1515 132ND ST SE Geotech Report 2022-10-25

Proposal for Geotechnical Engineering Services Proposed Bank: 1515 132°d Street Southeast, Everett, Washington March 15, 2019 Soft or yielding areas identified during proofrolling should be moisture conditioned as needed and re -compacted in place. If soft areas are still yielding after re -compaction, they should be overexcavated and replaced with structural fill to a depth that will provide a stable pavement base. The optional use of a geotextile subgrade stabilization fabric, such as Mirafi 600X, or an equivalent product placed directly on the over -excavated surface may help to bridge excessively unstable areas.. Overexcavated areas should be and backfilled with WSDOT 9-03.9(3) Crushed Surfacing Base Course, or WSDOT 9-03.14 (1) Gravel Borrow (WSDOT, 2018) compacted to the requirements of structural fill. The subgrade preparation should be observed by an individual experienced with earthwork construction, to verify the adequacy of the prepared subgrade. 6.2 TEMPORARY EXCAVATIONS AND SHORING Temporary excavations should be constructed in accordance with Part N of WAC (Washington Administrative Code) 296-155. The contractor is responsible for maintaining safe excavation slopes and/or shoring. It is our opinion temporary excavations in the fill soils and underlying native soils may be cut at a maximum 1 H:1 V inclination. Temporary excavations should be evaluated in the field during construction based on actual observed soil conditions. If seepage is encountered, excavation slope inclinations may need to be reduced. During wet weather, the temporary slopes may need to be flattened to reduce potential erosion or should be covered with plastic sheeting. 6.3 MATERIAL REUSE The native soils underlying the site are moisture sensitive, and will become disturbed and soft when exposed to inclement weather conditions. We do not recommend reusing the native soils as structural fill. If it is planned to use the native soil in non-structural areas, the excavated soil should be stockpiled and protected with plastic sheeting to prevent it from becoming saturated by precipitation or runoff. 6.4 STRUCTURAL FILL AND COMPACTION Structural fill, should be free of organic and inorganic debris, be near the optimum moisture content and be capable of being compacted to the recommendations provided below. The site soils are relatively fine grained and, in our opinion will not be suitable for re -use as structural fill and an imported structural fill will be needed. Fill for use during wet weather 19-049 1515 132nd St SE Page 11 PanGEO, Inc.