SF-80 Bayshore Viaduct Seismic Retrofit Projects Report

To achieve compliance with the California Environmental Quality Act (CEQA) throughout the SF-80 Bayshore Project, ASC archaeologists monitored I-80 footing excavation at selected bents and directed the mechanical excavation of soil in sensitive areas. The predictive model developed for prehistoric deposits in San Francisco was found to be accurate; intact historic ground surfaces - a prerequisite for the occurrence of important remains - were located in the majority of footings monitored. Archaeological deposits that met the criteria described in the research design were excavated stratigraphically, by hand, using rapid-recovery methods. To identify potential prehistoric deposits associated with buried soil horizons that would be impacted by the new freeway piles, a program of geoarchaeological soil coring wasa performed.

Through this coring program, an important stratigraphic sequence was defined that has since been used to refine predictive modeling for prehistoric sites in the city. Seven California Register-eligible collections discovered during archaeological monitoring are statistically compared with those found during the West Oakland/Cypress Project. Truly comparable samples of a population size unprecedented in the West are here availble for statistical analyses, revealing patterns at the household, neighborhood, and city levels, as well as consistencies and contrasts between San Francisco and West Oakland.