4815 EVERGREEN WAY 2016-01-01 MF Import

JP Morgan Chase April 29, 2010 Geotechnical Investigation Proposed Chase Bank Everetf, WA PSI Report No. 0704186 site excavations have been completed to determine if there are areas of unsuitable soil. Our representative should observe a procfroll of the site using a fully-loaded 18-ton dump truck to identify areas of excessive yielding. If areas of soft soil or excessive yielding are identified, the material should be over-excavated and replaced with compacted materials as recommended for structural fill. We note that removal of the existing structures and subsequent foundation and utilities will most likely disturb the upper 2 to 4 fFet of these areas. Such areas will require removal and re-compaction as discussed herein. Proofrolling of the subgrade should not be performed during wet weather or if wet ground conditions exist. Instead, the subgrade should be evaluated by probing. Soils that have been disturbed during site preparation activities, or soft or loose zones identified during prabing, should be removed and replaced with structural fill. 4.3 CONSTRUCTION CONSIDERATIONS The near surface fiil materials at the site might not support heavy trucks or line trucks when wet. We recommend constructing access roads for construction vehicles consisting of at least 6 inches of crushed rock that conforms to the gradation as recommended below in the "Structural Fiil" section of this report. 4.4 UTILITY TRENCH EXCAVATION AND BACKFILL Excavations should be made in accordance with applicabte Federal and 8tate Occupational Safety and Health Administration regulations. Utii!`.y trenches in the near surface silty sands should stand vertical to a depth of approximately 2 to 4 feet. Flatter inc!inations may be appropriate and will ultimately depend on the soil conditions encountered during earthwork. While we may provide certain approaches for trench excavations, tha contractor should be responsible for selecting the excavation technique, monitoring the lrench excavations for safety, and providing shoring, as required, to protect personnel and adjacent improvements. Excavalion and construction operations may expose the on site soils to inclement weather conditions. The stability of exposed soils may deteriorate due to a change in moisture content or the action of heavy or repeated conslruction tra�c. Accordingly, foundation and pavement area excavations should be protected from the elements and from the action of repetitive or heavy construction loadings. Trench backfill should conform to the recommendations provided for structural fill. In addition, backfill of the pipe embedment zone, including the bedding zone and pipe zone, should be placed and compacted in maximum lifts of 6 inches. Trench backfill above the pipe zone should be placed and compacted with a minimum of two lifts. A minimum cover of 3 feet over the top of the pipe should be placed before compacting with a hydraulic plate compactor(hoe-pack). P�`�� 4