Proposed facilities that are major emissions sources subject to Prevention of Significant Deterioration (PSD) regulations are required to evaluate air quality at specially protected national parks, wilderness areas, and wildlife refuges (Federal Class I areas) in their permit applications. Because PSD Class I considerations have become the most critical and constraining aspects of permitting new sources, it is important for applicants to determine at the outset how these issues could affect a proposed project.
Today, the role of the FLMs in reviewing PSD permit applications has increased significantly due to a number of developments:
An FLM workgroup on air quality related values (AQRVs) has published final guidance on assessment techniques for visibility and acidic deposition with more stringent significant impact thresholds, so that impact assessments for these issues are now required and are a limiting factor in successful permitting.
EPA has published a final rulemaking, as of April 15, 2003, regarding a preferred dispersion modeling technique (the CALPUFF model) for long-range transport applications. CALPUFF applicability range is up to 300 km, according to the FLMs.
As shown in Figure 1, this expansion of the area of influence affects new PSD sources over most of the United States.
Visibility Criteria: A New Hurdle
As a result of the finalization of the Regional Haze Rule (July 1, 1999 Federal Register), the FLMs have recently tightened the criteria even further for the background visual range, as noted above. In late 2000, the Federal Land Managers' Air Quality Related Values Workgroup (FLAG) published Phase I guidance that now governs the FLM review of PSD permits. In a major policy shift, FLAG's guidance changed how FLM determines visibility impairment.
The FLAG guidance replaces the 90th percentile criterion with that of a 'natural' background. Citing the 1977 Amendments to the Clean Air Act, FLAG interprets natural background as the concentration level that would exist in the absence of human activity on earth. This is inconsistent with the purpose of National Parks, which have been established for the enjoyment of human visitors.
The new criteria are more restrictive to permitting, especially in the eastern United States. Ironically, this could increase pollution, because procedures developed to protect Class I areas from further visibility degradation from new sources will hamper development of new, less-polluting power plants that would replace the generation capacity provided by older sources that are less efficient and emit more pollutants per unit of energy produced. Thus, in the near term, the FLAG guidance could aggravate rather than improve the regional haze conditions in PSD Class I areas.
In light of these emerging requirements, ENSR recommends the following strategies to developers of new emission sources:
Check the location of the source relative to the map that shows areas within 300 km of a Class I area. If the source is within that range, prepare to assess the effect of the proposed source on PSD increment consumption, visibility, and acidic deposition effects.
If the source is within 50 km of a Class I area, prepare to apply short-range dispersion modeling procedures that are used for the ambient air impact assessment surrounding the facility. If the source is farther than 50 km from the Class I area, apply CALPUFF.
The FLMs will closely scrutinize the emissions of a project relative to recent Best Available Control Technology assessments. Careful attention should be paid to this issue. One benefit of proposing lower emissions is that it is more likely the project will pass the modeling thresholds.
Check with the FLMs to see if a refined analysis may already have been done for that area. If not, an experienced air quality meteorologist will be needed to conduct the required refined CALPUFF analysis. If the proposed source alone shows an insignificant impact within the Class I area, no further analysis is required. Otherwise, a cumulative analysis with all PSD sources within at least 100-200 km of the Class I area is necessary.
ENSR's experience indicates that cumulative analyses are most often triggered by two criteria, the PSD Increment for sulfur dioxide and regional haze, with the latter typically more constraining. In conducting the refined analysis, the meteorological conditions should be carefully scrutinized for factors that may negate visibility as an important air quality- related value. For example, because the modeled haze is very sensitive to relative humidity, periods of fog or inclement weather may be excluded because the visibility is already naturally reduced.
Seek ways to refine estimates of natural background to include regional or local contributions. For instance, for coastal areas, include sea salt particles in the background.
Use of more advanced meteorological data, especially that from recent years of National Oceanic and Atmospheric Administration (NOAA) models, could significantly improve CALPUFF predictions and reduce conservatism in the model predictions.
· Because of the many complicated technical, regulatory and policy issues, ongoing communication with the permitting agency and the FLMs is essential for the expeditious and successful permitting of any new major emissions source.
In any critical flaw assessment of a proposed project, the impacts of the project emissions on PSD Class I areas may result in constraints to the project. A thorough understanding of the issues associated with modeled impacts at these areas is essential to a successful permit.