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LAFARGE <br />NORTH AMERICA <br />Construction Materials <br />Division how the topsoil piles will be protected from the mining operation where slopes <br />will be mined to near-vertical. If the pit is to be mined to a depth of 25 feet at a 0. Sh: l v <br />slope, the topsoil piles may become unstable and slope,failure may occur if an adequate <br />buffer distance is not established. <br />The mining and reclamation plan has been revised to reflect 1:Sh:ly mining face slope. <br />Based on mining experience, an angle of repose equal or less than 1.5:1 achieves a factor <br />of safety greater than 1. Exhibit C has been revised to reflect the change in mining slope; <br />the sealed and signed map is enclosed. <br />4. The groundwater hydrology report prepared by the Applegate identified three wells <br />registered with the Office of the State Engineer (OSE) that may be impacted as a result of <br />the mining operation. The wells were identified within % mile of the pit, and are depicted <br />on Figure 1. The well to the south appears to be closer than '/z mile and possibly as close <br />as 500 feet. Lafarge will need to accurately locate all wells, including wells that may not <br />be permitted with the OSE. <br />The OSE identifies wells within aquarter-quarter section, Figure 1 depicts the well to the <br />south in its appropriate quarter-quarter section but not precise location. Lafazge has <br />identified a well at the 2999 WCR 20'/z residence. The field inspection conducted by the <br />Commissioner found no wells located closer than 600 feet to the site. The attached "Well <br />Monitoring Program" specifically addresses how Lafarge will monitor, and if necessary, <br />mitigate impacts to this and any other nearby well. <br />5. ...The applicant must obtain permission from the ditch company to discharge water into <br />the ditch. The applicant should submit documentation to the Division for review as to the <br />proposed maximum discharge rate into the ditch and specifications as to how much water <br />the ditch can carry without experiencing erosion, <br />The Smith & Emmons Ditch Company's permission to discharge water into the ditch is <br />included in the signed, notarized agreement. The capacity of the new concrete-lined <br />ditch, according to the final engineering plans, is 20 cubic feet per second (cfs) with 1 <br />foot of freeboard. The maximum discharge rate of 1,141 gallons per minute (gpm) <br />converts to 2.54 cfs. The ditch typically carries 5 cfs of water; the addition of 2.54 cfs of <br />water for a total of 7.54 cfs is still well within the capacity of the ditch. Because the ditch <br />is concrete-lined, erosion is not an issue. <br />6. The Applicant should submit a map identifying the locations of the monitoring wells for <br />the Division to review. <br />LAFARGE NORTH AMERICA INC. -Lafarge Construction Materials <br />1400 West 64~' Avenue, Denver, Colorado 80221 <br />Telephone: (303) 657-4000 Facsimile: (303) 657-0037 <br />