(1) If assessment monitoring of an unlined coal ash impoundment confirms the presence of groundwater contamination in excess of maximum contaminant levels in effect as provided in section 6 of the safe drinking water act, 1976 PA 399, MCL 325.1006, or a groundwater protection standard established under 40 C.F.R. § 257.95(h), the owner or operator of the coal ash impoundment shall do all of the following:

  (a) Notify the department of the confirmation within 14 days.

  (b) Cease acceptance of coal ash at the impoundment within 180 days after the confirmation.

  (c) Begin to implement closure as described in R 299.4309(7) of the part 115 rules not more than 180 days after such confirmation and diligently pursue the closure. The closure shall be completed in compliance with 40 C.F.R. § 257.102(c), with 40 C.F.R. § 257.102(f)(1) and (2), or with 40 C.F.R. § 257.103.

  (d) Prepare a response action plan in compliance with R 299.4442 of the part 115 rules and submit the response action plan to the department for review and approval. Upon receipt of department approval, the owner or operator shall implement and diligently pursue the response action plan and shall comply with R 299.4443 to 299.4445 of the part 115 rules.

  (2) For purposes of this section, “unlined coal ash impoundment” means a coal ash impoundment without a liner as described in 40 C.F.R. § 257.70(b) or another construction or system in place that is determined by the department to be as protective as a liner as described in 40 C.F.R. § 257.70(b).