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Figure 4. Northwest view of rockslide (shown by dashed yellow line) showing pressure nage against <br />the active production bench that was being drilled at the time of failure. Note drill rig and blast hole <br />pattern on bench floor. <br />5. Potential rock damage to the base of the quarry wall from production blasting in the Area <br />H hole. From the steep dips that are apparent in Figure 3, any damage to the rock that <br />buttresses the base of the quarry wall will drive instability of the entire quarry wall. <br />6. Water contributions onto the slope face from off-site drainage swales on the USFS <br />property above the slope. These swales have a relatively small drainage area and are <br />dry most of the year. However, during times of precipitation, water is being conveyed by <br />these drainages directly onto the quarry wall and infiltrating into the fault zone, <br />contributing to the ongoing weathering of the rock both chemically and through <br />mechanical processes such as freeze-thaw cycles, as well as increasing pore pressures <br />and adding a lubrication factor that would decrease the overall driving force required for <br />failure.