The EPA is implementing a project under the Project XL program for the Merck & Co., Inc. (Merck) Stonewall Plant, in Elkton, Virginia. The terms of the project are defined in a Final Project Agreement (FPA) which is available in the docket for this action. In addition, EPA is promulgating today a site-specific rule, applicable only to the Merck Stonewall Plant, to facilitate implementation of the project. This site-specific rule provides regulatory changes under the Clean Air Act and the Resource Conservation and Recovery Act (RCRA) to implement Merck's XL project, which will result in superior environmental performance and, at the same time, provide Merck with greater operational flexibility. The site-specific rule changes the requirements under the Clean Air Act which apply to the Merck Stonewall Plant for the prevention of significant deterioration of air quality and certain new source performance standards. EPA also is promulgating a site-specific rulemaking under RCRA to provide regulatory changes pertaining to air emissions standards.