d) Once compliance with the groundwater quality standards set forth in Section 840.116 of this Subpart has been achieved in accordance with Section 840.118(a) of this Subpart, the owner or operator of Ash Pond D may discontinue operation of the groundwater collection trench.

1. 1) Upon discontinuing operation of the groundwater collection trench, the owner or operator must perform four quarterly sampling of the groundwater monitoring system wells as identified in the post-closure care plan, or modification of that plan, to ensure compliance with the applicable groundwater quality standards set forth in Section 840.116 of this Subpart.
2. 2) Results of the four quarterly samplings must be included in the post-closure report documentation. If compliance is not confirmed, operation of the groundwater collection trench and discharge system must be resumed.