[Code of Federal Regulations] [Title 40, Volume 8] [Revised as of July 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR61.255] [Page 171] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 61_NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS --Table of Contents Subpart W_National Emission Standards for Radon Emissions From Operating Mill Tailings Sec. 61.255 Recordkeeping requirements. The owner or operator of the mill must maintain records documenting the source of input parameters including the results of all measurements upon which they are based, the calculations and/or analytical methods used to derive values for input parameters, and the procedure used to determine compliance. In addition, the documentation should be sufficient to allow an independent auditor to verify the accuracy of the determination made concerning the facility's compliance with the standard. These records must be kept at the mill for at least five years and upon request be made available for inspection by the Administrator, or his authorized representative.