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<br /> <br />Roquirement <br />Require-ment <br />citation Require- , <br />ment <br />complied I <br />with 7 <br />es/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 /> i effective porosity and a hydraulic gradient of O.125ft/ft). A <br /> ground water point of compliance is not warranted for the <br /> ~ QR due to the limited area[ 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 /> i outside the permit boundary indicates there is no potential for <br /> negatively impacting the QR sequence. <br /> ~ 3'" White sandstone iu Flume Gulch -The 3`a White <br /> Sandstone is the only sttatigraphic unit having significant <br /> ~ permeable that is in the ground water flow path of any coal <br /> spoil leachate; therefore, the 3`a White is the only <br /> stratigraphic unit whose ground water quality may be <br />R. Basic Standards CWQCC ~ negatively impaacted by mining at Trapper. Well GP-9 <br />for Ground regulations yea , monitors the 3 White immediately downgradient from <br />' <br />Water 41.4 and 4I.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 pointof <br /> compliance for the 3`a White sandstone as explained on <br /> ~ permit page 2-242. Data from well GP-9 in 2006 indicates <br /> Trapper is in compliance with the Basic Standards for <br /> Ground Water for a domestic use classification for the 3'a <br /> White in a Specified Area that extends outward from <br /> Trapper's northern permit boundary on the east half of the <br /> i mine to the axis of the Big Bottom Syncline, a distance <br /> ranging between I/2 and 3/4 mile from the boundary. <br /> ' Trapper is not expected to negatively impact water quality in <br /> the 3`a White outside Flume Gulch, as documented in the <br /> ~ spreadsheet attached to DRMS's review memo for the 2004 <br /> '~ AHR. <br /> 3'a White sandstoue and HI aquifer outside Flume <br /> ~ Gulch. Artesian conditions are well-documented in the 3`a <br /> ' White sandstone throughout the Trapper mine site. High <br /> head in the 3`a White sandstone and HI coal sequence will <br /> 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). High head.appears to <br /> have prevented subsurface leachate invasion at well GF-5 in <br /> ~ No Name Gulch. See a e of coal s oil leachate from near <br />Page 3 <br />