Delta Tunnel: DCA submits Final Central and Eastern Corridor Conceptual Designs to DWR

The Delta Conveyance Design and Construction Authority has completed the Engineering Product Reports for the Central and Eastern Corridor Options for the Delta tunnel, according to the February 2021 Board report. Deliverables included “engineering drawings, GIS mapbooks, and all associated technical memoranda (TMs).”  The DCA has also delivered draft documentation to DWR on the Bethany Reservoir alternative.  The information will be the basis of the conceptual engineering design for the project.

From January through August of 2020, the DCA published draft mapbooks of the Central and Eastern Corridor Options for input from the DCA’s Stakeholder Engagement Committee, and is currently publishing draft mapbooks for the Bethany Reservoir alternative.

The DCA is planning to do additional geotechnical exploration in support of the project in Spring of 2021, and is currently doing laboratory analyses of the samples obtained from the Fall 2020 geotechnical drilling, according to the February 2021 schedule. Settlement studies are also being conducted.

Delta Stakeholder Input

According to an August 26, 2020 presentation, the DCA has made the following changes to the project as a result of input from the DCA’s Stakeholder Engagement Committee:

  • Reduced site footprints throughout
  • Maximized reclamation of impacted agricultural land
  • Shifted facilities away from natural areas including Stone Lakes and Woodbridge Reserves
  • Eliminated barging and associated affects [sic] to recreational boating
  • Reduced traffic along Hwy 4 by eliminating structures
  • Reduced traffic along Byron Hwy by adding infrastructure and shifting material to rail
  • Reduced borrow requirements to reduce traffic loads
  • Added rail and expanded roads to maintain acceptable levels of service

However, some Stakeholder Engagement Committee members have been strongly critical of the DCA’s stakeholder engagement process. Karen Mann, the DCA’s South Delta Business Representative, sent a letter to the DCA in November 2020 requesting that the DCA “respond to the real issues”, including the following:

moving the intakes; disposing of the tunnel muck by hauling it to appropriate licensed disposal facilities instead of making up the name “reusable tunnel material” and dumping it on our farmland and islands […]; developing and considering a Natural Systems Alternative that would reduce the size of thekaren-mann-11.6-letter-to-mallon.pdf ( project and its intakes, reducing construction and operating impacts on Delta communities; requiring increased conservation by Water Contractors as a permit condition of any new point of diversion […]; recognizing that a primary function of the SWP is to repel salinity in the Delta and orienting the project to repel salinity in the Delta and enhance water quality in the Delta, rather than abandoning the south and central Delta to salt water […]

CEQA Alternatives

Environmental, tribal, fishing, and Delta organizations have proposed many alternatives in the CEQA scoping process, including “no tunnel” alternatives.

In a November 5, 2020 letter to the Delta County Supervisors, DWR Director Karla Nemeth, stated that a portfolio alternative would not be analyzed in the Delta tunnel EIR, stating:

While suggestions such as conservation, recycling and desalination are important elements addressed in the Water Resilience Portfolio—and a priority for many local water agencies—they would not address the fundamental project purpose to continue reliability of SWP water deliveries by protecting infrastructure from climate change and seismic threats. However, these alternative actions may be addressed by local water agencies in the absence of a Delta Conveyance Project. Therefore, DWR will include an evaluation of them as likely conditions if the project does not move forward. This “No Project” alternative will identify and analyze the effects of the additional actions that local water agencies may take under these conditions.

The Sierra Club et. al. have filed a Petition for a Writ of Mandate for DWR to rescind the resolution authorizing revenue bonds for the Delta tunnel project planning and construction, arguing that the Department of Water Resources has improperly foreclosed alternatives.

Leave a Reply