Laserfiche WebLink
February 2014 Page 3 -3 <br />Mine. These changes are probably a result of natural lowering of water purity due to geologic <br />parameters, geography (Stonewall is located on the Middle Fork of the Purgatoire River as is the <br />New Elk Mine, the Golden Eagle Mine is located below the confluence of the Middle Fork, and <br />Madrid is located yet below the confluence of the South Fork above Trinidad Reservoir), <br />contributions from the New Elk and other land uses (point and area sources water quality <br />change) between the two stations. The Stonewall site (07124050) acquires water from a <br />52.1- square mile area and the Madrid site (07124200) measures water from a 505- square mile <br />watershed. <br />There is a natural deterioration of water quality as the stream flows out of the igneous <br />terrains, through sodic sediments, and into marine sediments. There is a relationship between <br />Purgatoire River water quality and flow quantities. From historic (USGS) information the <br />minimum flow of the Purgatoire River at Stonewall, above the mine site, is 4 cfs. The <br />conductivity was deduced to be 345 umhos /cm at a flow of 4 cfs. The minimum flow of the <br />Purgatoire River at Madrid, below the mine site, is 10 cfs and the average conductivity is <br />125 umhos /cm. In general, conductivity values are higher at lower levels of flow (suggesting <br />dilution during periods of snow melt or rain). <br />In terms of local water quality of the Purgatoire River and associated alluvium, mine <br />discharge and leachate from refuse contribute to higher ionization of the water and increased <br />amounts of trace elements. The main parameters of interest are sodium and other dissolved salts <br />which 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 natural <br />deterioration of water quality as the river flows to the east. Figures 3 -1 and 3 -2 presents graphs <br />of the total dissolved solids at stations PRS -1 and PRS -4 on the Purgatoire River. The PRS -1 <br />period of record is 1984 through 2012. The PRS -4 period of record is 1992 through 2012. The <br />linear trend line for both stations is downward which means improving quality over time. The <br />total dissolved solids for both the upstream (PRS -1) and the downstream (PRS -4) stations are <br />similar which means very little, if any, degradation of the river as it flows past the mine site. <br />Discharges from the site pass through treatment facilities or sediment impoundments. <br />Copies of the Discharge Monitoring Reports are sent to DRMS as they are filed quarterly and are <br />included herein by reference. <br />3.2.3 Alluvial Groundwater <br />Wells in the Purgatoire River alluvium, (stations PAW -1, PAW -2, PAW -8 and PAW -9) <br />were monitored during the year. Water quality graphs of wells PAW -1, PAW -2, PAW -8 and <br />PAW -9) in the alluvium at New Elk are shown in Figures 3 -3 through 3 -6. The linear trend line <br />for all four stations is upward which means reduction of quality over time. The linear trend line <br />for PAW -1 is between 100 and 150 mg/1 TDS. The linear trend line for PAW -9 is between 430 <br />and 460 mg/1 TDS. This would equate to and increase in TDS of around 350 mg/1 between the <br />upstream and downstream monitoring wells. <br />Historic Allen Mine waste materials appear to be the major contributors to saline alluvial <br />groundwater quality in the vicinity of the New Elk Mine. Saline conditions were anticipated in <br />the Probable Hydrologic Consequences (PHC), and conductivities and TDS concentrations have <br />