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Probable Hydrologic Conrequencer - L7iimnry Rock Mine <br />A conservative estimate of salinity from backfilled spoils discharge loading on Stollsteiter Creek <br />was developed based on a recharge model. Average precipitation at the site is 13.41 inches/year <br />(1.1175 feetlyear). Discharge from the pits will be based on infiltration from precipitation and <br />flow from the underburden materials. <br />The area of the East Pit is approximately 46 acres, the area of Barren Ridge is approximately 39 <br />acres, for a total area of 85 acres. The East Pit and the Barren Ridge are actually two areas <br />separated by Stollsteimer Creek. The Barren Ridge Area is to the west of the creek, while the <br />East Pit is to the east of the creek. Assuming that 25 % of precipitation infiltrates, the pits will <br />receive approximately 23.75 acre-feet per year or 14.92 gpm of recharge from infiltration. <br />1175 ~ x85acres=94.98 acft x25%=23.75acft/year <br />year year <br />23.75 acft x325,851 gallons =7 738,961 gallonslyear <br />year ac(f <br />7,738,961 gallonsx year x days x lhour=14.92gpm <br />year 360days 24hours 60min <br />Discharge into the pits also results from the flow of water from the underburden into the pi[. This <br />flow is related to the hydraulic conductivity of the material and the area of the discharge. The <br />flow into the pit was previously calculated by D. R. Piteau and Associates (1982) by performing <br />groundwater modeling of the pit area. The calculated flow into the pit was approximately 10 gpm. <br />The total flow into the pits would therefore be 24.92 gpm or 0.056 cfs. <br />The flow data on Stollsteimer Creek is limited to data collected by Kaiser. The lowest flow <br />recorded occurred in June 1989, at Station S-1 and was 1.78 cfs. The TDS was 557 mgll. A <br />weighted salinity loading between the low flow and the projected spoils (0.056 cfs) discharge <br />yields a total dissolved solids concentration of 608 mgl1. <br />((1.78 cfs x 557 mg/1) + (0.056 cfs x 1064 mg/1))/1.84 = 571 mg/l <br />This concentration would not pose a limitation to downstream users. <br />The ground water velocity of the influent to the Barren Ridge Pit is calculated as 0.94 ft/day, with <br />the flow in the direction of Stollsteimer Creek (Figure 4). A preliminary estimate of the potential <br />Revised hydrologic-0S7\OS-27-0(S:OOAM) 12 <br />