Concrete drilled shaft fousdations will be used at a site where sand soils exist At one building location, the foundation will be required so support a downward structural loading of 255 kips. For the conditions indicated, determine if a single proposed size drilled shaft foundation will be adequate. Use the empirical method shown in Table 14. The fouadation will be straightsided, have a 3-ft diameter, and a 30-ft embedded length. Soil borings indicate a very deep groundwater table, and the SPT results indicate that $N_{\mathrm{avg}}$ is 14 for the soil zone between the groand surface and the 10 -ft depth (with a soil unit weight of $110 \mathrm{pef}$, and $N_{\mathrm{avg}}$ is 25 for the soil zone berween 10 -ft and 40-ft deep (with a soil unit weight of $118 \mathrm{pch}$ ).