2010-03-22_REPORT - C1980005 (2)

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Finally, a sample could not be collected at the Seneca II shop well (STCS) for this year (see above), so a comparison of its water quality to drinking water standards could not be made. Ground Water Points of Compliance GWPOC's have been established for the Seneca II Mine. Attachment 7-3 of the Seneca II PAP provides the details. The ground water standards for Grassy Creek Alluvial Well SGAL70 are provided in this AHR on Table 7. No exceedances of those standards were observed on samples collected from this well this year. The ground water standards for Fish Creek Alluvial Well SFAL72 are provided in this AHR on Table 8. The only standard that was exceeded this year was iron (0.35 mg/1) with values of 3.52 and 3.85 mg/1. However, the maximum iron value observed this year upstream at Alluvial Wells SBAL68 and SCAL69 was 0.04 mg/1. Therefore, the high iron values observed at Well SFAL72 are not likely to be the result of discharges from the Seneca II Mine. The high levels of iron displayed at this well are likely the result of naturally occurring organic matter and plant debris present in the alluvium (Hem, 1989, pg. 77) at this particular location. Ground Water Quality Summary. TDS values at five out of the fifteen wells sampled the year displayed increasing TDS trends. TDS trends at all other wells were either stable or decreasing. CDPHE agricultural ground water standards for pH, fluoride, iron and selenium were exceeded at certain monitoring wells. With the exception of iron (see above), no GWPOC standards were exceeded this year. In the area surrounding Seneca II, ground water is not being pumped for irrigation or livestock watering purposes, nor has the CDPHE classified any aquifer in this region for any use. The above discussion is provided only to serve as a comparative basis to judge ground water quality. Domestic wells that provide drinking water for local residents are not from aquifers impacted by mining. Y 8 fr`F?' f