I doubt very seriously that the slab work on the spillway would be done with local aggregate.
Local aggregate is used for mass concrete, but often there is too large a percentage of extraneous materials, clays, lignites, and such to have a good mix. Likewise, there is no history on a mix design from the local aggregate.
For durability this needs to be done with the right type of limestone aggregate in a proven mix design.
The RCC could be done with something local but I doubt that such will be the case. I imagine a local batch operation however.
Perhaps recycled concrete from the existing slab?
DWR is treating the area as a "contaminated site" including monitoring the air at the work site and nearby neighborhoods. DWR is assuring the public that risk to workers and the surrounding community is minimal.
I'm guessing that is not exactly comforting to the nearby residents - especially when this giant stockpile may be used for access roads throughout the hillside areas along Oregon Gulch Road. These residents are already complaining about the "dust" from existing construction work. Now they have to face asbestos concerns & assurances.
Mercury News Article on the Oroville Dam natural Asbestos:
Oroville Dam: Asbestos found in spillway rock; dust controls increased
SacBee news with interesting info. They can't get the formulations of crushed rock from the reclaimed stockpile to work (RCC intended use). This could be a significant disaster in that IF they were planning on using this material for the voluminous RCC construction repairs & building to quality standards of ES & MS new spillways. They would need a plan "B" to get known quality rock & materials to meet schedules. But this would be equivalent to trucking in nearly the same volume of the stockpile with "known good" RCC base rock & material.
Other news in this article are that new plans are afoot inferring that only "minor work" will be done in the Upper Main Spillway in 2017, leaving the upper spillway "mostly untouched".
Article excerpts: === (emphasis mine)
"In a 16-page report made public late Wednesday, the engineering consultants concur with DWR’s plan to leave the dam’s upper spillway mostly untouched this summer while focusing efforts on the heavily damaged lower spillway."….."However, DWR redacted five paragraphs that spell out the consultants’ recommendations for making the plan work."…..
"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.….
== end excerpts.
Oroville Dam: The latest on spillway repairs – and what state won’t tell us
Concrete mix quality discussion: stockpile rock vs "known quality" aggregate
Asbestos found in stockpile rock - DWR treating site as "contaminated".