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KLE/NFELOER �Bright People.Right Solutions. The lime quality and spreading, mixing, and compacting operations should conform to Section 24 of the Caltrans Standard Specifications, latest edition. At least two to three days prior to spreading or mixing the lime, the moisture content of the underlying, untreated clay soil should be checked. If the soil moisture content is found to be dry of optimum, the soil moisture content should be raised using liberal sprinkling, flooding or another suitable method. Following lime treatment, the treated soil should be properly cured by continual sprinkling with water to keep the surface damp, combined with light rolling to keep the surface knitted together. The subgrade soils should be covered with at least two inches of Class 2 aggregate base within three days of lime treatment in an effort to reduce drying. Periodic sprinkling is still required to keep the surface damp. As an alternative, the treated soil could be cured as discussed in Section 24 of the Caltrans Standard Specifications. Although lime treatment has performed well for hundreds of developments in the general project area, isolated problems have occasionally occurred due to a lack of quality control during construction, swelling if the underlying, untreated clay is dry, and/or inadequate curing following lime treatment. Accordingly, these factors are considered critically important. Prior to earthwork operations, our firm should review the lime contractor's proposed treatment procedures. Laboratory tests should be performed at least two weeks prior to earthwork operation in order to assess or revise the required lime application rate. Also, a representative from our firm should be on-site during treatment operations to document spreading, mixing and compaction operations and provide supplemental/revised recommendations, if warranted, based on the soil conditions observed. 5.6.3 Capillary Break Groundwater should not rise near surface and adversely impact the structural performance of the floor slabs. In areas where the floor slabs will be covered with moisture-sensitive flooring, it has been common practice and industry standard in the project area to place a capillary break consisting of at least 4 inches of free draining crushed gravel on the finished subgrade soil that, in turn, is overlain by a flexible sheet membrane, such as Stego WrapTM, Moistop PIusTM, or an equivalent meeting the requirements of ASTM E1745, that serves as a water and/or moisture vapor retarder. The crushed gravel should be graded so that 100 percent passes the 1-inch sieve and less than 5 percent passes the No. 4 sieve. Care should be taken to properly place, lap, and seal the membrane in accordance with the manufacturer's recommendations to provide a vapor 20210067.001A/ST020R111447 Page 22 of 37 May 11, 2020 ©2020 Kleinfelder www.kleinfelder.com