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EARTH STRATA GEOTECHNICAL SERVICES 17 March 30, 2023 Project Number 234812-10A Preliminary Post Tensioned Foundation Slab Design PARAMETER VALUE < 40 percent (assumed) variation distance, em 5.5 feet 3.0 inches em 4.0 feet 1.5 inches Negligible 120 pci 24 2Under Slab Moisture/Vapor Barrier and Sand Layer 10-mil thick moisture/vapor barrier meeting the requirements of a ASTM E 1745 Class A material 2. Recommendations for foundation reinforcement are ultimately the purview of the foundation/structural engineer based upon the geotechnical criteria presented in this report, and structural engineering considerations. Corrosivity Corrosion is defined by the National Association of Corrosion Engineers (NACE) as “a deterioration of a substance or its properties because of a reaction with its environment.” From a geotechnical viewpoint, the “substances” are the reinforced concrete foundations or buried metallic elements (not surrounded by concrete) and the “environment” is the prevailing earth materials in contact with them. Many factors can contribute to corrosivity, including the presence of chlorides, sulfates, salts, organic materials, different oxygen levels, poor drainage, different soil types, and moisture content. It is not considered practical or realistic to test for all of the factors which may contribute to corrosivity. The potential for concrete exposure to chlorides is based upon the recognized Caltrans reference standard “Bridge Design Specifications”, under Subsection 8.22.1 of that document, Caltrans has determined that “Corrosive water or soil contains more than 500 parts per million (ppm) of chlorides”. Based on limited preliminary laboratory testing, the onsite earth materials have chloride contents less than 500 ppm. As such, specific requirements resulting from elevated chloride contents are not required. 2130 E 4th St 2/11/2025