The United States Environmental Protection Agency (USEPA) is investigating the asphalt concrete production source category to identify and quantify emissions of hazardous air pollutants (HAPS) from rotary aggregate dryers used at these facilities. There are two types of rotary drum dryers in use at asphalt concrete production plants; parallel flow, wherein the direction of travel of the drying aggregate is the same as the direction of travel of the burner exhaust gases, and counter flow, wherein the aggregate and exhaust gas flows are opposite to each other. On May 7, 1997, a work assignment was issued by EPA's Office of Air Quality Planning and Standards, Emissions Measurement Center, (OAQPS, EMC) to Pacific Environmental Services, Inc. (PES), of Research Triangle Park, North Carolina. The work assignment specified that emissions testing for HAPS be conducted on one of each type of aggregate dryer. Two candidate facilities were therefore identified and selected as host facilities for the testing program. This document describes the test procedures, results, and quality assurance procedures that ivere employed during the testing of a counter flow rotary drum aggregate dryer, which was located at Asphalt Plant 'A' in Clayton, North Carolina. The facility was identified as a candidate by EPA due to its location close to EPA facilities in Research Triangle Park, North Carolina, and because it is typical of counter flow rotary dryers in the asphalt production source category. The results of the emissions testing program conducted at a facility employing a parallel flow rotary aggregate dryer are presented in a separate report. The scope of the work assignment was to plan and conduct an air emissions testing program to quantify' emission rates of HAPS from the rotary aggregate drier located at Asphalt Plant 'A'.