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Letter from engineer Stephen Koshy, regarding
Klamath dams catastrophic collapse, to our KBC News readers
From Stephen Koshy April 27, 2018
"I amended my further comments, editing the earlier one (from 4/17/18) and adding some more comments.
The BOR sent me a printed version of the EIS/EIR in Oct 2011. I thank them for that. I do not have it with me now. I can see their online version, which seems to have some changes from the printed version from which I had quoted in my earlier comments.
I sent 2 letters/comments to the Bureau of Reclamation (BOR) on Nov 18, 2011 and on Dec.21, 2011, that removing the Klamath dams is technologically not doable and even dangerous.. The BOR replied to my comments with a technical Memorandum in 8 pages, signed by five engineers. However, I find the BOR reply to be incomplete, factually incorrect and evasive.
BOR in response says that they are giving ‘detailed responses to my each comment’. Unfortunately, they are not. Below are a few.
<Quote> relatively steep slopes, underlain by tuff ….. wave action at the shoreline of the reservoir has eroded sand and volcanoclastic tuff beneath diatomite beds and has resulted in the calving of diatomite into reservoir creating vertical exposures as high as 20 ft. in the diatomite.”…….”the (fine grained) red volcanoclastic material underlying the hill slopes ……. may be vulnerable to rapid erosion, if subjected to concentrated water flows.” Also that ….
Chapter 3. Figure 3.11-2 identifies existing potential landslide areas in the iron gate and Copco 1Reservoir areas. EIS/ EIR has enough information to suggest the certainty of slope failures on draw down, but failed to investigate them. The slope failures will add to the sediment release. <end of quote>
The BOR, in reply, does not either deny or respond to the likelihood of slope failure. BOR informs only that they did not conduct detailed slope stability analysis because there are no important structures atop the slopes. But my concern is not about structures on top of the slopes, but about slope failures that would cause additional sediment release. BOR reply does not address this issue.
BOR reply states that they will consider detailed stability analysis during dam removal. My further comment to BOR is that it will be too late by then. I have also, concern that possible instability of the abutments during 174 ft. draw down will be catastrophic to the safety of the iron gate dam.
In reply, the BOR says that …….. “it is Reclamation’s understanding that they are primarily composed of silt and sandy silt”. They are wrong.
The core is to be impervious, that is water tight, to prevent reservoir water from leaking through. Only clay makes the core impervious. There are several Engineering Manuals on the subject. The Manual on earthen dams by the Food and Agricultural Department (FAO) states that the core should have a minimum of 55% clay.
The Manual by the United States Society on dams (USSD) on para 3.5.1 says <Quote> historically, it was believed that core material should be constituted of clay rather than silt. The belief was popular because clay is less permeable than silt.< End of Quote>
The Iron Gate dam was completed in 1962 and therefore was designed some years earlier in the 50’s. It would qualify to the term “historical times”.
Fortunately they did not have to go far to look for clay. It was locally available in the volcanic ash deposits at the site.
The BOR document “ Detailed plan for Dam Removal, Klamath River dams, US Department of the Interior, Bureau of Reclamation Sept. 2011” on page 19 says:
<Quote> ”The embankment includes a central impervious clay core with filter zones and a downstream drain and is flanked by compacted pervious shells” <end of quote>
According to BOR’s own document, the core is of impervious clay .The central impervious clay core described as above in the EIS/EIR, is predominantly of clay. It validates my contention in para 1.1 to 1.6 of my original comments/letter dated Nov. 18, 2011 that the dam will collapse catastrophically. For the sake of brevity, I do not copy them here.
The core is made from the “fine grained red volcanoclastic material underlying the hill slopes” at the site described in the EIS/EIR. BOR should please re-examine the borrow areas from where the material for the core was dug up and processed. It is true, it would have some silt, even some fine grained sand. But the predominance of clay gives it the properties of clay. The question is what % is clay, what % is silt and what % is fine sand. The BOR ought to respond.
To me, the sediment behind the iron gate dam gives a clue . After all, the sediment consists of the erosion of volcanoclastic material similar to material in the core of the dam. As per, the online version of the EIS/EIR, the sediment in the lower section of the iron gate reservoir consists of 60.7% clay 25.5% silt, 2.4% sand and 0.4% gravel. Mind you, the gravel and sand were already there before constructing the dam. A lot of the clay particles, being in the top layers of the reservoir, have been washed away from the reservoir with the overflow during the past 56 years. The % of clay in the core could be even higher than these % in the reservoir sediment.
For the lay peoples’ information, silt is less than 74 microns or 0.074 mm in size, passing the ASTM 200 sieve. Clay is classified arbitrarily as less than 2 microns or 0.002 mm in size What passes through the 200 sieve or 74 micros size contain also 2 microns size which is clay. In this instance it is predominantly clay so that BOR terms the core as impervious clay core. Sand is classified as more than 74 microns or 0.074 mm in size. Sand itself can be graded as very fine sand, fine sand, medium sand, coarse sand or very coarse sand depending on its particle size.
To say that it is BOR’s understanding is a vague language and to me it smacks of heresay. Engineers look at facts and evidence and not heresay. The BOR ought to examine the dam’s permanent records since every dam’s specifications and test results of samples are kept as permanent records.
For the lay peoples’ information, the EIS/EIR has little information on the engineering geology of the vicinity of the iron gate dam. From my reading of the print version of it, I recall that the area was formed during a past geological period by repeated lava flows that formed its volcanic rocks. After each lava flow, there were volcanic ash deposits. It is from these volcanic ash deposits that they dug up and processed the material for the core of the dam.
This lateral pressure is huge and can be calculated. It depends on the internal friction of the gravel shell. It approximates to 0.7 of the vertical pressure at each level. At 1 ft. from top, it may be 84 lbs. per sq ft progressively increasing by same 84 lbs per sq ft per every additional ft. At 100 ft from top, it would be about a whopping 4 tons per sq ft.
When the deconstruction (of the iron gate earth dam) reaches the level of the saturated clay, the clay will yield to the lateral pressure of the gravel shell and the dam will collapse. It would be catastrophic. The material in the core is above its plastic limit, due to voids in the core material, (especially in the clay) being filled by reservoir water under pressure for decades. The water content in the clay would exceed the plastic limit or even the liquid limit, if the voids % permits. At progressive depths water pressure is progressively greater. The BOR argues that the pore pressure is not great. I would say, it is immaterial. My contention is that the core will yield to the outer gravel shells’ pressure, since its water content will exceed the plastic limit.
Voids in clay is at times even more than its solid particles. I believe the % voids in the clay core that will be filled with water under pressure, is way above its plastic limit. BOR may articulate the % voids in the material of the core, the % for plastic limit and the % for liquid limit. These are not in the EIS/EIR. It seems, the BOR was not aware of it at the time. They should be aware now.
For lay people to understand, plastic limit is the water content that makes the clay plastic-like, when it will yield to the slightest outer pressure. The Swedish scientist Atterberg defined the plastic and liquid limits, which are universally accepted.
Conclusion. My analysis is purely technical. I do not have any political affiliation. I am not a stakeholder. I do this for God and Country, for the Glory of God and duty to the Country. I accept my limitations. I am not in the engineering field for over 3 decades. My training by the United Nations at the University of Queensland, Brisbane, Australia, was over 45 years ago.
I have consulted no one. I am merely sharing my own knowledge and experience to technical people at the BOR and nontechnical people who make informed decision. As a civil servant all my life, I am chagrined to bring out the error of my fellow engineers. But this error has dire consequences and I can not be silent. I am only helping the BOR to avoid an error.
I wish I could write more about more issues. But I have several limitations. I am aged 83 and suffered a stroke that affected my capability for effective writing and arranging ideas in logical order. My poor health after the stroke is preventing me from writing more. I do not have Engineering Manuals or other literature with me.
I anguish over the unfortunate Salmon. If Salmon would be helped by removing the dams, I would be very happy and would be all for it. But that is not the case. As I said in earlier letters to BOR, its effect on the Salmon would be adversarial. About six years ago, I offered to help with an engineering solution, but BOR would not accept. After all, it is their turf and I understand. But I have concern about the error in the EIS/EIR, which has dire consequences and hence this effort.
My request is that the County Board of Supervisors, the County Counsel and others such as Honorable Senator Dennis Linthicum, Members of Congress on both sides of the border who have the resources, refer my submission to peer review by engineering authorities on the subject, who are without conflict of interest. I would abide by their review results.
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