Continuing from a discussion:... "When such entities encounter critical design issues, the dynamics of this "political sense of engineering" may result in consequential outcomes. THE MOST consequential outcome, for Oroville's Flood Control scheme, originated from a crisis from hydraulic fluid flow test studies. A huge problem forced a re-design of the original concept, that ultimately led to the design as it is today. From the series of events that followed, a decision tree may be traced that reveals a "political dynamic" in tradeoffs that occurred."...
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The information below reveals the evidence of "political forms of engineering decisions" that resulted in a flawed total spillway design (true specs/performance) & violated the norms of high standards of dam engineering safety assurance. By simply "deeming" the use of a Weir based Emergency Spillway as "infrequent" and exceeding estimates of 10,000 yr maximum usage conditions, a "rationale was justified" to allow a "political solution" to introduce a significant design flaw in engineering judgement. This dangerous "rationale" justification propagated into other evidence of lesser importance consideration factors including non-anchoring of the Weir, non-concern for damaging erosion, no consideration to construct armor protection of the hillside, make the Weir long enough as needed to meet a flow "number", etc. All justified due to an introduced "reasoned minimal use" of a long Emergency Spillway Weir [6]. LEFT OUT of this "rationale" was the imperative safety necessity of REDUNDANCY in case of failure. i.e. The Main Spillway became supercritical in that any failure to the Main Spillway structure HAD NO backup (no redundancy as ES had high risk - unproven/tested [5]- and validated to be flawed) & that could risk the entire dam.
These type of "rationale" justified decisions, that lack a full comprehensive engineering thoroughness, is what leads to grand failures (in the politics of engineering judgement).
The Original Oroville Dam Spillway was presented to the public where it had a design capable of handling standard condition floods up to 440,000 cfs and worst case floods up to 720,000 cfs (reservoir inflow). As presented, the public could be assured that the design could handle worst case conditions such as the 1861-1862 MegaFlood. To meet this criteria, the flood control spillway was originally designed for a total 620,000 cfs flow using a massive "delta" set of combined gate structures of a "main" and "emergency" headworks. See the Artist's concept painting [1]. IN this design, there is NO erodible hillside flow spillway [2].
Then a Crisis occurred in scale model testing of this design. "Fins", "Standing Waves", and "monster splashing" (up to 100+ ft re: model scale) were becoming too challenging to resolve [3][4]. Turbulence and Eddy swirls aggravated the challenge. The cost of the fixes, in the fix design construction, was becoming more extensive from deeper rock excavation and higher concrete volume requirements. In the summation of these mounting design challenges, the California Department of Water Resources stepped in and made a "command decision" to break the combined design into two separate structures[5]; A main spillway with a separate Emergency Spillway Weir (as it is today & Failed at 12,000+ cfs [6]).
+Image [1] Original Design proposed to the public for funding - a combined high capacity spillway - Artist's concept painting.
+Image [2] Original Spillway design with Combined Flood structure - 620,000 cfs total capacity (370,000 cfs main flow + 250,000 cfs emergency flow).
+Image [3] Original Spillway model testing reveals "Fins", "Standing Waves", and "monster splashing" (up to 100+ ft re: model scale) @ 620,000 cfs total capacity (370,000 cfs main flow + 250,000 cfs emergency flow).
+Image [4] 3rd round of "fixes" in model testing still reveals challenges @ 620,000 cfs total capacity (370,000 cfs main flow + 250,000 cfs emergency flow).
+Image [5] California Department of Water Resources steps in and makes a "command decision" ("political engineering") when faced with this design crisis challenge.
+Image [6] Failure is introduced from the "a political engineering decision" with flawed rationale/justification (excludes full scrutiny in engineering thoroughness).
Image [1] Original Design proposed to the public for funding - a combined high capacity spillway - Artist's concept painting.
Image [2] Original Spillway design with Combined Flood structure - 620,000 cfs total capacity (370,000 cfs main flow + 250,000 cfs emergency flow).
Image [3] Original Spillway model testing reveals "Fins", "Standing Waves", and "monster splashing" (up to 100+ ft re: model scale) @ 620,000 cfs total capacity (370,000 cfs main flow + 250,000 cfs emergency flow).
Image [4] 3rd round of "fixes" in model testing still reveals challenges @ 620,000 cfs total capacity (370,000 cfs main flow + 250,000 cfs emergency flow). Note the "hand control angle experimentation" of vanes by engineers.
Image [5] California Department of Water Resources steps in and makes a "command decision" ("political engineering") when faced with this design crisis challenge.
Image [6] Failure is introduced from the "a political engineering decision" with flawed rationale/justification (excludes full scrutiny in engineering thoroughness).
