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CORNERSTONE EARTH GROUP 9.2 PORTLAND CEMENT CONCRETE The exterior Portland Cement Concrete (PCC) pavement recommendations tabulated below are based on methods presented in the PCA design manual (need reference). Recommendations for garage slabs-on-grade were provided in the "Concrete Slabs and Pedestrian Pavements" section above. We have provided a few pavement alternatives as an anticipated Average Daily Truck Traffic (ADTT) was not provided. An allowable ADTT should be chosen that is greater than what is expected for the development. Table 8: PCC Pavement Recommendations (R-value = 70) Allowable ADTT Minimum PCC Thickness (inches) 0.8 5 13 5.5 130 6 The PCC thicknesses above are based on a concrete compressive strength of at least 3,500 psi, supporting the PCC on at least 4 inches of Class 2 aggregate base compacted as C recommended in the "Earthwork" section, and laterally restraining the PCC with curbs or concrete shoulders. Adequate expansion and control joints should be included. Consideration should be given to limiting the control joint spacing to a maximum of about 2 feet in each direction for each inch of concrete thickness. 9.3 VEHICULAR CONCRETE UNIT PAVERS Where vehicular concrete unit pavers are desired in standard traffic areas, we recommend that the pavers be underlain by a 6-inch-thick concrete sub-slab designed as discussed above, including the aggregate base section. Pavers should be placed on a bituminous or mortar setting bed over the concrete sub-slab. Where the pavers will be used as an emergency vehicle access (EVA), the pavers should be placed over at least 12 inches of Class 2 aggregate base and prepared subgrade as recommended in the "Earthwork" section. A maximum 1 inch thick sand setting bed may be used to level the pavers on the aggregate base. 9.4 PAVEMENT CUTOFF Surface water penetration into the pavement section can significantly reduce the pavement life, due to the native expansive clays. While quantifying the life reduction is difficult, a normal 20- year pavement design could be reduce to less than 10 years; therefore, increased long-term maintenance may be required. A curb subdrain should be incorporated into the design of the street sections in accordance with the City of Pleasanton Public Works Department Curb subdrain, Detail No. 209. Ponderosa Active Adult Community Page 22 132-2-1