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Fish Creek installed in 1994) were 31.5 cfs, 490 mg/L and 196 mg/L respectively. The flow value is equivalent
<br />to the modeled low flow of 23.4 cfs and the TDS and sulfate levels of 420 mg /L and 172 mg/L for baseline
<br />conditions.
<br />• The conclusion regarding the potential impacts of the TCC longwall operation in the EMD on the local surface
<br />and ground water resources is that the effects will be very limited due to the depth and lithological composition
<br />of the overburden above the mined Wadge Coal Seam. Impacts on surface and ground water resources are
<br />possible within 340 to 380 feet above the mined coal seam and within an angle of draw of about 17 degrees
<br />from the longwall panels. An analysis of the geologic composition of the Wadge Coal Seam Overburden
<br />indicated that only limited sandstone strata in the mined coal seam overburden are impacted by subsidence. The
<br />conclusion is confirmed by the limited ground water inflow into the current mining operation.
<br />The predicted ground surface subsidence within the Foidel Creek alluvium would reach up to 86 inches during
<br />mining in Panel 6- Right, where the overburden is 600 feet thick (SubTerra, Inc., 1996). This rate of subsidence
<br />could cause short-term changes in the Foidel Creek stream gradient. However, the calculated maximum slope
<br />change (SubTerra, Inc., 1996) of 13.9 x 10 (panel 6 Right) would not have any significant long -term impact on
<br />the stream flow and/or water quality. The meandering character of Foidel Creek, cutting through fine - grained
<br />sediments, would facilitate the fast - healing process of any temporary changes in the streambed gradient.
<br />The predicted ground surface subsidence for the Middle Creek alluvium would reach up to 84 inches during
<br />mining in Panel 8- Right, where the overburden is 530 to 670 feet thick (SubTerra, Inc.,1993). This rate of
<br />subsidence could cause short-term change of the Middle Creek streambed gradient. The maximum calculated
<br />slope change (SubTerra, Inc., 1993) of 20 x 10 ft /ft for Middle Creek is associated with a lower overburden
<br />thickness of 580 feet in the area of Panel 8- Right. This change of slope would not have any significant long-
<br />term impact on the stream flow and/or water quality. The meandering character of Middle Creek, cutting
<br />through fine- grained sediments, would facilitate the fast - healing process of any temporary changes in the
<br />streambed gradient.
<br />The above predictions were verified by Mr. Ramsay M. McDermid, P.E.; his report is presented in Exhibit 7i,
<br />Review Cyprus Twentymile Subsidence Effect on Streams.
<br />The predicted ground surface subsidence for areas underlying the Fish Creek alluvium would reach up to 69
<br />inches during mining in Panels 12 -Left to 15 -Left, where the overburden is roughly 1,100 -1,200 feet thick
<br />(SubTerra, Inc.,2009). This rate of subsidence could cause short-term changes in the Fish Creek streambed
<br />gradient. The maximum calculated slope change (SubTerra, Inc., 2009) of 7 x 10 ft/ft (0.7 percent), coupled
<br />with subsidence features, could result in some localized ponding, excursion of the creek from its bed, and
<br />expansion of Fish Creek within its floodplain, especially during high flows. The change of slope, and seasonal
<br />excursions would not have any significant long -term impact on the stream flow and/or water quality. The
<br />meandering character of Fish Creek, cutting through fine- grained sediments, would facilitate rapid- healing of
<br />any temporary changes in the streambed gradient.
<br />It should be noted that coal is mined beneath significant bodies of surface water, including the sea, in many
<br />nations (Great Britain, Canada, Australia, Japan, Chile, and Turkey). The minimum cover to seabed for total
<br />extraction (longwall mining) ranges in various nations from 60 meters (197 feet) in Japan to 213.4 meters (700
<br />feet) in Nova Scotia. The guidelines recommended by the U.S. Bureau of Mines (Wardell, 1976) state that,
<br />"any single seam of coal beneath or in the vicinity of any body of surface water may be totally extracted,
<br />whether by longwall mining or by pillar drawing, provided that for each 1 foot thickness of coal seam extracted
<br />a thickness of 60 feet of solid strata cover exists between the proposed workings and the bed of the body of
<br />surface water." This shows that at the Foidel Creek Mine the longwall operation extracting 9.5 feet of coal
<br />would be safe 570 feet under a seabed.
<br />. The conclusion of our studies of subsidence, and the potential impacts of subsidence on the Foidel and Middle
<br />Creek alluvium and Alluvial Valley Floor, is that the mining in Panels 2 -Right through 9 -Right will not have
<br />any detrimental impacts on the water quantity and quality, or on the essential hydrologic function of the AVF.
<br />PR09 -08 2.05 -166 04/29/09
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