1996-02-08_HYDROLOGY - M1977378 (2)

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999 � 2- 9 -96 mediation Work Plan: Columbus Mine Portals Remediatin,g Party: Sunnyside Gold Corporation Jj ; rn(y P.O. Box 177 Silverton, CO 81433 contact William B. Goodhard Resident Manager Identification of Lands The Columbus mine portals and waste dumps lie immediately north of Animas Forks, San Juan County Colorado. See attached location and site map. Identification of the Waters of the United States Potentially Affected This property sits between the confluence of the Animas River and the West Fork of the Animas River. See attached location map. Physical Description of Conditions The area consists of; two mine portals and two waste dumps. The lower portal discharges onto the mine dump and percolates through it. The dumps are exposed to rainwater and snowmelt as well. The regional geology is volcanic rocks with narrow veins containing base metals; Fe, Pb, Cu and Zn. Sampling of the waters in this area indicate that even though the portal discharge is small, there is a substantial increase in dissolved metal loading to the Animas River. Site Loading Estimate Based on limited information the site loading estimate for this project site is based on: Adits- Using available data,zinc loading was calculated based on the average flow and average zinc values. Mine Waste Dumps and Tailings Piles- Site composite soil samples were tested using a water bath extraction. This test consists of exposing a 1:1 ratio by weight of material to deionized water. The mixture is briefly mixed then allowed to set for 30 minutes. The sample was then filtered ( 0.45-Micron)and analyzed for metals, Annualized loading was calculated using rainfall data (proportionally adjusted for site elevation between the Silverton and Red Mountain weather stations), exposed area of waste dump or tailings site and loading based on 1:1 water bath test results. For comparison to adit flow loadings projects, the annualized loading was converted to an average daily loading.