Section 840.112  Groundwater Monitoring System

The owner or operator of Ash Pond D must design and install a groundwater monitoring system that enables it to monitor groundwater to evaluate post-closure groundwater quality and trends and to demonstrate compliance with the applicable groundwater quality standards at designated compliance points as set forth in Sections 840.116 and 840.118 of this Subpart. If approved in the closure plan, any groundwater monitoring well in operation since 1999 that complies with the requirements set forth in this Section may be used in satisfying the requirements of this Section.

a)         Standards for monitoring well design and construction.

1)         All monitoring wells must be cased in a manner that maintains the integrity of the bore holes.

2)         Wells must be screened to allow sampling only at the specified interval.

3)         All wells must be covered with vented caps, unless located in flood-prone areas, and equipped with devices to protect against tampering and damage.

b)          The groundwater monitoring system must consist of a sufficient number of wells, installed at appropriate locations and depths to yield groundwater samples to:

1)         Represent the quality of background water that has not been affected by contamination from Ash Pond D;

2)         Represent the quality of groundwater at the compliance point or points; and

            3)         Determine compliance with Sections 840.116 and 840.118 of this Subpart.

c)         Monitoring wells must be located in statigraphic horizons that could serve as contaminant pathways.

d)         The groundwater monitoring system approved in the closure plan must include a maintenance plan.