Thomco Construction Inc. 6/14/2021

I KRAZAN&ASSOCIATES, INC. KA Project No. 092-20006 DRAFT Geotechnical Engineering Investigation Everett Water Main"V" May 7,2020 Page No. 14 soil boring B-9 from about 0.5 to 4.5 feet in depth. Groundwater levels may fluctuate within respect to time and location. In our opinion, there is the potential for perched groundwater seepage to occur during construction. Moisture Sensitive Soils: The soils encountered in our explorations are considered to be moisture sensitive and will be difficult or impossible to compact in wet conditions. Some of the site soils may be suitable for use as trench backfill; however, this will depend on the moisture content of the soils at the time of construction. It may be prudent to include the cost of imported all weather fill material in the project budget in case of wet weather. Krazan and Associates is available on request to evaluate the suitability of the on-site soils for use as structural fill material at the time of construction. Temporary Excavations I The onsite soils have variable cohesion strengths,therefore the safe angles to which these materials may be cut for temporary excavations is variable. The soils may be prone to caving and slope failures in111 temporary excavations. Temporary shoring such as trench boxes may be used to support steep cuts for the trench walls. The dense to very dense granular glacial till may be temporarily stable with near vertical inclinations of the trench walls up to about 4 feet in height depending on surface water and groundwater conditions. All temporary cuts should be in accordance with Washington Administrative Code (WAC) Part N, 1 Excavation, Trenching, and Shoring. The temporary slope cuts should be visually inspected daily by a qualified person during construction work activities and the results of the inspections should be included in daily reports. The contractor is responsible for maintaining the stability of the temporary cut slopes and minimizing slope erosion during construction. The temporary cut slopes should be covered with plastic sheeting during wet weather to help minimize erosion and the slopes should be closely monitored until trench backfill is complete. A representative of the geotechnical engineer should observe, at least periodically, the temporary cut slopes during the excavation work. The reason for this is that all soil conditions may not be fully delineated by the limited sampling of the site from the geotechnical explorations. In the case of temporary slope cuts, the existing soil conditions may not be fully revealed until the excavation work exposes the soil. Typically, as excavation work progresses the maximum inclination of the temporary slope will need to be evaluated by the geotechnical engineer so that supplemental recommendations can be made. Soil and groundwater conditions can be highly variable. Scheduling for soil work will need to be adjustable to manage unanticipated conditions, so that the project can proceed smoothly and required deadlines can be met. If any variations or undesirable conditions are encountered during construction, the geotechnical engineer should be notified so that supplemental recommendations can be made. Krazan&Associates,Inc. 1 Offices Serving The Western United States I