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a SCOPE This report presents the results of our Stability Evaluation for six Sedimentation Pond Embankments (Ponds 004, 006, 010, 011, 012 and 013) planned at the Lorencito Canyon Mine in Las Animas County, Colorado. The evaluation was performed in accordance with our proposal No. 97-636, dated August 26, 1997. This report includes results of laboratory testing of samples of the foundation soils and anticipated fill to obtain information regarding gradation and strength properties, and analyses of stability of the proposed sedimentation pond embankments. Recommendations regarding construction procedures are also discussed. The conclusions presented in this report are based on topographic information and proposed pond configurations provided by Greystone. The report is intended to satisfy the regulations of the Colorado Division of Minerals and • Geology (CDMG), Rule 4.05. 4.05.6 (11) related to stability analysis and embankment construction. A summary of our conclusions is presented below. SUMMARY OF CONCLUSIONS 1. The site and soil conditions found are considered generally favorable for construction of the proposed sedimentation pond embankments. At most embankment locations, clayey sand or clay soils are available to construct the embankment. At Pond 010 removal of 4 feet of topsoil will likely expose primarily granular soils with little fines. The clean granular materials are permeable and are not suitable for embankment construction. Importing clayey sand or clay soils may be required at this location. The relatively clean granular soils were also found in one test pit at Pond 012. The test pit was located in a lower portion of the pond near the existing drainageway. Another test pit found clay soils in the north- western portion of the proposed pond; the clays will be suitable for embankment construction. • LORENCI70 COAL COMPANY, LLC SMALL SEDIMENTATION EMBANKMENTS CTL/T 26,559 1