1010 N BROADWAY EVCC 2018-01-01 MF Import

PROPOSED LIBERTY HALL,EVERETT COMMUNITY COLLEGE _- Everett,Washington actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. All disturbed areas should be finish graded and seeded as soon as practicable to reduce the risk of erosion. Erosion and sedimentation control measures should be installed and maintained in accordance with the requirements of the City of Everett. Excavations Excavations up to about 10 feet deep will be needed to construct the building. We anticipate that excavations can likely be made as temporary open cut slopes depending on site constraints. Where temporary cut slopes are.not feasible temporary shoring will be required. Excavations may also required for underground utilities. The stability of open cut slopes is a function of soil type, groundwater seepage, slope inclination, slope height and nearby surface loads. The use of inadequately designed open cuts could impact the stability of adjacent work areas, existing utilities,and endanger personnel. The contractor performing the work has the primary responsibility for protection of workmen and adjacent improvements. In our opinion, the contractor will be in the best position to observe subsurface conditions continuously throughout the construction process and to respond to variable soil and groundwater conditions. Therefore, the contractor should have the primary responsibility for deciding whether or not to use open cut slopes for much of the excavations rather than some form of temporary excavation support, and for establishing the safe inclination of the cut slope. Acceptable slope inclinations for utilities and ancillary excavations should be determined during construction. Because of the diversity ofconstruction techniques and available shoring systems, the design of temporary shoring is most appropriately left up to the contractor proposing to complete the installation. Temporary cut slopes and shoring must comply with the provisions of Title 296 WAC, Part N,"Excavation,Trenching and Shoring." The excavations will be completed primarily in fill, stiff to hard silt deposits, and dense to very dense silty sand. The following sections summarize the general excavation recommendations. If conditions allow, excavations for the proposed building may be accomplished using temporary cut slopes. • Potentially Contaminated Soil Excavations will occur in the vicinity of the Phase II environmental remediation areas. The contractor should review environmental documents for the site and understand potential environmental constraints. Temporary Cut Slopes For planning purposes,temporary unsupported cut slopes more than 4 feet high may be inclined at 2H:1V maximum steepness within the silt and clay soils and no steeper than 1.5H:IV in the dense glacially consolidated soils. If significant seepage is present on the cut face or if fractures and shear zones are'encountered in the silt and clay deposits then the cut slopes may have to be Page 10 'June 10,2010(GeoEngineers,Inc. File No.5836.010.00