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M03107GE material exposed in the foundation excavation should be removed prior to placing foundation concrete. The bottom of the foundation excavations should be compacted prior to placing compacted structural fill or foundation concrete. '~ We suggest the materials exposed be compacted to at least ninety (90) percent of the materials moisture content-dry density rela- tionship (Proctor) test, ASTM D1557. Excavation compaction is to help reduce the influence of any disturbance that may occur during the excavation operations. Any areas of loose, low density or yielding soils evidenced during the excavation compaction operation should be removed and replaced with compacted structural fill. Caution should be exercised during the excavation compaction { operations. Excess rolling or compacting may increase pore pres- sure of the subgrade soil material and degrade the integrity of the support soils. Loose or disturbed material in the bottom of the foundation excavations which are intended to support structural members will likely result in large and unpredictable amounts of ~ settlement, if the loose or disturbed material is not compacted . The bottom of any footings exposed to freezing temperatures should be placed below the maximum depth of frost penetration for the area. Refer to the local building code for details. All footings should be appropriately proportioned to reduce the post construction differential settlement. Footings for large .localized loads should be designed for bearing pressures and footing dimensions in the range of adjacent footings to reduce the y potential for differential settlement. We are available to discuss I this with you. Foundation walls may be reinforced for geotechnical engineering purposes to help provide the walls with additional beam strength and help reduce the effects of slight differential settlement. The structural engineer should be consulted for foundation design tailored for this project. 6.1.1 Spread Footings The soil materials encountered in the test borings contained cobbles. Cobbles encountered at foundation depths may apply point loads on the footings. The foundations should be placed on uniform bearing conditions. For this reason we suggest if spread footings are used that they be placed on a compacted blanket of structural fill. The compacted structural fill blanket should be at least one (1) foot thick placed in six (6) to eight (8) inch lifts and extend beyond each edge of the footings a distance at least equal to the fill thickness. This concept is shown on Figure 8. Geotechnical lambert ana ~,s:sociate.s CDNSUI IJNG GEOTECHNICAI ENGINEERS AND MATERIAL TES i1NG