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. The groundwater data presented in Table 7-l, 7-2 and 7-3 clearly indicates that the
<br />alluvial aquifer in the immediate vicinity of the Loadout has not historically had and
<br />does not presently have any irrigation or livestock water use potential.
<br />CDMG indicated in their adequacy comments to TA-O6 that HGTI's alluvial groundwater
<br />monitoring program was inadequate and that these was insufficient characterization
<br />performed to date to validate HGTI's opinion that the Dry Creek alluvial groundwater was
<br />of "Limited Uee and Quality." HGTI completed an alluvial groundwater characterization
<br />study during March 2005 that validates the alluvial groundwater, both upgradient and
<br />doangradient is of "Limited Use and Quality." The groundwater characterization study is
<br />presented in Appendix 7-2, Dry Creek Alluvial Groundwater Evaluation.
<br />RGTI reviewed existing off-site data collected in 1998 by Peabody Holding Company, Inc.
<br />(PHCI), HGTL's pazent company. Data reviewed includes well depth, completion information,
<br />lithologic information, groundwater chemistry and groundwater flow and gradient. The
<br />demonstration presented in Appendix 7-2 shows that the background, or upgradient, alluvial
<br />chemistry is comparable in water type and dissolved solid loads to the downgradient
<br />alluvial chemistry. Potentiometxic data (see Appendix 7-2) indicates the groundwater
<br />movement in the area of the Loadout is northward towazda the Yampa River and generally
<br />follows the area streams and surface water features. Alluvial groundwater, both
<br />upgradient and downgradient of the Loadout, contains total dissolved solids concentrations
<br />greater than 10,001 mg/1, and consequently, is of "Limited Uee and Quality," Table 7-4A,
<br />summarizes select construction information, 1998 water level elevations and 1998 sodium,
<br />• sulfate and total dissolved solid concentrations for the alluvial monitor walla used in
<br />the water quality characterization study.
<br />
<br />TABLE 7dA
<br />Select Well Construction, Surface Water Elevation and Dissolved Constituent Concentration Data For Dry Creek
<br />Alluvial Monitor WellsZ
<br />Well IDS Land Surface Total Well Depth Static Water Sodium Sulfate Total Dissolved Solids
<br /> Elevation (ff BGS) Level (mg11)
<br /> m0 m8
<br />Upgradient Well
<br />DCAL-3A 6,417.8 19 6,411.5 800 2,670 4,880
<br />SGAL-3 6,402.4 18 6,397.2 4,480 20,500 33,000
<br />HGDALI< 6,394.6 6,391.7 9,992 27,001 42,934
<br />DCAL-5 6,387.7 16 6,382.6 1,800 6,880 10,800
<br />DCAL-6 6,388.5 17 6,383.8 6,320 24,200 38,100
<br />Downgradient Well
<br />HGDAL2 6,384.0 26 6,380.1 4,371 14,088 23,147
<br />HGDAL3 6,380.4 14.4 6,375.7 2,700 10,300 17,700
<br />DCAL-4B 6,372.3 9 6,368.7 10,500 35,000 61,800
<br />Notes: 1) Surface water elevation data presented in an average of the 1998 measurements, with the exception of wells
<br />HGDALI and HGDAL2; elevation values for these wells is an average for the period 1993 to 1995.
<br />2) Concentration data is for May or June 1998, with the exception of wells HGDALI and HGDAL2, which is an
<br />average for the period 199310 1995.
<br />3) Wells DCAL-3A, SGAL-3, DCAL•5, DCAL-6 and DCAL~B are off-site PHCI alluvial monitor wells. DCAL-3A is
<br />located adjacent to Dry Creek just downstream of RCR 53; SGAL-3 is located adjacent to Stokes Gulch just
<br />upstream of RCR 53; DCAL-5 is located adjacent Dry Creek just upstream of the TAHR; DCAL-6 is located
<br />east of the railroatl loop, north of the TAHR, adjacent to RCR 37; DCAL•46 is located adjacent to Dry Creek,
<br />downstream of the rail spur crossing on RCR 37.
<br />Wells HGDALI, HGDAL2 and HGDAL3 are on•site HGTI wells.
<br />4) Select well construction information for HGDALI is not known.
<br />TR-06 14 Revised OS/OS
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