[EarthResearcher333]

There is some information that I haven’t shared in investigating the full history of the engineering & the project at Oroville.

This information reveals a series of engineering decisions involving multiple special groups
+financial,
+meteorological history estimates,
+original ambitious higher flow capacity MS design,
+Finite Element Analysis simulations (for solid concrete structure integrity in Modified Mercalli intensity shaking scale [earthquake max estimate]), +hydraulic model testing flow -100ft high rooster tail problems,
+unexpected discovery of less than acceptable substructure rock & how it was addressed,
+worst case flow estimated once in 10,000+ years, etc.

Short of the long, the project was large and involved many facets of these groups working together.

There are strong indications that some decisions were made dependent on constrictions found, and in other cases liberal estimates that were “best practices & knowledge” at that time.

This is a classic combination that have led to failures, not by intentional means, but of a collective set of circumstances. When I mentor engineers, one of the first tasks I make them undertake is to read Henry Petroski’s book on Design Paradigms, “Case Histories of Error and Judgement in Engineering”.

I’m convinced Oroville will become a classic in engineering history and will be added to books of this genre.

The tough part right now - this situation is a very very expensive problem to fix. At least they have good information on the exposed geology (save’s ‘em a survey & a huge number of drill holes)... :-)

[EarthResearcher333]

Ping to 1,801 FYI

[LucyT]

Ping to 1,801 ...

Thanks, EarthResearcher333.

[Mariner]

Is the essence of most of these issues the rock the structures were built upon?

[KC Burke]

Did you get a chance to study the slab remains in Ray’s post 1811.

That is very enlightening. Now, I imagine that this is from prior to the 14th when the spillway was shut down for assessment and not later as the spillway is still flowing as far as I am aware.

All evidence of slab sub-base has washed away but it appears obvious that some of the slab areas appear to have been placed on competent rock cut to slab subgrade. It also appears there were slab areas where competent rock was not available to provide the grade needed for slab placement. This means that water that got under the slab under pressure would have wedged under that portion placed on rock and lifted it.

When placing a large concrete apron in an area where rock strata underlaid a PART of the area, I have never had a designer not require a substantial overcut of the rock so that all concrete pavement is on a similar sub-base for drainage purposed, uniformity of performance, heave characteristics and the like.

Now at the time of this picture, all sub-base would have washed away but it seems to clearly show slab on rock in a lot of areas.

Now, I will once again state that I am talking of large concrete bearing aprons of this size for large truck traffic or military vehicles. That being said, I don’t like the design I see.