Pipeline and Hazardous Materials Safety Administration Office of Hazardous Materials Enforcement Operations Manual [open pdf - 3MB]
"The purpose of this Operations Manual is to describe the policies and procedures to be used for inspections and investigations conducted by OHME [Office of Hazardous Materials]. This manual addresses the entire spectrum of procedures and policies, in addition to focusing on more field-oriented aspects of a compliance inspection or investigation. It is intended as a training manual, desk reference, and field manual for trainees, field investigators, unit supervisors, and program management personnel. Although not specifically written for them, the manual will also be of assistance to legal personnel."
United States Department of Transportation, Pipeline and Hazardous Materials Safety Administration: http://www.phmsa.dot.gov/