I thought 'rip rap' meant like dumping gravel then concreting like they did on the emergency spillway. maybe someone could write the company and ask them how they filled the voids.
The BOC refers to this concrete over rock as cyclopean backfill on page three of their memo:
"cyclopean backfill placed downstream of the approximately 1,000-ft-long monolithic ogee weir section."
Which does not really jive with the definition from Wiki that describes Cyclopean as "Cyclopean masonry is a type of stonework found in Mycenaean architecture, built with massive limestone boulders, roughly fitted together with minimal clearance between adjacent stones and no use of mortar."
So I assume the term is used in dam construction circles and all those guys know what they mean. Rip rap is pretty commonly used as above in Aaron Z's post.