Emergency: California’s Oroville Dam Spillway Near Failure, Evacuations Ordered

That’s a great plan.

Kind words - thanks. btw- you seem pretty handy on graphics & data. I’ll contact my sources to see if I can obtain dated images of the dam backside greening.

2014: 96% of dam Piezometers inoperative - only 3 left & "thought" to be functional - FERC directing DWR to develop plan to monitor internal water levels in dam (Phreatic surface)

I found one of the FERC references where FERC Part 12/DSRB Report states "…a plan for long-term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented."

Essentially, DWR doesn't have working piezometers to give "health" status on this indicator of the internal water pressure levels from piezometers. Based on a piezometer reading, it indicates the water pressure & thus the inferred water level above the sensor. Only 3 sensors are "thought" ?!? to be working. Two are in the core and one is in the upstream zone 2 transition layer. No indication as to the centering of these sensors with respect to the abutments.

Grout Galleries have seepage measurement weirs at sectioned elevations - allows seepage measurement in left abutment - "porting" around dam should be detected by these weirs

Seems there are built in detection systems for abutment seepage at sectioned elevations. Measurement weirs are emplaced in drain channels in the Grout Gallery tunnels. These weirs provide a seepage "flow rate" measurement capability. Upthread I had surmised that seepage could be detected in the CtJ's of the Gallery concrete enclosure, however, they already designed in a "seepage" detection system. This weir detection system should have given DWR indicators if there was "porting" of water around the core of the dam through the hillside. Seepage would increase in these collection channels & weirs (fractured "weathered" rock would leak downslope to these weirs even if the porting was at/near high a crest elevation). This may lessen Scott Cahill's theory on the hillside "porting" around the dam.

What is interesting is that there was an "action item" given to DWR to analyze an unusual sediment collected in one of the weirs. The concern was that this sediment could have been from the core. The soil test results came back as having a high organic content. DWR's engineers "believed" that this sediment was from particulates accumulating in the tunnel and then in the drain weirs from the airflow from the Grout Gallery entrance Ventilation fans.

Note: the DWR's Board concerns over the 50 year old anchor tendons to the Radial Trunnion Gates of the main spillway (i.e. concerns of failure and/or loss of tensioning).

The Green Area, at the June and August combined dates of this inspection report noted that it was dry. The reservoir level was low at that time and precipitation was very low to zero during that time.

The solution to all problems...

https://www.flextapeoffer.com/FLXTP/4.0000/Index.dtm?otsid=3758

Hi Ray76, There may be an odd plot discrepancy on the linear X axis reservoir levels in your graph - OR - the DSOD reference data is somehow off. I'm using CA Division of Safety of Dams (DSOD) report data. They read the reservoir levels personally at station gauges for DSOD report purposes. Since they are using fractions of a foot, it infers they have access to a precision gauge.

I've been only able to reference two points so far. The first point -in 2015- seems to be shifted by 14 to 15 days in order to match your plots with the DSOD reservoir level to intersect equal elevations. The second point -in 2016- is pretty much in agreement.

Using DSOD data the reservoir was at 723.0 ft on 2/3/2015. Your Plot has it at/near 748 ft. (delta near 25 ft).

Second reference point, DSOD data, the reservoir was at 778.8 ft on 8/22/2016. Your Plot is pretty much accurate at that date (estimated at 775 ft on your plot slope).

I'll try to get other DSOD data to compare against (you have to dig to find these tidbits in reports).

Just saw this....from the blasting? 2.2M near the DAM

A micro quarry occurred at 11:43:17 AM (PDT) on Thursday, May 4, 2017.
The magnitude 2.2 event (a probable quarry explosion) occurred 10 km (6 miles) N of Oroville, CA.
The hypocentral depth is -0.37 km (-0.2 miles).

post 3567
looks like there is a quarry in that area with small microquakes in the past....disregard

The chart shows average monthly elevation rather than daily elevations. Perhaps a scatter chart would have been a better choice than a line chart, which could be misleading.

The lake elevation data in the graph in post 3560 is based on data from https://cdec.water.ca.gov/cgi-progs/queryMM

with parameters: Station ID:ORO Sensor Number:6 Date:04/17 Span:144

Which provides the daily lake elevation in feet to two decimals places. The daily elevation values were averaged for each month and rounded. The same data is in a table in post 3549.

I sought to identify periods of low precipitation and elevated lake levels to help determine whether the occurrence and size of the green area correlates with precipitation or with raised lake elevation.

Monthly Precipitation and Average Lake Elevation

Data in tabular form here.

As I mentioned upthread to jpal, the strong cobble fill evaporative effect on this seepage will mislead any precip to lake level correlation. I've been investigating this correlation with years of pictures going back almost 10 years. Working on this well over a month ago. The study data was being thrown into a loop & not making sense. That is, until the embankment Infrared absorption, low humidity, high temperatures, and wick factor to the plants were taken into account. Knowing this relationship, and figuring out the key to greening, that is when I decided to bring this issue to the forefront as it definitely was more than precipitation.

What does align with the precipitation is the cooling of the zone 3 cobble shell's effect allowing the subsurface percolation to wick to the surface. Essentially, the furthest reach of the broad seepage percolation into the Zone 3 fill is what meets the wet area surface. There is more water behind and deeper that is in this broad seepage. That is what is causing the erosion channels (deeper seepage just under the surface).

Oroville's strong heat, low humidity, winds, and the huge heat sink of the mass of the southern facing rock face cobbles, boulders, gravels effectively neutralize the wicking/seepage at the surface in summer. This neutralization goes to a depth to the heat penetration of the infrared absorption & the atmospheric temperature base.

This is a key reason why DWR has been puzzled over the variances.

They DO know there is a water source. I have new documents that have stronger notations on their investigation(s).

The other key piece that throws off a correlation to this mid-slope area is what keeps DWR from putting the last pieces together --- that is an "erosion soil/silt/sand semi-pervious "shelf" has formed from the migration of internal erosion. Normally, seepage past the core would be caught in the drain zone. Since there is an issue where seepage gets past the core (whether its arguable from the hillside or core) the puzzle would be how does the water flow in a horizontal formation to create the outer horizontal seams of the greenage wet areas. This can only be facilitated by an original consolidation "shelf" that erosive flows have subsequently deposited soils/silts/sands (zone2 & core) upon. These SAME materials are ported to the surface where this material forms the growth medium the plants feed off of.

Post 3,546 clearly demonstrates this internal soils porting to the surface in the two large soil patches (after a strong seepage differential settlement stage in the early dam operation). These large soil patches have since been washed away and there is no green patches or wet areas there today. BUT the process never "sealed" or stopped in the left abutment. Now the Green Wet area has matured to a full soil patch and feeder of internal waterflow. It is just that the flow has internal percolations & the flow has an "outer" finger of reach to the surface that can be neutralized to some inches below the surface by the hot Oroville weather conditions.

DWR knows there is a water source. They are not telling the public. They are trying to figure it out thinking it is coming from the hillside. The DWR engineer, at the first town hall, let it slip as to what DWR really thinks. They believe its from a natural spring flowing from the hillside into the zone 3 fill. However, this is bad PR to admit this. That is why the new message is "rain falls... grass grows". They are burying the "natural spring" statement as this wouldn't be good for an earthen dam to have penetrating it.

To ER333:

I really like your 7 step plan for conducting more through diagnostics of the cause and extent of the dam “green spot” and associated settlement (post 3554). The only way to make sure that “unseen unknowns” don’t bite you in the ass is to make them seen and get to know them.

However, more extensive dam diagnostics are not in this year’s current work plan (that we know of). But putting in some or most of the spillway is in the current work plan.

I’d like to get your thoughts on what types of diagnostic instrumentation should be included in, under, and around the spillways. The contract specs for any such instrumentation are probably just now being drawn up, so it seems such focused speculation could be timely.

My preliminary thoughts:

Any modern embedded sensor should be wedded to a microcontroller to continuously check for threshold changes and to handle communication. Temperature and acceleration are basically builtin to many embedded controllers. Pizos could be added for pressure. Acoustic microphones are simple and cheap. Flow and turbidity sensors could be added to the drain pipes. Embedded strain gauges can be temperamental and break easily, so where possible, strain and settlement might best be measured externally via terrestrial scanning Lidar or perhaps inSAR satellite. The more critical instrumentation should be accessible and replaceable for upgrades, where access should be easier in a spillway than a dam. If someone were to put together such a extendable instrumentation package, now would be the time to prototype and test it.

Better diagnostics can lead to applying an once of prevention, rather than the current pound (or a ton) of cure. What types of diagnostics should be built in to the new spillway?

Thanks again for the detailed reply, ER333.

You are going to have me give away some of my secrets... :-)

I wouldn't mind prying a few more out of you if I thought the Oroville Dam guys would take note, but horse-water-drink, etc.

TIR/FLIR inspection is interesting - never thought of the utility of that method. A search online produced no images I could post here as an example, but I noticed a few inspection firms had specifically mentioned the service. The cameras/scanners are getting better every year. It would be great to see a time series over days-weeks of the spot in the fall as the reservoir rises.

The metrology toys just keep getting better.

InSAR imagery for those interested (because I'm a picture/cartoon kind of primate):

Source: Norwegian Geotechnical Institute captioned "Deformation analysis of the Svartevatn dam, based on the InSAR technique, shows a settlement rate of approximately 3 mm/year at the centre of the dam. Satellite scans were taken by the ERS satellite between 1992 and 2000. (Satellite data: Copyright © European Space Agency)"

And a study of the Mosel Dam subsidence:

From Space geodetic monitoring of engineered structures: The ongoing destabilization of the Mosul dam, Iraq

I was hoping to find an good image of terrestrial RADR or LIDAR interferometry studies of an embankment dam, but couldn't locate anything. I know they have issues with rough surfaces, but should still be useful with the image processing software currently available. Visible monument markers would probably be needed too, but I think they 'lost' some of them on Oroville if I remember right from one of the inspection reports.

Electrical resistivity tomography is also mentioned by some dam inspection firms. It's done by taking a series of measurements from electrical probes inserted at the surface. This appeals to that Break-it-down-Barney-style mentality: blue = leaks (well, sort of...).

Source: Geophysical investigation of earth dam using the electrical tomography resistivity technique

Chinese engineers love the fact that resistivity tomography can also help locate those pesky 'termite chew cavities' in small earthen dams. Apparently, the voids are significant enough to compromise the structures. That's some aggressive termites!

It's also sort of sad about the state of the piezometers at Oroville. I remember reading about the proud claims of it being one of the most heavily-instrumented dams at the time of construction. I wonder how the long-gone original engineers would feel about the missing geometry monuments and the dam only having three of the 50 piezometers functional? You can't out-engineer poor maintenance (or termite chew cavities) unless you have a good time machine.

There are two outwardly visible characteristics of the Oroville dam “wet spot”. First, it’s “green”, indicating it generates enough water sustain plant growth. Second, there are visible vertical streaks below it, indicating at some point there was enough water percolating out for multiple channels to flow down the surface of the dam for some distance.

One hypothesis is that this flowing water originates from within the reservoir. When the reservoir level drops below the elevation of the wet spot, the wet spot dries up. Conversely, when the reservoir rises, the wet spot must get wetter. Ultimately the flow rate to and through the wet spot would have to be a function of the driving head, or reservoir water level.

Six years ago, around this date, Oroville was running close to 890’. According to DWR’s online records, the reservoir stayed in this range through mid August. No one registered much concern about it at the time. Indeed, most would consider it prudent to max out the use of the reservoir, assuming its safety was assured.

During the 3 months in 2011 that lake was at this 890’(+) stage, thousands of people drove over the dam to get to the boat ramp. One might assume these individuals would be highly motivated to notice an unusual green spot, water percolating out of the dam, or any other visible sign that the reservoir they entrust their family’s lives to was in any way impaired. This (apparently) wasn’t an issue at the time.

Even if there is a delay in water getting to the wet spot due to some hysteresis effect of pressure migrating through the dam stratums, the pressure and flow would stabilize after 3 months of constant 890’(+) head. The maximum flow rate to the wet spot would be when the head was highest for the longest period, which would have been in the summer of 2011. Even if much of this water evaporated when percolating out the SW facing slope in the daytime, the vegetative green spot should have become and stayed greener longer than has been the case in 2017, when the average lake level has been 40’ lower.

Alternate hypothesis:

It appears that the local geology consists largely of weathered brown rock and harder blue rock fractured together so as to easily form erosion channels. There is a large hill at a high elevation on the left bank. It is plausible that rainwater flowing in a ravine above the left channel sinks down into a plunge pool, through a million year old erosion channel, and into a river bank somewhere under the area where the dam got built. This either wasn’t noticed or was’t patched correctly during dam construction.

This high pressure water, injected from the hill above, would flow through the various dam fill stratums and not necessarily come out at one place or one elevation. One might assume that if a 700’ earthen dam has a maximum settlement of less than a foot (0.1%), then all the various stratums were fairly well compacted, and pressurized water might migrate between the fill layers rather than through them.

If this hypothesis is viable, then DWR’s half assed explanations may be half assed valid. The green spot is due to a local ground water “spring” or pathway that is only active when it is raining. This could help explain why some water flowing in the galleries appears to have higher organic content than might be expected from dam fill material alone.

Now DWR may not want to outright admit that spring water from the adjacent hillside occasionally flows through their dam. However, this would be an order of magnitude better than having water from the reservoir flowing through the dam, because once started, that pathway might not stop.

I think that everyone reading this forum agrees that a more through examination of this “green spot” should take place. When examining “unseen unknowns”, no plausible hypothesis should be rejected without due cause.

Hi PavewayIV, DWR has ran into the exact issue that the InSAR images reveal. Settlement can be very delicate to precisely monitor. Especially in shorter time periods. DWR ran into difficulty with the GPS uncertainty in the millimeters. Thus they didn't know if the quality of the data was accurate for trending or even an absolute. InSAR provides very high precision verses the thorn in the side of GPS in dealing with scintillation error from the ionosphere + the orbital correction reprocessing of the GPS satellites. Even the USGS has "error bars" on their high precision fixed GPS monitoring station readings. They "average" the noise out to a degree with numerous measurements throughout a long period of time.

Have you seen one of the USGS GPS precision monument antenna stations? They are bulky. I can't imagine these installed in a matrix array on the dam. Too invasive + FERC might have a heart attack.

The TIR/FLIR imagery for dams are mostly on "research paper" sites. You have to pay to get these research papers. You can tell when something is a hot field and where people are willing to invest in paying for research - is when you can't find much open info (with good data) except on the "pay" for research papers websites.

The electrical resistivity method has a few variants. They still involve inserting probes into the surface. A big no-no for US dam safety regulations. The non-invasive version of this (magneto-electroresistive) is not 100% until you follow-up with a verification drill. Another no-no. But its good that other entities, such as the Chinese and the Australians have more flexible test standards. This environment can help prove out any new tech that the US may adopt quicker than if tried in the US trying to fight through the red-tape bureaucracy.

Hi jpal, most people do not understand how modern electronics, with microprocessors, can be a disaster. I've physically designed ASIC's, FPGA's, microcontroller systems, microprocessor high reliability code, and dealt with the system FIT or MTBF (calculated MIL217 & modern FIT hybrid - to actual "tested" confirmation of the bathtub curve). (worked & designed systems/boards for massively parallel supercomputers down to the smallest of microcontrollers).

I would keep sensors as simple and reliable as possible. I would provide accessibility for service, and have redundancy to systems.

Modern microprocessor or microcontroller units, even simplified, rely on expertise you do not know if the engineers are versed in the subtle failure modes (physics, truncated branch code threads, code loop proven certainty, power supply integrity, component ratings margins for extra life & certainty, etc).

I helped on a case where a very rare & unknown glitch in a natural gas customer electronic microprocessor unit caused an $80,000 dollar overcharge. The customer proved to the utility that this was impossible based on their average use and the weather at that time. It turns out that the engineers designed the EEPROM storage of flow rate data to be without ECC (error check and correct). Thus, a single bit degradation of the "tunneling" charge method to a floating gate substrate could experience a "charge" loss resulting in a soft bit error. Either the engineers were completely oblivious to this real effect or they didn't think that the calculated possibility of the datasheet spec rate for this phenomenon would manifest. The other issue is code reliability. Compilers can be so high level that you don't always know what the core executable assembly language instruction blocks/loops are generated. That is why they have revisions - due to the bugs in compilers.

In high reliability systems, even the microcontroller code has to be carefully written, tested, and verified in all combinations of input conditions and timing loops. Not many engineers are versed in this ability today. Even then, microcontroller designers have integrated "watch dog" reset circuits - just in case.

Choose wisely if anyone wants to install modern electronics into a high reliability complex system. There is nothing wrong with a very reliable but old fashioned mechanical system (such as the hydraulic piezometers & tubing).

Jpal,
You reach a logical conclusion in this post. There is either information not being publicly shared due to “terrorist concerns” per the official report above or there is this quote from ER33 above:

“...what's going on, do you have a problem?” response from FERC if someone wants to figure out an unexplained anomaly (such as Greenage). Unless there is a collective will in “belief” that there is a real puzzle that needs to be investigated, they likely will take “heat” from upper management, directors, and the Board in triggering a FERC intensive inquiry. You can degrade your career [by standing up for the truth]...”

Or both. Either the good engineers have a plan which will be kept secret (most likely to prevent mass panic and criticism of Moonbeam's DWR) or Atlas Shrugged has come true. The Christy Jones Memorial Green Spot will become famous if the worst is true.

“...”The consultants’ report, their fourth, was more heavily redacted than the previous memos released by DWR. Erin Mellon, a spokeswoman for the Natural Resources Agency, which oversees DWR, said the latest report contains more information that was considered “critical energy infrastructure information,” or CEII. That rule, intended to prevent terrorist attacks, allows DWR to seal sensitive information.”…..

“There was more CEII in the fourth consultants’ memo,” Mellon said Thursday.”….”In their memo, the consultants also sign off on DWR’s plan to fill in the gaping chasms in the spillway with fast-drying concrete made from recycled rock that’s been recovered from the Feather River channel below the dam. However, they add that so far the methods used for crushing the rocks don’t produce “suitable material” and need to be refined.….”

Thank you, ER333, for this week's analysis and the above official news. I had jumped on the thread to see if the snow melt is causing trouble yet. I've been reading the daily outflow/inflow summaries at the DWR reservoir site. So far the dams below Oroville are max capacity while the managers keep Oroville beneath 80% capacity. Shasta today is almost at 100%. My question is: when does the snow pack melt usually reach its peak and/or has the massive amount of snow mostly melted by now? I'll ping Ray76 over to see what he knows.

"During the 3 months in 2011 that lake was at this 890’(+) stage, thousands of people drove over the dam to get to the boat ramp."..."No one registered much concern about it at the time."...."This (apparently) wasn’t an issue at the time."

Why are you making these inferred assumptions? (thousands driving over & no one registered much concern about it at the time) & (This (apparently wasn't an issue at the time)?

I'm not intending to be adverse, but just curious. What documentation do you have that supports these statements? Or is this just discussion "what if's" context of a form of speculation?

First - "hysteresis", as used in the prior upthread discussion was strictly in the greening or death of the plant itself. Perhaps I could have made that distinction more specific in my writing as it was "greening" - could be interpreted as specific or in general. The greening or death of the plant, I was intending to describe, is based on the localized state of hydration, soil nutrition, sunlight, and including summer heat (infrared absorption of zone fill region surface temperatures + direct spectral light to plant + atmospheric temperatures + aridity). At a certain threshold, the plant will degrade and turn brown.

As far as "890'(+) 3 month stage" and "thousands" and "no one registered much concern".

IN fact DWR DID note the most documentation I have run across to date during this exact 3 month window in DSOD documents: "Lush grass and weeds covered this area", "The ground remains wet..". They even revealed that they were trying to figure out the "water source".

DWR/DSOD's two leading theories in their discussions were (1) possible mechanism causing "perched rain water" to gather in this localized area, (2) a possible "abutment seepage source" (aka "natural spring" theory). They even researched construction archives and found that during original construction it was noticed that there was some seepage "wetting" in the left abutment.

But their words are revealing, they say "Another possible source could be an abutment seepage..". They didn't know, but they were surely trying to figure this out. DWR - DSOD's 2011 documents have had the most revealed information than the other remaining years regarding the wet area notation & engineering discussion.

If you read carefully, (docs below), DSOD showed their concern of the risk factor this posed in noting that they need to "monitor the area for unexpected changes in the seepage pattern or flow quantity". This is the very first valid "alarm", albeit low key, of the risk they knew an "unexpected change" could mean - a failure mode may be developing.

Yet none of the posited theories has been able to explain the uphill angle away from the abutment in a highly linear longitudinal structure. Source water speculation is one thing, but fluid flow hydraulics does not operate in a highly linear longitudinal alignment structure, besides the fact of an upward elevation formation away from the abutment.

DSOD Feb 2011 Inspection report - "damp to wet".."no moving water was observed" - "cause".."yet to be determined" - "could be an abutment seepage".

DSOD May 2011 Inspection report 1 of 2 - "Lush grass and weeds cover this area" - "The ground remains wet, but no active flow was observed".

DSOD May 2011 Inspection report 2 of 2 - ""staff should continue to monitor the area for unexpected changes in the seepage pattern or flow quantity" - KEY POINT: 100% of Piezometers are admitted to be non-functional as the last 3 are considered useless.

New facebook video from May 5. Homes inundated and waterfalls creating rivers in streets. If this is what Oroville side of the snow melt basin faces in any quick melt off, there could be a strong surge of inflow.

May 5: Gushing Water river flows in streets - homes North Lake Tahoe Snow melt, facebook video

The California Department of Water Resources issued a sudden evacuation order shortly before 5 p.m. Sunday for residents near the Oroville Dam in northern California, warning that the dam’s emergency spillway would fail in the next 60 minutes.