1004 BROADWAY EVCC STUDENT HOUSING - REPORTS & FINAL DOCUMENTS 2017-01-13

Geotechnical Report - iu; e�ised � Proposed Apartments: 1002, 1006, and 1008 Broadway Street, Everett, Washington May 12, 2015 S.2 TEMPORARY SHORING In our opinion, soldier pile walls with timber lagging or ecology block walls are appropriate temporary shoring options. The shoring system should be designed to provide adequate protection for the workers, adjacent structures, utilities, and other facilities. Excavations should be performed in accordance with the current requirements 01� WISHA. Construction should proceed as rapidly as feasible, to limit the time temporary excavat�ons are open. S.3 SOLDIER PILE TEMPORARY SHORING Soldier pile temporary shoring consists of vertical steel beams, typically spaced from 6 to 8 feet apart along the proposed excavation aligninent, spanned by timber lagging. Prior to the start of excavation, the steel beams are installed in holes drilled to a design depth and then backfilled with lean mix or structural concrete. As the excavation proceeds downward and the steel piles are subsequently exposed, timber lagging is installed between the piles to further stabilize the walls of the excavation. Tiebacks are typically used for wall heights greater than about 12 feet to achieve a mare economical design� With the planned excavation extending to a maximum depth of about 10 feet, we do not anticipate tie-backs will be needed. 5.3.1 Wal! Design Parameters The earth pressures depicted on Figure 3 lnay be used for the shoring design. The vertical capacity of the soldier piles should be determined using an allowable skin friction value of 0.5 ksf for the portion of the pile below the bottom of the excavation, and an allowable end soil bearing capacity vahie of 10 ksf. 5.3.Z LQag111a Lagging design recommendations are presented on Figure 3. Lagging located within 10 feet of the top of the shoring which inay be subjected to surcharge loads from construction equipment or material storage should be designed for an additional uniform lateral surcharge pressure of 200 psi�. This pressure approximately corresponds to a vertical uniform surcharge load of 500 psf at the top of the wall. I �-048 1008 Broadway, Revised PagO 1 1 PanGEO, InC.