MPCA e-Services user account. Instructions for doing so are in the file below.
  • In the account, on the My Workspace tab, Service Selection section: Use the Configure Services button to add the Aboveground Storage Tank Reissuance Service (choose this for permit issuance as well).
  • On the My Workspace tab, My Facilities section: Add the facility for which the AST permit will be requested. To ensure that the application is submitted for the correct facility, the most accurate method is to contact the AST program to obtain the Facility ID Number. Currently permitted facilities may use their AST permit number preceded by Tank Site (TS) to search by Alternate/Historic Name/ID. The facility may also be located by searching Facility Name. Especially when using this method but for other searches as well, check the default facility information to ensure the correct facility is selected.
  • Facility Access Type: Any person authorized by the company, including consultants, may use the service to work on an AST application. However, the user who electronically certifies and submits the completed application must be a member of the tank owner company management, as shown by the user’s title, and have the Facility Access Type of Aboveground Storage Tank Signatory. Note that some companies may choose to internally control Access Type.
  • A proposed new facility will not appear in the MPCA database yet. These users need to contact the AST program to find out what information is required to obtain a Facility ID Number.
  • To initiate an application, from My Workspace click on Aboveground Storage Tank Reissuance Permit and select the facility to be permitted.
  • Multiple users, including consultants, may work on, review and certify the permit using the Sharing tool. Each user will need a separate account.
  • For a modification being processed as a reissuance, the company must attach to the application a description of the requested change to the current permit.
  • If the company proposes to construct a new field-erected tank containing one million gallons or more of hazardous materials, the company must attach to the application a completed File Environmental Review Pre-Screening Form.
  • If the company proposes to construct a new field-erected tank of any size or contents, or a new buried underground piping segment, as part of either an initial permit issuance or a permit modification, the company must attach a completed File New field-erected above ground storage tank and underground piping design (t-a1-24) File New field-erected above ground storage tank and underground piping design (t-a1-24)
  • When working in the online application, instructions for the screen and Help for each field are available on all screens. You can review the complete Instructions and Help for the application on the Getting Assistance: Aboveground Storage Tank Permit page.
  • For questions regarding the online application, contact the MPCA staff person assigned to your facility if you already know, or another AST program contact listed at the bottom of this webpage.

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 an API 653 authorized inspector. Below is a list of companies that provide API 653 inspection services. The MPCA does not endorse any of the companies that appear on this list.

When an inspection is performed, AST permits require that the API 653 Inspection Summary form be completed and submitted to the MPCA. The form is attached to the permit and is found here:

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 webpageEmergency 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.

Cleaning up leaks and spills

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.


For more information

If you have questions about permitting of facilities with a capacity of one million gallons or greater, please call Chris Bashor, 651-757-2215, John Chikkala, 651-757-2271, or Sandy Johnson, 651-757-2469.