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<br />• <br />• <br />flows into a collection box within the landslide zone. The ditch and French drain are now thought to <br />act as infiltration sources into the landslide. The ditches will be lined to prevent infiltration of water <br />into landslide. Figure H2 of the 1999 Addendum shows a preliminary layout of the proposed plan. <br />Construction for the project is contingent on availability of capital funding and movements observed in <br />the slide. <br />• Maintenance work consisting of regrading and relining of ditches damaged by previous landslide <br />movement, and repair of subsurface water and sewer lines. <br />J3.1 Potential Corrective Measures <br />Potential corrective measures are ready to be implemented if conditions warrant. These ongoing measures <br />include the following work. <br />Replacement and Retirement of Piezometers and Inclinometers. As part of the ongoing monitoring <br />program, work will be performed to replace piezometers and inclinometers that have been damaged by <br />landslide movement, thus allowing continued monitoring of landslide behavior. At the same time, mirrors, <br />piezometers, and inclinometers will be evaluated to determine if sufficient baseline information has been <br />collected at this time. If these monitoring devices are non-critical for on-going monitoring of the landslide, <br />they will be retired from active monitoring or the frequency of monitoring will be reduced. Because <br />sufficient baseline data had been accumulated, the retired monitoring device can be reactivated if deemed <br />necessary without losing significant data. <br />Surface Water Ditches. A routine maintenance plan is in place to repair ditches (especially in the spring) <br />to prevent infiltration of surface water. Long-term reclamation will remove the ditches to prevent <br />concentrated flow. <br />Portal RetaiDmg Structures. Further studies have found that repair of the portal retaining wall is not <br />essential for stabilization of the landslide. More likely, future removal of a portion of this wall and re- <br />grading of the portal bench will be performed to improve mining operations. The benefit of this re-grading <br />will be to close tension ctacks at the head of the slide, thereby preventing infiltration of surface water. <br />Barr Englneering Company <br />PCDOCS~230503/CAK <br />December 15, 2000 <br />Appendl: J <br />2007 Addendum to <br />7997/99 Landsllda Corraetlve Measures Report <br />