40 CFR §63.9060

1. (a)Your records must be in a form suitable and readily available for expeditious inspection and review, according to § 63.10(b)(1).
2. (b)As specified in § 63.10(b)(1), you must keep each record for 5 years following the date of each occurrence, measurement, maintenance, corrective action, report, or record.
3. (c)You must keep each record on site, or readily accessible from on site through a computer or other means, for at least 2 years after the date of each occurrence, measurement, maintenance, corrective action, report, or record, according to § 63.10(b)(1). You can keep the records off site for the remaining 3 years. Records may be maintained in hard copy or computer-readable format including, but not limited to, on paper, microfilm, hard disk drive, floppy disk, compact disk, magnetic tape, or microfiche.
4. (d)You must keep each previous (i.e., superseded) version of the site-specific monitoring plan and the LDAR plan for a period of 5 years after revision of the plan. If, at any time after adoption of a site-specific monitoring plan or an LDAR plan, your affected source ceases operation or is otherwise no longer subject to the provisions of this subpart, you must retain a copy of the most recent plan for 5 years from the date your source ceases operation or is no longer subject to this subpart.