The ES concrete blocks were poured "monolithically" which means "individually". So there are seams that will leak too. The "green grass" area near the far or third arrow in your pic aligns near the area that "bubbles" were observed on the other side of the ES. So there are likely "piping" channels that are making there way through in different paths besides the foundation itself.
Having Piezometers installed would be a good idea as they can determine how much water may be coming from the nearby hillside vs when the reservoir rises to a level to contribute.
Article clip: === Headworks Cracking Risking 3 Highest Level FERC Category 1 Potential Failure Modes? New Design Flaws Discovered?
Evidence of multiple serious Design Flaws in the Headworks Radial Gate Structure? Diagonal cracking in the end Piers in the Spillway, including a Large 14 foot crack in one of the 5 foot thick piers confirming this serious Flaw? Chipping of the bridge abutment concrete risking a spillway bridge collapse? Is there a legal liability exposure by reputable professionals or construction companies regarding a damage contribution to these serious FERC Category 1 PMF Failure modes?
LOS ANGELES, CA (California Network) - The Federal Energy Regulatory Commission (FERC) requires Potential Failure Mode (PFM) assessments at dams in a process to proactively identify modes of "potential" failure as a method to ensure appropriate safe operating performance margins [21]. PFM's are an integral part of the FERC Dam Safety and Surveillance Monitoring Reporting process (DSSM's). High Reliability Systems, such as a dam and a spillway structure, require a constant assessment of conditions where FERC and the dam owners cooperate in this proactive DSSM's based exercise. Thus any findings requiring actions, whether further assessment or structural remedies, provide safeguarding the level of failure probabilities to "As Low As Reasonably Practicable" (ALARP)[20]. Civil law is based on this principle when entering into "controlling risk as effectively as possible" (See Fig 4).
Another critical component to Civil law and Risk Liability is noted as "standard of care" (SOC). Engineers have a duty to provide their services in a manner consistent with the 'standard of care' of their professions [19]. J. B. Kardon notes: "A good working definition of the standard of care of a professional, derived from case law (City of Mounds View, 1978; Gagne, 1934, and others), is presented in a standardized jury instruction, Book of Approved Jury Instructions, 6.37, The Duty of a Professional, (BAJI, 1986), which reads: In performing professional services for a client, a professional has the duty to have that degree of learning and skill ordinarily possessed by reputable professionals, practicing in the same or similar locality and under similar circumstances. It is his or her further duty to use the care and skill ordinarily used in like cases by reputable members of his or her profession practicing in the same or similar locality under similar circumstances, and to use reasonable diligence and his or her best judgment in the exercise of professional skill and in the application of learning, in an effort to accomplish the purpose for which he or she was employed. A failure to fulfill any such duty is negligence."
What does all of this have to do with Oroville dam? Everything. These conditions establish the framework for legal liability and duty bound responsibilities by engineers, professionals, and contractors working on high risk structures such as at Oroville Dam. This framework includes the application to professionals that "practice" their services whether through consulting or through contract work. The specific application of these standards become relevant in the case of a "reasonable skill, possessed by reputable professionals" in light of an exposure to Potential Failure Modes (PFMs). This includes the obligation to recognize and appropriately respond to such PFMs as a "duty" whereby "A failure to fulfill any such duty is negligence.".
What if a contractor isn't notified of a PFM risk by the dam owner? Under Civil Law, the contractor still has a professional "duty" in the "standard of care" to exercise their expertise in recognition and awareness of such conditions within the reasonable performance of their services. Indeed, under these conditions, both the dam owner and the contractor could be held legally liable if a subsequent PFM occurs that is attributed to action (or inaction).
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Fig 1. (from article) Fig 1. Over half of bearing support of 5 inches of concrete lost in areas from cumulative "chipping" (wide red paint area) in bridge support abutment. Heavy Loads may cause a sudden bridge failure. Design Flaw with no bearing plates causes "concrete on concrete" sliding induced fracture chipping. Growing diagonal crack due to another "design flaw". Threatens Trunnion Radial Gates & anchorage from shear forces and shifting of the 5ft thick Pier Column.
Fig 2 (from article) Fig 2. "Flaws in Headworks Design" - 3 serious FERC Category 1 PMF failure modes. Legal liability arising from "load flexing" of the spillway bridge? Will DWR inform Kiewit or any other engineering services contractors of these PMF bridge associated conditions?
Fig 3 (from article) Fig 3. DSOD Inspection report revealing settlement evidence of Bridge Abutment "design flaw" as evidenced in diagonal cracking at the Pier support notch corner in both Piers 1 and 10 - shear forces created in notch by bridge slab from bridge "load flexure".