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Requirement: As an additional precaution, the southern side of the pit will not be mined within 300 <br />feet of the river until any s[reambank stabilization on the river bank has developed to a point where <br />it can protect the bank from undercutting. For [he first two or three years of the operation in <br />Phase 2, mining will stay north of that 300 foot setback. <br />Requirement: A temporary overflow protection berm will be constructed along the south edge of <br />the affected land. This berm may require FEMA approval prior to construction. <br />DISCUSSION: This berm will be five to six fee[ high. That height was selected because theme <br />flood waters from the 2006 flood rose [o between five and six feet above the normal level of the r]vCt. <br />This rise in the river amounted to about three [o four fee[ above ground level in the vicinity of the south <br />side of the affected land for Phase 2. <br /> <br />Requirement: Another overflow berm will be constructed along [he south end of the large drainage <br />channel that extends along the west side of the site. This berm shall be an extension of the berm on <br />the east side of the drainage that runs along [he west side of Phase 2. The berm shall connect with <br />the overflow protection berm along the river. <br />DISCUSSION: More northerly locations already have a deep channel and secure containment <br />berms, but the south end of that channel does not have [he containment berms and presents an additional <br />location where floodwaters from the river or the drainage channel could flow into the pit. <br />I[ is unlikely any additional protection will be needed on the east side of Phase 2 and certainly <br />nothing is needed on [he north side <br />Requirement: These berms shall remain in place throughout the duration of the operation and v <br />until the sealed area is filled with water so as to reduce groundwater barrier wall damage as a <br />result of river overflows causing headward erosion into the pi[ wall. Once the sealed portion of the <br />pi[ is filled with water these berms should no longer be necessary. <br />Step 2: Installation of the Phase 2 Groundwater Barrier Wall <br />Requirement: Prior [o mining the land within the groundwater barrier wall the groundwater <br />barrier wall shall be installed approximately following the path shown on the maps in Exhibit C-3 <br />and C-4C. <br />Pueblo East Pit Amendment 3 (2007) Exhibit D Page 24 of 34 <br />