Well I'm the plumbing ppl so no I didn't tell myself that. But I will now you bring it up.
Jokes aside. If you are doing a chamber system Do not ever driver over it with equipment or large trucks. They will collapse!
Creek rock is rock from the creek. It's used as a base for the driveway and site. It packs well and "locks" in for a solid road bed. It's also really cheap at $180 bucks a dump truck load. If we didn't do the creek rock, putting down gravel would have it mushed into the road bed and gone in a few months not to mention rutting would be bad too. Our soil here is very fine clay and loose churt.