FLAG Aftermath: Effects of the Federal Land Managers' Modeling Guidance on CALPUFF Applications for New Source Permitting

摘要

In late 2000, the Federal Land Managers' Air Quality Related Values Workgroup (FLAG) finalized the Phase I guidance that will govern the FLM review of PSD permits in the years to come. In April 2001, the guidance, which applies to all new permitting projects, went into effect. The methods to evaluate visibility impacts associated with sources located from 50 to 200+ kilometers from Federal Class I areas (National Parks and Wilderness Areas) have undergone substantial revision from previous guidance. A major shift is the use of "natural background" as the basis for determining significance rather than the "existing" visibility. "Natural background" is used because it represents the year 2064 target in the Regional Haze Rule. However, in many cases, it is not representative of conditions that have existed since the establishment of National Parks and Wilderness areas. The authors have conducted PSD Class I modeling analyses for a variety of newly proposed power plants, using a variety of fuels (natural gas, distillate oil, and coal) that are affected by FLAG guidance. This paper includes an analysis for a well-controlled hypothetical coal-fired power plant placed at various distances from a hypothetical PSD Class I area. The analysis indicates that there would be significant challenges in permitting even this well-controlled source in the aftermath of FLAG as currently proposed and implemented with the use of CALPUFF. This paper also discusses technical issues that the authors consider to be either model formulation or procedural problems that contribute to the CALPUFF results for regional haze impacts.