Do not care how they treat it or compact it it is the nature of concrete to shrink and swell with moisture and or temperature. It is going to crack, just how bad is up to the elements and the batch master.
I was watching them wash and scrub and thinking, open the spillway a bit, it'll wash everything off in a hurry even with the gap in the upper spillway, maybe use some of that 18 inch heavy wall flexible plastic pipe, start a siphon and aim it with the excavator.I wondered how they got that rock so clean with just fire hoses, now I see, rubber squeegee (cut up old tire) on an excavator.