Laserfiche WebLink
July 1999 Solaa Cad C-'m~pary * Senaa 17 WMirr Selnro'tntiat 1'ar1016 Srabiluy Analysis ~ 2 <br />sand clay mixture (SC) the cohesion can vary from 0 to 100 psf and the angle of internal friction can vary <br />from 27.9 to 33.8 degrees. The following conservative strength pazameters were used for the sand. <br />• ~ Cohesion 40 psf <br />Angle of Internal Friction 28 degrees <br />The following soil parameters for the embankment material were obtained from similar fill materials used <br />at Pond 010: <br />Cohesion 485 psf <br />Angle of Intemal Friction 14.2 degrees <br />The parameters described above were input into the XSTABL program to evaluate static stability of the <br />Pond 016 structure and are shown in the attached program printouts with associated results. <br />2.0 RESULTS <br />Using the described inputs, the stability analysis indicates a static SF of 1.5, which meets the required <br />FOS under applicable provisions of Rule 4.05.6(11)(k). The XSTABL computer printouts, located in <br />Appendix B, document all inputs and stability analysis results. <br />3.0 RECOMMENDATIONS <br />In order to achieve the design parameters, it is recommended that the following procedures be <br />utilized in the construction of the sedimentation pond embankments: <br />1) Given the location of the dam, the height of the dam (greater than 10 feet), and the <br />• us of published soil strength data in the analysis, and a SF of 1.5; prior to <br />I construction, soil samples should be collected from the base and borrow areas and <br />tested to verify the subgrade and borrow material strength perimeters used in <br />association with this stability report. <br />2) Also, have Registered Engineer verify embankment fill properties prior to <br />construction. <br />3) Construct embankment in maximum 1-foot horizontal lifts. <br />4) Compact each individual lift to 95% of standard proctor using available equipment. <br />5) Maintain upstream and dowrvstream slopes no steeper than 3H:1V. <br />` 4.0 REFERENCES <br />Huang, Yang H. (1983). Stability Analysis of Earth Slopes. University of Kentucky. Van Nostrand <br />Reinhold Company, New York, NY. <br />Leidich, Tom (1999). Proposed Pond 016 Design. Exhibit 13-l2.2, Seneca 11 W Permit. Prepazed for <br />Seneca Coal Company. <br />Lou L. and Peng S.S. (June 1999). Integrated Approach for Predicting Mining Subsidence in Hilly <br />Terrain. Mining Engineering. p. 101. <br />NCRS (1999 draft). Soil Survey forRouttCounty. NCRS. Craig, Colorado. <br />Northwest Colorado Consultants (July, 1994). "Geotechnicat Investigation, Haulroads Y-A & Y-B and <br />Sedimentation Pond 010, Seneca !I W Mine Area, Routt County, Colorado". Prepared for Seneca <br />Coa] Company. <br />. ~ Momtgrrrry Watswa Anxnvns, Inc 165 South Unia313vrJermrl, Suite 410 * LakereaYi, Cdarado 80228 * (303J 763-5140 <br />J \851 \iep°rt\prdl6srabil¢y <br />- ]0/OS/99~ <br />