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<br />TABLE TWO -- BOULDER COUNTY <br />MINE NAME COMMENTS ON FEATURES <br />Marshall S, F: Area 100' or so south of liquor, store has underground mine fire. Like #1 above, area has <br />Nos. 1,3,4 many subsidence pits 10' to 30' long, 6' to 12' wide, 3' to 6' deep; pits caused by <br />(cont.) collapse of supporting coal pillars. Open flames not observed but smoke occasionally seen <br /> coming from earth. Smell of burning coal can be strong depending on wind and temperature. <br /> Extent of burned-out area and of currently burning area is not known; subsidence pits <br /> (perhaps at least partially induced by burning) cover 5 to 10 acres. <br /> Reclamation scheduled Spring (1984); backfilling of Marshall No. 3 <br />Marshall *: Horizontal opening. Portal of ad it is 8' wide by 3' high and is well supported by a <br />No. 5 massive sandstone ledge. Opening goes underground an unknown distance. No access deterrent <br /> but entry is fairly well hidden from view. <br /> D: Water flowing from portal of Marshall #5 mine at estimated rate of 2 to 3 gpm on 12/31/80. <br /> Yellow brown limonite deposits on rocks in stream channel and in soil of overbank areas <br /> indicate water is highly charged with iron. It is not likely that flow and recharge is due <br /> to leakage from nearly Community Ditch because ditch was dry for at least three months <br /> before observation was made. <br /> Reclamation Scheduled for Spring 1984: (Marshall #5) constructing a porous portal barrier <br /> out of large riprap which will allow the mine to continue draining. Acid mine drainage <br /> water will be treated through construction of a series of low- to no-maintenance ponds <br /> which contain material capable of neutralizing the water. <br />Marshall D: Water seeping from beneath material of collapsed ad it of Marshall #6 ad it on 12/31/80. <br />No. 6 Seepage collects in small pool from which a rivulet flows at an estimated rate of 1 gpm. <br /> Source of water does not appear to be the nearby Community Ditch because ditch was dry for <br /> at least three months prior to field observation. <br />Key to unique features symbols: Z Multiple mining zones <br /> * Mine opening information <br />Reclamation and/or plans -- Table Two S Subsidence features <br /> lists hazard abatement work F Mine fires <br />+ Discrepancy between two sources D Mine drainage -34- <br />