2631 WALNUT ST JACKSONS Geotech Report 2025-07-28

1 Jackson's aka PacWest Energy LLC JN 13465 ' December 9, 2013 Page 4 The drainage and/or waterproofing recommendations presented in this report are intended only to prevent active seepage from flowing through concrete walls or slabs. Even in the absence of active seepage into and beneath structures, water vapor can migrate through walls, slabs, and floors from the surrounding soil, and can even be transmitted from slabs and foundation walls due to the concrete curing process. Water vapor also results from occupant uses, such as cooking and bathing. Excessive water vapor trapped within structures can result in a variety of undesirable ' conditions, including, but not limited to, moisture problems with flooring systems, excessively moist air within occupied areas, and the growth of molds, fungi, and other biological organisms that may be harmful to the health of the occupants. The designer or architect must consider the potential vapor sources and likely occupant uses, and provide sufficient ventilation, either passive or mechanical, to prevent a build up of excessive water vapor within the planned structure. We recommend including this report, in its entirety, in the project contract documents. This report ' should also be provided to any future property owners so they will be aware of our findings and recommendations. ' SEISMIC CONSIDERATIONS ' In accordance with the International Building Code (IBC), the site soil profile within 100 feet of the groundsurface is best represented by Site Class Type C (Very Dense Soil and Soft Rock). As noted in the USGS website, the mapped spectral acceleration value for a 0.2 second (Se) and 1.0 ' second period (Si)equals 1.16g and 0.41g, respectively. The site soils are not susceptible to seismic liquefaction because of their dense nature. CONVENTIONAL FOUNDATIONS ' See the section entitled Genera! Earthwork and Structural Fill for recommendations regarding the placement and compaction of structural fill beneath structures. We recommend that continuous and individual spread footings have minimum widths of 16 and 24 inches, respectively. Exterior ' footings should also be bottomed at least 18 inches below the lowest adjacent finish ground surface for protection against frost and erosion. The local building codes should be reviewed to determine if different footing widths or embedment depths are required. Footing subgrades must ' be cleaned of loose or disturbed soil prior to pouring concrete. Depending upon site and equipment constraints, this may require removing the disturbed soil by hand. ' Depending on the final site grades, overexcavation may be required below the footings to expose competent native soil. Unless lean concrete is used to fill an overexcavated hole, the overexcavation must be at least as wide at the bottom as the sum of the depth of the overexcavation and the footing width. For example, an overexcavation extending 2 feet below the ' bottom of a 2-foot-wide footing must be at least 4 feet wide at the base of the excavation. If lean concrete is used, the overexcavation need only extend 6 inches beyond the edges of the footing. A typical detail for overexcavation beneath footings is attached as Plate 8. ' An allowable bearing pressure of 2,500 pounds per square foot (psf) is appropriate for footings supported on competent native soil. A one-third increase in this design bearing pressure may be ' used when considering short-term wind or seismic loads. For the above design criteria, it is anticipated that the total post-construction settlement of footings founded on competent native soil, 1