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Page 2 <br /> <br />The site is relatively flat; and we understand that additional grading / raw cut/raw fill is <br />not proposed for the site. <br /> <br />Geotechnical Conditions <br /> <br />The subject site is a previously graded lot where a house exists. The on-site soils were <br />previously properly treated, as necessary, and evaluated to be suitable for structural <br />support prior to approval for construction of the existing house. Distress to the existing <br />house due to settlement and/or any other geotechnical issues was not observed / reported. <br />Therefore, deep-seated settlement of the soils underlying the site is not considered to be a <br />concern for the proposed addition of an ADU onto the subject approved lot. <br /> <br />Based on the State of California SEISMIC HAZARD ZONES Map, Orange Quadrangle, <br />the subject site is located within a potential liquefaction zone. For conservative purposes, <br />we assume that the site will be subjected to the liquefaction; and to mitigate the potential <br />adverse effects due to potential liquefaction, as for other recent near-by projects, a <br />strengthened/stiffened foundation system [in accordance with the Special Publication <br />117A (SP117A), “Guidelines for Evaluating And Mitigating Seismic Hazards in <br />California” dated 2008, published by California Geotechnical Survey (CGS), page 60] is <br />recommended to be used for the proposed new structure. <br /> <br />To verify the near ground surface soils, a 5 ft. deep test hole has been drilled using a <br />hand-held drilling tool and soil samples were collected for laboratory testing. The <br />approximate location of the test hole is depicted on the Site Plan / Geotechnical Map. The <br />geotechnical boring log and summary of results of the laboratory testing are included in <br />Appendix B. <br /> <br />Based on the data of our test hole, the near ground surface earth materials generally <br />consisted of silty fine sand with minor clay, damp to moist, medium dense and have a <br />very low expansion potential. <br /> <br />It is noted that, based on the State of California SEISMIC HAZARD ZONES Map, <br />Orange Quadrangle, the subject site is located within a potential liquefaction zone. For <br />conservative purposes, (instead of performing a conventional site-specific geotechnical <br />including drilling a 50 ft deep test hole with soil sampling, laboratory testing and <br />engineering calculations / analysis to verify whether the site is subject to liquefaction or <br />not), we assume that the site will be subjected to the liquefaction; and to mitigate the <br />potential adverse effects due to potential liquefaction, as for other near-by projects, a <br />strengthened/stiffened foundation system [as mentioned in the Special Publication 117A <br />(SP117A), “Guidelines for Evaluating And Mitigating Seismic Hazards in California” <br />dated 2008, published by California Geotechnical Survey (CGS), page 60] is <br />recommended to be used for the proposed new structure. <br /> <br /> <br />Groundwater <br />