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Mr. Tom Schreiner, Division of Minerals and Geology March 23, 2005 Page 2 ~~ CIVIL RES'JURCES, LLC Secondary Containment: The applicant/operator will install/construct adequate secondary containment to satisfy the State of Colorado regulations under the Division of Oil and Public Safety, and the US Environmental Protection Agency (EPA). The operator may use double-walled tanks, dikes, berms, curbing, sorbant materials, or other acceptable methods of secondary containment as allowed under these regulations. The secondary containment will be sufficiently impervious to contain discharged oil and provide a means of containing the entire capacity of the largest single container with sufficient freeboard to contain precipitation. The operator/applicant may contract with an oil supplier for tank, containment and bulk product delivery. 2. The applicant specifies on page 12 that the mining operation will include pit de-watering and offsite discharge of recovered groundwater in accordance with a Colorado Discharge Permit System/NPDES regulations. It is the Division's understanding that recovered groundwater from pit de-watering operations will be discharged offsite and into the South Platte River. Please clarify where the point(s) of offsite discharge will occur, the method(s) used to safely discharge the recovered groundwater, and what structure(s) the recovered groundwater will be discharged into. Also, please specify the rate at which recovered groundwater will be discharged offsite, and the capacity of the structure(s) receiving the discharged water to convey the water to the South Platte River. The discharge water will be conveyed by pipeline located along the western permit limits to two existing concrete box culverts (CBC) located in the northwestern comer of the permit boundary. This water will then flow by gravity back to the South Platte River via the Porter and Ogilvie seepage ditches. These existing seepage ditches are used by the landowners/farmers to return irrigation excess to the river. We have attached the ditch decrees for proof that the landowner has the legal right to enter these ditches. The proposed conveyance structures will be pipes and channels and they will tie into the two CBCs and concrete pipes that pass under Highway 85. The conveyance structures have adequate capacity to carry this water. The rate that water will be removed from the pit will be approximately 45 cubic feet per second and the approximate capacity of the CBC is 800 cubic feet per second. 3. The water management system as described on page 12 requires clarification. Specifically, please revise the Mining Plan Map (3 of 7) to show the location(s) of the sump and settling ponds. Will the location of the sump vary with each phase of the mining operation or will there be one main sump used throughout the mining operation? Please describe how the recovered groundwater from pit de-watering operations will be hansferred to the silt ponds in the northwestern portion of the permit area. Or, will the pit water from de-watering operations be directly discharged offsite through some other method? Please provide representative plan view and cross sectional diagrams of the sump, wash ponds, and silt ponds to 6e used in the operator's water management system. The sump will likely be located at the lowest point of each mining phase. The location will be approved by an engineer so that it does not affect slope stability and to minimize the distance to discharge. The processing water for phases 4 through 9 will be diverted to the settling pond on the north end of the site and the fines/silts will be allowed to settle out. Water will be drawn from the top of the pond and pumped to the fresh water pond so that it can be reused in the washing process. The water will be conveyed via the pipeline shown on the Mining Plan Map between the processing area and the settling pond in phase 3. The pipe would run in conjunction with the conveyor crossing across Weld County Road 8.