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16 In general, the thermal conductivity increases as: a) the degree of saturation increases, b) the conductivity of the saturating fluid increases, and c) the density increases. The natural materials that underlie the site to about 14- to 16-ft depth, are primarily dry to moist, silty sands and glass. A thermal conductivity (k) of about 1.5 x 10-3 cal/cm sec °C is typical for a dry, dense clean fine to medium sand (Woodside & Messmer, 1961) . In contrast, the thermal conductivity of a water saturated, dense fine to medium sand is typically about 9 x 10-3 to 12 x 10-3 cal/cm sec °C. For the existing materials underlying the San Joaquin site, a thermal conductivity of between 0.2 x 10-3 cal/cm sec °C and 3 x 10-3 cal/cm sec °C is probably appropriate for evaluating the heat dissipation around buried steam ducts. If the materials are improved or removed and recompacted or discussed subsequently, a thermal conductivity of between 1 x 10-3 cal/cm sec °C and 6 x 10 3 cal/cm sec °C is suggested for evaluating heat dissipation. Suitability of On-Site Soils for Use as Compacted Fill The upper soils can be used as structural fill. These soils typically include native silty sands with variable amounts of glass and ash. Two compac- tion tests were performed on these sands. One test was performed on a sample of silty fine surface materials. The second test was performed on blend of 80 percent (by volume) silty sand and 20 percent flat, angular glass fragments. The - glass fragments generally were coarse sand to fine gravel size particles. Sieve analyses for the blend sample before and after compaction indicate only a minor breakdown of the glass fragments occurred during laboratory compaction. Representative samples of the potential fill material were prepared to estimate the engineering properties of compacted fill. The samples were prepared by compaction to about 90 percent of the maximum dry density at about the optimum moisture content as evaluated by ASTM D 1557 standard test. Laboratory tests indicate the existing surface sand fill materials, when free of debris, organics, and other deleterious material, are suitable for use as compacted fill. The engineering properties of the blend sample (80 percent silty sand; 20 percent glass fragments) suggest that silty sand with up to 20 percent glass also is acceptable for use as fill, provided that the glass fragments are less than 3-in in maximum dimension. 1144A/CC-16 L7,McClelland