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

Geotechnical Report - _ __ . _sed Proposed Apartments: 1002, 1006, and 1008 Broadway Street, Everett, Washington May 12, 2015 Point loads located close to the top of the wall, such as outriggers of heavy cranes, may apply additional loads to the lagging. These loads, if applicable inay need to be individually analyzed. We recommend voids behind the lagging be backfilled with CDF. 5.4 ECOLOGY BLOCK SHORING Ecology blocks consist of concrete blocics with a typical din�ension of 2 feet high, 2 feet deep and 6 feet long. Based on the encotmtered soil conditions, in our opinion, ecology blocks can be used to shore the lower partion of the west excavation with a maximum height of three blocks, or 6 feet, with a 6V:1H (Vertical:Horizontal) batter. The blocks should be placed in a running bond pattern and the space between the blocks and excavation backfilled with clean crushed rock meeting the requirements for Permeable Ballast in the WSDOT Standard Specifications, Section 9-039(2) (WSDOT, 2014), or an approved equivalent. Clean rounded gravel such as pea gravel or washed gravel/drain rock should not be used to backfill the block wall. The base course of blocks should be embedded at least one foot below the construction subgrade elevation. The grade above the wall may be sloped at a 1 H:1 V inclination. The ecology block shoring may be placed in alignment with the walls of the building and can be used as the backform for the permanent basement walls. The joints between the blocks will allow groundwater to seep through the shoring. As the wall will be faced by the concrete basement walls, it will be necessary to provide drainage to collect the seepage and prevent hydrostatic pressures from building up behind the wall and concrete facing. For this application, a geotextile sheet drain incorporatin� a filter fabric such as Miradrain 6000, or equivalent, should be used. The sheet drain should connect to piping extending through the basement wall that connect to a collector pipe on the inside edge of the perimeter foundation. We recommend the ecology blocks be stockpiled on site before commencing with the excavation. This will allow for placing the blocks as the excavation progresses. PanGEO personnel should also be on site to observe the stability of the excavation and to monitor the ecology block wall construction. IS-048 100313roadway, Reviscd Pa�Te IZ PclnriEO., Inc.