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Analyses at the Madrid station indicate a low-yield watershed with the mean annual runoff <br />volume measured at 28,980 acre feet. <br />In terms of local water quality of the Purgatoire River and associated alluvium, mine discharge <br />and leachate from refuse contribute to higher ionization of the water and increased amounts of <br />trace elements. The main parameters of interest are sodium and other dissolved salts which <br />may affect downstream use of the water for irrigation. In the worst case, during low flow <br />conditions, effects of ionization caused by mining are insignificant when compared to the <br />natural deterioration of water quality as the river flows to the east. Figure 3.2-1 presents stiff <br />diagrams of water quality at stations PRS-1 and PRS-4 on the Purgatoire River for November <br />1997 through 2001. As shown, water quality above the mine is similar to water quality below <br />the mine. <br />Discharge from the site passes through treatment facilities or sediment impoundments. Copies <br />of the NPDES Discharge Monitoring Reports submitted to the Colorado Department of Public <br />Health and Environment are sent to CDMG as they are filed quarterly. No discharges were <br />noted at any of the ponds in 2006. <br />3.2.3 Alluvial Groundwater <br />Wells in the Purgatoire River alluvium, (stations PAW-1 through PAW-9) were monitored <br />during the year. Stiff diagrams of wells PAW-1, PAW-2, PAW-8 and PAW-9 in the alluvium at <br />New Elk are shown in Figure 3.2-2. This shows slight decreases over the past six years in <br />salinity in alluvial ground water quality in response to decreased mining activity. <br />Historic Allen Mine waste materials appear to be the major contributors to saline alluvial <br />ground water quality in the vicinity of the New Elk Mine (PAW-3 and PAW-4) (Figure 3.2-3). <br />Saline conditions were anticipated in the PHC, and conductivities and TDS concentrations <br />have been far lower than expected. During March and April of 1985, 500 feet of the Middle <br />Fork of the Purgatoire River was diverted to the north to create additional room for the coal <br />stockpile at the New Elk Preparation Plant. The original channel was backfilled with mine <br />waste, and two alluvial wells, PAW-3 and PAW-4, were established to monitor water elevation <br />and chemical parameters. Water quality does not appear to deteriorate significantly due to the <br />presence of refuse in the backfill between PAW-3 and PAW-4 and measures of salinity, <br />sodium, and sulfate are far lower than predicted by the PHC. A threefold increase over historic <br />values in iron quantities in PAW -3 and PAW-4 may be due to the steel casing of the wells. No <br />further monitoring is required for PAW-3 and PAW-4. Data on PAW-8 (Table B-5) and the <br />Stiff Diagram indicate that seepage from the current refuse disposal area contains similar <br />concentrations of sodium, potassium and calcium to the pre-law mine waste (PAW-4). <br />Leaching may be a cause for lower values from the old materials. Data from PAW-9 <br />downstream of the New Elk facilities indicated dilution having an effect on concentrations. <br />• <br />16