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• TABLE 7 Comparison of CP - 1 Baseline and 1989 Sampling Results, Gunnison No. 1 Mlne <br />Sampling <br />Date <br />Turbidity pH <br />(units) Conduct. <br />(µmhO~j TDS <br />(mg/L) Temp. <br />(°C) Fe <br />(mg/L) Mn <br />(mg/L) <br />08/08/85 048 7.5 990 s66.0 10.1 <0.02 0.21 <br />oaros/Ss <br />(Dup) 048 7.s 990 526.0 10.0 <0.02 0.21 <br />10/10/85 Os4 -- 693 870.0 7.5 <0.02 0.05 <br />05/01/89 006 7.0 922 558 8.7 <0.02 <0.01 <br />06/05/89 025 7.6 880 554 10.5 <0.02 <0.01 <br />09/06/89 029 6.5 9s7 s46 8.8 3.60 0.09 <br />casing was apparently damaged by <br />subsidence as described earlier in <br />this section. <br />• The shallow subsidence monitoring <br />wells, SW-1 through SW-6, were gen- <br />erally the same as in previous years. <br />• Barren Member well 38-H-3 provided <br />• no useful well data in 1989. Moisture <br />problems with the casing and later <br />communication with the mine work- <br />ings, probably caused by subsidence, <br />precluded the determination of water <br />levels. <br />• Barren Member well B-32 exhibited <br />virtually no response to seasonal in- <br />Ilucnces which indicates no apparent <br />connection to surface recharges. <br />• "F'-seam wells SOM-2, and SOM-16 <br />show no seasonal or annual Ouctua- <br />tion and have little or no surface <br />water connection. <br />• Barren Member wells SOM-13 and <br />SOM-80 have shown seasonal varia- <br />tions in previous years. During 1987, <br />SOM-80 showed very little or no <br />response to seasonal Ouctuation while <br />SOM-13 was similar to previous years. <br />In 1988 and 1989, neither well showed <br />response to seasonal fluctuation. <br />C~ <br />Lower Refuse Pile <br />During 1989, mine development waste from the <br />underground mining operations was placed in the <br />lower refuse pile. The lower refuse pile was per- <br />mitted for permanent disposal of some 1.7 million <br />cubic yards of mine development waste, coal <br />processing waste, and sediment pond cleanout <br />material. In 1989 approximately 46,922 tons <br />(42,000 cu. yd.) were placed in the lower refuse <br />pile in the phase III and IV areas. <br />Table 7 shows the 1989 sampling results from <br />monitoring well GP-1 as well as baseline data from <br />the well. The sample results indicate the lower <br />refuse pile is not impacting the groundwater zone <br />near Sylvester Creek. Due to the low permeability <br />of the colluvial soil and the lack of a groundwater <br />table near the surface in the colluvium (except <br />along the margin of Sylvester Creek), no significant <br />future impacts to the groundwater regime arc <br />anticipated. <br />Conductivity and TDS from samples of monitoring <br />well GP-1 were closely monitored because conduc- <br />tivity was slightly higher than the baseline samples <br />in some instances during 1986. However, this does <br />11 <br />