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dense clearing a narrow path through the vegetation may be the only feasible approach to defining the <br />affected land boundary without risking the possibility of disturbing land too close to the river. It is often <br />difficult to even see the river bank from a distance of as little as 25 or 30 feet, much less from 100 feet or <br />more. This is especially true along much of the river bank in the Phase 2 area. In these cases, defining [his <br />line during the winter or with careful GPS measurements is often useful. The problem with using GPS in <br />thick vegetation during the summer, however, is [hat the dense overhead leaf cover can absorb much of <br />the energy in the weak radio signals from the satellites and result in greatly reduced accuracy, even when <br />using highly sophisticated GPS equipment. In summer, as difficult as it may be [o do, actual <br />measurements should be used to se[ the boundary rather than relying on GPS equipment. <br />Requirement: No disturbances between the affected land boundary and the river are allowed other <br />than the s[reambank stabilization work described in this plan. No soil or overburden can be <br />stockpiled or placed for other purposes in the river setback zone. <br />DISCUSSION: The affected land boundary is defined to exclude all land within the setback <br />from [he river. No disturbance, including the stockpiling of overburden or soil, can be made within the <br />setback zone. This setback zone varies slightly in width depending upon the location relative [o [he river. <br />In no case is the setback zone less than I00 feet from the river, but in other cases it is a bit more. This <br />boundary has been set primarily by [he characteristics of [he land adjacent [o [he river. If there are <br />wetlands or small channels that carry water during high or even moderate flows the landward side of <br />[hose edges are usually considered the functional edge of the river. It is critical to maintain the tree cover <br />in [he setback zone in as good a condition as possible. Placement of material around the base of the trees <br />will likely kill the trees. Without the trees there is an increased probability that the river could erode into <br />the mined area and eventually threaten the south side of [he groundwater barrier wall after it is <br />constructed. Unfortunately, as discussed elsewhere, even with [he trees there is no guarantee such erosion <br />will not occur. Bu[ good tree cover and a well vegetated bank, especially with dense willows, reduces this <br />possibility. <br />The only disturbances that can be made in this setback zone are those needed to construct any <br />streambank stabilization structures. This is addressed elsewhere in this plan. <br />PHASING: <br />Requirement: The eastern edge of [his mining operation is the eastern edge of Phase 1 as shown on <br />the maps. The Phase 2e area shown on the maps for Amendment 1 no longer exists and is not <br />included as a part of this plan. <br />Pueblo East Pit Amendment 3 (2007) Exhibit D Page 13 of 34 <br />