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<br /> <br />Requirement <br /> <br />Regulation Require- <br />ment <br />complied <br />with ? <br />(yes / no) <br /> <br />Comment <br /> QR coal sequence - As shown in the spreadsheet attached to <br /> DRMS's review memo for the 2004 AHR, spoil leachate <br /> plumes are capable of developing on the Trapper Mine only <br /> in aquifers in the QR coal sequence in D, F, G and Z pits. <br /> The QR sequence is monitored downgradient from the F pit <br /> in well GP-5. The QR is not monitored downgradient from <br /> G and Z pits. (D pit has undergone final bond release.) <br /> Hydraulic conductivity of the QR of 0.03 ft/day indicates it <br /> would take 20 years for a leachate plume to extend 548 ft. <br /> downgradient from the G, F, and Z pits (assuming 5% <br /> effective porosity and a hydraulic gradient of 0.125ft/ft). A <br /> ground water point of compliance is not warranted for the <br /> QR due to the limited areal extent of a plume (it would not <br /> extend offsite) and the dilution of the plume that would <br /> result from dispersion. A dilute plume that does not extend <br /> outside the permit boundary indicates there is no potential for <br /> negatively impacting the QR sequence. <br /> 3rd White sandstone in Flume Gulch - The 3rd White <br /> Sandstone is the only stratigraphic unit having significant <br /> permeable that is in the ground water flow path of any coal <br /> spoil leachate; therefore, the 3rd White is the only <br /> stratigraphic unit whose ground water quality may be <br />R. Basic Standards CWQCC negatively impacted by mining at Trapper. Well GP-9 <br />for Ground regulations yes monitors the 3rd White immediately downgradient from <br />' <br />Water 41.4 and 41.5 Trapper <br />s pits at a location where a leachate plume can be <br /> expected to form, as explained in the PHC (Section 3.8.3 of <br /> the permit). Well GP-9 is Trapper's ground water point of <br /> compliance for the 3rd White sandstone as explained on <br /> permit page 2-242. Data from well GP-9 in 2007 indicates <br /> Trapper is in compliance with the Basic Standards for <br /> Ground Water for a domestic use classification for the Yd <br /> White in a Specified Area that extends outward from <br /> Trapper's northern permit boundary on the east half of the <br /> mine to the axis of the Big Bottom Syncline, a distance <br /> ranging between 1 /2 and 3/4 mile from the boundary. <br /> Trapper is not expected to negatively impact water quality in <br /> the 3rd White outside Flume Gulch, as documented in the <br /> spreadsheet attached to DRMS's review memo for the 2004 <br /> AHR. <br /> 3rd White sandstone and HI aquifer outside Flume <br /> Gulch. Artesian conditions are well-documented in the 3rd <br /> White sandstone throughout the Trapper mine site. <br /> Potentiometric surfaces significantly above the tops of the <br /> formations in the 3rd White sandstone and HI coal sequence <br /> will prevent invasion of these formations with spoil leachate <br /> outside Flume Gulch (see spreadsheet attached to DRMS's <br /> review memo for the 2004 AHR). A high potentiometric <br /> surface appears to have prevented subsurface leachate <br />Page 3