Comment on FR Doc # 2010-24683

...The City of Casa Grande strongly opposes stretching the PM10 nonattainment area beyond the limits of Governor Brewer’s recommendation. While it has been, and will continue to be, the City of Casa Grande’s position that the City should not be included within the PM10 nonattainment area, the City understands that EPA has a desire to establish a new PM10 nonattainment area in order to lower PM10 concentrations within the area. To that end, the City is willing to compromise by accepting Governor Brewer’s recommendation for the PM10 nonattainment area. The City does not agree with the EPA’s assessment that the PM10 nonattainment area should include the whole western half of the county. Along with many other municipalities, the City of Casa Grande is completely included within the EPA’s proposed PM10 nonattainment boundary. This being said, none of the EPA monitors that are located within Casa Grande’s city limits have registered exceedances above the EPA standards, except on days of exceptional events (as flagged by Pinal County Air Quality). As you know, “the Exceptional Event Rule (EER) became effective May 21, 2007. The EER allows the ambient air quality data which is submitted to AQS and used in making regulatory decisions, to be, in some cases, flagged and, where appropriate, excluded from calculations in determining whether or not an area has attained the standard.” It is inexplicable that the EPA lists Casa Grande (and surrounding areas) as having violating PM10 monitors in the EPA’s Technical Support Document (TSD), when these violations are explained by “non-reasonably controlled or preventable events” of high wind, each of which has been flagged by Pinal County. While the EPA’s TSD justifies the inclusion of southern Pinal County in the nonattainment areas because of wind source data, it is unreasonable to assume that this area contributes to the PM10 problem, as none of the monitors in the southern part of the County are in violation of NAAQS standards....