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2.4 Purpose and Scope <br />The purpose of this report is to assess the hydrogeologic and hydrochemical aspects <br />of the proposed underground bulkheads. Specifically this report addresses: <br />the likely rate of leakage in the immediate vicinity of the bulkheads; <br />the anticipated equilibrium water level in the flooded mine workings; <br />the approximate rate at which the mine workings will fill with water; <br />the nature, rate, and timing of movement of water from flooded workings to <br />the surface along natural and man-made pathways; <br />the likely chemistry of water which would be impounded; <br />the expected reactions between impounded water and country rock and <br />mineralized veins; and <br />the effects of the proposed bulkheads on the chemistry of local surface water. <br />This report builds upon an understanding gained during preparation of the earlier <br />report, "Preliminary Characterization of the Hydrology and Water Chemistry of the <br />Sunnyside Mine and Vicinity, San Juan County, Colorado" (Simon Hydro-Search, <br />1992). Additional work conducted in support of this report included: <br />Field examinations of proposed bulkhead sites in the American Tunnel, Terry <br />Tunnel, F-Level Brenneman vein, and B-Level Brenneman vein; <br />Conducting flow tests from boreholes in the American Tunnel in order to <br />estimate the hydraulic conductivity of the fractured volcanic rocks; <br />Laboratory measurement of permeability of rock cores taken from proposed <br />bulkhead locations; <br />Detailed calculation of the volume of mine workings (in vertical increments of <br />100 feet) for use in estimating flooding rates; <br />Simple numerical modeling of the rate of mine flooding; <br />A detailed analysis of the data to estimate hydraulic aspects of the proposed <br />bulkheads; <br />Petrographic analysis of wall rock from the vicinity of proposed bulkheads; <br />Coliection of secondary mineralization (wall encrustations) and subsequent <br />testing for acid-generating capacity; <br />Geochemical modeling of water/rock interactions using the MINTEQA2 code; <br />and <br />A detailed analysis of water chemistry and mineralogic data to estimate the <br />hydrochemical impacts of the proposed bulkheads. <br />aunnylwpltreci\22911Mar1993.gpt 9 <br />NCI S{(11011 HYDRO-SERRCH <br />