8417 EVERGREEN WAY Geotech Report 2022-10-25

Geotechnical Engineering Report-Revised lierracon Proposed CFT Retail •Everett,Washington February 1, 2018 •Terracon Project No. 81185002 In addition, SSC-6 precludes site infiltration of stormwater in the"uncontrolled or non-engineered fill soils" at the site observed above the till. As required by SSC-7, impacts to neighboring properties, would also indicate that on-site infiltration is not feasible as collection and infiltration of storm water run-off may create a slope stability of an approximate 2.5 horizontal: 1 vertical slope approximately 8 or so feet in height located on the neighboring property near the southern property line of our site. In review of the above, site infiltration does not appear feasible per the requirements of the manual. 4.2.6 Construction Considerations It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment, although cobbles and boulders may be encountered. Upon completion of filling and grading, care should be taken to maintain the subgrade moisture content prior to construction of floor slabs and pavements. Construction traffic over the completed subgrade should be avoided to the extent practical. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. If the subgrade should become frozen, desiccated, saturated, or disturbed, the affected material should be removed or these materials should be scarified, moisture conditioned,and recompacted prior to floor slab and pavement construction and observed by Terracon. Surface water should not be allowed to pond on the site and soak into the soil during construction. Construction staging should provide drainage of surface water and precipitation away from the building and pavement areas. Any water that collects over or adjacent to construction areas should be promptly removed, along with any softened or disturbed soils. Surface water control in the form of sloping surfaces, drainage ditches and trenches, and sump pits and pumps will be important to avoid ponding and associated delays due to precipitation and seepage. Conventional dewatering methods, such as pumping from sump pits, may be adequate for temporary removal of groundwater encountered during dry months. Construction in wetter months may require a more robust dewatering system to remove water from excavations. It should be noted that dewatering systems are typically designed by the contractor performing the work. Temporary excavations will likely be required during grading operations. The grading contractor, by contract, is usually responsible for designing and constructing stable, temporary excavations and should shore, slope or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. All excavations should comply with applicable local, state and federal safety regulations, including the current Occupational Health and Safety Administration (OSHA) Excavation and Trench Safety Standards. All excavations should be sloped or braced as required by OSHA regulations to provide stability and safe working conditions. Responsive ■ Resourceful ■ Reliable 8