Laserfiche WebLink
• S, _ [ (Fc x Sc) - (Fi x S1) - (Fz x SZ) - (F3 x S3) + F, <br />Sq - [(100 x 381) - (72.06 x 133) - (0.01 x 3,940) + (1.97 x 3,925) <br />= 25.96 <br />Sq = 837 mg/1 <br />As before, in order to achieve the flow and TDS levels measured at <br />TR-b/TR-D, flow from other sources equivalent to 25.968 (7.61 cfs) of the <br />measured flow at TR-b is required containing TDS levels of 837 mg/1. This <br />outcome is not unexpected because surface irrigation water runoff diverted <br />upstream of TR-a on the west side of Trout Creek constitutes the majority <br />of the flow from other sources. <br />The flow and TDS balances previously performed indicate that the data <br />collected during monitoring activities at the Edna Mine are reliable and <br />reasonably accurate. Therefore, the data base may be used to examine the <br />potential impacts to Trout Creek from the mining operations. <br />II. Impacts of Mining <br />The database used in the above analysis extends over the time period <br />of all mining and reclamation activities at the Edna Mine performed under <br />• the Colorado permanent regulatory program. If it is assumed that the TDS <br />concentrations observed during the entire period of record are part of a <br />normal distribution, 99.878 of the possible TDS concentrations to be <br />encountered in Trout Creek at TR-D can be predicted to be below an upper <br />limit using the mean of the sample population plus three standard <br />deviations. Using this method, TDS concentrations in Trout reek. may-be <br />expected to reach an upper limit of approximately 1,186 mg/1 at some time' <br />during the mining and postmining era at the Edna Mine (1,166 mg/1 = average <br />(992 mg/1) + 3s (s = 296 mg/1). Except for one observation, all TDS <br />concentrations are below this statistical upper limit. The single <br />observation above this limit, 1,990 mg/1, occurred on April 16, 1996. The <br />next highest TDS concentration observed was 1,076 mg/1 (July 25, 1999). <br />Although the single highest value lies outside the expected values <br />anticipated by the statistical analysis, the value is reasonable when <br />reviewing the various records of early spring flows which contribute to <br />Trout Creek. Over the record term, 93.98 of the flow at TR-b was accounted <br />for from the combined flows of TR-a and the CDPS discharge points. <br />However, on April 16, 1996, only 80.78 of the flow at TR-b was accounted <br />for by flows from the monitored sites. Employing the data collected on <br />• that date and average TDS values for the month of April to the mass balance <br />equation (individual TDS values for the CDPS discharge points were not <br />Renewal 3 2.SA-7 June 13,1997 <br />