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Confirmed: Pre-indicator Failure detection optical targets bolted to Spillway Sidewall backside (two targets)

New DWR hi-res image confirms that two more targets were bolted at abutting expansion joints on the left spillway sidewall (this was inferred from a longer distance image from a post on 3/21 - see link below). These optical targets have concise black and white aligned stripes. Each panel is bolted to one side of the expansion joint seam. Any differential movement would indicate a potential "pre-failure" development of downslope shifting of the damaged end of the spillway. These two sections are in an area that was heavily re-inforced by the installation of drilled emplaced "rock bolts" via repair work. The repairs are designed to (1) consolidate the weathered rock substructure by injection of pressurized grout into any fractures and (2) to provide an anchoring of these deep "bolts" to the top surface of the concrete. In order to safely view these optical targets, the hillside was excavated.

The green pipe reveals the sidewall drain water flow that normally would be connected to the pipe coupling in the sidewall. The original connecting pipe to this coupling has broken away from the hillside erosion.

Not sure yet what to make of the "wet" spots in the green "hydro seeding grass"' area in the excavated bank and the lower leveled off region. The darker green indicates moisture. (other than subsurface soil waterflow from recent rains). The reason for the interest in potential "wet spots" is due to the Board Of Consultants note of extended release waterflow in the drains after the spillway gates are closed. If the "basin" of backfill was pooling the underdrain water (as the source of a back flow into the low point of the drains after the gates were closed) there is the potential that this water would work its way in saturating the surrounding hillside.

One of the upper spillway sidewall drains circled. Just a note in comparison to the other drains of a higher flow.

The four concrete blocks just above the hydro grass seeding embankment may have been the footings of the removed electrical tower as they remain in a matching footing pattern (in comparison to the other tower footing(s)).

Spillway Slippage Targets on Sidewall backside - cleared foundation area of Elect Tower (straight view to targets)..

New DWR hi-res image confirms that two more "slip" detection targets were bolted at abutting expansion joints on the left spillway sidewall. "Wet spots" in hillside. Stronger sidewall drain flow. Green repair pipe dumps broken drain line water on shotcrete repair area.

Thanks for the update. I agree that the 4 points near the remaining transmission tower are the footers for the one removed.

If what JanetJanet posted is correct, they’ll be shutting down the spillway around mid-day tomorrow. It will be interesting (probably very interesting to them) to see what kind of movement, if any, was experienced on the end of the remaining spillway.

I hope that they take a close look at the drain outflows compared to pre-shutdown too. I know that they did a good deal of sealing and patching, and it would be interesting to see the effects based on equal flow rates. It is interesting that the one drain is flowing higher. Probably significantly higher, even though it doesn’t appear to be anything like last month when they were pushing 100,000 cfs down the spillway.

Another Headache: Large amount of Water Flow Escaping into Hillside of Spillway - An Answer to BOC noting "drains" running for "extended period" after gates closed (pooling into hillsides of spillway chute)

Water is looking to be "Escaping" the whole spillway chute and running up in elevation into the embankment & saturating hillsides. The curious line from a prior picture - when zoomed - revealed what this feature was. DWR emplaced a drain line in the hillside to re-route the saturated area via a perforated type of collection drain in the ground. Images reveal/confirm the original suspicion of the Hydro-seeding area "wet zones" as coming from the spillway. What is notable is that the hillside water level is much higher with respect to the water elevation at the adjacent spillway flow. This directly infers that the high saturation hillside water level is from further upslope on the spillway. This significant hillside waterflow is AFTER all of the recent meticulous repairs on all of the cracks and seams in the spillway concrete.

IF such a high "escape" water level exists even further up the spillway, then there may be concerns that there could be a "gate structure" level source of piping. The presence of such saturation of the hillside + the BOC concerns about "needing to investigate why" on the "extended release of waterflow" after the gates are closed is a valid issue. BOC's report commented to a potential causal source as "piping" (i.e. "channels" of waterflow paths underneath). The hillside saturation provides an answer to the "why" on the drains continuing to flow after the gates are closed. The "pooled" water into the hillside is re-entering the lowest point in the sub-slab drains.

If anything, this evidence demonstrates just how much water is not captured by the sub-spillway drain system. Prolonged waterflows in the hillside would erode small material ("fines") and could further introduce "voids" - including "voids" into the hillside.

Prior Post discussion link & larger image:

Suspected: Spillway is pooling water from upslope & saturating the spillway hillside (large photo)

DWR buried a linear water collection pipe to capture surface hillside water from the spillway chute. Infers Water is saturating the embankment further up the spillway - i.e. large areas of the spillway chute hillside. Waterflow from a broken longitudinal drain observable separate from green pipe "fix" outlet flow.

Buried linear water collection pipe "fill" line - pipe & fill designed to capture the volume of penetrating & saturating hillside via water escaping from the spillway chute. Saturated Hydro-seeding areas observable from the high water level(s) of the escaping spillway chute waterflow.

Strong waterflow from the buried linear pipe outlet demonstrates the significance of the escaping water into the hillside. Depth of the "collection pipe" inferred from the elevation differential of buried soil top surface to lower outlet of drain below.