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Project No. 9929.G Geotechnical Investigatioa/Vineyard Avenue, Pleasanton 8 August 2003 embedment) maybe used in the design. Spacing should be determined, as required, by the load distribution but minimum spacing should not be less than 3 pier diameters, center to center. Maximum spacing should be determined by the Structural Engineer. 47. Reinforced concrete grade beams should be used to support the perimeter walls and, if desired, certain bearing walls of the building structure. Reinforcing steel should be provided as necessary for structural support and continuity of pier and grade beam. 48. The bottom of friction piers must be cleaned to remove excessive loose material that may accumulate at the bottom during drilling. Up to a maximum of 4 inches of loose soil is permitted to be left in the bottom of the pier hole, provided the loose material is tamped prior to steel placement or concrete pour. The Soil engineer must verify that the piers have been cleaned or sufficiently tamped. 49. It is important that care be exercised to ensure that any concrete spills during the concrete pour must be removed and no "mushrooming" effects are allowed to remain around the top of the pier or bottom of the grade beam. Concrete Flatwork Slab-on-Grade Construction 50. It is expected that the concrete slabs-on-grade including public sidewalks, driveways and other landscape flatwork may experience some cracking due to the expansive nature of the soil on the site. To reduce the potential cracking of concrete, the following are recommended: a. To decrease the amount of potential swelling, the driveway subgrade soil in the upper 12 to 18 inches should be saturated until a moisture equilibrium is achieved (minimum 5% above optimum moisture) before the slab is poured. The Soil Engineer should observe and verify the subgrade soil saturation before the slabs are poured. Typically, 12 inches of penetration with a thin metal probe may TERRASEARCH, inG Page 24 of 53