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Areiic~oN Frn rf~r¢T ~ saRF~ce as turo>~aoorm MINING rcriviTZr~ - <br />c RnQcr>It~arrs >~ ormazzcPr nNa Rncr.~rmTlav rrar~. <br />riitigation of Surface Coal Mining Operation Impacts. (Cont'd.) <br />(b) (iii) (Cont'd.) <br />E7~closed coal handling facilities acid the general cleanliness of the <br />areas further prevent detrimental contact with groundwater sources. <br /> <br />~oundwater is monitored at the Orchard Valley Mine area, the Orchard <br />Valley West Mine area, and at the coal stockpile/truck dump/train <br />loadout area. Boreholes B-1 through B-7 were installed in the fall of <br />1981, aryl borehole B-8 was installed in 1982 to ascertain the stability <br />~nditions of the fills and the proposed waste disposal sites at the <br />orchard Valley Mine. Refer to the Phase II and Phase III Geotechnical <br />Studies in Volumes 6 an3 6A for further discussion regarding the <br />installation aryl initial data obtained from the boreholes. 'Though <br />these boreholes were not drilled as part of the groundwater monitoring <br />program, some hydrology data is obtained from the lroreholes. <br />Boreholes in the vicinity of the Orchard Valley Mine are currently <br />monitored when accessible in accordance with the requirements of Volume <br />4, Table 4B. Boreholes B-1 aril $-2 are located at the Fast mine fan <br />level. YYtese holes have been dry since they were installed. Borehole <br />B-3 is located at the east end of the ~zvshing and screening level. <br />Ibis borehole typically exhibited approximately 6 feet of water at the <br />bottom of the hole thought to originate from colluvial seepage. The <br />rasing for borehole B-3 failed at depth in the spring of 1988 and no <br />water has been detected since. B-3 was originally drilled to a total <br />depth of 89 feet and now measures approximately, 73 feet. Boreholes B-4 <br />and B-5 are located belay the crushing and screening fill and were <br />installed to detect possible seepage in the original grade material. <br />B-4 typically has 15 feet of water present at the bottom of the hole <br />and B-5 is dry. Borehole B-6 is located upslope of the reclaimed waste <br />disposal pile and is monitored for interface seepage in connection with <br />slope and waste pile stability. Borehole B-6 is dry. Borehole B-7, <br />also referred to as Node 22, is located below sedimentation pond #4 and <br />is periodically monitored for water quality to ascertain potential <br />grourxiwater contamination attributable to the Fast Mine facilities <br />area. Parameters measured include alkalinity as CaCO3, bicarbonate as <br />CaO~, carbonate as Ca003, dissolved calcium, chloride, conductivity @ <br />25° C, pH, Hardness as CaCOs, dissolved magnesium, dissolved sodium, <br />sulfate, TDS ratio (gray./talc.), and total dissolved solids. Borehole <br />B-8 is located below the West Ridge Waste Pile sedimentation pond and <br />monitors subsurface groundwater flow from the sedimentation pond. <br />Borehole B-8 is dry. <br />One piezometer (OVtai) is installed in the fill at the Orchard Valley <br />West Mine. This well is currently monitored when accessible for water <br />levels to evaluate fill stability in accordance with the requirements <br />of Volume 4, Table 4B. <br />Monitoring wells MW-1, MW-2, and MW-3 are located at the coal <br />. stoc)q~ile/truck dump/train loadout area and were drilled during <br />TR 93-24 Revised 12/10/93 <br />115 <br />