Cal. Pub. Res. Code § 43503

The closure plan and the postclosure maintenance plan shall be submitted not later than the first date after July 1, 1990, that the solid waste facilities permit is required to be reviewed or revised pursuant to Section 44015. The closure plans and postclosure maintenance plans shall be included in that review. If the owner or operator intends to close the solid waste landfill on or before September 28, 1992, or if the solid waste landfill does not have sufficient permitted capacity to operate after September 28, 1992, the owner or operator shall submit the plans on or before July 1, 1990, or upon application to become an operator of a solid waste facility pursuant to Section 44001.