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SENT BY~ 8- 4-93 ;12~45PM ; CANONIE ENGLE190DD-~ ;#13/19 <br />' • <br />S <br />8.0 CONCLUSIONS AND RECOMMENDATIONS <br />The results of the evaluation Indicate tfiat there has been no statistically siglnificant <br />Impact on the Williams Fork River from the operations et Henderson Mill. Based on <br />the comparison of upgradient samples IHW-1) with downgradlent samples (HW-4), <br />cadmium, copper, Iron, lead, manganese and zinc from the mill operation have not <br />significantly impacted Williams Fork River below Ute Creek. life large percent of <br />nondetecta for cadmium, copper, lead and zinc, listed In Table 4, indicate that these <br />metals occur only in trace concentrations at HW-4. Manganese also is frf:quently <br />below detection and is well below the inatream standard. Iron at HW-4 exceeded the <br />instream standard for 8 of 94 sampling events (less than 10 percent), but was not <br />statistically different from iron at HW-1. <br />Future sampling at F11N-1 and HW-4 should be based on the large database <br />accumulated over eight years, the lack of significant impacts, geochentical rc:latlons, <br />the likelihood of releases from the site and regulatory concerns. Quarterly s~empling <br />maybe sufficient to confirm the baseline ranges of values that have been established. <br />Monltadng of iha geechemical Indicator parameters of pH, sulfate and manganese Is <br />recommended to monitor the movement of seep water. Monitoring of iron at an <br />Intermediate location between HW-1 and HW-4 may be helpful in determlr:ing the <br />source of iron. It monitoring of copper or lean is continued, use of a aliTferent <br />analytical technique with a detection method below the Instream standard is <br />recommended. <br />Respectfully subntltted, <br />~! ii~' JV <br />Anna Lewis-Russ. Ph.D. <br />Tecluiical Manager/Staff Consultant <br />AEL/alg <br />~1w:}x,3in0~MU.11R I~,o.41M]I <br />