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Hi Repeal The 17th, they need to assess "piping" risk.....

Coring/Drilling in Front of Emergency Spillway - Most Likely Trying to Understand "This" (submerged flow paths - troubling "piping" under/through weathered rock & grout curtain)

"This" => Bubbles observed from prior ES use observed from multiple locations in front of the Emergency Spillway. Any new proposed fix to the Emergency Spillway could be undermined if a "piping" channel exists in the highly fractured rock. A Grout Curtain (pumping grout into cracks and seams to form a water barrier) may have "cracks" where subsurface waterflow is not contained. Any waterflow under newly placed RCC for the New Proposed Spillway would face a "voiding" risk & eventual failure mode from an accelerated underground erosion channel or channels. The New Project Plans may need remedial construction measures depending on what they find (i.e. new excavation, sealing, new grout curtain,…)

Coring/Drilling in Front of Emergency Spillway - Most Likely Trying to Understand "This" (submerged flow paths - troubling "piping" under/through weathered rock & grout curtain)

Waterflow under Emergency Spillway? - Notable flow exiting emplaced Corrugated Steel Pipe - April 14

I've been waiting for a better "dry" day to get a capture of this water "underflow" behind the emergency spillway Weir from an earlier emplaced corrugated steel pipe. The outlet elevation of this pipe is 797ft. Reservoir levels were near 866 ft at the time of this image (April 14). Thus, given the amount of the observed seepage flow, this may be an indicator of a "piping source" or "sources" through the grout curtain under the Emergency spillway. The dried shotcrete contrasts well with this waterflow, revealing the extent of the amount of water collecting in this basin area underneath the shotcrete "armoring". (If this flow were to be from nearby ground water from percolation through soil, there would have to be a high saturation of the soil in the exposed hillsides in addition to the unusual flow angles necessary to reach the upslope inlet of the steel pipe). All indictors point to seepage from the reservoir & underneath the emergency spillway.

This is another inferred link to why DWR was conducting all of the core sample drilling in front of the Emergency Spillway - an investigation into "piping" which would answer the large air "bubbles" (reservoir side) observed shortly after the overflow of the Emergency Spillway.

Coring/Drilling in Front of Emergency Spillway - Most Likely Trying to Understand "This" (submerged flow paths - troubling "piping" under/through weathered rock & grout curtain)

Waterflow Seepage Under the Emergency Spillway Armoring at elev 797ft - Potential "piping" from the reservoir side