What flood standard is being used to determine the height of the shaft pads compared to what DWR has analyzed in the fourth climate change assessment for storm surge and downstream flood risk?
June 12, 2020Why all of this for one region?
June 12, 2020During the ITR team review, it was discussed that use of maintenance shafts approximately every 5 miles with full maintenance procedures at those shafts would substantially reduce the probability of failure between shafts. In addition, it is understood that tunnel boring machine technology is continually evolving and many of the maintenance procedures can be completed from within the tunnel. The ITR team documented one case study that included a main bearing being replaced from inside the tunnel. Technology will continue to change significantly five years from now when the Delta Conveyance program is projected to be under construction. During the design phase, additional ITR reviews will be conducted to incorporate new technologies. DCA is being conservative in planning full maintenance shafts every 5 miles in order to avoid the need for an emergency shaft.