2010-01-21_PERMIT FILE - M2009082 (11)

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assessed relative to one standard deviation from the mean of measurements collected during the applicable season. In addition, wells in river corridor areas adjacent to active mining phases will be monitored monthly during the growing season. If monitoring indicates a drop of 1 foot below the historic baseline or if abnormal vegetation stress is otherwise noticed, dewatering flows or a portion thereof will be directed into established wetland areas and the riparian corridor to maintain the vegetation. In addition to the river corridor, a pond and associated wetlands are located just south of the Phase 2 mining area and immediately south of MW-4. MW-4 will be monitored monthly during Phase 2 mining operations. If monitoring indicates a drop of 1 foot below the historic baseline or if abnormal vegetation stress or pond levels are otherwise noticed, dewatering flows or a portion thereof will be directed into established wetland areas and/or the pond. Groundwater monitoring and modeling indicate that dewatering operations would not have a significant effect on flows in the Jones Ditch. However, Lafarge will enter into an agreement with the Jones Ditch Company that allows for dewatering water to be returned to the ditch to make up losses. This agreement will be in place prior to dewatering and mining south of the Cache la Poudre River. If such an agreement cannot be reached, Lafarge will first submit and obtain approval of a Technical Revision proving that the mining and dewatering operation south of the Cache la Poudre River will not adversely impact the Jones Ditch. Groundwater modeling (Attachment G-2) indicates that there should be no significant effect on surrounding groundwater wells due to the Parsons mining operation. If Lafarge receives a complaint from a well owner, Lafarge will initiate an evaluation of the cause and notify the DRMS immediately (within 24 hours). After the DRMS has been notified, Lafarge will review the available data and information and submit a report to the DRMS within 30 days. To the extent practicable, the report will identify the extent of potential or actual impacts associated with the changes. The evaluation will include discussions with any well owner who has contacted Lafarge regarding a concern and review of available data from the well and vicinity to evaluate the cause of any changes (e.g., seasonal variations, climate, mining by Lafarge, mining by others, or other factors). Lafarge would also enlist the service of a contract professional hydrogeologic consultant to provide an opinion and meet with the Division to discuss the findings. If the claim cannot be resolved with this information, Lafarge would fund the service of a 3rd party consultant agreeable to the Division to render a separate opinion. If Lafarge's mining or reclamation activities are determined to be a significant contributing factor that has or may create adverse impacts, the mining-associated impacts will be addressed to the satisfaction of the DRMS. Lafarge West, Inc. - Parsons Mine 7 Groundwater Monitoring and Mitigation Plan