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March 2000 HayAex Gukb Loadout - 2005 Anuua! the primary use, HGTI has compfled a list of applicable agriculture water quality criteria. Table 5, Comparison of 2004 Surface Water Qualify to Agriculture Standards, summarizes the applicable standazds along with a compazison of those standazds to 2005 surface water quality data. The manganese standard of 0.200 mg/1 was exceeded at both surface water sites for both sampling events. However, this has been typical of previous yeazs sampling results. While sulfate and total dissolved solids (TDS) do not have agriculture standards promulgated in Colorado, the Wyoming Department of Environmental Quality has established livestock drinking water standazds for these constituents that can be used as benchmazk values to assess the appropriateness of water for agriculture use. Sulfate and TDS concentrations commonly exceed the WDEQ values. • sulfate (guideline of 500 mg/1) HGSD1 - 5/20/05: 1,650 mg/1; 10/20/05: 1,180 mg/1 HGSD3 - 5/20/05: 1,420 mg/1; 10/20/05: 1,570 mg/1 • total dissolved solids (guideline of 2,500 mg/1): HGSDl - 5/20/05: 3,010 mg/1 HGSD3 - 5/20/05: 2,640; 10/20/05: 2,840 mg/1 While these values were greater than the benchmazk values used by WDEQ, historic values for these constituents at both locations typically exceeded the respective benchmazk values. Time-trend plots of manganese, sulfate and TDS concentrations aze presented in Appendix C. 3.3 GROUNDWATER DATA Groundwater data for 2005, as well as historic data collected since 1993 aze presented in Appendix D, Groundwater Quality Data. In 1993, HGTI installed HGDAL3 as a "new" downgradient alluvial monitor well in response to CDMG concems that the two existing alluvial wells, HGDALl and HGDAL2, might have been paztially completed in the Lewis Shale, which could comprise the data. Groundwater quality data was collected from monitoring wells HGDALI and HGDAL2 between 1987 and 1995. Groundwater monitoring of these two monitor wells ceased in 1995; these two wells aze inactive. As pazt of the TR-06 adequacy review, CDMG raised concems about the lack of an upgradient alluvial monitor well at the Loadout. Consequently, HGTI installed a "new" upgradient well, HGDAL4 in November 2005. A sample was collected in December 2005. The locations of the groundwater monitoring wells aze shown on Figure 1, Monitoring Site Locationr. The spring runoff monitoring event occurred on May 20, 2005. The fall monitoring event was conducted on October 20, 2005. A third groundwater event, wMch included sampling both HGDAL3 and HGDAL4, occurred on December 2, 2005. In general, the alluvial groundwater concentrations from HGDAL3 in the 2005 samples were similaz to previously observed values. All constituent concentrations were within historic ranges. While the boron concentrations exceeded the boron agricultural use standazd (0.75 mg/1) in all three samples (5/20/05: 0.80 mg/1; 10/20/05: 0.82 mg/l; and, 12/2/05: 0.90 mg/1), the tktree values were within the previously observed range. The manganese concentrations also exceeded the manganese numeric standard (0.2 mg/1) in all three samples, however, the values were within the historic range. Due to an analytical suite oversight, the selenium analyses were for total recoverable instead of dissolved. However, the total recoverable analysis should result in a higher concentration than the dissolved Hydro-Environmental Solutions, Inc. P.O. Box 772996 57 10'" Street, Suite B Steamboat Sprrugt, CO 80477 (970) 877-6725