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bicarbonate with a total dissolved solids concentration on the order of <br />1000 mg/1 or less. Trace element concentrations will be very small with <br />iron and manganese being present at levels of about 0.3 mg/1 and 0.03 m3/1, <br />respectively. These conclusions are based on the chemical analyses of the <br />final effluent samples fran the leach tests conducted on existing refuse. <br />As mentioned previously, surface runoff fran the exposed refuse <br />will be routed to a sediment pond. The pond is designed to retain for at <br />least 24 hours the total runoff from a 24 hour storm with a 10 year <br />recurrence interval. Applicable limitations on suspended and settleable <br />solids will be achieved prior to discharge. <br />Average precipitation at the New Elk Mine is about 17 inches per <br />year. In an abnormally wet year, the annual precipitation may be as great <br />as 23 inches. The corresponding quantities of direct runoff from the <br />refuse are estimated at 1.5 and 2.5 inches per year. Expressed as a <br />percentage of precipitation, these runoff values are sanewhat greater than <br />" the measured values for entire watershed above the Madrid gaging station. <br />The maximum surface area of exposed refuse will be about 66 acres. The <br />expected range of runoff volume is 7.6 - 12.7 arft/yr. Using a total <br />dissolved solids concentration of 1000 mg/1 for discharge fran the sediment <br />pond, about 10 to 17 tons of dissolved solids will be added to the river in <br />the year of maximum exposed refuse area. These values of salt loading <br />represent 0.1 to 0.2 percent of the total salt load as measured at the <br />Madrid gaging station. The corresponding average increase of in-stream <br />concentration of dissolved solids is 0.3 to 0.5 m4/1. flirthecmore, runoff <br />fran the refuse will occur when runoff is high fray other parts of the <br />watershed and dilution will be a maxmimum. <br />The proposed refuse pile will be located well above the floor of <br />the Picketwire Valley. The foundation material, beneath the generally thin <br />soil cover is bedrock that dips to the northeast, away fran the valley. <br />The small draw in which the refuse is to be placed has incised the bedrock, <br />z.os-a7 <br />