Environmental Impact Statement - Sonoma Land Trust

California Department of Fish and Game
U.S. Fish and Wildlife Service
Section 3.1. Geology, Soils, and Paleontology
induced levee failure are expected to decrease because of the improved
construction standards required by the project. Although there would be some
residual risk, as is the case in any seismically active area, impacts are considered
less than significant. No mitigation is required.
Bridges, Boardwalks and Undercrossings
As discussed previously, the proposed bridges, boardwalks, or undercrossings
could be subject to strong seismic groundshaking and ground failure related to
liquefaction. Exposure of these facilities to groundshaking and/or liquefaction
could result in structural damage and/or risk of injury. However, all bridges,
boardwalks, or undercrossings would be designed and constructed to meet or
exceed the Institute of Transportation Engineers’ (ITE’s) pedestrian facility
standards and Caltrans’ bikeway and bridge design standards. Furthermore, all
facilities would incorporate any additional recommendations identified in sitespecific
geotechnical evaluations completed during detailed design.
Consequently, seismic risks to project structures (and their users) would be
reduced consistent with current engineering standards. Although there would be
some residual risk, as is the case in any seismically active area, impacts are
considered less than significant. No mitigation is required.
Conclusion: Less than Significant.
Full-Tidal Alternative
The potential for damage to occur to proposed facilities to settle as a result of
strong seismic groundshaking, liquefaction, or other seismic-related ground
failure would be the same as for similar to the Project with the possible
construction of a box culvert under the SMART rail line to provide tidal
connectivity to the area north of the rail line. This structure would be designed to
meet all applicable engineering standards and in consultation with SMART.
Impacts are considered less than significant, and no mitigation is required.
Conclusion: Less than Significant.
Impact GEO-2: Settlement of Proposed Facilities as a
Result of Static Fill Loads on Compressible Substrate
Materials
Proposed Project
Implementation of the Project would involve the construction of a levee in the
southern portion of the project site, one or more bridges and/or boardwalks north
of the rail line, a possible grade-separated crossing underneath the SMART rail
line, and modifications to an existing undercrossing beneath Highway 37. The
project would also involve the placement of dredged materialssoil and sediment
to create conditions suitable for tidal wetland habitats. The Reyes clay soils and
the Bay mud deposits that underlie the site are compressible (Miller 1972) and
Sears Point Wetland and Watershed Restoration
Project Final Environmental Impact
Report/Environmental Impact Statement
3.1-15
April 2012