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June 24, 1985 6 853-2038 It is not currently proposed to perform temporary mitigating measures on either the conveyor portal or substation landslides in the near future. In some circumstances, the simplest and most cost-effective solution to structural problems within landslides is to move the structure to a stable area. This option should be evaluated for the switching shed. If it is elected to move the switching shed, a geotechnical evaluation of the new site should be undertaken to ensure that it lies within a stable area. We do not feel this is appropriate or necessary for the substation, since the landslide above the substation does not appear to constitute an imminent hazard. Monitoring of landslide movements provides another simple solution in some cases. We believe that monitoring by visual observations is appropriate for the substation landslide, since deformations are currently small. Regular visual observations should provide adequate warning of any significant new deforma- tions. Regular visual observations should also be used to ensure the area above the main portal remains stable. While this area currently appears to be stable, continued deformation of the central and conveyor landslides could result in their extending to the area of the main portal. This should be prevented if the stability of the main portal is to be preserved. When an important structure is located within an active landslide and cannot be relocated, stabilization of the landslide is fre- quently necessary. For cases where surface water drainage does not provide sufficient stabilization, other more expensive stabilization measures may be required. These measures include regrading of the landslide to provide a more stable configuration, and drainage of subsurface water using methods such as horizontal Golder Associates