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development oP the operational monitoring program during Technical Revision No. L. ~ The following summarizes the conclusions reached. The upgradient surface water and groundwater variability (potential contaminant sources from irrigation return flows, adjacent dryland farming drainage and seeps, seeps or subsurface flow from the Lewis shale, and adjacent industrial sites [i.e., Routt County Road and Bridge Department Shop) cannot be totally eliminated or quantified regardless of the location of upgradient monitors. Gain/loss studies performed on Dry Creek during 1993 (see Tabs 7 and 15) do not indicate that groundwater inflow from either side of the Dry Creek drainage into Dry Creek is occurring during the principal growing season. Because of the positioning of alluvial wells HGDALI and HGDAL2, their completion and the timing of their construction, the baseline data from these wells may not be representative of Dry Creek alluvial aquifer chemistry. Chemistry information obtained from downgradient alluvial well HGDAL3 indicates the alluvial chemistry in this well is very similar "- to the chemistry depicted by wells HGDALI and HGDAL2. A coal leachate study and impact analysis performed in winter 1993/1999 (see Tab 15, Table 15-1) demonstrates the coal leachate will not measurably impact the Dry Creek and alluvial water quality and is not responsible for the existing water quality observed in the data ~, from monitor well HGDAL3. The alluvial aquifer has been and continues to be unsuitable for use as irrigation or stock water. Dry Creek has been and cont lnues to be unsuitable for irrigation use and suitable to marginally suitable for stock use. The downstream and downgradient monitor locations immediately below the facilities area replace monitoring sites HGSD2 and HGDAL2 and remove the potential for any additional downgradient natural chemical variability to be introduced in the water quality analyses. At the request of CDMG, HGTI revisited the potential for shallow alluvial groundwater contamination to the alluvial groundwater system downgradient of the Loadout facility in 2005. The evaluation is presented in Appendix 7-2, Shallow Alluvial Groundwater Evaluation. In summary, the evaluation indicates that the regional alluvial groundwater is generally of "limited use and quality^, and that there appears to be no significant impact from the Loadout to alluvial groundwater chemistry downgradient of the facilities area. Samples from collected both upgradient and downgradient had total dissolved solid concentrations that exceed 10,000 milligrams per liter, which is the groundwater standard for agricultural water. To verify the conclusions presented in Appendix 7-2, HGTI installed a new TR-06 6 Revised O6/OS