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• be constructed with a slope configuration of 255 (Hori2ontal) to 1 (Vertical) or flatter. However, if groundwater seepage is encountered in the cut slopes, the slope configuration recommended above may not be suitable. Groundwater seepage encountered in the excava[ions will significantly increase the risk of slope failure in the cut slopes. If seepage is encountered in the cut slopes, this office should be called to the site to determine if the seepage will adversely affect the stability of the cut slope, as well as to advise on"additional stabilization requircmenu. We also recommend that the proposed embankment fill slopes be constructed to a 2 (H) to 1 M or flatter configuration. We believe that the embankment fill slopes that are properly conswcted, drained and keyed into the existing embankmenu or hillsides should be stable at this slope configuration. We recommend that the ground surface underlying all embankment fills be cazefully prepared by removing all of the topsoil and organic materials, scarification to a minimum depth of 8 inches and then recompacting the soils to at least 959a of the maximum standard Proctor density (SPD) prior to the placement of the fill matcrials. The embankment fills should be properly benched/keyed into the natural hillsides or existing embankment fills. The fill materials should be uniformly placed and compacted in 6 to 8 inch loose lifts to at least 9590 SPD and within 3 percent of the optimum moisture content determined in accordance with ASTIY: D 698 or AASHTO T-99. A'here encountered in [he roadway, ezisting fill materials should be scarified to a depth of 12 inches and compacted to at least 9590 SPD. Based on our experience, we recommend that the new roadway be paved using a gravel section consisting of at least 24 inches of pit run sand and gravel subbase materials and 6 inches of Class S or 6 (CDOT) aggregate base course materials. The existing roadway (Op[ion lf2) has an adequate subbase section but should be surface with a minimum 6 inches of Class 5 or fi aggregatt base course. We recommend all subbase and base course materials be uniformly placed and compacted to at least 9890 SPD within 2% of the optimum moisture content. These recommendations • should be reevaluated when more accurate vaffic loadings can be provided. Drainage: The collection and diversion of surface and subsurface drainage away from paved areas, cuu and earthen embankments is extremely important to satisfactory performance of the pavement materials and unretained slopes. Surface and subsurface drainage at the site may contribute to eazly pavement distress or embankment failures. Runoff water at the site is capable of entering the subgrade soils and base course gravels beneath the pavement, .vhich causes them to lase strength and can cause premature pavement failure. Limitations: The recommendations presented are based on the subsurface conditions encountered during the field investigation and our experience with these pipes of soils. The test holes were widely spaced and the locations were based on our understanding of the proposed roadway alignment. Subsurface profiles along the proposed roadway alignment could differ significantly from those encountered during the field investigation, and construction plans and documents should anticipate this possibility. If subsurface conditions or construction plans differ significantly from those assumed or anticipated, we should be informed so that our recommendations can be reevaluated. It is the responsibility of the owner or his representative to ensure that these recommendations are incorporated into the construction plans and doctunenu. If you have any questions concerning this report, our observations or recommendations, or if we may be of any further service, please contact this office. • Job Numlxr: 05.6818 NWCC, Inc. Page3