A nearly Unbelievable Answer from DWR: Reporter Dan Brekke at KQED news is on a roll. Corners DWR & DWR responded with what only can be categorized as a "whopper". This is beginning to feel like the saga of what the definition of "is" "is".
Erin Mellon (spokesperson for DWR) stated that historical documents of geologic studies, included in a Potential Failure Mode Analysis (PFMA) in 2014, were looked at and it was concluded by this evidence that the Spillway rock beneath it was extremely competent.
This now has to be the biggest provable "whopper" from DWR to date. The reporter tried to contact the four consultants that did this PFMA of the main spillway breaking and then the Emergency Spillway dangerously eroding, but these consultants did not respond back (no surprise?).
Here is the "Whopper" and why it is such. DWR's own historical Final Geology Report Spec 65-09 documents a massive seam of clay/clayey foundation (intensely weathered rock = hard clay) EXACTLY starting at the blowout failure area (and going upslope to the point of the upper spillway remains). Below is a picture of this from their own report. Prof Robert Bea & the team of contributors documented this in the July 20 Failure Analysis Report. (picture is from Appendix B, Fig B.21).
Erin Mellon must be unaware that even the DWR Field engineers told contractors NOT to excavate down to hard competent rock - that they felt the contractors were trying to get extra $'s by backfilling concrete at $30 cu/yd. Told the contractors to dig only "to grade". (See Fig B.17 below)
Erin Mellon must be unaware that DWR Field engineer's orders meant that the Final Geology Report's noting of massive clay seam areas were left "as-is" as identified by the Final Geology Report Spec 65-09. (See Fig B.21 below)
Erin Mellon must be unaware that DWR anticipated in placing anchor bars in clay seams as they tested the bars in clay to test in "the worst foundation available". (See Fig B.20 below)
Erin Mellon must be unaware that the "blowout failure" of the Main spillway occurred EXACTLY at the seam boundary of this clay/clayey foundation (i.e. "worst foundation available" as noted by DWR's Final Construction Report 65-09 - Fig B.20). Blowout - see Fig. B.10.
I certainly hope the Forensic Team picks up on what is being said. If not, they could be caught up in this extreme dichotomy of truths, non-truths, fact, and fiction.
Note: Much more in Dan Brekke's article - read the full story at the link (only one main issue brought up in this post).
= = Article Clip: (Whopper by DWR's spokesperson) (emphasis mine):
"Department of Water Resources spokeswoman Erin Mellon said in an email Monday the evidence presented for the potential failure mode analysis included a site inspection and historical documents including past geologic studies of the area." "While not offering specifics about the data considered, Mellon said “the information gathered showed the spillway was in good condition and the rock beneath it was extremely competent.”
= = end clips More at Link:
Panel Weighed Oroville Spillway Failure in 2014 - and Called It Unlikely
Professor Robert Bea CCRM et al Final Report link (team of 14 contributors): sections above from Appendix B:
https://drive.google.com/open?id=0Bz1I1mIutSEnbFJuVUJZWWNNVlU
Fig. B.21. DWR Final Geology Report Spec 65-09 denotes the foundation geology of the subgrade quality of foundation material that the invert concrete chute was constructed upon. The Seam (marked as a series of "S"'s) follows the dashed line seam in Fig. B.10. This drawing reveals the same foundation structural integrity transition region of the quality of the foundation material as in the blowout failure erosion images in Fig. B.10 and Fig. B.11. This geologic report drawing identifies that DWR was aware of the type of foundation material at this future blowout location. DWR BOC report Memorandum No. 1 notes that "Compacted clay is also a term sometimes used to describe highly weathered rock."
Fig. B.17. Dispute arose between original specifications intended to excavate the spillway to strong fresh rock or strong weathered rock. Specification stated: "Excavation for the chute shall be to fresh or moderately weathered rock that cannot be further removed by heavy duty power excavating equipment." DWR Field Engineer intervened and directed the contractor to only "excavate to the grades shown on the drawings". The contractor was following specifications to where any poor foundation material would be backfilled with concrete to "grade level".
This report statement infers that DWR believed the contractor was using this specification in a desire for the additional pay of $30 per cubic yard of concrete in backfill work. This DWR Field Engineer intervention "orders", in contrast to the accuracy of the "specifications" in excavation, is evidence that a financial decision was a basis to not excavate to strong competent rock. If this "intervention" by DWR Field Engineer had not occurred, it may be possible that the large seams of highly erodible soil-like foundation material would have been fully repaired to competent backfill of concrete. The DWR Field Engineer's "intervention" evidences that a serious flaw was introduced that was a primary cause for the instability and the subsequent "blowout failure".
Fig. B.10. Initiating Failure Hole location reveals a deep seam of highly erodible foundation material (incompetent rock) that is many feet deeper than the grouted 5 foot deep slab anchor bars. Angle of seam inferred by dashed line. Image reveals the nature of why the "hole" location and the full 178 foot wide seam area was a structural problem area. The upslope "soil-like" foundation material is in a transition zone between the incompetent rock and the competent rock (downslope from the dashed line). Thus, the "communicating" slab forces through the load transfer bars would have experienced a differential in structural integrity or stability.
Fig. B.20. DWR Final Construction Report FCR 65-09. Critical Design Flaw linked to blowout failure. DWR reveals that the spillway foundation will include anchor bars emplaced in "clay seams". This evidences that DWR was allowing the slab design to have anchor bars to function from the "worst foundation available". This would include poor foundation materials such areas of clay and areas of soil-like highly erodible extensively weathered rock. The blowout failure area reveals this type of material (poor foundation materials). This evidences the non-ability of the anchor bars to maintain the integrity of anchorage in these clay and soil-like foundation materials. These materials are highly erodible in subsurface slab water flow. Scouring erosion would remove these seams of materials rendering a significant loss of pounds per square inch in anchorage strength of the anchor bars.
