by Natura Naturans
Is Oroville dam going to fail AGAIN? This article notes it is leaking in the same places it did in the last failure under the spillway:
March 18, 2019
Complete failure at Oroville Dam
By Chriss Street
The $1.1 billion spent to repair Oroville Dam is failing as water is seeping through the rebuilt spillway threatens new mass evacuations over the risk of the dam collapsing.
According to national dam expert Scott Cahill of Watershed Services of Ohio, Oroville Dam is on the same failure track as in 2017, with visible water seepage trickling from the foot of the dam and dozens of points along the dam’s principal spillway. Cahill warns that warming temperatures magnified by precipitation is a growing threat to the dam.
The only real fix is to drain the dam and put a fully concrete dam in front of it to block the leakage. It would cost far more than it would be worth. But that is the ONLY way to stop leakage in a leaky Earthen dam. Here is what Oroville dam is facing:
All earth dams leak to some extent and this is known as seepage. This is the result of water moving slowly through the embankment and/or percolating slowly through the dam’s foundation. This is normal and usually not a problem with most earthen dams if measures are taken to control movement of water through and under the dam. If uncontrolled, seepage can progressively erode soil from the embankment or its foundation, resulting in failure of the dam. Typically, erosion of embankment soil begins at the downstream side of the dam and progressively works toward the reservoir eventually developing a path to the reservoir which is referred to as “piping.” Piping action can be recognized by an increased seepage flow rate, the discharge of muddy or discolored water, sinkholes on or near the embankment, and possibly a whirlpool at the surface of the reservoir. Once a whirlpool (eddy) is ovserved, failure of the dam may follow. As with overtopping, fully developed piping is virtually impossible to control and will likely cause failure.
Seepage can also cause dam failure by saturating the embankment, thus weakening the dam, or by increasing internal pressure within the embankment. Saturation and internal pressure within the dam are difficult to determine without proper instrumentation.”
If this were to happen at Oroville the evacuation area would be massive. When the evacuation took place in 2017 after the spillway failed it took several days to a week to complete evacuation of the at risk people downstream. In the Teton dam case there was very little time to act as the initial leak widened very quickly into failure. If I could give any advice to those living downstream from Oroville it would be to watch the dam carefully in the weeks to come because the dam is almost at capacity, the most dangerous time. A warm spring storm could bring torrents of water into the dam from the record snowpacks. Here is a site that records the height of the water behind the dam:
Here is a Spillway cam for current views of the spillway. The spillway has now been used for several days as a test but we don’t know when it will be used again:
If you go to this link you can see some water coming down the spillway right now.