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To: KC Burke
Sleeves were used. After Post-Tensioning, they emplaced grout within the sleeves to fully encase the tendon. The grout had an alkali component as an additional corrosion prevention measure.

Yet, the failed Anchor Tendons at Oroville, AND the failed Anchor Tendons at Clifton Court Forebay Dam both had poorly placed grout within the sleeves. The "failed steel" in the rod is where "voiding" areas were found between the sleeves and the tendon where moisture collected and corroded the tendon to failure (original construction technique caused the "voiding").

Finding a matching construction issue at two separate DWR dams (sleeve grouting) is concerning. Since Ultrasonic testing, that DWR is using in yearly Inspections of the Steel Rod Tendons, only reveals "defect reflections from cracks and/or corrosion" to only 3 to 4 feet of a 37foot 6inch long tendon, then 90% of the tendon is not verified. Combine this fact with the known construction defects of "voiding" in the original construction, this means DWR is "flying blind" on 90% of the linear component of an unknown number of potentially failed tendons (note: 384 tendons are needed for the 48 each for a single gate).

That is why they are "scrambling" to get a new technology verified - the Dispersal Wave Technique - where its goal is to verify the tensile component of the steel tendon to see how much (or if zero) of the tension is left (outright fail or creep tensile reduced). They have asked FERC for an extension to Sept 2017 as their estimated results by April 2017 has been delayed. Thus, I suspect the free flowing money opportunity (as you worded) will be used to replace them all & give up on the Dispersal Wave Testing lab pattern resonance verification.

How DWR can say "satisfactory" or "safe" for these critical components for safe operation of the Main Spillway Radial Gates during spillway flows is questionable.

3,110 posted on 04/13/2017 11:46:26 AM PDT by EarthResearcher333
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To: EarthResearcher333; KC Burke

All of this to say that if enough tendons for enough (blocks?) for a given gate lose enough of their tension, apparently the gate will fail. Does a “failed gate” mean the gate won’t open or close or will stay stuck either opened or closed?

If enough gates fail, do we have yet another avenue for a potential catastrophe with this dam? It looks like failed gates means that either water continually spills or no there’s spillway capability or a % of both. Is there any reasonably potential scenario where the dam itself could fail as a result of the failed gates?

Honestly, this Oroville dam thing is starting to look like a soap opera. Everywhere you turn there’s dysfunction.


3,111 posted on 04/13/2017 1:54:09 PM PDT by Jim W N
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To: KC Burke
Correction: The Clifton Court Forebay Dam Anchor Tendons indicate that they did not have sleeves, but were "grouted" within cored holes, pre-tensioned, then cured in place (this was in the bid repair specifications). No mention of re-installation of sleeves.

Another differential point: Forensic failure analysis pointed to poor anchorage of the grout at the anchor region (voiding of the grout) - yet the report also stated that these "voiding" areas allowed severe corrosion. The Clifton Court Forebay design uses two large anchor tendons per trunnion pin anchor plate. They found both anchor tendons in poor conditions via conductive tests on another gate (likely ready to fail after another gate completely failed (gate 2)). Oroville's spillway has 48 tendons per gate (24 tendons per side).

3,116 posted on 04/13/2017 8:51:10 PM PDT by EarthResearcher333
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