General Conformity Training Module 2.3: Demonstrating Conformity

Words that are shown in bold and italics are defined in the Glossary.

2.3.1 Overview

Emissions caused by activities proposed for a federal project that would originate within a nonattainment area or maintenance area must be evaluated in the federal agency's screening applicability analysis, so long as the activities meet the applicability requirements under 40 CFR sec. 93.153(a) or (b). In the screening analysis, the federal agency would examine each activity and exclude from the analysis those activities for which the EPA allows a presumption of conformity (referred to as presumed to conform or PTC), or where the project's description of the activity meets the specific scope of an exemption EPA lists under section 93.153. In addition, the agency may claim other activities are PTC if they are specifically described within the agency's own list of PTC activities published in the Federal Register or are listed as PTC in the State's own applicable implementation plan. Emissions caused by the activities that remain are included in the federal agency's net emissions applicability analysis, where for each year analyzed, as specified under section 93.159(d), emissions from the activities projected for future years are compared to the emissions from existing sources of the same pollutants for the same future years. The difference between the two is referred to as the total of direct and indirect emissions (also referred to as "net emissions"), and the results could show annual increases as well as decreases in the emissions. If the federal agency finds the annual net emissions would cause an increase in emissions that would meet or exceed the associated the de minimis threshold rates under section 93.153(b)(1) and (b)(2), the agency must prepare a demonstration (analysis) using EPA criteria under section 93.158 and follow the procedures under section 93.159 to show how the emissions will conform to the purpose of the applicable implementation plan, which is defined under Clean Air Act (CAA) section 176(c)(1)(A) and (B). The federal agency must then prepare a written conformity determination, based on the results of the demonstration, and stipulate that the emissions from the federal project will meet the conformity requirements and will not interfere with the State's or Tribe's ability to meet and maintain the NAAQS.

There are several methods for demonstrating conformity of the project's activities' annual increases in net emissions that meet or exceed the associated de minimis threshold rates. The federal agency must apply one or a combination of the following methods to demonstrate, for at least each year specified under section 93.159(d), that the annual increases in net emissions of relevant pollutants caused by the federal activities is reduced to zero or the agency must otherwise show the emissions will conform to the purpose of the applicable implementation plan, as required under CAA section 176(c)(1)(A) and (1)(B):

1) Document that some or all of the annual increases in net emissions are specifically identified and accounted for in the applicable implementation plan's attainment or maintenance demonstration, in the plan's reasonable further progress milestones, or in a facility-wide emissions budget included in the applicable implementation plan in accordance with section 93.161;

2) Document that some or all of the annual increases in net emissions are specifically accounted for in the applicable implementation plan's Early Emissions Reduction Credits program, developed by the federal agency with approval by the state or Tribal air agency, according to section 93.165;3)

3) Apply mitigation measures or obtain emissions offsets to reduce the annual increase in net emissions according to the methods and requirements under section 93.161, section 93.163, and section 93.164, and according to the definition of emissions offsets under section 93.152;

4) Obtain documentation from the Metropolitan Planning Organization (MPO) that some or all of the annual increases in net emissions are included in a current transportation plan or transportation improvement plan, either of which must have been found to conform to the applicable implementation plan under Transportation Conformity (40 CFR part 93 subpart (A), 40 CFR part 51 subpart T, 40 CFR 51.851, or General Conformity (40 CFR part 93 subpart B). Conformity means the emissions caused by activities included as part of the federal project and which are applicable under the provisions of Geneal Conformity, will conform to the purpose of the applicable implementation plan within nonattainment areas or maintenance areas, and will not cause or contribute to a new NAAQS violation within the area, will not increase the frequency or severity of the area's existing NAAQS violation within the area, and will not delay timely attainment or maintenance of the NAAQS within the area.

5) Request the state or Tribal air agency responsible for the applicable implementation plan to agree to submit a revision to the applicable implementation plan that will include some or all of the annual increases in net emissions caused by the project's activities;

6) If the area was so recently designated, reclassified, or redesignated that the responsible air agency has not yet completed the development of the required revised implementation plan or the EPA has not yet approved the plan, the agency must document that the annual increases in net emissions for the future years specified under section 93.159(d) do not increase with respect to the baseline emissions, according to the criteria under section 93.158(a)(5)(iv); or

7) The agency may, but is not required to, conduct air quality modeling to demonstrate that the annual increases in net emissions will meet the conformity requirements under CAA section 176(c)(1)(A) and (1)(B). Conformity means the emissions caused by activities included as part of the federal project and which are applicable under the provisions of Geneal Conformity, will conform to the purpose of the applicable implementation plan within nonattainment areas or maintenance areas, and will not cause or contribute to a new NAAQS violation within the area, will not increase the frequency or severity of the area's existing NAAQS violation within the area, and will not delay timely attainment or maintenance of the NAAQS within the area.

8) The agency may redesign the federal project or the individual activities subject to General Conformity to reduce all or part of the annual increases in net emissions, for instance, lengthen the construction phase of the project to distribute construction emissions over a longer period of time (more years, lower emissions per year). EPA notes that redesigning the planning, if not done before the draft General Conformity Determination is published, may require the preparation of a supplemental NEPA document because other NEPA environmental categories could be affected.

2.3.2 Mitigation of emissions

Federal agencies can apply mitigation or obtain offsets to eliminate or reduce emissions. Mitigation measures and offsets must meet the following requirements:

Mitigation measures, and in some cases plans to obtain emissions offsets, must be in place before the federal agency can rely on the strategies to demonstrate conformity and make its positive conformity determination, and before the agency takes the action (i.e., makes its decision to fund, permit or license, approve or conditionally approve implementation of the federal project). This means that any written agreement between two or more parties that is needed to accomplish the reduction in emissions below what was reported in the published draft conformity determination, must be signed and a copy included in the agency's conformity determination. All parties to the agreement must meet their obligations under the agreement;
An agency's plan to reduce emissions through mitigation or offsets requires the reduction to be more than equal to the annual increase in net emissions caused by taking the action, depending on the area's classification (e.g., ozone Serious nonattainment area or a PM3.5 Moderate nonattainment area) as required under section 93.163 Timing of offsets and mitigation measures. For example--

If a project's activities would cause 150 tons of NOx emissions, per year, for 3 years, in a Serious ozone nonattainment area, that would be 450 tons of NOx emissions over the 3 years. For a Serious ozone nonattainment area, that would require 1.2 tons of reduced NOx emissions for every ton of new NOx caused by the project over the three years. The calculation is 450 tons NOx multiplied by 1.2 tons = 540 tons that need to be reduced. The mitigation or offsets must cause a reduction of 540 tons over a maximum of 6 years (3 x 2 = 6 years or twice the number of years needing the reduction to meet conformity.) Therefore, mitigation or offsets must provide 6 years of reductions of 90 tons of NOx per year to meet the requirements under section 93.163, because 540 tons / 6 years = 90 tons per year for 6 years.

Mitigation measures can be modified after the federal agency has completed its conformity demonstration by following the procedures used to establish the original measures;
The emissions reductions from an offset or mitigation measure for the purpose of demonstrating conformity must occur during the same calendar year in which the project's emissions causing the need for the offset or mitigation occur; the ratio of tons of emissions reduction per ton of emissions requiring reduction are established under section 93.163(b)(1); and the time period for completing the emissions reductions must not exceed twice the period of the emissions.
Emissions offsets, as defined under section 93.152 must be:
- Quantifiable – The federal agency must be able to quantify the emissions reduced by the offset method using standard techniques or strategies for determining emission reductions;
- Surplus – The emission reductions must not be required by the applicable implementation plan, or other environmental laws or regulations;
- Enforceable – EPA or the state, Tribal or local agency must have the ability to enforce the offsets. This can be done by including the measure in an operating permit or similar mechanism or by including the reductions in the applicable implementation plan;
- Permanent – The emission reductions must be permanent within the timeframe the emission increases caused by the action occur.
- Adequately supported – The federal agency must show that there are adequate resources to implement the emission reduction strategy or technique;
EPA, states, Tribes, and local agencies must be able to enforce the requirements of the emission reduction strategies or techniques used as an offset. If a third party fails to meet its commitment in implementing the measures, the enforcement will generally be against the third party and not the federal agency.

2.3.3 Demonstrating conformity in the absence of an approved SIP

A federal agency may be taking actions in a nonattainment area where EPA has not approved the SIP/TIP for the area. In such a case, the federal agency’s options for demonstrating conformity for the action are limited. Since there is no SIP/TIP, the federal agency can secure a commitment from the state or tribe to include the emissions into the future SIP/TIP. The federal agency may still conduct modeling to demonstrate conformity or it may secure emission reductions to mitigate or offset the emission increases.

A second case of a federal agency addressing conformity in the absence of a SIP/TIP occurs when the emissions from a federal action will occur after the time period covered by the SIP/TIP. In this case, the federal agency can demonstrate conformity for the last budget in the SIP/TIP and assume that the future SIP/TIP will allow that quantity of emissions. The state, tribe or local agency would be responsible for developing the SIP/TIP to account for the emissions from the action. If the emissions from the action are greater than the emissions allowed in the last budget in the SIP/TIP, then the federal agency can secure a commitment from the state or tribe to include the emission in the future SIP/TIP.

2.3.4 Required analysis years

Federal agencies can choose to demonstrate conformity on a worst-case basis or on a year-to-year basis. Under the worst-case approach, the federal agency would show that the maximum emissions from the action would conform with the most stringent budget in the SIP/TIP. Under the year-to-year approach, the federal agency would demonstrate that each year the emissions for the action would conform with the SIP/TIP. The year-to-year approach may be useful for actions with specific end dates or with widely varying emissions such as construction projects.