3400 RIVERFRONT BLVD Geotech Report 2022-10-25

• • • site should be classified as seismic site class E based on blow count data collected during the site . investigation. In Table 3 we have provided seismic design parameters that can be used with the • 2012 IBC to compute base shear forces. These parameters were obtained from USGS seismic design maps (USGS, 2014). • • Table 3. IBC Seismic Design Parameters • • Parameter Short Period 1 Second • Spectral Acceleration SS = 1.302 g S1 = 0.495 g • Site Class E • Site Coefficient Fa= 0.900 F = 2.400 • Adjusted Spectral Acceleration SMS= 1.172 g • SM, = 1.188 g Design Spectral Response Acceleration Parameters • SDS= 0.781 g SDI = 0.792 g Spectral Peak Ground Acceleration 0.47 g • • Design Spectral PGA 0.31 g • 6.16 PAVEMENT • Core Design, Inc. designed the pavement sections for this project. The design pavement • sections have been included in the plan set that was submitted to the City. • We recommend that the pavement subgrade be prepared in accordance with the "Site • Preparation"and "Structural Fill" sections of this report. As stated in these sections, we • recommend that the upper 24 inches of subgrade beneath roadways be properly compacted. We • recommend that fine-grained subgrade be compacted to 92 percent of the material's maximum • dry density and that coarse-grained subgrade be compacted to 95 percent of the material's . maximum dry density, as determined by ASTM D 1557. In addition, we recommend that the moisture content of the compacted subgrade be within 2 percent of the material's optimum • moisture content. A sufficient number of moisture-density tests and hand probing should be performed to verify that adequate subgrade compaction has been achieved. As an alternative to • scarifying and compacting the subgrade, the upper 16 inches of subgrade could be cement amended, as discussed further in the "Cement Amendment" section of this report. The subgrade should be evaluated by proof rolling with a fully loaded dump or water truck. Areas that exhibit yielding or pumping should be repaired, as described in this report. We • recommend that a subgrade geotextile be installed between fine-grained subgrade soil and the • aggregate base to provide separation between the two materials. The aggregate base rock should meet the requirements for imported granular material outlined in the "Structural Fill" • section of this report. After the aggregate base material has been placed and compacted, we • recommend that another proof roll be performed with a fully loaded dump or water truck to . identify any areas that exhibit yielding or pumping so that they can be repaired before asphalt • concrete paving is performed. G EODESIGN= 22 Polygon-128-01:091615 •