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r The value (330 mg/I) noted by the Division refers to a specific part of the mass balance analysis performed during the initial PHC study. That analysis is concerned with the long-term TDS concentrations in Trout Creek as stated on page 2.5-103. The analysis predicts an average TDS value of 196 mg/I with the 330 mg/I potentially occurring if the ~ mine had a normal preripirs ~ ear and the vvatershedabove the mine had only half of , the no~nal_pr~ci$ilation. As stated on page 2.5-105, approximately 300-400 years would be required to reduce the leachate TDS to these conditions. On page 31 of the 1999.9 HR, Pd AI indicates that the elevated levels of TDS in Well TR- /.~ Wray be from an old abandoned underground mitre up the Little Trout G-eek drainage or possibly fi-onr the inundation of the area in late spring of 199.1 mzd the laying aj telephone cable upstream of [he areas during the s:unmer of 199.1. To aid in identifj ing the source oft{re elevated TDS values. the Division is requesting additional infa~mat{on regarding the on-site allrn•ial monitoring wells. Please provide survey information (including ground sarfcrce elevation crud top of well casing/measan•ing point elevation) and depth to water measurements fot• {99.i through /999 for l4'ells TR-{.~, and 6PR-1. Also, the Db1G cannot locate the we(1 log for l{~ell TR-3. Please provide this mazitor well log, if available. The completion log of well TR-!. d uzdicates that this well was only dz•i(led [0 6.0 beloro grouzrd szuface and water Ieve! eras uvrially 3.0 jeer below ground surface. GD'ell TR-l..i is located below [he reclaimed b['est Ridge Area and does not appear to be enlriely upgradient of the disturbance area. Further review ojthese data may determine the source of the elevated levels of TDS at well TR-L~. Please provide crny information that P&A! mcry have concerning the location and operation of the referenced old abandoned zmderground mine up the Little Trout Creek drainage. Survey information for Wells TR-1.5 and WR-1 are as follows: TR-1.5: Ground Elevation = 71T3 ft. (amsl) Casing Height = 235 ft. WR-1: Ground Elevation = 7168.0 ft. (amsl) Casing Height = 2.38 ft. Water measurement information for 1995 through 1999 is attached. Well log for TR-3 is attached. Well TR-1.5 may not appear to be upgradient of all mining disturbance when viewed in plan view. However, when the strike and dip of the various formations in the West Ridge area are taken into consideration as shown on Exhibit 2.1-1, the upgradient position of Well Tr-1.5 becomes readily apparent. The abandoned underground mine referred to in the AHR, in fact, is a reference to 3 separate underground mines which may be influencing Well TR-1.5. The Big Mack Mine closed in 1944, the Blue Spruce Mine closed in 1941, and the Moffat Coal Co. Mine closed in 1941. These mines are shown on Exhibit 3.1-1. As noted in the Section 3.3.1, these mines extracted coal from the Pinnacle Coal seam.