1584 E Santa Clara Ave - Soils Report

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11932.003 Drainaqe The lateral active and at-rest pressure values presented in Table 1 are based upon drained conditions behind the wall. Therefore, design of the retaining walls should include provisions for drainage such as a permanent subdrain at the base of the wall that is sloped at a minimum of one percent toward an approved non-erosive outlet. The subdrain is recommended to consist of 4-inch diameter perforated pipe (perforations at bottom) embedded within a free-draining, clean %-inch nominal diameter crushed aggregate (typically 1 cubic foot per lineal foot) wrapped in filter fabric. Surface drainage should be designed to direct water away from foundations and toward approved drainage devices. lrrigation of landscaping should be controlled to maintain, as much as possible, consistent moisture content sufficient to provide healthy plant growth without ovenltratering. Review of the precise grading plans indicates the garage driveways will consist of Portland cement concrete of a thickness in accordance with the recommendations of the geotechnical engineer. Recommendations specific to driveway pavement were not presented in the referenced geotechnical reports by Alta (2015, 2017a,2017b,2017c and 2018). Therefore, we recommend that the driveways consist of a minimum S-inch thick Portland cement concrete pavement supported by a properly prepared subgrade. Preparation of the subgrade prior to concrele placemenl is recommended to include scarification, moisture conditioning as necessary followed by recompaction of the soils to a minimum of 90 percent of the ASTM D1557 maximum dry density. Unless superseded by the recommendations presented in this report, the recommendations presented in our previous report (Leighton, 201 8b) and the referenced reports by Alta (2015, 2017a, 2O17b, 2017c and 2018) remain valid and should be incorporated in the design and construction of the project. 5 € Leighton Drivewav Pavement Desiqn Considerations