Posted by: Deirdre Des Jardins | May 10, 2018

WaterFix hearing: chief tunnels engineer on sea level rise

Metropolitan Water District’s Chief Engineer, John Bednarski, testified in the WaterFix hearing on Tuesday, April 25, 2017 about the WaterFix facilities design and construction. Mr. Bednarski addressed numerous issues raised in testimony by California Water Research’s principal scientist, Deirdre Des Jardins on the inadequacy of the sea level rise analysis for the WaterFix tunnel design.

The WaterFix Final Conceptual Engineering report states that the WaterFix facilities are being designed for  an 18 inches of change in high water levels in the North Delta.   As reported by California Water Research, the WaterFix EIR/EIS discloses that underestimating sea level rise in the design of the WaterFix facilities could result in harmful impacts such as flooding.

Liberty Island, flooded in 1998

Mr. Bednarski testified on cross-examination that he believed that 55 inches of sea level rise at the Golden Gate translated to 18 inches of sea level rise at the Delta tunnel intakes at Hood. This was based on a 2009 Technical Memo by Phillip Mineart . Cross-examination by California Water Research on the Technical Memo that Mr. Bednarski was relying on showed the following:

  1. The increase in mean high water elevation at Freeport and other locations in the Delta with 55 inches of sea level rise at the Golden Gate was predicted by the technical memo to be 54 inches

  1. The change in predicted 200 year flood elevation was dominated by river flows, so was less, but varied throughout the Delta.
  2. The analysis of 200 year flood elevation was based on very simplistic analysis (Manning’s equation) from the Delta Risk Management Strategy that assumed that the Delta channels would be unchanged by sea level rise.
  3. The DRMS analysis had been criticized by one of the Independent Science Panel reviewers as very simplistic and inadequate even for the Delta Risk Management Strategy.

It is difficult to believe that a $17 billion project has had ten years of engineering design without doing an adequate analysis of the effects of sea level rise on water levels in the Delta.

Bednarski testified on cross-examination that they would be addressing sea level rise in the next engineering revision.


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