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Reclamation Feasibility Report - Virginia Canyon <br />m Heavy Metals in Sediments <br />The sediment analysis shows that mine waste eroded into the stream channel is a major source of <br />metals. In general, the sediments contain 2 to 3 orders of magnitude more metals than the soils. <br />Heavy metals concentrations of the sediment leachate are often comparable to the concentrations <br />from the mine waste piles. The average zinc concentration from the sediments is approximately <br />half the average of the mine waste piles. The average manganese concentration from the <br />sediments is approximately 90% of the average from the mine waste piles. In comparison, the iron <br />and copper concentrations from the sediments are only 2% and 40% of the average concentrations <br />from the waste rock piles, respectively. <br />The sediment sampling does not provide an indication of the sources of mining waste to Virginia <br />Canyon. The metals concentrations in sediments above and below and at the bottom of the <br />tributaries are approximately equal. Even sediments from Buttermilk Gulch and Robinson Gulch <br />had high metals %oiceitratioiis. in general., general., the concentrations of heavy metals in the stream <br />sediments are higher in the upper portions of the tributaries below the waste piles exhibiting the <br />severe erosion. <br />WATERSHED CHEMISTRY <br />Virginia Canyon is an intermittent stream throughout most of the watershed. The upper reaches of <br />the stream are ephemeral, while lower Virginia Canyon is perennial. As such, flow in Virginia <br />Canyon generally occurs during spring snowmelt and summer thunderstorms. There is some flow <br />following snowstorms during the winter, because much of Virginia Canyon is south facing. During <br />spring snowmelt, a portion of the flow infiltrates into the alluvium, then periodically resurfaces. <br />Because of the losing and gaining reaches of the stream, mass loading analysis is difficult. <br />Virginia Canyon contributes many heavy metals to Clear Creek. The main metals of concern <br />include cadmium, copper, iron, manganese and zinc. <br />Spring Snowmelt <br />Virginia Canyon was sampled during snowmelt on May 9, 2000. The winter of 1999-2000 was <br />drier than normal, so flow in the stream was lower than normal. During a normal snowmelt runoff <br />event, all the 24 stream stations planned to be sampled would be flowing, based upon 15 years of <br />observation. However, only 14 of the 24 stations were flowing. Measured flows at the sites were <br />erratic, with some upstream sites having higher flow than the downstream sites. To better <br />determine where metals loading was occurring, the flows were "Normalized". Where measured <br />inflows occurred, the flow was added to the upstream site resulting in a "Normalized" flow <br />measurement. The Normalized flows and loadings are presented in Appendix 1. <br />During the spring snowmelt event, the majority of the heavy metals loading occurred in the area of <br />the Two Brother/Bald Eagle mine. Minor loading of heavy metals was measured from Robinson <br />Gulch and Seaton Gulch. Buttermilk Gulch had no flow at the time of sampling. The second <br />largest source of heavy metals was Boomerang Gulch. There was no stream flow above the <br />Crown Point and Virginia Mine area. <br />The highest concentration of aluminum was measured at sampling site VC-2 below the Crown <br />Point and Virginia Mine. The highest concentration of iron, cadmium, copper, arsenic and zinc was <br />measured at site VC-6 above Robinson Gulch. The highest concentration of manganese and <br />silver was measured at site VC-18 at the mouth of Seaton Gulch. The highest concentration of <br />lead was measured at site VC-11 at the mouth of Boomerang Gulch. <br />14 <br />rx <br />M