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bedding is not dipping unfavorably from a stability standpoint. Expect occasional unraveling of <br />the landslide scalp at the transition between the through -cut and cut -fill sections, potentially <br />requiring occasional removal of this material to maintain road access. <br />Our test pits indicate that the fill is benched into the rock, a favorable condition from a roadway <br />stability standpoint. The upper approximate 12 inches of roadway fill is dense and properly <br />compacted (this is confirmed by the test results in the May 26 report). Below this depth, the fill <br />is loose and appeared to have been poorly compacted if at all Except for the presence of <br />occasional oversize cobbles near the bottom of the test pits, our test results indicate the fill is <br />suitable for its intended use. Atterburg limits results are within acceptable range for structural <br />fill; no organic material was observed in the fill exposed in the test pits. <br />The retaining wall across the drainage appears to be performing well, except for some outward <br />leaning of vertical members on the river side. The retaining wall along cut -fill section of access <br />road appears to be performing poorly in its present condition. The side slope retaining wall has <br />either: undergone extensive movement and, for all intents and purposes, is failing and/or is <br />exhibiting characteristics of poor workmanship during its construction. The silt fence is in poor <br />condition and is not capable of performing its intended function, much less resisting soil and <br />rock sloughing off the steep slope directly above it. <br />In summary, the good news is as follows: no seepage, good quality fill, fill appears to be <br />constructed on bench in the rock, the load has survived 2 winters intact, bedding of rock in cut <br />slope is not unfavorable from a stability standpoint, retaining walls on either side of drainage fill <br />appears to be performing well The bad news includes the following: retaining wall current <br />performance and future capabilities to perform as intended uncertain at best, loose fill at depth, <br />fill slopes of unknown quality and thickness on slopes steeper than 1.5:1, roadway steeper than <br />15 percent. <br />Recommendations <br />To utilize the road for the intended purpose, we recommend a work plan be prepared and <br />implemented that at a minimum addresses the following: <br />Roadway fill: Complete construction of the road in a manner that results in road grades less than <br />15 percent._ The upper 30 inches of road should be compacted to at least 90 percent relative <br />compaction per ASTM D1557-02. In areas where less than 3.0 inches of fill will be placed to <br />complete the road, over- excavate as necessary, scarify to a depth of 6 inches, moisture condition <br />as necessary, and compact to at least 95 percent relative compaction per ASTM D1557 -02. <br />Remove loose logs, branches, and other debris from the steep slope on the outboard side of the <br />road. Replace repair silt fence at bottom of slope. Construct new flI slopes no steeper than 1.5: <br />1 Where the minimum allowable roadway width cannot be achieved at these fill slope <br />inclinations, utilize horizontal reinforcement in the fill, such as Hilfiker walls to construct the fill <br />slopes. These slopes, where horizontally reinforced, can be increased to 3 / :1 or steeper. <br />May 30, 2010 <br />