40 CFR §63.2863

1. (a)Your records must be in a form suitable and readily available for review in accordance with § 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 for at least 2 years after the date of each occurrence, measurement, maintenance, corrective action, report, or record, in accordance with § 3.10(b)(1). You can keep the records off-site for the remaining 3 years.