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<br />• The scope of the investigation was aimed to gather sufficient <br />data for the design of a stable road. Both the design <br />engineer and the geotechnical engineer were in agreement that <br />for this project it would be irrelevant, technically <br />unnecessary, and costly to try to further define the <br />hydrogeological regime in any specific location of the <br />proposed road. The elevations of the proposed road are well <br />above ground water elevations as evaluated from the basin <br />characteristics and available monitoring well data, mostly in <br />the alluvium. <br />An adequate number of soil borings were performed along the <br />proposed road alignment. These borings provided in situ soil <br />strength data from standard penetration test (SPT) results and <br />soil classification. The laboratory investigation included 35 <br />samples that were tested for index tests, 8 swell- <br />consolidation tests, 13 unconfined compression tests, 6 <br />Proctor compaction tests, and three consolidated undrained <br />(CU) triaxial tests with pore water measurements using 3 <br />samples per test. All tests were performed in accordance with <br />the pertaining ASTM standards. The triaxial shear tests of <br />representative soil samples were conducted to evaluate the <br />stability of the fill material based on representative shear <br />strength soil parameters for the short term (immediately after <br />construction) and for the long term. The stability evaluation <br />• was performed by using the respective representative "total" <br />and "effective" shear strength parameters from the triaxial <br />test results in the slope stability calculations. <br />The road cuts have been designed at slopes no steeper than <br />1.5:1 horizontal-to-vertical (1.5H:1V). Under these <br />conditions, the factor of safety was maintained above the <br />regulatory minimum of 1.5. The road embankments were designed <br />at slopes no steeper than the regulatory limit of 2H:1V. The <br />slope stability analysis shows the calculated safety factor of <br />these embankment slopes exceeds the regulatory minimum of <br />1.25. The lowest calculated safety factor was 1.36, obtained <br />under "total" stress conditions in Section 77+50, Road B. <br />This is a conservative safety factor since the "total" stress <br />conditions apply to short-term loading (immediately after <br />construction). The safety factor of the same slope under more <br />representative "effective" stress conditions was calculated as <br />1.92. This clearly demonstrates the proposed road structure <br />is stable even when conservative soil properties are used for <br />evaluation and exceed regulatory safety factor requirements. <br />Data does not exist to determine the seepage possibilities in <br />the road cut and fill areas. Seepage can and will occur <br />almost anywhere in Routt County in any given wet year. Most <br />of the field investigation was conducted in October 1993, <br />which was the wettest month of the year with 3.02 inches of <br />• precipitation. Therefore, the in situ SPT results represent <br />these wet conditions. Under these conditions (with the <br />11 <br />