Within 60 days after the closure of each unit is completed, the owner or operator must submit to the Agency, by registered or certified mail, a certification that the unit has been closed in compliance with the closure requirements. The certification must be signed by the owner or operator and by an independent registered professional engineer. Documentation supporting the independent registered professional engineer's certification must be furnished to the Agency upon request.
Ill. Admin. Code tit. 35, § 616.303