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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 35th 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 35th 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" Avenue Mine (M-1977-036) <br />DRMS 112 Reclamation Permit Amendment Application <br />Groundwater Monitoring and Mitigation Plan <br />Page 1