Approval and Promulgation of Implementation Plans; Arizona Maricopa County PM-10 Nonattainment Area

EPA is approving in part and disapproving in part the final Plan for Attainment of the 24-hour PM-10 Standard--Maricopa County PM- 10 Nonattainment Area, (May 1997) (microscale plan) submitted by the Arizona Department of Environmental Quality on May 7, 1997. The microscale plan evaluates attainment of the 24-hour particulate matter (PM-10) national ambient air quality standard at four monitoring locations in the Maricopa County (Phoenix), Arizona, PM-10 nonattainment area. EPA is approving the attainment and reasonable further progress demonstrations for two of these sites (Salt River and Maryvale) and disapproving them for two other sites (West Chandler and Gilbert). EPA is also approving the reasonably available control measure/best available control measure demonstrations in the microscale plan for some significant source categories of PM-10 but disapproving them for others.