1996-02-08_HYDROLOGY - M1977378 (4)

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� II I I II I II I II IIII III 999 L In -- 1 777- 37S '- emediation Work Plan: Boulder Creek Tailings Project ✓2 ��9( Remediating Party: Sunnyside Gold Corporation m P.O. Box 177 Silverton, CO 81433 contact William B. Goodhard Resident Manager Identification of Lands Lands he between Colorado 1 l0E and the Animas River to the north of Boulder Creek, San Juan County, Colorado. See attached location map and site map. Latitude 37 degrees 50 minutes Longitude 107 degrees 38 minutes Identification of the Waters of the United States Potentially Affected Boulder Creek and the Animas River at the confluence of Boulder Creek. See attached map. Physical Description of Conditions An old retention pond exists along the west bank of the Animas River. The pond is dry and consists of tailings. There is minimal vegetation on the pond and it is exposed to rainfall and snowmelt. There is an estimated measured total of 1300 cubic yards of tailings. 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.