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ii equipment, (b) foundation loads and tolerable settlements, and (c) the degree of risk that can be accepted relative to unacceptable foundation performance. Because extensive glass deposits are present at the location of the boiler and turbine, we recommend that this settlement-sensitive equipment be founded on piles driven into the sands that are present below about E1 -20 to -25 ft. An allowable axial compressive capacity of about 60 to 80 kips is appropriate for 12-in.-square concrete piles. Beneath other equipment, tanks, and moderately loaded structures, we suggest that the subsurface soils be improved using dynamic deep compaction (DDC) or partial removal and replacement of the existing soils and glass. With either method, the bearing capacity of the soils is expected to be adequate for the planned equipment and structures and the potential for large and variable settle- ments will be reduced. DDC will accomplish these purposes by compacting the soils in-place whereas removal and replacement with compacted structural fill will provide a mat of engineered material that will help to spread and distribute the loads. The existing surface silty sand fill materials, when free of debris, organ- ics, and other deleterious material, are suitable for use as compacted fill. Tests also suggest that silty sand with up to 20 percent glass fragments, that are less than 3-in. in maximum dimension, is acceptable for use as fill. The approximate range of shrinkage factors for dry to slightly moist surficial soils is 5 to 12 percent. The shrinkage factor where glass-filled trenches are replaced by compacted fill is estimated to be 10 to 20 percent. The project site is located in a seismically active region of central California. The plant facility should be designed in accordance with criteria for UBC Zone 3. No evidence was found to suggest that the proposed project site will experience ground rupture due to fault movements. Provided the site is improved as recommended previously, the potential for liquefaction at this site is judged to be limited. 1144A/H-2 McClelland