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Attachment G-1 <br /> Lafarge West Inc. —Amendment to Greeley 35th Avenue Mine <br /> Groundwater Monitoring and Mitigation Plan <br /> PURPOSE <br /> This Groundwater Monitoring and Mitigation Plan is prepared as part of Lafarge's application to <br /> the Colorado Division of Reclamation, Mining and Safety(DRMS) for a permit to Amend the <br /> Greeley 351h Avenue Mine Permit M-1977-036 to add the Lafarge Brown property to the permit. <br /> This plan presents the methods and locations for monitoring of groundwater during gravel <br /> mining and site reclamation activities. Although adverse impacts to groundwater are not <br /> anticipated as a result of Lafarge's activities at the Lafarge Brown property, this plan also <br /> addresses how any adverse effects to groundwater would be mitigated, should they occur. <br /> Lafarge will amend the Temporary Substitute Water Supply Plan on file with the State <br /> Engineer's Office to address any additional depletions due to operations on the Lafarge Brown <br /> property. The temporary substitute supply plan is designed to protect senior vested water rights <br /> and mitigate potential depletions of flows in adjacent waterways. <br /> BACKGROUND <br /> The Lafarge Brown property is located in Greeley, Colorado. The site occupies approximately <br /> 12.4 acres in the northeast quarter of the northeast quarter of Section 35, Township 6 North, <br /> Range 66 west. <br /> The Cache La Poudre River channel is on the west and north site boundary. On the adjacent <br /> property to the east and south of the site, Lafarge mines sand and gravel from the existing <br /> permitted Greeley 351h Avenue Mine which will extend onto the Lafarge Brown property. <br /> Dewatering flows are discharged to the Cache la Poudre River. <br /> Sand and gravel will be extracted by the "dry"mining method. Mine cells will be dewatered <br /> using a perimeter drain to facilitate extraction of the gravel. The actual mining limits are <br /> anticipated to cover approximately nine acres. The rate of mining and overall life of the mine is <br /> dependent upon demand and market conditions. The reclamation of the Lafarge Brown property <br /> will be part of a larger unlined pond. <br /> The dewatering system will discharge to the Cache la Poudre River via discharge points at the <br /> existing permitted mine. Dewatering of the Lafarge Brown part of the mine would lower the <br /> groundwater levels to a limited extent in the surrounding alluvial aquifer. Effects on <br /> groundwater levels beyond the Lafarge Brown property are projected to be limited due to the <br /> boundary affect of the Cache la Poudre River. Mining should not have significant adverse <br /> effects on groundwater users in the adjacent areas as such users are located on the opposite side <br /> of the river or at relatively lengthy distances. <br /> Greeley 35`h Avenue Mine(M-1977-036) <br /> DRMS 112 Reclamation Permit Amendment Application <br /> Groundwater Monitoring and Mitigation Plan <br /> Page I <br />