Purpose

To consolidate, disseminate, and gather information concerning the 710 expansion into our San Rafael neighborhood and into our surrounding neighborhoods. If you have an item that you would like posted on this blog, please e-mail the item to Peggy Drouet at pdrouet@earthlink.net

Monday, August 24, 2015

SR710 Geotechnical Report submitted to CalTrans

From Sylvia Plummer, August 24, 2015

 SR-710 geotechnical report final.pdf

Here's a list of reasons (from the attached SR-710 Geotechnical Report)  why the Tunnel should not be build.  The 27 page report is ATTACHED.and was part of a larger report that was  submitted as a comment to the SR-710 Draft EIR.
"The SR-710 Tunnel will be one of the largest and longest highway tunnels in the world. Challenging geotechnical conditions have been identifiied along the potential tunnel routes, including variable geotechnical conditions ranging from unconsolidated alluvium to strong granitic rocks, high groundwater pressures, active earthquake faults, significant seismic hazards, formations with a high potential for methane and hydrogen sulfide gas, and contaminated soils and groundwater associated with Superfund sites."
"The geological conditions along the proposed tunnel are probably the most difficult ever encountered in a major tunnel project."

"During the course of studying these issues it became apparent to us that the tunnel project as proposed was most likely not feasible and that attempting to build it would end either in abandonment or radical modification of the project to a degree that would render our findings on local and detailed impacts meaningless."

 "Close reading of the EIR support documents shows that consultants and project sponsors are themselves uncertain with respect to the feasibility of the project as proposed. Instead the study suggests that necessary data will have to be obtained before even the preliminary design of the project. As far as we are able to see, an explicit declaration of technical feasibility of the project is never made in the EIR or supporting documents."

 "Possible fate of SR-710 project. From studies such as those discussed above we can suggest that reasonable scenarios of a serious failure of the SR-710 tunnel alternative project could include abandonment of the TBM construction technique, rerouting of the alignment, worker casualties, potential for sudden collapse features reaching the ground surface, major delays and cost
overruns, TBM breakdown with the attendant need for rescue excavation from the surface (as in Seattle), and even possibly abandonment of the project.  These suggestions are not exaggerations."

 "In our view it would hardly be surprising if the costs and construction time of the SR-710 tunnel were twice the predicted amount..."

 "The environmental impact of the tunnel project is currently unknowable because the project as proposed features unacceptable risks including construction safety problems and a high likelihood of needing a major redesign or realignment during construction with unknown risks of massive cost overruns and delays of possibly years. In the end, the tunnel may even prove to be technically infeasible."