Laserfiche WebLink
New Model <br />The updated computer mode] should be submitted in conjunction with the monitoring and compliance <br />points for the C and A pits. The results of the model and the monitoring compliance points must be <br />submitted to the Division no later than November 1, 2004. Please be reminded that such information <br />may need to be filed as a revision to the permit. <br />Monitorine and Comnliance Points <br />As noted above, such information will need to be submitted with the new model by November 1, 2004. <br />In addition, the operator will need to discuss if the Dakota well is a suitable groundwater monitoring <br />location, including DMG access to the well. <br />Source Removal <br />On page 2 of 4 of the letter, CEMEX states that long-term mitigafion would be best accomplished by <br />eliminating the pond. This statement conflicts with the language on page 3 that states, "minimize the <br />amount of water entering the C-pit" and "continue to use C-pit water yeaz-round For operational <br />demands." CEMEX will need to clarify this discrepancy. In addition please clarify the amount of water <br />that will remain in the pond after 12 months, and if this water will ultimately need to be treated. <br />Inflows <br />CEMEX states that runoff from precipitation and snowmelt will be prevented from entering C-pit where <br />practical by use of diversion ditches and berms. Please be awaze that the construction of any diversions <br />and berms on the Lyons site will need to be submitted in the form of a revision to the permit. The <br />revision must be approved and reclamation bond posted prior to construcfion. <br />The Division concurs that a water balance analysis will need to be submitted to the Division within 60 <br />days of issuance of this letter. <br />C-Pit Water Treatment <br />At the meeting it was discussed that CEMEX will submit a source removal and treatment plan by <br />December 1, 2004. Such plan will address the issues raised by DOW/USFS, how the water level in the <br />pond will be reduced/eliminated over the next 12 months, trigger points for water treatment, and when <br />water treatment will commence. In addition, while water treatment may lower the pH it may not lower <br />the concentrafion of selenium. CEMEX will need to address the long-term solution to reduce selenium <br />in the C-pit. <br />Compliance <br />CEMEX states that the A-pit water is the approved monitoring and compliance point. The Division will <br />determine if the A-pit is a suitable compliance point upon the submittal of the new computer model and <br />the results of the investigation to examine the degree of hydraulic connection between the A-Pit and the <br />C-Pit. <br />If you have any questions, please do not hesitate to contact me at 303-866-4943 <br />s' ty,~ <br />rica ScCrosb~~~~~ <br />Environ/mental Protection Specialist <br />cc: / Carl Mount; DMG <br />/fjairy Posey; DMG <br />,~j{ate Pickford; DMG <br />Paul Banks; Banks & Gesso <br />