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appeared that a small channel/ditch had been constructed across the road to direct it away from the failed area. Based on our measurements, it appeared that the water was flowing over the road at a rate of approximately 10 gpm. We followed the water back to its apparent source, which appeared to be in the natural drainage that is situated to the south of the failed area. The water appeazed to be flowing out of the boulders that were located within the drainage. Based on the amount of vegetation (dense willows), it appeared that this area had not been disturbed during the construction of the irrigation ditch that was located above and crossed the drainage. We visited the project site a third time on May 6, 2003 to observe the conditions at the site. We were advised that the subject slope failure had increased in size over the previous weekend and that a crack was now apparent in the road berm located above the slide. We met at the site with Allan Wheately, Gary Bumgarner and Mike Ritchard (ditch owners), as well as with Rick Wahl and Randy Keck of Elk Fork ~ Ranch and Tim Boch, a local excavation contractor. We were advised that the ditch had been shut off on Sunday May 4, 2003 after the crack was observed. However, the ditch was discharging at a rate of approximately 2 cfs at the time of our visit on Tuesday. At the time of our visit, we could not observe the crack that had been observed on Sunday, due to the disturbance caused by a large number of elk tracks in this area. However, it did appear that the fill materials on the outside edge of the road/betm had settled at least one inch since our previous site visit. In addition, it appeared that the scarp face had propagated uphill towards the berm and ditch by approximately 5 to 7 feet. It also appeared that the debris/mud flow from the failed area had increased significantly since our previous site visit. We were advised that the mudflow had crossed the roadway that is located immediately adjacent to the creek that is situated below the slide. Based on our observations, we recommended that they turn off the flow to the ditch, we also recommended that they have the excavator remove the fill materials from above the scarp face as soon as possible and then lay the soils back to as flat as a slope that they can achieve without cutting into the side of the ditch. We also discussed several options for stabilizing the failed area. These options will be discussed later in this report. Conclusions and Recommendations: Based on our observations made at the site and our experience with similar projects, we believe that the slope failure that occurred below the irrigation ditch is a result of a failure in the natural topsoil materials that were overlain by the fill materials from the ditch excavation. ~ Factors most likely contributing to the failure include the surcharge pressure applied by the overlying fill materials and saturation of the soils by seepage from the irrigation ditch. The resultant mud and debris flow that occurred below the failed area likely contributed to the lower road embankment failure. Based on our cursory observations, we believe that the most likely source for the water that is seeping out of the failed area is from the portion of the ditch that had been constructed over the natural drainage, which is situated downstream of the failed area. However, the water could be coming from fractures in the bedrock that is exposed upstream of the failed area in the cut slopes above the ditch. The source of the water could probably be determined; however, it would take a lengthy investigation to verify the source of the water. Based on our cursory observations made at the site and our experience with similar projects, we believe that there are two feasible solutions for stabilizing the subject slope failure and allowing the irrigation ditch to be put back in use. The fast alternative would be to reconstruct the natural hillside and road/berm • Job Number. 03-5547 NWCC, [nc. Page 3