Commingle Permit Application.

Just received certified letter that says it is a notice of Commingle Permit Application. It says it is provided to give me 21 days notice as they are requesting exemption to statewide rules 26 and/ or 27. Anyone have knowledge about this rule to share? It says it is for offsite storage and separation of oil; and casing gas metering by allocation of test well. Other items are also checked. Thanks for any information and feedback.