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Geotechnical Investigation Report 03/11/2025 2234 S Lowell St., Santa Ana, CA 92707 Page | 4 Surface Conditions The topography of the project site and the surrounding area is relatively flat, and the area is residentially developed. The site’s topsoil consists of clayey fine sand. Based on the ASCE Hazard Tool, the site’s elevation is 46 feet with respect to north American Vertical Datum of 1988 (NAVD 88). Subsurface Conditions Based on the extracted soil samples, the subsurface formations are mainly alluvium deposits consisting of clayey fine sand. The field penetration resistance testing indicates that the apparent density of the subsurface formations within the investigated depth is loose to medium dense. Caving Potential The proposed site is underlain mainly by coarse-grained sandy soils with relatively little apparent cohesion; therefore, caving potential is expected during foundation’s excavation work. Shallow temporary non-surcharged excavations (less than 5 feet deep) sloped (1H:1V) should be considered stable during the foundation construction time. Cal/OSHA safety regulations should be taken into consideration for any underground construction. Expansion Potential The subsurface formations consisted mainly of cohesionless coarse-grained sandy soils; therefore, expansion potential was not tested and considered not exist for the project site. Soil Corrosivity During the investigation, a bulk soil sample was collected from the top two (2) feet for corrosion testing. The result of the corrosion test indicates that the subsurface soil is not corrosive to the foundation’s concrete. Corrosion test results are presented in Table -1: Table 1– Corrosion Test Results Sample Materials Elevation (feet) Minimum Resistivity (Ohm-cm) PH Chloride content (ppm) Sulfate Content (ppm) Corrosive? Clayey fine sand 46-42 3242 7.0 37 397 No Soil Shrinkage and Bulking Bulking is the increase of volume of the earth material when it is excavated. Shrinkage is the decrease in volume of the earth material when it is compacted. Contingencies should be made to adjust the earthwork balance when grading is in progress and the bulk-shrink is better defined. The bulking factor is estimated to range from 10 to 20 percent. The shrinkage factor is estimated to range from 10 to 20 percent. These estimated values are based on the limited data collected from the subsurface exploration, available information at the time of this report,