Bricks, Masonry, Asphalt and Concrete - millings for driveway sub base

Hi all I got a load of millings delivered to my house the other day. my plans are to use it as a sub base for a K turn off my driveway. I had to raise the grade with the millings. some of the depth is about 12 inches. I plan to use a compactor plate on it to compact it down. someone told me that 12 inches is too thick. Can someone verify that it is too thick?? that person said they should only be 4 to 6 inches at most for ideal compaction. I eventually will have my entire driveway resurfaced....probably next year. It is a residential driveway with some parked cars on it or to backup and pull out. not a heavy traveled road. thanks in advance for any comments.

Kurt

Millings of what? Are they metal shavings or something? Also, is this an asphalt or concrete driveway?

I'm not the expert, but I wouldn't go more than 4-6"/lift if I wanted to go that thick. Proper compaction of the base is the key to longevity.

Just as an update. Millings by me here in jersey are asphalt that are chewed up by a big machine. they chew down a few inches on a road....load them into tandems and are brought to wherever.....(not my job)....then they resurface with new blacktop...however I got a load from a guy...I ran a plate compactor on it last weekend. packed great. I talked to a friend of mine that has done excavation and he said I should be OK because it isn't a road. I thank the members for the input.

Kurt