2012-04-27_REPORT - C2009087 (2)

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drinking water standards developed for ground water by the CDPHE. No human health standards were exceeded. The CDPHE secondary standard for sulfate, 250 mg /l, was exceeded with a value of 560 mg /1. Well STC5 has historically exhibited sulfate concentrations higher than the secondary drinking water standard for this parameter. However, bottled water is consumed at the PSCM. Ground Water Points of Compliance A GWPOC have been established for the PSCM (PSCM PAP page 2.04 -103, Vol.1). Attachment 7 -3 of the Seneca II PAP provides the details of how the standards were established. 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. Ground Water Quality Summary. TDS values at four of the seventeen wells sampled the year displayed increasing TDS trends. TDS trends at six wells were either stable or decreasing. TDS trends could not be determined at the remaining seven wells due to the limited number of samples collected so far. CDPHE agricultural ground water standards for pH, fluoride, iron and selenium were exceeded at certain monitoring wells. No GWPOC standards were exceeded this year. In the area surrounding the PSCM, 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 mine employees or local residents are not from aquifers impacted by mining. Surface Water Table 8 lists pertinent information on all NPDES, stream, and spring monitoring sites at the PSCM. The PSCM surface water plan is summarized on Table 2.04.7 -T11 (page 2.04 -107, Vol. 1 of the PSCM PAP). All NPDES Discharge Points are monitored monthly for field parameters (flow, 8