2011-04-29_PERMIT FILE - M2011001 (21)

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I N %J= TETRA TECH Page 5 of 8 Mr. Peter Hays April 29, 2011 25. The Applicant states the registered alluvial wells within 600 feet were identified based on SEO records. Were field inspections conducted to identify ALL wells within 600 feet? Will any wells beyond the 600-foot radius be affected by the mining operations? Field inspections were conducted to confirm the locations of wells within 600 feet. The wells that were field located are on property owned by Joe and Kortney Nelson, Lowell Three and Four LLC, and Tim and Jeanne Iverson. The SEO records indicate that there are existing wells on the Bonnie J. Beebe, Vera A. Smotherman Trust and Jeanne B. Creech Trust property that could be within 600- feet of the Iverson Mine. We contacted Mrs. Beebe to request permission to access her property to field verify the location of her wells; however, she refused to grant us access to the property. Therefore, we have not performed a field inspection of these wells. At this time, we cannot definitively say if wells beyond the 600-foot radius will be affected by the mining operations. However, at the request of well owners, Lafarge has agreed to monitor several wells beyond the 600-foot radius and the groundwater mitigation techniques outlined in the Groundwater Monitoring and Mitigation Plan will apply to these wells beyond the 600-foot radius. 26. The Applicant needs to describe how the drawdown of the pit and any shadowing/mounding effects will impact the structural integrity of the surrounding wells, surface water drainages, activities which rely on ground water in the vicinity of the site, and vegetation on or near the site (including the cottonwood trees in the riparian area near the Cache La Poudre River and the wetland area adjacent to the pit). The Applicant must also describe any mitigation measures to be implemented and trigger points that would put mitigation measures into effect. The pond is to be unlined; therefore, mounding effects will not occur during mining. The estimated limits of the cone of depression are discussed in response to comment 23. 27. The mitigation section of the application states mitigation measures would be implemented after receipt of an owner complaint and confirmation of the two foot trigger point. The Applicant should be aware that mitigation measures should be implemented once the two foot rigger point is confirmed during two sampling events. If the Applicant desires, a separate set of mitigation measures to be incorporated once the two foot trigger is reached without an owner complaint may be proposed, the Applicant may submit these to the Division for review. Lafarge believes it is unnecessary to have a separate set of mitigation measures for if a two foot trigger is reached without an owner complaint. Past compliance issues have all been dealt with satisfactorily by Lafarge without a separate set of mitigation measures. 28. The submitted information also indicates that there are other potential impacts to depression of the groundwater elevation, specifically with regard to vegetation in the area. It appears there may be cottonwoods located adjacent to the river which would be impacted by the drawdown from dewatering the pits. These trees are likely critical winter roosting habitat for raptors, the Applicant should submit information to the Division committing to measures to protect these trees from the impacts of dewatering. Additionally, the Applicant should submit information to the Division regarding other areas that may be negatively impacted by drawdown of groundwater, for example, any sub-irrigated pasture in the proposed cone of depression, and measures it will take to mitigate these effects. The cottonwood trees that could potentially be impacted by the mine are those located on the south side of the river on the Iverson property. Lafarge has spoken with Mr. Iverson about the fact that there is a chance the cottonwood trees on his property could be stressed or die as a result of the mining of his property. He said he understands this risk and is willing to accept it. In addition, based on the findings outlined in Exhibit H, which was prepared by Buys and Associates, we do not agree with the comment that "these trees are likely critical winter roosting habitat for raptors". As stated in Exhibit H, A majority of the habitat in the Project Area has been altered by agricultural practices. As such, impacts associated with disturbance of this habitat are likely to have minor impacts to wildlife species....higher quality habitats are located in close proximity to the proposed project area. Although some of the resident wildlife species utilizing the property may be temporarily displaced by the proposed mining activity, final reclamation would provide more diverse and higher quality habitat for wildlife currently utilizing the site and would likely draw many other species."