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<br />Disadvantages of total backtill of the quarry access roads <br />Tables I and 2 depict the characteristics of the points along the upper and lower access <br />roads. Figures 1 through 5 depict scaled (1"=20") cross sections of the selected <br />points, and bacldtll scenarios. Discussions of the disadvantages to the total backfill <br />scenario will refer to the tables and figures. <br />Material characteristics <br />Potential backfill material along the access roads is that which has been placed as fill on <br />the outslope of the roads. While we did not characterize this material, it appears to be <br />largely colluvium and decomposed rock material. Whether this material is suitable for <br />backfill from an engineering standpoint is questionable. As the potential bacldill <br />material was removed from the cut slopes and road surface, the material properties of <br />the fill were altered. Given the nature of the material observed along the access roads <br />and within the quarry, I question the cohesive properties of the fill material, and <br />whether the available fill would have material properties which would allow placed <br />backfill to be stable. For the sake of discussion, I will presume that bacldtlling this <br />material to a 2:1 (horizontal:vertical) slope would be stable. <br />Material availability <br />Point 4 was selected as representative of the majority of the cut and fill slopes as well <br />as road width along the upper access road. Figure 1 depicts a scaled (1"=20') cross <br />section of the cut slope, road, and fill slope at this location. The desirability of <br />backfilling to a 2:1 slope (horizontal: vertical) was detailed earlier. From the cross <br />section, it is evident that a 2:1 slope cannot be achieved at this location given the slope <br />and road configuration. Bacltfilling from the outslope edge of the access road to the <br />cut slope at a 2:1 slope would not cover the entire cut slope. 13ackfilling at a 2:1 ratio <br />from the top of the cut slope would require additional fill beyond the outslope edge of <br />the road. Therefore, complete backfilling of the access road at this location is not <br />possible, given the available material and access road configuration. <br />Figure 2 depicts the access road and slope configuration at point 8. Point 8 represents <br />the location with the longest cut slope length, 57 feet. I3ackfi1ling from the top of the <br />cut slope, a 2:1 slope can be achieved within the access road width. However, the <br />amount of material available from the fill outslope is far less than the amount of <br />material required to complete the backfilling. Again, complete backfilling of the access <br />road at this location is not possible given the lack of available backfill material. <br />The access road and adjacent slopes at point 13 are represented in Figure 3. This point <br />was selected as the point along the upper access road with the shortest cut slope length. <br />Given the available material in the fill slope and [he relatively gentle angle of the cut <br />slope, a complete backfilling of the cut slope could be achieved at this point with a 2:1 <br />slope. At this location there are no material availability concerns. <br />-3- <br />