Geology, Soils, and Paleontology

G-1 Protect Against Slope Instability. Design-level geotechnical investigations performed by the Applicant shall be performed by a licensed geologist or engineer and shall include evaluation of slope stability issues in areas of planned grading and excavation, and provide recommendations for development of grading and excavation plans. Based on the results of the geotechnical investigations, appropriate support and protection measures shall be designed and implemented to maintain the stability of slopes adjacent to newly graded or regraded access roads and work areas during and after construction. These measures shall include, but are not limited to, retaining walls, visqueen, removal of unstable materials, and avoidance of highly unstable areas. SCE shall document compliance with this measure prior to the start of construction by submitting a report to the CPUC and Forest Service (for areas on NFS land) for review and approval. The report shall document the investigations and detail the specific support and protection measures that will be implemented.

G-2 Minimization of Soil Erosion. The Construction SWPPP for the Project shall include BMPs designed to minimize soil erosion along access roads and at work areas. Appropriate BMPs may include construction of water bars, grading road surfaces to direct flow away from natural slopes, use of soil stabilizers, and consistent maintenance of roads and culverts to maintain appropriate flow paths. Silt fences and straw bales installed during construction shall be removed to restore natural drainage during the cleanup and restoration phase of the project. Where access roads cross streams or drainages, they shall be built at or close to right angles to the streambeds and washes and culverts or rock crossings shall be used to cross streambeds and washes. Design of appropriate BMPs should be conducted by or under the direction of a qualified geologist or engineer.

G-4 Minimize Project Structures Within Active Fault Zone. Perform a geologic/geotechnical study to confirm location of mapped traces of active and potentially faults (the San Gabriel and San Andreas Faults) crossed by the alignment. Tower locations shall be adjusted as necessary to avoid placing tower footings on or across mapped fault traces. Towers on either side of a fault shall be designed to provide a significant amount of slack to allow for potential fault movement and ground surface displacement.

G-5 Geotechnical Investigations for Liquefaction and Slope Instability. Since seismically induced ground failure has the potential to damage or destroy Project components, the Applicant shall perform design-level geotechnical investigations specifically to assess the potential for liquefaction, lateral spreading, seismic slope instability, and ground-cracking hazards to affect the approved Project and all associated facilities. Where these hazards are found to exist, appropriate engineering design and construction measures shall be incorporated into the Project designs. Such measures could include construction of pile foundations, ground improvement of liquefiable zones, installation of flexible bus connections, and incorporation of slack in cables to allow ground deformations without damage to structures.

G-6 Reduce Effects of Groundshaking. The design-level geotechnical investigations performed by the Applicant shall include site-specific seismic analyses to evaluate the peak ground accelerations for design of Project components. The Applicant shall follow the Institute of Electrical and Electronics Engineers (IEEE) 693 "Recommended Practices for Seismic Design of Substations" which has specific requirements to mitigate the types of damage that equipment at substations have had in the past from such seismic activity. These design guidelines shall be implemented during construction of substation modifications. Substation control buildings shall be designed in accordance with the Uniform Building Code for sites in Seismic Zone 4 with near-field factors.

G-7 Geotechnical Studies for Corrosive Soils. In areas underlain by potentially corrosive soils or in areas of unknown corrosion potential (primarily in the ANF), the design-level geotechnical studies performed by the Applicant shall identify the presence, if any, of potentially detrimental soil chemicals, such as chlorides and sulfates. Appropriate design measures for protection of reinforcement, concrete, and metal-structural components against corrosion shall be utilized, such as use of corrosion-resistant materials and coatings, increased thickness of Project components exposed to potentially corrosive conditions, and use of passive and/or active cathodic protection systems.

G-8 Geotechnical Studies for Problematic Soils. The Applicant shall perform design-level geotechnical studies to identify areas with potentially problematic soils and develop appropriate design features, including excavation of potentially problematic soils during construction and replacement with engineered backfill, ground-treatment processes, and redirection of surface water and drainage away from expansive foundation soils.

G-9 Geotechnical Surveys for Landslides. The design-level geotechnical investigation performed by the Applicant shall include detailed surveys to evaluate the potential for unstable slopes, landslides, earth flows, and debris flows along the approved transmission line route and in the vicinity of other Project facilities. Based on these surveys, approved Project facilities shall be located away from known landslides, very steep hillsides, debris-flow source areas, the mouths of steep sidehill drainages, and the mouths of canyons that drain steep terrain. Where these landslide hazard areas cannot be avoided, appropriate engineering design and construction measures shall be incorporated into the Project designs to minimize potential for damage to Project facilities.

G-10 Protection of Paleontological Resources. The certified paleontological monitor retained by SCE to supervise monitoring of construction activities shall be responsible for the following:

· Monitoring shall be conducted where excavation is being conducted in geologic units of moderate to high sensitivity. Monitoring need not be conducted where excavation is being conducted in geologic units with zero sensitivity, such as the Pelona Schist and granitic and volcanic formations.

· If fossils are present in the construction area, then grading shall be temporarily diverted away from exposed fossils in order to recover the fossil specimens.

· If microfossils are present in the construction area, the monitor shall collect matrix for processing. In order to expedite removal of fossiliferous matrix, the monitor may request heavy machinery to assist in moving large quantities of matrix out of the path of construction to designated stockpile areas.

· Stockpiles shall be tested by screen washing small samples to determine if significant fossils are present. Productive tests shall result in screen washing of additional matrix from the stockpiles to a maximum of 6,000 pounds per locality to ensure recovery of a scientifically significant sample.

· Young Quaternary Alluvium, Colluvium, and Quaternary Landslide Deposits, which have a low paleontological sensitivity level, shall be spot-checked on a periodic basis to insure that older underlying sediments are not being penetrated.

· Recovered fossils shall be prepared to the point of curation, identified by qualified experts, listed in a database to allow analysis, and deposited in a designated repository.

· At each fossil locality, field data forms shall record the locality, stratigraphic columns shall be measured, and appropriate scientific samples submitted for analysis.

· A monthly progress report shall be prepared by the supervising paleontological monitor and filed with the client. A final mitigation report shall be filed with the client, the lead agency, and the repository.

· If fossils are found on NFS lands, a special use permit will be required to allow for any recovery actions to occur.