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NORTHWEST COLORADO CONSULTANTS, INC. <br />FIELD REPORT <br />Project: Pond 16 -Area Project No.: 08 -8099 Date: 10/03/11 <br />Remediation Time: 3.5 <br />Location: Seneca IIW Mine Report No.: 11 Mileage: 74 <br />Client: Peabody Energy Engr. rrech: BDL <br />Work Performed: <br />As requested, we visited the project site on this date and conducted compaction test No.'s 54 through 56 on the <br />material being placed for Pond 16A fill. <br />The excavation contractors, Seneca Mine, were placing and compacting on site borrow material in the south third of <br />Pond 16A for pond backfill. In addition, crews were in the process of cutting in the PM -2 drainage channel southwest <br />of the shrub plot <br />Several test pits were excavated within the proposed PM -2 drainage channel below the shrub plot to try and evaluate <br />the depth to groundwater seepage. The soils exposed at the base of the excavated channel consisted of organic fill <br />materials that were saturated. Groundwater seepage was encountered surfacing in these materials however not <br />observed in the sidewall of the excavation. A test pit was excavated in the base of the channel and to a depth <br />approximately 12 feet below the existing channel excavation. A considerable amount of groundwater seepage was <br />observed at a depth of approximately 4 feet beneath excavated channel subgrade. Natural clays were encountered <br />below the organic fill materials at this depth. The moist natural clays extended to a depth of 11 feet and were <br />underlain by weathered shale which was moist to slightly moist. Two additional test pits were excavated upstream <br />(northeast) of the excavated PM -2 channel. Groundwater seepage was not encountered in either test pit. The test <br />pits were excavated to a depth of 15 feet and mine spoils were encountered to the maximum depth investigated. <br />The portion of the PM -2 channel above Pond 16A was near completion and it appeared that the base and sidewalls <br />of the channel excavation had been constructed into competent bedrock materials. We did not observe any <br />groundwater seepage in the exposed overburden soils or bedrock materials along the uphill side of the trench or in <br />the base of the trench. <br />Remarks: <br />The material tested generally met the project specifications for compaction. <br />Please refer to the attached sheet for the results of today's testing. <br />Verbal Discussions: <br />Jim Rolando of Seneca Mine was aware of today's compaction test results. <br />We also advised Mr. Rolando and Roy Karo of our observations made in the test pits excavated along the PM -2 <br />channel. We advised them that the channel excavation below the shrub plot would have to be extended to a depth <br />at least 5 feet lower than the present channel excavation so that the groundwater is effectively cut off. We also <br />suggested that they shift/move the channel excavation to the northwest so that a 3 (horizontal) to 1 (vertical) cut <br />slope can be maintained between the shrub plot and the base of the excavation. Based on the saturated condition <br />of the fill materials overlying the natural clays, we stated that additional stabilization of the exposed fill materials may <br />be required along the uphill side of the trench excavation. <br />