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• Section 780.211b) Continued. 1. Installation of one spoil monitoring well in the reclaimed portion of the 720 Pit to monitor water levels and quality in the backfilled spoil material. See Map 48, Mine Area Monitoring Stations, for the proposed location of the new spoil well (designated Well 99-1 ). This well should be adequate to monitor resaturation, water level, and water quality in backfilled areas since the spoil unit is relatively continuous and semi-homogenous as illustrated by Figure 40, Projected North- South Pit Bottom Profile, Pit 1, Marr Pit and 20 Pit. The Johnny Moore Syncline plunges moderately to the south, and the Kerr mining operations recovered coal reserves along a portion of the west limb of the syncline. Map 15a, Mine Area Ground Water Hydrology, indicates that the prevailing direction of ground water flow is eastward toward the axis of the syncline (parallel to the dip of the Sudduth coal seam on the west limb of the syncline) and then southward with the plunge of the syncline. Prior to mining, ground water flow was affected by both structural boundaries and minor lithologic differences in the coal and overburden sequence. As mining progressed through • the Marr Pit, 720 Pit, and Pit 1, however, the entire overburden sequence from the southern end of the 720 Pit to the northern end of Pit 1 was disturbed and replaced by undifferentiated backfill materials. Backfilling effectively eliminated structural and lithologic boundaries, resulting in a relatively continuous, semi- homogenous, unconsolidated spoil "unit" within the surrounding undisturbed sedimentary sequence. Given that the spoil unit is both unconsolidated and relatively continuous, spoil water levels and quality should generally be consistent within the unit. In order to monitor the rate of spoil resaturation and spoil water levels and water quality, Kerr proposes to establish a spoil well in the central portion of the backfilled 720 Pit area. This location is slightly south of the center of the spoil unit and should be adequate for monitoring spoil ground water conditions while avoiding potential secondary ground water effects from the nearby reclaimed Canadian Strip Mine. Installation of the proposed spoil monitoring well will be deferred to allow reasonable settlement and consolidation of the 720 Pit backfill, with installation anticipated by fall of the year 2000. TR-19 780-108a Revised August 1999