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<br />Brighton Water Storage Projec[ <br />Slope StabiliTy Calculations <br />Adams County, Colorado <br />The position and type(s) of inlet -outlet works for the project-have not yet been selected. <br />Therefore, the possibility of a `rapid draw-down' condition occurring cannot be 'assessed, <br />' although it appears relatively unlikely based on the general site coriditions. Therefore, this <br />condition was not addressed in this study:. GROUND can provide additional slope stability <br />assessments in that regard upon request. <br />' Stability calculations following Bishop's method were performed with the Slope/W computer <br />' program, published by Geo-Slope International, of Calgary, Alberta, Canada, copyright 1999. <br />Output from the program, presented the lowest factors of safety obtained for each condition are <br />presented in the Appendix. ~ , <br />' The parameters used to model the project earth materials also are presented in the Appendix. <br />Values for the alluvialsands and gravels were based on field and laboratory moisture and density <br />tests, and on penetration resistance values through- the correlation 'presented by Bowles <br />' (Foundation Analysis and Desien, 2nd Edition, McGraw-Hill Book Co., 1977). The values for the <br />clay liner material were based on the data obtained from testing of a re-molded sample of the <br />material. The bedrock values were assumed, based on various published and unpublished values <br />' and GROiJND's experience with similar sites. (The bedrock parameters do noYaffect the results, <br />strongly.) These parameters aze considered to be conservatively representative of the site soils <br />' and bedrock. <br />' The input values used for the `miscellaneous fill,' however, are necessarily assumed_ 1 Those <br />material(s) have not yet be identified or placed. We have assumed that clayey soil and bedrock <br />materials will comprise the bulk of those soils, together with on-site silts and sands,'as well as <br />' possibly imported materials. Again, the values used for the slope stability modeling are <br />considered to be reasonably conservative, but the actual materials placed should be tested by the <br />' - Geotechnical Engineer, and the findings and recommendations in this "report modified, as <br />appropriate.- <br />' Findfnas and Recommendations ' <br />' - Reservoir Liner Material Based on the testing performed for this study, claystone material. <br />excavated from the project area.appeazs suitable fpr use as reservoir liner. The laboratory ;data for <br />the three samples tested indicate that the local bedrock material generally falls well within the , <br />pazameters specified by the State of Coloradd regarding plasticity and gradation (Division of <br />Mines and Geology, 2000). The measured hydraulic conductivity on the order of 1.2 x 10-' cm/s <br />~.. <br />Job No: 02-0065 ~ ~ ' Cround~Engineering Consultants, Ina Page 5 <br />