THIS JUST IN … Oroville Dam Incident Independent Forensic Team releases second interim status memo; also latest video from Oroville

Memo contains a summary of findings and opinions to date, as well as some lessons learned

This morning, the Oroville Dam Spillway Incident Independent Forensic Team delivered the second interim status memo to the California Department of Water Resources, giving a summary of findings and opinions to date regarding the chain of conditions, actions, and inactions from the February 20, 2017 Oroville incident.  John France, the team lead, was on a media call to give a brief recap of what’s in the memo.

Here is what he had to say.

Our team began its work back in mid-April and shortly after that, on the 5th of May, we issued a memorandum with a group of candidate physical factors that we were looking at as possible causes or contributors to the incident at Oroville Dam.  We didn’t have opinions or conclusions regarding those factors at that time; they were just a list of factors that we were going to be considering and they were issued then to help with input for the ongoing design and construction of repairs that were being done by DWR.”

Since that time, we’ve progressed the investigation substantially, both from the standpoint of looking at physical factors and also looking at human and organizational factors, and we’re at a point where we’re nearly complete with the physical factors, and we have some opinions and findings that we’ve presented in the memo regarding human and organizational factors that is more so a work in progress.  We’ve indicated in the report what we’re going to be doing to finish that work and the work that’s been done so far, but we really have not reached a lot of findings on the human and organizational factors.”

We have also noted that there are ongoing spillway evaluations in California and elsewhere, and the Division of Safety of Dams has required evaluations of a number of spillways, 93 I believe.  The Federal Energy Regulatory Commission, the FERC, has required evaluation of spillways from its licensees’ projects across the country.  The primary reason we are issuing this interim report before we get our final report completed in the fall is that we have reached some conclusions about what happened, and we wanted to make that available to people who are doing these evaluations of spillways so they can be a bit better informed while they are doing their evaluations of the spillways.

The memo includes status of findings on several items: the initiating event, the failure of the surface spillway chute at Oroville, the physical factors that we believe contributed to that, the design and construction related factors that we believe contributed to it, and then the physical factors that we believe contributed to the emergency spillway damage that resulted during the incident also.”

The last thing that the memo includes is a set three lessons to be learned that we believe have come out of the work we’ve done so far.  We expect that there will be more lessons to be learned as the human and organizational factors study continue, but at this point, there were three broader overarching lessons that we thought could be learned from what we have done so far.

The physical factor side of things that the memo talks about, we really concluded that we’re rather confident that what happened is through a set of mechanisms.  Water pressure developed under a sections of spillway chute, lifted that section of the spillway chute, and it allowed that high velocity water flowing into the spillway to get to some erodible materials that were under that section of spillway chute and that led to the erosion that we saw.  There are multiple physical factors that we think contributed to that and unfortunately one of the problems that we have is that all of the material that was involved in the actual failure site, the initial failure site, no longer exists because it was carried away by the erosion that happened.  It is difficult, if not even impossible, to come to an exact explanation of what happened, but we believe that we have identified a number of possible things that contributed and we think it was some combination of those things that caused this incident and the details are in the memo.  We also talk about some of the design and construction characteristics that made the situation such that those factors could come into play, so with that …

Question:  You don’t use the word ‘design defect’ or ‘maintenance shortcomings’ … were there defects?  Were there shortcomings?

Defects, there are things that we certainly would call defects, yes.  We know that over the years, there have been some damage to the spillway.  There’s been falling concrete, there have been cracks that have expanded, and there were repairs done over the years, so there are things that are a defect in terms of that they contributed to the problem and the occurrence of the incident that happened.  As far as whether they are things that should have been identified in normal practice and to what degree things should have been done differently when they were done, that’s part of the human factors and organizational factors investigation that is ongoing right now, and we’re not prepared to render those opinions yet, but those kind of opinions will be in the final report when we finish that part of the investigation.”

Question: As I was looking at the lessons learned part of this report, it seemed like, it’s almost an indictment of the inspection process as it currently exists.  Is that too strong of word?  How would you characterize that?

I would say indictment of the process is a bit strong.  The way I would look at it is that any profession, any technical practice like this, has ways it goes about doing business and unfortunately sometimes we learn how to improve the way we do things comes from things that don’t go well, and we have here a situation where something did not go well.  Earlier when I did a discussion with you all back in May, we likened the investigation to what the National Transportation Safety Board does when it investigates airline accidents or train accidents.  In many of those cases, they learn that there are things and processes that were in place for doing things that didn’t work as well as we expected them to work, and we need to change them and improve them.”

That’s more the way I look at those lessons learned, is that there are ways that have been customarily done in the dam safety business that in the light of Oroville, we are now thinking we maybe need to do some things different than what we have done.  We recognize where most of the state dam safety programs in the US have been driven by physical inspections and what can be identified with physical inspections; we may need to recognize there are some things that we can’t identify just simply by a physical inspection, we may need something more, like that suggested periodic comprehensive review where you go back and look at the design compared to how you would design it today.  We’re always learning how to design and build things better.  If we go back and look at something that was built in the 1960s, we might find that although they may have done what others were doing at the time, we know better now, and the question then to ask is, is the difference between what was designed and built in 1960 versus what we’d do today, is it significant, could it lead to a problem, and do we need to do something to fix it, and that’s what the going beyond the inspection process is what we’re suggesting we need to start doing that because as  routine, that is not necessarily being done.”

Click here to read the documents.

The latest video from Oroville …


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