Heated Discussion - "Leak" in Dam - Public meeting with DWR - April 27
The DWR sponsored "information Q&A" meeting became heated when the "Leak" in the dam was brought up. Apparently, there was a professional moderator handling the Q&A with the packed hall of concerned residents. Here is a transcript of a particularly heated interchange with a resident, a male "chief DWR engineer", and the moderator.
= = = April 27 2017 DWR informational meeting interchange responding to a question from a resident speaking of the "green" wet area on the left side of the dam & asking DWR about this "Leak":
Resident: "There is a leak above the Hyatt power plant...its been there for years…grass doesn't grow unless you've got water…when the lake level goes down...you can see the grass die..because the water is not going through…you got water...you pressurize the dam to the most its been pressurized in the history of that dam…and now...with the green patches... where the grass is growing..were saying that leak..nobody wants to talk about it at your office?...I mean… there's water coming through…let the water out before it all comes out..on us."
DWR Chief Engineer: "The um, the, the dam was built..the regulators know about it….we..we inspect it...when we monitor it...it is not going through the dam…"
Resident: "Sure and you inspected and you monitored that spillway too…"..[crosstalk]
2nd resident, woman: "...they've had the same problem at another dam…and it failed.."
Moderator: "So, so I really need to… to ask people who are… who've asked to speak.. I..I just want to make sure we get your comments sir..so…"
Resident: "Well I hadn't got an answer…[inaudible]"
Moderator: "Well….I think what...what you're hearing.."
Resident: "About the leak…"
Moderator: "Well, what I understand that, what, you're hearing from the chief engineer, is, that.. it.. but it doesn't.. you..you..let's just hear that again, okay ..:"
DWR Chief Engineer: "That…that…leak…its…its a natural spring that has been documented...for decades….and we are measuring it on an annual basis…and… [crosstalk - crowd noise]
Moderator: Shhh…ok…lets…lets...let him answer the question.. okay?…
DWR Chief Engineer: "Do you have anything to add on that?"
end clip - of interchange.
My Discussion/commentary:
= = = I've never seen a "natural spring" flow uphill. The horizontal bench of the "wet area" green vegetation actually increases in elevation the further it is from the left abutment. The assumption is that a "natural spring" does not exist from "inside" of an earthen dam. IF there were to be a "spring" it would have to originate from upslope on the left abutment then would have to defy gravity and flow up in elevation". So why has DWR drilled a "test hole" near the green wet area at the left abutment in 2016 (DWR asking FERC) as DWR wants to figure out what is causing this seepage?
= = = So? How's the decades of Monitoring & measuring been going? Here are the California Division of Safety of Dams (DSOD) Inspection reports on "their monitoring" -
CA Division of Safety of Dams Inspection Report 2014 - Recommendation to implement a method to "monitor the mid-slope seepage" on the backside mid-slope of Oroville's earthen dam
CA Division of Safety of Dams Inspection Report 2015 - Stronger Recommendation to "investigate" wet area "to ensure the long term stability of the slope"
2016 FERC doc - DWR wants to relocate (from FERC request) a proposed drill hole to 670ft Left Bank near Green Wet Area to help understand the cause of the Seepage.
Oroville Dam Leak - Topo Map & DWR's "natural spring" theory - Water must flow uphill from abutment
Using elevation markers on the clear water leakage causing green vegetation growth reveals that any proposed "natural spring" theory requires uphill water flow. DWR engineer's statement that the water is from "a natural spring" cannot explain how the water climbs in elevation along the backside of the dam. The topography map places more difficulty in this theory as the 700 ft elevation level "retracts" from the leaking area (further into the dam to the core). Therefore, any "natural spring" would be flowing DOWN the original canyon rock abutment as the Zone 3 Shell, where the leakage is flowing through, is designed to be non-pervious (which means water percolates downward through - as it is designed). Since there is NO topography higher and to the left of the greening wet area ANY clear water would have to FLOW UPWARD to get to the greening elevation.
The only DOWNWARD flow of water to the greening wet area must be from the reservoir (i.e. "through the dam" seepage). The reservoir has been at record levels for a prolonged period. So too has the greening been at its greatest. The horizontal "greening" has a strong inference to a horizontal seam source or sources to this clear water flow. DWR absolutely must respond in identifying the risk to this situation. The public should know that DWR does not know the source to this water flow as they asked FERC to relocate a test drill well near the embankment to figure this out - in 2016. DWR has no standing in saying that this is a "natural spring". In fact, the dam leakage could give water readings in the abutment's highly fractured rock as if there were a "spring" - but from DOWNWARD flow from the core.
At the DWR town hall Q&A, the DWR engineer denied that the water flow was through the dam ("it is not going through the dam"). The evidence infers otherwise.
DWR engineer - at DWR town hall Apr 27 2017 Q&A stated "a natural spring" was water source - elevation data proves this to be incorrect - water must flow upwards
Dam topography map of the inner canyon wall abutment re-inforces the error of stating "a natural spring" - elevation & location of the topography reveals water must flow upwards. Best fit is seepage "through the dam". DWR engineer denied "seepage through the dam".
Resident: "There is a leak above the Hyatt power plant...its been there for years…grass doesn't grow unless you've got water…when the lake level goes down...you can see the grass die..because the water is not going through…you got water...you pressurize the dam to the most its been pressurized in the history of that dam…and now...with the green patches... where the grass is growing..were saying that leak..nobody wants to talk about it at your office?...I mean… there's water coming through…let the water out before it all comes out..on us.""There's no seepage, but we're going to investigate possible seepage (and not tell you)" - DWR.
The grass could be turning brown for a couple of reasons - overall drought, or lack of pressure from behind the dam. If it's due to lack of pressure behind the dam, then there is seepage. If it's due to overall lack of precipitation, then it 'might' be coming from elsewhere (i.e., the hillside to the right (left if you look from the reservoir side). The fact that there are shallow erosion marks below the green area indicates that there is, at times, a fairly large amount of water there.
Regardless, they need to KNOW what's happening in order to mitigate it before it becomes a huge problem.