4102 RUCKER AVE SAFEWAY FUELING STATION 2016-01-01 MF Import

GEOTECHNICAL ENGINEERING STUDY Inform, Inc May 9, 2002 E-8493-5 Page 10 Temporary cuts greater than four feet in height in Type C soils should be sloped at an inclination no steeper than 1.5H:1 V(Horizontal:Verticaq. The underlying dense to very dense native soil would be classified as Type A soils, provided the soil is not wet at the time of excavation. Temporary slopes in Type A soils should be inclined no steeper than 0.75H:1 V. If the soils are wet to saturated at the time of construction, the soils should be treated as a Type C soil and the temporary slope gradient reduced accordingly. Because of the many variables involved, the inclination of temporary excavation slopes must be evaluated by the geotechnical engineer during constructioii, as the actual soil conditions become more apparent. If slope inclinations described above cannot be constructed, temporary shoring may be necessary. Shoring will help protect against slope or excavation collapse, and will provide protection to workers in the excavation. If temporary shoring is required, ECI will be available to provide shoring design criteria. Permanent cut and fill slopes should be inclined no steeper than 2H:1 V. Cut slopes should be observed by ECI during excavation to verify that soil and groundwater conditions are as anticipated. Supplementary recommendations can then be developed, if needed, to improve stability, including flattening of slopes or installation of suriace or subsurface drains. Site Drainage Moderate to heavy groundwater seepage was encountered in localized zones from five feet below c�rade to the maximum exploration depth at our borinfl locations. As such, groundwater will likely be encountered in the underground storage tank and deep utility excavations, dependinp on the time of year the excavation is completed. ECI should observe the tank oxcavation to verify proundwater conditions. As proviously discussed, ECI should also review the underground storage tank design to assess possible uplift forces created by groundwator conditions. If seepage is encountered, tho bottom of the excavation should be sloped to one or more shallow sump pits. Thc collected water can then be pumped from thesa pits to a positivo and permanent discharpe, such as a nearby storm drain. Depending on the magnitudo ot such seepafle, it may also be necessary to connect the sump pits by a system ot connector trenches. Cnnh Cnnaullnnh, Inr..