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Crack _BEST_ Advance Steel 2017 Crack _BEST_

A threatening 14 foot crack growing in a massive 5 foot thick concrete pier at Radial Trunnion Gate 8 in Oroville's Spillway Headworks? DWR Board investigating how many of the internal cracking of the 50 year old aging "end of life" 384 steel anchor tendons may fail before they deem the Headworks operationally unsafe? Two steel tendons have already failed, test data reveals 28 more with crack indicators in the steel, some near the "critical failure size". Yet DWR doesn't know with certainty how many more are at risk of failure? Are there any plans to fix these major spillway Gate Headworks issues with emergency repairs for 2017? Why hasn't DWR revealed this information to the public?

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LOS ANGELES, CA (California Network) - On May 11, 2017, at a California State Assembly joint oversight hearing at the State Capitol Building, for an update on the damaged Oroville Spillway, legislators were surprised in testimony that revealed new concerns regarding structural cracking issues in the Radial Gate Spillway "Headworks" in addition to the issue of the leaking "Wet Spot" on the dam. James Gallagher, Committee Vice-Chair, District 3, revealed this new information while grilling DWR for answers.

As reported by Valerie L. Price [1], "Gallagher explains that at the "head-works of the spillway" there is a "diagonal crack in the left side of gate eight," and he reveals that "there's also a crack in the center of the head-works of the spillway." He states that the crack is serious. He asks, "Is there a plan to fix the head-works? You know, these cracks are probably going to require complete replacement of the head-works. What's the plan on that?" Bill Croyle states that DWR is focused on the emergency, but he says that a "small" team is considering "what the permanent repair would look like." Gallagher says, "The wet spot. The green spot... on the left groin." He asks if "piezometers" have been put in to monitor the wet spot. He says that originally, 56 piezometers were installed, but now only 3 are active to be read to monitor "the seepage and the pressure on those areas." He says, "I've heard it said that it's not a problem to the stability to the dam. Okay, well, prove that to me." Bill Croyle answers, saying, "I can't speak to whether there has been any instrumentation" installed to monitor the wet spot."

This "structurally significant" near 14+ foot crack, with an offset of near 4 inches, is being monitored by DWR using red paint (See Fig 1). As the crack grows, more red paint is applied. In a Feb 3, 2015 California Division of Safety of Dams (DSOD) Inspection report, the inspector noted a new growth close to 2+ feet in length as "fresh red paint had been applied" [2]. Why is "watching" with red paint the only action being taken? This concrete pier is 5 feet thick. For a crack of this magnitude to exist in a critical support structure area, near the Radial Gate Trunnion anchorage & pivot pin, it is surprising to hear that there are no planned repairs in 2017 to address this notable structural defect. Why "only" repair the main spillway to 100,000 cfs if the Spillway Gates may be under threat of failure at this flow rate?

Further testimony, by Professor Robert Bea, Phd Professor Emeritus, Center for Catastrophic Risk Management, UC Berkley, as reported by Valerie L. Price [1], "Dr. Bea warns that "nature [is] unforgiving of ignorance." He makes 3 recommendations. "Look out for the spillway gates," because the inspection reports show cracks in the head-works, "that they've had to paint over the cracks, so you can watch the two sides moving relative to each other. And then you look at the anchor tendons for the gates; two of them are broken. The wet spots, have been explained away as natural. In my world there's nothing like that that's natural unless proven natural. The piezometers are a clue." He warns to pay attention to the wet spots, because they are "part of this problem of growing old." Implicit in his remarks is a grave warning of the potential for catastrophic failure of the Main Spillway gate head-work structure, and consequently, the earthen part of the dam."

Professor Bea's testimony reveals another structural threat to the Radial Trunnion Spillway Gates in the "end of life" 50 year old steel anchor tendons. Two have failed at the spillway prior to 2000. Many more are known to have internal "flaws" that are typical of corrosion cracking [3][5][6]. In fact, the US Army Corps of Engineers issued a report in 2013 over concerns of increased failure risk at dams from old and aging steel anchor tendons (called "Post-Tensioned rods") [4]. Oroville DWR test data shows that every single gate of the spillway has defect "flaws" in steel anchor tendons with noted crack dimensions stated as "considered significant" in the original 2000 Ultrasonic testing report [3] (See Fig 2). Powerful Ultrasound is used to stimulate the ends of the exposed steel rods to look for "echoes" from "reflections" that internal cracks or flaws bounce back. However, DWR has found that this method is limited to a maximum of 4 feet and more specifically is useful to about 10 inches [7]. This means that only 10 inches of a 40 foot total length steel rod is able to be effectively tested. This is a coverage of only 2.1% of the length of the rod. What about detecting defects in the rest of the 97.9% of the rod?

If DWR is missing 97.9% in flaw detection, and within their limited 2.1% detection "tip area" testing ability - which discovered 28 "considered significant" reflector echoes indicating cracks - how could DWR know if the gates are near failure? Only when "failure" occurs will DWR know - just as a sudden failure of Radial Gate 2, from failed anchor tendons, occurred at Clifton Court Forebay Dam in 2013 [8]. Pyramid dam has also experienced a tendon failure in their Spillway Radial Gates. Not only is there a pattern emerging to three dams failing in 50 year old anchor tendons, there is another common issue identified in substandard grouting around these anchor tendons - confirmed in all three dams [3][8]. The original construction grouting was discovered to have "voids" that was believed to allow moisture to collect and accelerate corrosion cracking. With a common pattern of aging tendons failing, and a common pattern of insufficient or poor quality grout sealing protection around these steel anchor tendons, these common patterns should elevate the engineering concerns of a bigger threat exposure to sudden "failure" risks.

Why not replace all of the high failure risk tendons at Oroville? DWR spent $827,000 in 2013 to emergency fix & replace 100% of the anchor tendons and refurbish gates at Clifton Court Forebay Dam (CCFD) for Gates 1, 3, 5 (plus the prior emergency fix in 2013 to Radial Gate 2) [9]. Yet this 100% replacement of the tendons was triggered by another "emergency" at the CCFD dam. Isn't Oroville a more significant threat to the public, if there is a sudden failure, than the smaller Clifton Court Forebay Dam? The Army Corps of Engineers 2013 report notes that time increases the odds of this micro-cracking tendon failure mechanism - "older rods continue to be in-service and defects continue to slowly propagate until reaching a threshold total failure point" [4]. At "end of life" aging of 50 years, grout flaws, and with continued time ticking away, when will this threshold escalation of "total failure" of tendons occur? Why wait?

Another disturbing "engineering" modification to the description of what is considered a "defect" is revealed in Oct 31, 2012 FERC/DWR communications where DWR's original 2000 denoted report of a 1/32 inch "considered significant" flaw [3] was now redefined to be as 1/16 inch as "minor flaws" [14]. How did this redefinition occur? In 2000, DWR notes a 1/32 inch flaw as "considered significant". Then in 2012, DWR's communications to FERC, surprisingly notes that 1/16 inch or less is a "minor flaw". This is an increase in crack dimensional area of 281% [6]. In engineering, the clues of "rounding numbers" from a 1/32 to a 1/16 formulation is indicative of number fudging. If there were a true determination from new study findings supporting a change, you would likely find a value that is more precise in a dimensional area than simply from a "rounding of numbers".

Why is this important? Because the known "critical crack failure" dimension has already been determined to be 1/8 inch from the original 2000 DWR failure analysis data [3]. There is not much margin to be just "rounding numbers". Worse, DWR fails to reveal to FERC, in this Oct 31 2012 communication, that the original 2000 testing has TWELVE tendons that are ABOVE the 1/16 inch dimensional area. Cracks to not reverse themselves. Does DWR consider these 12 tendons "minor flaws" too? Then how may DWR answer that ONE of these original dimensional cracks is close to the 1/8 inch "critical failure size" [3]. Accuracy in engineering specifications and communications, on such important failure related information, to FERC should be clear and concise. Did DWR intentionally leave out these facts to FERC? Why has DWR now introduced an "ambiguous" definition of "minor flaws"? Why introduce a new ambiguous definition while increasing to a "rounded fractional number"? Where is the supporting data to justify this new description & sizing flaw determination(s)?

Essentially, DWR's Board has directed that analysis be performed to determine how many anchor tendons may fail to where the spillway is inoperable. In a normal safety review of a Potential Failure Mode Analysis (PFMA) at a dam, this type of calculation would be part of a safety assessment IF the dam had a low risk of failure of these anchor tendons. However, given that all of Oroville's 384 anchor tendons are at high risk and are "uncertain" on their "end of life" condition in internal cracking and progressing stress losses (plus elastic relaxation & concrete creep), this type of an action by the board should be considered a serious problem. Why? Because this may indicate that the backup plan is to anticipate the "failing" of these anchor tendons, due to the inability to fully test the 100% length of the tendons and due to the known pattern of failures encountered. 350c69d7ab


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