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Based on the design loads and the allowable soil bearing capacity, the post can be set on un, disturbed earth at the bottom of the hole as shown in Figure 3,14, In this case, the bearing capacity of the soil will govern the elevated foundation design as presented in Chapter IV, "Design of Elevated Foundations," Figure 3.14 Post Set on Soil Where additional support is needed because of inadequate soil capacity, bearing capacity can be improved by pouring a concrete bearing pad at the bottom of the hole as shown in Figure 3,15, This pad should have a diameter at least twice the post diameter and be one post diameter thick (a minimum eight inches thickness is recom- mended), After proper post alignment in the hole is achieved, clean, well-compacted backfill is necessary to ensure a post configuration with good lateral stability and resistance against wind and flood loads, Common backfill materials are sand, gravel, crushed rock, pea gravel, soil cement, concrete, and earth with granular fills that provide good drainage, Backfill materials should be dampened and mechanically tamped during construction to provide adequate compaction, Backfilling the hole with concrete, as shown in Figure 3,16, rather than gravel or sand adds stability to the structure and increases the bear- ing area, Soil cement is an economical alternative to concrete and attains nearly equal strength in all soils except clay. Soil cement is made by mix- ing the earth removed from the hole with cement in a ratio of one part cement to five parts earth, Figure 3.15 Post Set on Bearing Pad plus water as directed by the manufacturer. To achieve the best results, all organic matter should be removed from the earth, and it should be sifted to remove all particles larger than one inch, Figure 3.16 Post Backfilled with Concrete Flood and wind forces are less likely to overturn or uplift posts if the posts are anchored to a foun-