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<br />the levels expected at the discharge to Roan Creek. Therefore, the results are conservative and do <br />not account for dilution by mixing with other surface waters or the fact that Logan Wash is an <br />ephemeral drainage and the distance to Roan Creek is several miles from the mine site and <br />existing NPDES discharge points. <br />The constituent of primary concern in the retort water is sulfate. Constituents of secondary <br />concern include ammonia, boron, benzene, and the metals azsenio, iron, mercury, and selenium. <br />Note that in Table 1, the results for ammonia and mercury are undetectable, but that the detection <br />limit was greater than the established water quality standard. The ability of the passive treatment <br />system to treat sulfate will be of primary importance. <br />Retort and mine-water discharge for the period February 1996 to August 1999 is summarized in <br />Table 2. The table shows the minimum, maximum, and average flow rates from the retorts are <br />1.3 gpm, 7.0 gpm, and 4.3 gpm, respectively. The proposed treatment flow rates are discussed in <br />Section 4.0 of this report (Pilot Treatment System Design). <br />The calculated average flow for the mine water (non-retort water) discharge for the period of <br />February 1996 to August 1999 is 7 gpm with a range of 0 to 37.5 gpm. The calculated average <br />flow for the mine water discharge at the 002 outfall for the period of February 1996 to August <br />1999 is 7.7 gpm with a range of 0 to 30 gpm. This flow represents the discharge from the <br />Research Mine portal. Outfall 002 data shows awell-defined cyclic fluctuation in flows that <br />correlates well with spring runoff. <br />4.0 Pilot Treatment System Design <br />GSHI, in an effort to evaluate long-term treatment of retort- and mine-water discharge from the <br />Logan Wash Mine, proposes to construct and test areduced-scale passive treatment system at the <br />mine. The goal of the passive treatment system is to investigate the effectiveness of treating <br />retort water by way of biomass reactions (sulfate reducing bioreactor, SRB). The SRB cell will <br />treat between 1 to 3 gallons per minute (gpm) of retort drainage water from the mine. In later <br />stages of testing, the treatment system may be used to test the treatment of mine-water drainage <br />(non-retort drainage) and/or a combination of water types. However, the total influent flow rate <br />will not exceed 3 gpm. <br />