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. 17 the U.S. Standard No. 200 Sieve). All structural fill material should be submitted for approval to the geotechnical engineer at least 48 hours prior to delivery to the site. Fill soils should be placed in horizontal lifts not exceeding 8 inches in thickness prior to compaction, moisture-conditioned as necessary, (moisture content of soil shall not vary by more than±2 percent of optimum moisture) and the material should be compacted to at least 95 percent of the maximum dry density based on ASTM D1557 Test Method. In-place density tests should be performed on all structural fill to document proper moisture content and adequate compaction. Additional lifts should not be placed if the previous lift did not meet the compaction requirements or if soil conditions are not considered stable. Erosion and Sediment Control Erosion and sediment control (ESC) is used to minimize the transportation of sediment to wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures should be taken and these measures should be in general accordance with local regulations. As a minimum, the following basic recommendations should be incorporated into the design of the erosion and sediment control features of the site: 1) Phase the utility and other work,requiring excavation or the disturbance of the site soils,to take place during the dry season (generally May through September). However, provided precautions are taken using Best Management Practices (BMPs), utility installation activities can be undertaken during the wet season(generally October through April),but it should also be known that this may increase the overall cost of the project. 2) All site work should be completed and stabilized as quickly as possible. 3) Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering the surface water. This may include the construction of small berms or other filtration systems. 4) Any runoff generated by dewatering discharge should be treated through construction of a sediment trap if there is sufficient space. If space is limited, other filtration methods will need to be incorporated. Groundwater Influence on Earthwork Construction The soil borings were observed for the presence of groundwater during drilling operations. We observed groundwater seepage in soil boring B-4 at a depth of approximately 5.0 feet, and in soil boring Krazan&Associates,Inc. Offices Serving The Western United States I