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ENGEO <br /> INCORPORATED <br /> <br /> <br />5150.100.101 <br />May 2, 2008 Page 6 <br />5. CONCLUSIONS <br /> <br />From a geotechnical engineering viewpoint, in our opinion, the site is suitable for the proposed <br />development. The primary geotechnical concerns that could affect development on the site are <br />areas of expansive soil, perched groundwater conditions, potential seismic hazards and <br />excavatability of native rock. We summarize our conclusions below. <br /> <br />5.1 EXPANSIVE SOIL <br /> <br />Expansive clay should not affect the proposed development based on our subsurface <br />explorations, laboratory test results, and preliminary project data presented in Section 4. Shallow <br />depths of expansive clay were found in Borings 1-B2 and 1-B3. Deeper areas of expansive clay <br />were found in 1-B1 and 1-B4, with thicker colluvium soils on the eastern portion of the site and <br />as discussed in Section 2.3. We anticipate that most if not all of this material will be removed <br />during site grading. If any expansive material is encountered at the base of the cuts, the cut <br />should be extended to non-expansive material or a maximum of 3 feet below finished grade and <br />backfilled with suitable material as discussed in the Acceptable Fill portion of this report. <br />Expansive clay should be off hauled from the site. In order to confirm our conclusions, we <br />should be retained to review final grading and site improvement plans, and to observe and test <br />site grading operations. <br /> <br />5.2 EXCAVATABILITY <br /> <br />We used a B24 drill rig to perform our exploratory work. Based upon our observation and <br />experience, conventional grading and backhoe equipment will likely be able to excavate the soil <br />and rock deposits in the upper 5 to 15 feet at the locations explored. More difficult conditions <br />are likely to be encountered below these depths that will require greater excavation effort. <br />