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KLE/NFELOER \\ J/Bright People.Rights f.o V If tripping hazards are a concern, smooth dowels should be provided at all joints to reduce differential displacement. The dowels should be at least 24 inches in length, greased or sleeved at one end, and spaced at a maximum lateral spacing of 18 inches. Furthermore, flatwork, including planter boxes, should not be attached to the proposed buildings or other structures. The flatwork should be allowed to "float" with the changes in volume of the soil. The near-surface soil conditions do not necessarily warrant the placement of aggregate base below flatwork from a geotechnical standpoint. Flatwork, however, tends to perform better during and following construction with less maintenance if it is underlain by a layer Class 2 aggregate base. The aggregate base serves to provide a firm/uniform surface directly below the flatwork where surcharge stresses are highest. As a result, we have found that flatwork supported on aggregate base tends to experience less stress cracking and movement or deflection at joints. If considered, the aggregate base should have a thickness of at least 4 inches and be compacted to at least 90 percent relative compaction. In areas where concrete flatwork will support construction equipment, trash collection areas, and/or vehicle traffic, we suggest that the aggregate base be increased to a thickness of 8 inches and be compacted to at least 95 percent relative compaction. 5.8 ASPHALT CONCRETE PAVEMENTS 5.8.1 Subgrade Preparation 5.8.1.1 Native Subgrade Per our discussion in Section 5.6.1, the near-surface soils that will be placed within pavement areas will consist of potentially expansive clay that poses a potential risk for post-construction heave and cracking of pavements. In order to reduce this risk and improve the service life of the pavement, the subgrade soils in pavement areas should be thoroughly scarified or ripped to a minimum depth of 12 inches below the finished subgrade elevation and uniformly moisture conditioned to a moisture content ranging from 2 to 4 percent above the optimum moisture content. During or following moisture conditioning, the upper 6 inches of subgrade soil should be compacted as engineered fill to at least 95 percent relative compaction. The underlying 6 inches of moisture conditioned subgrade soil should be compacted to at least 90 percent relative compaction. The subgrade soil should be in a stable, non-pumping condition at the time aggregate base materials are placed and compacted. The moisture content of the soils should be maintained until placement of the aggregate base by liberal sprinkling with water or other suitable method. If 20210067.001A/ST020R111447 Page 25 of 37 May 11, 2020 ©2020 Kleinfelder www.kleinfelder.com