200 W MARINE VIEW DR Geotech Report 2025-08-07

October 16,2020 Project No. T-8221 Groundwater should be anticipated within excavations extending below the existing fill into the native sands. If the excavation only extends two to three feet below the groundwater table, the volume of water and rate of flow into the excavation is expected to be moderate and are not expected to impact the stability of the excavations when completed, as described. Conventional sump pumping procedures, along with a system of collection trenches, if necessary should be capable of maintaining a relatively dry excavation for construction purposes. Deeper excavations that will require worker entry will likely require pre-draining using deep pump wells or closely spaced well points. Obstructions, debris, and rubble were found within the lower fills at some of the site explorations. For deep excavations at the site, such as those made for utility construction,the contractor should be prepared to remove the obstructions as needed for construction. This information is provided solely for the benefit of the owner and other design consultants, and should not be construed to imply that Terra Associates, Inc. assumes responsibility for job site safety. It is understood that job site safety is the sole responsibility of the project contractor. 5.4 Foundations The building may be supported on conventional spread footing foundations bearing on foundation subgrade prepared as recommended in Section 5.2 of this report. Perimeter foundations exposed to the weather should bear at a minimum depth of 1.5 feet below final exterior grades for frost protection. Interior foundations can be constructed at any convenient depth below the floor slab. We recommend designing foundations for a net allowable bearing capacity of 2,500 pounds per square foot(psf). For short-term loads, such as wind and seismic, a one-third increase in this allowable capacity can be used. Following successful completion of the preload program, estimated primary consolidation settlement due to building loads are less than one-half inch. For designing foundations to resist lateral loads, a base friction coefficient of 0.35 can be used. Passive earth pressures acting on the sides of the footings can also be considered. We recommend calculating this lateral resistance using an equivalent fluid weight of 300 pounds per cubic foot (pcf). We recommend not including the upper 12 inches of soil in this computation because it can be affected by weather or disturbed by future grading activity. This value assumes the foundations will be backfilled with structural fill, as described in Section 5.2 of this report. The values recommended include a safety factor of 1.5. 5.5 Slab-on-Grade Floors Slabs on grade may be supported on subgrade prepared as recommended in Section 5.2 of this report. Immediately below the floor slabs,we recommend placing a four-inch thick capillary break layer of clean, free-draining, coarse sand or fine gravel that has less than three percent passing the No.200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slabs. Page No. 7