Laserfiche WebLink
I <br /> KRAZAN&ASSOCIATES,INC. 1 <br /> KA Project No. 092-20006 <br /> DRAFT Geotechnical Engineering Investigation <br /> Everett Water Main"V" <br /> May 7,2020 <br /> Page No. 18 <br /> 1 <br /> B-7 at a depth of about 5.0 feet. Moist to wet conditions were encountered in soil boring B-9 from <br /> about 0.5 to 4.5 feet in depth. <br /> Groundwater fluctuations can occur over time. Therefore, it is possible that groundwater seepage could <br /> occur in different portions of the project areas during construction. If groundwater is encountered <br /> during construction, Krazan should observe the conditions to determine if dewatering will be needed. <br /> Design of temporary dewatering systems to remove groundwater should be the responsibility of the <br /> contractor. i <br /> If earthwork is performed during or soon after periods of precipitation, the subgrade soils may become <br /> saturated. These soils may "pump," and the materials may not respond to densification techniques. <br /> Typical remedial measures include: disking and aerating the soil during dry weather; mixing the soil <br /> with drier materials; removing and replacing the soil with an approved fill material. A qualified <br /> geotechnical engineering firm should be consulted prior to implementing remedial measures to observe <br /> the unstable subgrade conditions and provide appropriate recommendations. <br /> Lateral Earth Pressures <br /> The need for shoring, such as trench boxes, is anticipated to support excavation walls in the loose fill <br /> soils encountered in our explorations. Unrestrained shoring walls may be designed based on "active" <br /> earth pressure, if some movement of the retaining walls is acceptable. Acceptable lateral movement <br /> equal to at least 0.2 percent of the wall height would warrant the use of"active" earth pressure values <br /> for design. We recommend that walls supporting horizontal backfill and not subjected to hydrostatic <br /> forces be designed using a triangular earth pressure distribution equivalent to that exerted by a fluid <br /> with a density of 35 pcf for yielding (active condition) walls, and 55 pcf for non-yielding (at-rest <br /> condition)walls. <br /> The stated lateral earth pressures do not include the effects of hydrostaticpressuregenerated bywater <br /> Y <br /> accumulation behind the shoring walls or loads imposed by construction equipment,slopes,or roadways <br /> adjacent to the wall (surcharge loads). , <br /> Testing and Inspection <br /> A representative of the geotechnical engineer should be present at the site during the earthwork <br /> activities to confirm that actual subsurface conditions are consistent with the exploratory fieldwork. <br /> This activity is an integral part of our services as acceptance of earthwork construction is dependent , <br /> upon compaction testing and stability of the material. This representative can also verify that the intent <br /> of these recommendations is incorporated into the project design and construction. Krazan & <br /> Associates,Inc. will not be responsible for grades or staking, since this is the responsibility of the Prime I <br /> Krazan&Associates,Inc. <br /> Offices Serving The Western United States <br /> 1 <br />