1300 W MARINE VIEW DR WATERFRONT PLACE APARTMENTS 2022-07-28

RECENT DEPOSITS underly the fill and consists of poorly graded sand with silt(SP-SM)that is medium dense. This material extends to depths of 26 to 30 feet below ground surface. GLACIALLY CONSOLIDATED SOIL underly the Recent Deposits and consist of poorly graded sand with silt(SP-SM)that is dense to very dense with occasional interbeds of hard elastic silt(MH). The Geotechnical Report and BOD Memo indicate the Fill and Recent Deposits are susceptible to seismically-induced liquefaction under the design earthquake. Based on our review of the boring logs and CPTs and the design ground motions, we concur with this assessment. The underlying Glacially Consolidated Soil is considered non-liquefiable because of its dense to very dense state. The liquefaction and lateral spreading hazards would be damaging to the proposed building if left unmitigated. The ground improvement program has been designed to mitigate these hazards according to the design criteria described above. The ground improvement has also been designed to mitigate static settlements to levels consistent with the BOD Memo criteria. 3.0 DESIGN CALCULATIONS 3.1 Soil Engineering Properties Soil engineering parameters were developed from field and laboratory geotechnical data in the BOD Memo. We used the computer program CPeT-IT version 2.0.2.5 to process the CPT data and perform statistical calculations of tip resistance,relative density and undrained shear strength for the soil layers at the site. The following layering was established for the purpose of binning data and calculating engineering parameters for each layer: • FILL 0—SP-SM(granular layer) • FILL 1 —SM(granular layer) • FILL 2—ML(cohesive layer) • FILL 3—SM(granular layer) • Recent Deposits(granular layer) • TILL 1 —SP-SM(granular layer) The depth ranges where each layer was identified in each CPT are identified in the CPT data reports in Appendix A.1. CPeT-IT was used to estimate relative density for the granular layers as a function of tip resistance using the following relationship from Robertson and Cabal(2015): D. =100°/ QJ350 Eqn. 3-1 where Qtn is the dimensionless CPT tip resistance normalized for overburden pressure. The undrained shear strength of the cohesive FILL 2 ML layer was estimated using the following relationship from Roberson and Cabal(2015): Su =(q: -6vo)/Nkr Eqn. 3-2 where qt is the tip resistance(corrected for pore water pressures),6vo is the total vertical overburden stress and Nkt is an empirical coefficient that was set to 14. The normalized equivalent SPT blowcount was then estimated based on the relative density using the following equation(Idriss and Boulanger 2008). 3jPage