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SEP-9-2004 15: 1B FROM: BILL & JRNE JRNKE 1-970-728-6315 T0: 19702475104 P.8 <br />Mr. Bill Janke <br />December 23, 2002 <br />Page 2 <br />horizontal (50% slope) unless the permittee furnishes a soils engineer- <br />ing or an engineering geology report, or both, stating that the site has <br />been investigated and giving an opinion that a cut at a steeper slope will <br />be stable and not create a hazard to public or private property. " <br />I am not aware of any soils engineering or engineering geology reports that <br />address this slope. <br />W <br />3. It appears that two inclinometers and three piezometers have recently been <br />installed in the subject embankment. No readings for the inclinometers or <br />the piezometers are included in either the November 25, 2002 Pinnacle <br />Engineering, Inc. report or the October 9, 2002 Lambert & Associates <br />report. The only water level information provided in these two reports is <br />that shown on the boring logs presented in the October 9, 2002 Lambert <br />report. The boring log for Piezometer 1 indicates a water level at 8 feet <br />depth, Piezometer 2 at 49 feet depth, and Piezometer 3 at 5 feet depth. Both <br />phreatic surfaces used in the slope stability analyses aze significantly lower <br />than the phreatic surface indicated by Piezometers 1 and 3. The basis for <br />the phreatic surfaces used in the Pinnacle slope stability analyses should <br />have been provided in their report. Based on the information provided, the <br />stability of the subject embankment slope should have been evaluated using <br />a significantly higher phreatic surface. Use of a higher phreatic surface will <br />reduce the calculated factor of safety. <br />4. Critical details pertaining to how the Lambert & Associates direct shear <br />tests were conducted are not provided. Therefore, the nature of the shear <br />strength that was measured in these tests and the appropriateness of this <br />strength for use in the slope stability analyses is not known. Review of the <br />test results suggests that the shear strengths indicated by these tests are <br />significarttly higher than wotdd be expected for these types of materials. <br />These tests are presented in basically the same manner as the tests previ- <br />ously conducted for this project. Therefore, the shear strength of the <br />foundation on which this embankment was constructed remains in question. <br />5. Each of the three samples selected for direct shear testing are gravelly sands <br />(as indicated on the boring log for Piezometer 2). The boring logs indicate <br />that significant intervals of the foundation soils aze a sandy clay. These clay <br />materials will have a lower shear strength, and therefore, should have been <br />selected for testing. Failure of the slope would tend to occur through weak <br />clay soils instead of through the stronger sands and gravels. <br />6. The direct shear tests were conducted at low normal stresses. The highest <br />normal stress used, 13.9 pounds per square inch, corresponds to an <br />