I attended Rivendell from (I'm guessing) 1973 to 1978. My mother Ilana actually worked janitorial part time at the school in exchange for my tuition.
If I remember correctly, the school was somewhere prior to moving to the sunset.
I don't remember the insanely dangerous rock yard, but I do remember, in the older location, a bunch of us digging an insanely dangerous and insanely long and deep tunnel into the side of a wet muddy hill. We somehow worked on that thing in secret for about a week before any adults figured out what we were doing.
They were very big on "giving us space"
Well they were, project "BART 2" tightened things up a bit.
LOTS of field trips, weekly I think. Lots of camping trips, mostly Marin headlands.
We all decided we were missing something "regular kids" (public school) had at one point and voted for, and were awarded for our ignorant silly selves, regular homework assignments.
Two days later we changed our minds. No backsies.
All efforts at referendum, recall, recount etc were denied by upper management.
EVERY adult related to the school I any way, parent or staff, got on the EST train at some point. It was that kind of place.
Punishment for major infractions, at least at the sunset location, was to sit outside at the front door all day. I remember it because I spent enough time out there to know the mailmans name and most of the residents who would ask me what I did this time.
Teachers I remember: Steve Hess A (that's it, just the letter a) I believe she was Steve's wife My mom, Ilana Epstein, began doing more and more teaching-like activities as time went on.
I'm afraid that's it, all I can recall atm.
I will ask my mother your questions, and if you think of anything else I'll be happy to ask her those as well.
There's a Facebook group run by Hess. I'm a member but not at all active.