Do any of the images or videos shared show tunneling through peat soils?
June 15, 2020Regarding flow at the intake: At the last meeting someone asked about negative or reverse flow in the river at the intake. There was an instant response of, “No, never negative,” but I wonder what that looks like at high or low tide. That is a big issue out here, and I personally would like to understand those flows at the intake during the complete tide cycle, i.e., top, bottom, half tide rising (flooding), half tide falling (ebbing). At full “take” what are the flows just above, just below and going out of the system? I assume that just below there is always a positive downstream cfs there even when it is peak flooding. Specific numbers like that would help. It would probably be good to measure during the driest drought time, low river flow. If we can get those flows, I can put stuff like that to bed when talking with people.
June 15, 2020“The geotechnical team has collated data from soil borings conducted not only for the prior project but from other construction projects across the Delta, including design documents for roads, bridges and levee improvements. Based on this data, there is a reasonable understanding of the depth of the competent soils. While there is still some information that needs to be obtained, it appears that the tunnel would not be constructed in peat soils.
Additional geotechnical information would be collected prior to the completion of design. If peat soils occurred at depths considered for the tunnel, the design would be modified to lower the tunnel to competent soils below the peat soils.”