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

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TOM TETRA TECH Page 4 of 8 Mr. Peter Hays April 29, 2011 6.4.5 Exhibit E - Reclamation Plan 18. The Applicant states Russian Olives existing prior to mining will not be removed by Lafarge. Russian Olives are a B List noxious weed and must be eradicated from the site. Please commit to eradicating the existing Russian Olives at the site as part of the weed control program. Russian Olives are addressed on the attached Weed Management Plan (Attachment 5). Lafarge commits to eradicating the Russian Olives upon commencement of operations on the Iverson site. Exhibit E has been revised to remove the statement regarding Russian Olives (see Attachment 6). 19. The Applicant states the availability of the proposed seed mixtures may dictate the need for variety substitutions. Once approved by the Division, a revision to the seed mixture would require the Operator to submit and get approval for a technical revision, per Rule 1.9, to alter the seed mixture. Lafarge understands that a modification to the seed mixture would require a technical revision. In addition, as part of the Weld County USR review process, the County asked us to modify the proposed seed mix information listed in Exhibit E and F. Attached are updated versions of Exhibit E (Attachment 6) and Exhibit F (Attachment 7). 6.4.7 Exhibit G - Water Information 20. The application states the landowners are responsible for supplying all of the water required for augmentation during mining and after the mine has been reclaimed. The Applicant should be aware a permanent augmentation plan will need to be in place prior to release of the permit when reclamation is complete. Lafarge is aware that a permanent augmentation plan will need to be in place prior to release of the permit when reclamation is complete. 21. The application states the landowner will file a Temporary Substitute Supply plan to address any depletions due to operations on the Iverson property. The Applicant should be aware that this plan needs to be in place prior to exposure of groundwater. Lafarge is aware that a Temporary Substitute Supply Plan will need to be in place prior to exposure of groundwater. 22. Please commit to providing the Division a copy of the approved Temporary Substitute Water Supply Plan for the site. Lafarge will provide the Division with a copy of the approved Temporary Substitute Water Supply Plan prior to operations on site. 23. The Applicant states dry mining will occur at the site, and a rather limited extent of drawdown due to the mine dewatering operation is projected beyond the Iverson property. The Division requests the Applicant quantitatively define or predict the cone of depression expected for any areas to be dewatered and dry mined. The cone of depression and assessment of other effects should define, at a minimum, the horizontal and vertical extent of expected impacts. Attached is a Figure showing the estimated cone of depression (Attachment 8). The cone of depression is limited on the river side of the pit because the river forms a hydrologic boundary. On the river side of the pit, it is anticipated that stress to vegetation will occur and the property owner is aware of and accepts this. The cone of depression will also extend to the south and east of the mine. In these areas, impacts to wells are anticipated. Only two wells have been identified within the cone of depression. Both of these wells are owned by the property owner and he is aware that they will likely be impacted. If unforeseen well related issues occur, Lafarge will implement their groundwater mitigation plan that details responses and mitigations for well related concerns. Similarly, effects to vegetation may occur within the cone of depression to the south and east of the mine. If it is determined that the dewatering is affecting nearby trees or other vegetation beyond the property, Lafarge will implement corrective actions which may include pumping water from the pit to the affected area or supplying another source of water. 24. The Applicant has installed eight (8) monitoring wells in the area of the Iverson Mine. Monitoring wells are required to be permitted by the Office of State Engineer. Please provide proof of monitoring well permits to the Division. Attached are copies of the well permits (Attachment 9).