Hundreds of residents were evacuated while workers were removing buried chemical wastes from an abandoned plant in Columbia, Miss., but were expected to return to their homes today. The Environmental Protection Agency is picking up the tab for the cleanup at the old Reichold Chemical Co. Some barrels of chemicals were leaking as they were pulled from the ground. The site was not considered a serious threat but the evacuation was ordered because some of the burial sites were a few dozen feet from homes. The Reichold plant, where resins were removed from stumps for turpentine and use in plastics, exploded and burned in 1977. EPA officials said they were not sure what all of the buried drums contain. However, some of the material has been identified as pentachlorophenol, a wood preservative.