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i • Section 17, and the warranty deed included in Exhibit N references the SE I /4 N W 1 /4 of Section 17. Please clarify this discrepancy and revise the exhibits accordingly. 5. During the pre-operation inspection held on 8/27/98, two structures were noted south of the permit area. These structures are within 200 feet of the affected area, and must be included on Map #2 to be in compliance with Rule 6.4.3(b). Please revise the map accordingly. 6. The operator indicates that a dewatering trench will be constructed in order to expose and excavate the gravel deposit on the site. The dewatering trench depicted on Ivtap #3 will be constructed on the south and west portions of the pit. Please inform the Division if the dewatering trench will extend along the high pressure gas line and the unnamed creek. The proposed mine plan includes mining to within 200 feet of a high pressure gas pipeline. Rule 6.4.19 specifies that when mining will occur within 200 feet of any significant, valuable, or permanent manmade structure, an applicant may either: Provide a notarized agreement between the applicant and the person(s) having an interest in the structure, that the applicant is to provide compensation for any damage to the structure. Where such an agreement cannot be reached, the applicant shall provide an appropriate engineering evaluation that demonstrates that such structures shall not be damaged by activities occurring at the mining operation. The applicant has chosen to provide an engineering evaluation to demonstrate that the mine plan will be fully protective of the pipeline. Presumably the applicant has attempted to reach an agreement with the operator of the pipeline to allow mining within 200 feet, and was unsuccessful. If not, the applicant must contact the pipeline operator and attempt to reach an agreement, as this is the preferred mechanism for compliance under the regulations. Therefore, the Division reviewed the engineering demonstration of stability within the pipeline easement under the assumption that such an agreement will not be forthcoming. The elements of the mine plan directed toward protection of the pipeline include a five foot mining setback from the pipeline easement boundaries, as well as a commitment to maintain a maximum lh:ly cut slope at the mined face. A slope stability evaluation was prepazed for the applicant by Northwest Colorado Consultants, and was included in the permit application. The Division is in concurrence with the conclusions in the report that the cut slopes will be resistant to failure with adequate safety factors as long as the report's recommendations aze adhered to during mining of the pit. However, the stability analysis provided applies only to relatively large- scale earth movements, such as deep-seated circular failure. In addition, the report indicates that there is the potential for surficial sloughing on the lh:ly cut slopes that are proposed. The Division is concerned that smaller scale strains, such as may be caused by relief ofpre-existing stresses in the bank when the gravel is excavated, may be sufficient to adversely affect the pipeline. In order to address the Division's concerns related to protection of the pipeline, the applicant must address the following issues;