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<br /> <br />present during the spring runoff months. Analysis of water quality data <br />presented for sites 18, 60 and 29 indicate that concentrations of iron, <br />manganese and aluminum were occasionally above MLRD standards during the first <br />half of 1986. The concentrations of these ions was less in 1986 than the <br />concentrations recorded during previous spring runoff periods. <br />Analysis of data collected from sites 24 and 76 indicated that iron <br />concentrations were in excess of the MLRD material damage standard of 1.0 mg/1 <br />throughout much of the first half of 1986. No damage to (diddle Creek is <br />anticipated from these iron concentrations because the iron concentration of <br />Middle Creek during this time period was roughly equal to or greater than that <br />of the effluent from sediment ponds M3-N and M3-S. <br />The concentration of mercury present in water at all surface water sites often <br />exceeded the MLRD material damage limit of 0.00005 mg/1 due to a detection <br />limit that is larger than the material damage standard. CYCC often used a <br />0.20 microgram/1 detection limit for mercury for many of its surface water <br />sites. This detection limit is four times greater than the material damage <br />standard of 0.00005 mg/1 (0.05 microgram/1). <br />VI. Conclusions <br />Analysis of surface and ground water monitoring data for Mine No. 3 indicates <br />that no significant material damage to the hydrologic system is occurring at <br />Mine No. 3. Changes in the water chemistry of ground water in the Wadge <br />overburden aquifer indicates more soluble Na+ and HCO~ ions are being <br />leached from the ground water system. No concentrations of constituents in <br />the bedrock wells exceeded irrigation standards. <br />Mine No. 3 continues to contribute dissolved solids to Middle Creek increasing <br />the salinity of the stream. Salts from Mine No. 3 increase the salt load in <br />Middle Creek by 1323 tons (10 percent) per year. <br />CYCC is requested to make the following changes in the approved monitoring <br />plan to ensure compliance with the requirements of C.R.S. 34-33-101 et seq <br />and the Rules and Regulations promulgated thereunder: <br />1) The detection limit for both cadmium and mercury must be improved to <br />concentrations equal to or less than the material damage concentration <br />required for each element. <br />2) The discharge rating curve for site 29 must be recalculated to <br />accurately reflect Middle Creek flow at this point. The new discharge <br />curve must be capable of determining peak flows on Middle Creek. The <br />new discharge curve and previous discharge curves should be submitted <br />to the Division. <br />lal <br />cc: Cathy Begej <br />Robert Liddle <br />0989E <br />