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American Property Development ES-0599.06 <br /> June 9, 2016 Page 5 <br /> Revised October 16, 2017 <br /> With respect to adjacent property surcharge loading on the shoring system, further assessment <br /> of adjacent building structures and foundation elevations relative to the shoring system and <br /> foundation walls will be needed, as appropriate, based on the final siting and design finish floor <br /> elevation of the building. For purposes of this study, we have provided preliminary surcharge <br /> values for design of temporary shoring and permanent foundations walls, as appropriate. <br /> As previously, discussed, localized zones of groundwater seepage could be encountered. As <br /> such, groundwater seepage could be encountered in the proposed excavation which is <br /> anticipated to be advanced to depths of approximately 18 to 25 feet below existing grades. The <br /> presence of groundwater seepage in deeper utility excavations should also be anticipated. <br /> This geotechnical engineering study has been prepared for the exclusive use of American <br /> Property Development and their representatives. The study has been prepared specifically for <br /> the subject project. No warranty, expressed or implied, is made. This study has been prepared <br /> in a manner consistent with the level of care and skill ordinarily exercised by other members of <br /> the profession currently practicing under similar conditions in this area. <br /> Site Preparation and Earthwork <br /> The primary geotechnical considerations with respect to earthwork are related to the proposed <br /> building's excavation, temporary slope construction, temporary excavation support, and <br /> foundation subgrade preparation. The soils encountered in the building excavations should <br /> largely consist of dense to very dense silty sand deposits. These soils should generally be <br /> suitable for use as structural backfill, where needed. The native soils can be characterized as <br /> having a generally moderate sensitivity to moisture. Therefore, if the soils are exposed to <br /> excessive moisture, successful placement and compaction of the soil may be difficult. <br /> Excavations <br /> As excavation of the proposed building progresses, the soil relative density should generally <br /> increase and is expected to exhibit good stability in open cut excavations. Overall stability of <br /> the excavation is anticipated to be good, provided appropriate means for sloping and shoring <br /> the excavation are utilized. Based on the soil conditions observed at the test sites, the <br /> following allowable temporary slope inclinations can be used: <br /> • Upper 4 Feet of Excavation 1 H:1V(Horizontal:Vertical) <br /> • Below 4 Feet 0.5H:1V to 0.75H:1V <br /> The geotechnical engineer should observe the excavation and assess the allowable temporary <br /> slope inclination based on the soil and groundwater conditions exposed in the excavation. <br /> Supplement recommendations for sloping the excavation may be made by the geotechnical <br /> engineer based on conditions observed. <br /> With respect to temporary shoring, recommendations are provided in the Shoring <br /> Recommendations section of this study. <br /> Earth Solutions NW,LLC <br />