2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

sc 130 Milbor-Pita &S90CLAM W_ installation includes the presence of oversize materials, however these were not observed during our investigation. • Driven Piles: Installation of driven piles, steel pipe or pre -stressed concrete, should not be adversely affected by groundwater or the possible presence of oversize material underlying the site. As a result, few construction -related problems should be expected for driven pile installation. However, pile driving is not without its impacts. Pile driving is a noisy operation that can create undesirable vibrations in the ground and nearby structures. Pile driving in close proximity to brick and older masonry buildings can produce vibrations that cause some cracking to develop. Use of driven piles will necessitate construction of a below -grade pile cap that will require excavation and shoring. Shoring and excavation are discussed below in more detail. • Geotechnical Monitoring of Deep Foundation Installations: All pile or drilled shaft installation operations should be observed by the project geotechnical engineer. • Drilled Shafts and Auger -Cast Piles: During installation of drilled shafts and auger -cast piles, soil conditions encountered should be verified by the project geotechnical engineer. For drilled shafts, the project engineer will inspect the bottom of the shaft to verify that dense, competent soil is exposed. Because auger -cast piles are constructed without an open hole, cuttings should be observed during drilling by the engineer to verify sufficient embedment into the competent bearing soil. Grout volume and pressure should be measured during auger -cast pile installation to monitor pile integrity as well. While it is not possible when installing auger -cast piles, drilled shafts of sufficient diameter can be inspected following drilling. Inspection of drilled shafts involves physically lowering a geotechnical engineer/inspector or a remotely operated video camera into the shaft and visually observing the base of the cleaned -out shaft. As described earlier, if a shaft can be inspected, additional end bearing support can be assumed for des'Ign of the shaft. • Driven Piles: Steel pipe and pre -stressed concrete piles should be driven using an approved top -impact hammer; piles should not be jetted. Impact hammer selection will depend on pile type, pile section, design load, the contractor's methods, and other factors. Concrete piles are more sensitive to the level of driving energy applied by the Geoteclulic&l Tunnel and Environmental tii &eas 3080 1251° Ave NE Phane (425) 969-5778 nellnuc, WA98W5 Page 13 Fax (425)961-0677