Air quality permit for Enbridge Line 3

A facility that emits air pollutants above certain levels or that is subject to certain federal standards is required to have an air permit. Air permits, which are legally binding documents that owners and operators must comply with, include enforceable limits on air emissions, record keeping requirements, and reporting requirements. Air permits are designed to protect human health and the environment by limiting pollution so that our air quality remains within health-based state and federal ambient air quality standards.

Some air permits are general, covering facilities that have relatively low emissions and simple operations. These permits include registration, general, and capped permits. Examples of facilities that may obtain these permits include asphalt plants, sand and gravel operations, and auto body shops. Other air permits are individual, covering a specific facility with site-specific permit requirements. Examples of facilities that have individual permits include power plants, refineries, and taconite plants.

Enbridge currently has a registration permit for the Clearbrook Terminal. However, Enbridge would need to obtain a different type of air permit to accommodate the Line 3 Pipeline Replacement Project. As a result, Enbridge has submitted a capped permit application to the MPCA.

A capped permit is a rule-based permit in which all requirements are contained in state rules rather than in a site-specific permit document. The rule limits all air pollutant emissions below levels that would otherwise subject a facility to federal major source standards and requires an ambient air quality assessment to ensure that these levels will not exceed ambient air quality standards.

The MPCA follows the general process below for processing air permit applications. The step in green indicates the opportunity for the public to provide written comments. By rule, the MPCA is required to post notice of receipt of an application for a capped permit at and indicate the start and end dates of the public comment period.

Permitting process timeline showing a red "current status" arrow pointing at "Permit decision".

Current status

On September 14, 2018, the MPCA received a capped air permit application for the Clearbrook Terminal. Public comment was open from March 2 - April 10, 2020. The MPCA has responded to the public comments that were received. A final permit was issued on November 12, 2020.

Permit application and supporting documents

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