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,_ .;- <br />from the upstream monitoring point on Trout Creek (fR-A) to the downstream monitoring <br />point (IR-D) in conjunction with the mining and reclamation activities. <br />It also appears that the predicted post-mining mean annual concentration of TDS in <br />Trout Creek has been exceeded for the past several years at the downstream monitoring <br />point TR-D. The PHC predictions presented in the PAP indicate tha[ after mining the West <br />Ridge and Moffat Areas, the mean TDS concentration in Trout Creek would be expected to <br />increase to 330 mg/l. Monitoring data reported in 1999 show that the mean annual TDS <br />concentration for TR-D was 420 mg/1. Please clarify the statement on page 9 that all values <br />for TDS are consistent with the PHC projections. Exceedances of PHC predictions should <br />be addressed in future AHR's so that any significant trends can be identified and conclusions <br />regazding PHC predictions can be verified. <br />3. On page 31 of the 1999 AHR, P&M indicates that the elevated levels of TDS in Well <br />TR-1.5 may be from an old abandoned underground mine up the Little Trout Creek <br />drainage or possibly from the inundation of the area in late spring of 1995 and the laying of <br />telephone cable upstream of the azea during the summer of 1995. To aid in identifying the <br />source of the elevated TDS values, the Division is requesting additional information <br />regazding the on-site alluvial monitoring wells. Please provide survey information (including <br />ground surface elevation and top of well casing/measuring point elevation) and depth to <br />water measurements for 1995 through 1999 for Wells TR-1.5 and WR-1. Also, the DMG <br />cannot locate the well log for Well TR-3. Please provide this monitor well log, if available. <br />The completion log of well TR-1.5 indicates that this well was only drilled to 6.0 <br />below ground surface and water level was initially 3.0 feet below ground surface. Well TR- <br />1.5 is located below the reclaimed West Ridge Area and does not appear to be entirely <br />upgradient of the disturbance area. Further review of these data may determine the source <br />of the elevated levels of TDS at well TR-1.5. Please provide any information that P&M may <br />have concerring the location and operation of the referenced old abandoned underground <br />mine up the Little Trout Creek drainage. <br />4. During the last midterm review, P&M committed to revise the permit after DMG's <br />review of the 1999 AHR Please submit a technical revision to address those outstanding <br />items addressed in our January 5, 2000 letter. In the revision, please include a revised Water <br />Monitoring Location Map (Exhibit 4.6-26) to include the location of DMP 007. Responses <br />to the other comments in this letter can be addressed in a response letter. <br />If you have any questions regarding this letter, please contact me. <br />Sincerely, <br />Sandra L. Brown <br />Environmental Protettion Specialist <br />