Upper Reservoir II ?

On May 19, FERC sent Ameren a letter with comments about the reports that have been submitted to FERC. Here are some statements from the letter that I found interesting.

The BOC has concluded that a reinforced concrete faced symmetrical RCC dam is
the preferable option for re-building the upper reservoir dam and should be further
evaluated. We concur with this finding.

As indicated by the BOC, the selected dam section and material properties must
provide a safe and adequate structure to suit the foundation condition of the reservoir site.

The likely magnitude of earthquake-induced offsets must be determined because such
offsets could crack the concrete and cause increased uplift. In addition, large offsets
could cause degradation of dam/foundalion contact strength. The post-event stability
must be evaluated.

The section must be stable for the over-pumping case.

Please provide the Commission with as much information as possible so that a comparison
between the existing upper reservoir and project operation, and the proposed rebuilt project
features and operation can be made. Following our review of your proposal, we would be
in a better position to provide you guidance regarding which procedural regulations apply to
your proposed rebuilding of the upper reservoir.

It will be some time before a final report and whether FERC provides permission for Ameren to proceed with the rebuild, but you can see that work is going in that direction. If you want to read the entire letter it is on the FERC web site under correspondence.