The Environmental Protection Agency (EPA) is approving a state implementation plan (SIP) revision submitted by the Commonwealth of Pennsylvania. The revision was submitted by the Pennsylvania Department of Environmental Protection (PADEP) to establish and require reasonably available control technology (RACT) for sources at Hydro Carbide Tool Company (Hydro Carbide), a major source of volatile organic compounds (VOC), pursuant to the Commonwealth of Pennsylvania's conditionally approved RACT regulations. In this rule action, EPA is approving source-specific RACT determinations (also referred to as case-by-case or CbC) submitted by PADEP for certain VOC sources at Hydro Carbide, a facility in Westmoreland County. The RACT evaluation was submitted to meet RACT requirements for the 1997 and 2008 8-hour ozone national ambient air quality standards (NAAQS). EPA is approving this revision to the Pennsylvania SIP in accordance with the requirements of the Clean Air Act (CAA) and EPA's implementing regulations.