2015-10-08_REVISION - C1981041 (12)

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based on the relatively stable static water level exhibited by the alluvial monitoring wells installed in 1984 along these Creeks and below the confluence. Static water levels monitored along Cottonwood Creek and below the confluence of Cottonwood and Rapid Creeks remained stable or increased slightly over the monitoring period from 1984 to present. Water levels monitored along Rapid Creek decreased slightly over that same time period of approximately 20 years. The very gradual decline in alluvial water levels along Rapid Creek is consistent with the analysis presented above for surface water monitoring. The slight downward trend of static water levels along Rapid Creek was likely caused by climatic conditions as opposed to subsidence effects. Table G13-1 shows static water level measurements for May and September (high and low -flow seasons) for 1985 to present in the six alluvial wells located immediately adjacent to the creeks. The fact that the water levels remain static with no sudden drop in level indicates that subsidence has had no effect on the available water in the creeks. Further, a comparison of spring levels versus fall levels show higher static water levels in the low -flow season, verifying that there is some component of base -flow recharge from the alluvium to the creeks indicating a gaining stream as opposed to a losing stream. This is further evidence that water in Cottonwood Creek and Rapid Creek is not being lost to subsidence cracks. A review of mine inflow information and mine water discharge is pertinent to this Findings Document because there is some speculation by Mr. Fontanari that irrigation water from the surface may enter the underground workings and increase the outflow at CDPS discharge point 016 (refer to Mr. Fontanari's second objection letter dated February 20, 2014 in Attachment 3). Snowcap Coal Company experienced mine water inflow to the South Portal mine workings prior to 1986. SCC performed mine inflow studies at the South Portal from 1986 through 1999. During the time the mine was active; SCC maintained and operated three CDPS discharge points (001, 002, and 015) to handle mine water discharge. Discharge point 015 was permitted to allow pumping water from the south end of the Roadside South Portal out of the 2 West portals, but was never put into use. Discharge point 001 was primarily used as an overflow to a mine water system for the preparation plant during mine operations. As described previously, the South Portal dewatering pipe (Outfall 001) was reclaimed during the 1St quarter of 2008 and is no longer operational. Flow ceased at discharge point 001 on March 31, 2002. Discharge point 002 was water siphoned from the reclaimed Northwest Intake Portal at the Roadside South Portals. Mine inflows that were not pumped to the preparation plant were routed to an abandoned portion of the mine for discharge from this point. The preparation plant was shut down during December 1999 so all mine inflows in excess of those handled by Outfall 001 would flow north to the lower portion of the mine (referred to as the Northwest Intake Pool) where they were handled by the siphon, Outfall 002. Flow ceased at discharge point 002 on March 31, 2002. Discharge point 016 was put into service April 1, 2002 to replace the siphon. Outfall 002 will remain as a backup to Outfall 016 if needed. Discharge at Outfall 016 began April 3, 2002. This gravity discharge point handles all of the water that flows into the sealed South Portal. Since it is a gravity discharge point, the flow discharged will equal the flow into the mine. This is now the only mine discharge from the Roadside North and South Portals Mine. CDPS discharge point 016 is a perpetual discharge from the mine. SCC performed mine inflow studies at the South Portal from 1986 through 1999. There has been no annual mine inflow study performed since one was done during December 1999 and reported in the 1999 AHR. Since the North and South Portals have been sealed, there will not be any additional mine inflow studies. The following narrative is provided to summarize the mine inflow studies performed Page 29