I think the best explanation for avoiding total disaster over the last 72 hours at Lake Oroville is the British evacuation from Dunkirk, Belgium at the end of May, 1940. It wasn’t a “victory,” and it wasn’t a defeat, it was merely avoiding disaster. For any of you inclined to sneer at me, you need to take a look at the ongoing situation water situation in California. First, here is a link to a Briebart story that puts things into stark focus.
THE LINK IS HERE.
Oroville Lake Down 52 Feet, but 9 Upstream Reservoirs to Flood
Although the California Department of Water Resources is claiming Oroville Dam is safer because the water level has fallen by 52 feet, that feat was largely accomplished by over-filing 9 upstream reservoirs that are all expected to flood as another Pineapple Express storm-train brings 48 hours of heavy rain through Wednesday.
The last winter storm caused an evacuation of about 200,000 people downstream from Lake Oroville due to the threat of a catastrophic failure of the dam.
Although most Americans have been told that the fissure in the side of the dam has been stabilized by opening up the spillway to drain the lake, and helicopters have dropped huge bags of rocks in a crack, the water flow into Oroville Lake has been restricted by overfilling the upstream reservoirs.
The nine State Water Project and PG&E earthen reservoirs on the Upper Feather River Watershed that feed directly into Lake Oroville were already at maximum capacity prior to the new storms. This next storm is expected to bring 1-3 inches of rain in the valleys. But the Central Sierras are expecting 10 inches of snow and rain over the next 7 days.
With all the higher elevation reservoirs brimming, Supervisor Kevin Goss from mountainous Plumas County told the Sacramento Bee, “I’m watching, and I’m worried.” Flooding from the last set of storms shut down escape in all directions in his Indian Valley district.
The towns of Greenville and Taylorsville were isolated, and sewer systems for the sparsely populated county suffered extensive damage as many roads washed out. The flooding from the new storm is expected to be much more serious.
In addition,tRelatively warm temperatures of up to 49 degrees in nearby Tahoe caused snowmelt this week. With the “Snow Water Equivalents” for this time of year in the Central Sierras at 183 percent and the Southern Sierras at 205 percent; the National Oceanic and Atmospheric Administration warned that the mountains could see significant runoff.
The total capacity of the upstream dams is about 400,000 acre feet, or about one tenth the capacity of Lake Oroville. Last week, the upstream reservoirs were allowed to fill in an effort to take pressure of Oroville Dam. But with the dams full, virtually 100 percent of the rain and runoff from the coming storms will flow into Oroville Lake.
Despite the upstream restricting of water flow, Lake Oroville added over 1 million acre feet of water in three days during the last storm. Engineers from the California Department of Water Resources hope that a combination of releasing 800,000 acre feet of water from the lake will be enough to prevent another Oroville Dam flood.
HERE IS A LINK TO SCOTT CAHILL’S ESSAY ON WHAT IS GOING ON. HE SAYS IT BETTER THAN I CAN, PEOPLE.
In considering the events at Oroville, it is easy to concentrate on the negative. There is so much negative to go around.
The Principal spillway, the normal method of shedding water from the reservoir, has failed from scour, the soils being discharged downstream by the high velocity water. The Principal spillway is a controlled spillway, with gates at the dam crest to “control” the flow of water down the concrete “sluiceway” to the stream below, in Oroville’s case the Feather River. In a normal discharge, the sluiceway would conduct the flow down the grade, discharging into a plunge pool. Concrete block-like elements may serve to break and confuse the flow, the plunge pool, then absorbing the remaining energy and the water moving downstream. Oroville’s principal spillway failed because the sluiceway was undermined by voids, which became “charged” by high-pressure water introduced from the discharge through the gates. The result was a failure of the components of the sluiceway, plate slabs, and training walls were washed into the stream below, impeding flow, and causing a backup of the pool below the dam.
The emergency spillway is an uncontrolled spillway. It will pass as much water as entered the reservoir across its weir and the water is then transmitted downstream. The emergency spillway at Oroville is unlined, composed of indigenous earth and rock. Abutting rock is assessed in construction of a dam to attempt to understand its erosion characteristics. Rock of abutments is often considered “weathered” Weathered rock is rock which has been exposed at the surface and has become fractured and less sound. Sound rock is called “High Recovery” rock. Soft and fractured rock is called “Low Recovery” rock. Low recovery rock is prone to erosion. As an example, granite which is not weathered (granite is resistive to weathering) is high recovery rock. If it has seams of sands, silts, or clays, even granite can be considered low recovery. Shale is a rock that weathers rapidly. Shale abutments are often subject to erosion with high flows across these soils (rock). It is acceptable for an emergency spillway to lose soils and to be damaged in a discharge. The emergency spillway is used in special cases where there are severe flows (flooding rains or a break of a reservoir upstream for instance). Oroville’s emergency spillway was an earthen spillway. It is a weathered bedrock outcropping. Upon actuation, because of the failure of the principal spillway, it became apparent that the emergency spillway’s underlying rock was erosive, causing severe cutback, which threatened the foundation of the ogee weir. Noting this rapid evolution of the cutback, the operators opened the gates again to the failing principal spillway.
The argument has been offered that the dam has not “failed” in comments on my other writings. The failure that I refer to is the failure of elements of the dam, and the principal and emergency spillways are clearly elements of the dam. A dam failure does not require the complete loss of pool. In fact, few dam failures result in a complete loss of pool. My title, perhaps sensational, is accurate in describing the failure of these elements. A dam without a method to remove the water safely is clearly in a failure mode. Oroville Dam, as of this writing, is in a precarious situation. The spillways are in the process of failure. The losses already suffered are horrible. If we see the weir of the emergency spillway fail, the losses will be incalculable.
The Oroville Dam will probably not breech. I hope with all of my heart that it does not. Don’t ever take my criticism as some desire for catastrophe. It is just the opposite. I find the failure to maintain our elements of our infrastructure as a societal failure of a magnitude heretofore unseen. If we continue unchanged with these failures, if we fail to rebuild and maintain, we will become a third-world country. If the great United States of America is to step into the next few decades as a world power, it will be with renewed infrastructure. Without it we will fail as a nation and as a government.
We have watched as our great steel mills moved to Japan. We have watched as our great manufacturing move to Japan, then China. We have watched as our assembly move to Mexico. Through it all, we have watched. The time has come to act, or to surrender all that we once were. As a nation we have a debt of nineteen trillion dollars with a further commitment of four trillion dollars. We have a backlog of infrastructure improvement of an additional two trillion dollars. These numbers are so large that the human mind cannot comprehend them. As a nation we must satisfy this debt. We cannot save our way out of this problem. It is too large.
To survive, as a nation, and a model to the free world, we must work our way out of our smothering debt. To do this, we must have the machine of our economy operating unencumbered. Our infrastructure is a systemic element of our health as a nation. The social and societal failures that we now see as a nation are symptoms of a failing nation, a failing way of life. They will be repaired by the improvement of the whole. The despair of many is real. Men must see an avenue to success. They must be able to sustain themselves and their families.
Let us consider what it would be like if we were unlucky. Certainly, we may yet be unlucky, but what would California, the United States be like if Oroville had failed completely?
Imagine a nation and a state stretched to a fiscal breaking point encumbered with the costs of the rebuilding of a huge area of homes, schools, businesses. Imagine the mud and the cleanup. Imagine the lives lost. Remember Katrina, if you think that the white knights would come to fix all that is wrong, we have allowed ourselves to become something less than we once were. I believe that such a failure would be the first loss in a digression of our standard of living, it would certainly be so for the areas in the inundation zone, crops lost from need of irrigation, drinking water rationed, water quality reduced.
Some choose to defend the operation of a near-failing dam. I weigh the hurt feelings of a few men who failed to maintain, against all of the death and destruction. I wish that all could be happy and nice. It can not. Perhaps, many people will have to die to change the minds of men. There are so many dams that are balanced, waiting on that one storm. Let it be a lesser dam, a lesser population, if some must die to get the nation to hear this cry. Let it be faces that I do not know, voices that I have never heard, so that my dreams are not haunted for the rest of my life.
Blame must be assigned when all is lost, as it certainly must be. When it happens, that tragedy, it will not be the fault of the operators of Oroville. It will not be the failure of the state or the nation. It will not be the failure of the men who refused to fund maintenance.
It will be the failure of one man only, one who did what he could, but failed. It will be the failure only of one who cared too deeply. When it happens, as it must, It shall be my failure, and my failure alone.