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• • <br /> January 9,2019 <br /> age30t4 <br /> Lim e Geologic Evaluation <br /> If any variations or undesirable conditions are encountered during construction, we should be <br /> notified so that supplemental recommendations can be made. If room constraints or <br /> groundwater conditions do not permit temporary slopes to be cut to the maximum angles allowed <br /> by the WAC,temporary shoring systems may be required. <br /> The contractor should be responsible for developing temporary shoring systems, if needed. We <br /> recommend that Cobalt Geosciences and the project structural engineer review temporary <br /> shoring designs prior to installation,to verify the suitability of the proposed systems. <br /> Erosion and Sediment Control <br /> Erosion and sediment control (ESC) is used to reduce the transportation of eroded sediment to <br /> wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment <br /> control measures should be implemented, and these measures should be in general accordance <br /> with local regulations. At a minimum, the following basic recommendations should be <br /> incorporated into the design of the erosion and sediment control features for the site: <br /> • Schedule the soil,foundation,utility, and other work requiring excavation or the disturbance <br /> of the site soils, to take place during the dry season (generally May through September). <br /> However,provided precautions are taken using Best Management Practices (BMP's),grading <br /> activities can be completed during the wet season(generally October through April). <br /> • All site work should be completed and stabilized as quickly as possible. <br /> • Additional perimeter erosion and sediment control features may be required to reduce the <br /> possibility of sediment entering the surface water. This may include additional silt fences,silt <br /> fences with a higher Apparent Opening Size(AOS),construction of a berm,or other filtration <br /> systems. <br /> • Any runoff generated by dewatering discharge should be treated through construction of a <br /> sediment trap if there is sufficient space. If space is limited other filtration methods will need <br /> to be incorporated. <br /> Closure <br /> The information presented herein is based upon professional interpretation utilizing standard <br /> practices and a degree of conservatism deemed proper for this project. We emphasize that this <br /> report is valid for this project as outlined above and for the current site conditions,and should not <br /> be used for any other site. <br /> www.cobaltgeo.com (206)3314o97 <br />