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<br /> <br />Requirement <br />Require-ment <br />citation Require- <br />ment <br />complied <br />with ? <br />es/no <br /> <br />Comment <br /> QR coal sequence - As shown in the attached spreadsheet, <br /> spoil leachate plumes are capable of developing on the <br /> Trapper Mine only in aquifers in the QR coal sequence in D, <br /> F, G and Z pits. The QR sequence is monitored <br /> downgradient from the F pit in well GP-5. The QR is not <br /> monitored downgradient from G and Z pits. (D pit has <br /> undergone final bond release.) Hydraulic conductivity of the <br /> QR of 0.03 ft/day indicates it would take 20 years for a <br /> leachate plume to extend 548 ft. downgradient from the G, F, <br /> and Z pits (assuming 5% effective porosity and a hydraulic <br /> gradient of 0.125ft/ft). Aground water point of compliance <br /> is not warranted for the QR due to the limited areal extent of <br /> a plume (it would not extend offsite) and the dilution of the <br /> plume that would result from dispersion. A dilute plume that <br /> does not extend outside the permit boundary indicates there <br /> is no potential for negatively impacting the QR sequence. <br /> 3rd White sandstone in Flume Gulch -The 3`d 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 3`d White is the only <br /> stratigraphic unit whose ground water quality may be <br /> negatively impacted by mining at Trapper. Well GP-9 <br /> monitors the 3`d White immediately downgradient from <br />R. Basic Standards CWQCC Trapper's pits at a location where leachate plume can be <br />for Ground <br />Water regulations <br />41.4 and 41.5 yes 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 3`d White sandstone as explained on <br /> permit page 2-242. Data from well GP-9 in 2004 indicates <br /> Trapper is in compliance the Basic Standards for Ground <br /> Water for a domestic use classification for the 3`d White in a <br /> Specified Area that extends outward from Trapper's northern <br /> permit boundary on the east half of the mine to the axis of <br /> the Big Bottom Syncline, a distance ranging between 1 /2 and <br /> 3/4 mile from the boundary. Trapper is not expected to <br /> negatively impact water quality in the 3`d White outside <br /> Flume Gulch, as documented in the attached spreadsheet. <br /> 3rd White sandstone and HI aquifer outside Flume <br /> Gulch. Artesian conditions are well-documented in the 3`d <br /> White sandstone throughout the Trapper mine site. High <br /> head in the 3`d White sandstone and HI coal sequence will <br /> prevent invasion of these formations with spoil leachate <br /> outside Flume Gulch (see attached spreadsheet). High head <br /> appears to have prevented subsurface leachate invasion at <br /> well GF-5 in No Name Gulch. Seepage of coal spoil <br /> leachate from near the land surface down into the 3`d White <br /> appears to have occurred at well P-8 in East Pyeatt Gulch, <br /> but this seepage is expected to be of very limited areal extent <br /> com ared to that ex ected in Flume Gulch where the pit area <br />Page 3 <br />