2005-06-24_REVISION - M2000016 (13)

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~IFARG E NpRTH AMERICA AGGREGATES, CONCRETE Ee ASPHALT • For any offsite wetlands, please describe how any impacts to wetlands will be identifzed and the mitigation measures the applicant will take to minimize disturbances to the hydrologic balance to these wetlands. Please refer to the enclosed map, Riverbend Wetland Delineation, for the jurisdictional status of wetlands on the site. The Riverbend Delineation Studies, prepared by a qualified wetland ecologist and approved by the Corps of Engineers, has also been submitted for your review. The Jursdictional Determination issued by i"erry McKee of the Corps of Engineers has also been submitted. Lafarge is currently preparing a 404 Individual Permit application to impact wetlands on the Riverbend site. Until the permit is approved by the Corps, no jurisdictional wetlands on the site will be impacted. If Lafarge is granted a 404 permit that requires the construction of mitigation wetlands within the permit boundary, Lstfarge will submit the 404 permit to the Division for bond review and potential adjustment. Lafarge will not allow dewatering activities to impact identified wetlands on the site. Monitor wells are appropriately placed near wetland areas, mitigation will occur if a trigger point (defined in the previously submitted "Croundwater Monitoring Plan") is recorded near an area identified as dtetlands. Mitigation measures will consist of pumping dewatering water to the vulnerable wetland areas. 21. Metjto Item 13: Regarding the potential ffects of the pit dewatering on the amounts of water conveyed by the Fort Lupton Bottom Ditch, the Brighton Ditch, and the Big Dry Creek, the applicant refers to the AMEC report, which does no[ appear to address ditch losses or losses front Big Dry Creek as a result of pit dewatering and subsequent lowering of the ground water table. The applicant must project the amount of water that will be lost from these structures if these structures leak and the ground water level around the structures is lowered as a result of mining activities. The applicant needs to indicate whether this issue has been investigated and the 'results of that investigation. If this issue has not been addressed, please investigate the potential impacts to the water conveyed n these ditches and the creek, and submit the results to the Division for review. Losses from Big Dry Creek, that is to say out-of-priority depletions due to the dewatering opetation, will be addressed in the substitute supply plan approved through the SEO to the extent it rer,Iuires such replacements. To our knowledge the surrounding ditches are not hydraulically connected to the groundwater in the area„ though seepage from the ditches does contribute to the groundwater table. Though unlikely, to the extent that the mining operation increases seepage from the ditches, it has long been establi~;hed in Colorado that the constitutional right to appropriate water for beneficial use cannot be denied solely because a prior appropriator lacks an efficient means of diversion. (See, e.g., ('olorado Springs v. Bender, 366 P.2d 552 (Colo. 196],)). We recognize, however, that Lafarge is responsible for not impacting the structural integrity of the ditch. The slope stability analysis calculated offsets from waterways, taking hydrology into consideration. We will maintain that offset from the ditch and do not anticipate impacts to the structural integrity of the ditch. LAFARGE NORTH AMERICA INC. -Lafarge Construction Materials 10170 Church Ranch Way, Suite 200, Westminster, Colorado 80021 Telephone: (303) 6574000 Facsimile: (303) 6574037