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D04155GE not appear that rapid or catastrophic movement or raveling of the slope has occurred since cessation of the gravel mining activity. It is likely that some raveling of the slope is occurring and on-going simply due to the steepness of the slopes. 2.2.1 General Site Conditions and Comments for Adjacent Areas The Eureka Gravel Pit is situated near the head of the Animas River Valley. In general the area can be characterized by very steep talus slopes, cliff exposures, and debris fan deposits. The Alpine environment of the area often includes heavy precipitation and associated debris flow and sheetwash events. There is an active debris flow area located to the west of the subject eroding area. The debris flow channel originates in the volcanic rock and cliff exposures far above-the site. We understand that flow from this channel often deposits debris several feet deep which closes County Road 125. Other less significant flows are located throughout the area. There are many hazards that are inherent with travel in this Alpine region where most of the roads traverse areas with elevations in excess of 9,500 feet. The general hazards that motorists are exposed to along the roadways in the area include rockfall, debris flow, flooding and flash flooding, and during the portion of the winter when the unplowed roads are still accessible, avalanche. 2.3 Subsurface Conditions The subsurface exploration consisted of observing, describing and sampling the soil materials encountered in two (2) test borings along County Road 125 and two (2) test borings along the toe of the slope. The approximate locations of the test borings are shown on Figure 2. The logs describing the soil materials encountered in the test borings aze presented in Appendix A. We encountered loose fractured rock (talus) with a clayey matrix mixed with pulverized rock to depths as deep as seventy-five (75) feet below the ground surface in Test Borings One and Two, both of which were advanced along County Road 125 above the head scarp area. The strength characteristics of this material is influenced to some degree by the nature of the matrix, but since the majority of the material is fractured angular rock, the intragranular contact geometry of the fractured rock has a significant influence on the strength and global stability of the hillside. During the advancement of Test Boring One, the auger drifted significantly towazd the down- slope side of the roadway starting at a depth of about twenty (20) to twenty-five (25) feet below the ground surface. We do not know the definitive reason for this peculiar behavior of the auger, but we suspect that the auger bit may have encountered and traversed anear-vertical interface of the talus with the underlying formational material. The auger did not drift during the advancement of Test Boring Two. ~~1FXYCTITPY~ ~[YT~I ~1,SSFi;[FXtPB CONSULTING GEOTECHNICAL ENGINEERS AND -3- MATERIALS TESTING