Not too sure about what it's like, but it was up the road from where I went to Andrus (childrens' home). We were both on N Broadway., it's just that I was in Yonkers, not Nyack. Go north and cross the tappan zee bridge and continue up and there you are at Summit.
I'm a bit familiar with Pleasantville as well, (mentioned in the linked thread) since one of my friends from Andrus got sent there for a while because she went AWOL. It's what we used to call a "lock up". It was micromanagement to the nth. Locks on all doors, constant supervision, and they had things called quiet rooms where they would put kids when they "went off" (i.e. had a fit, threw a tantrum, etc.) Basically like a "time out" spot. At the time, it confused me why otherwise normal, high-functioning kids would start "going off" once they were placed in such a facility, especially since they never did that before. Some of us did it at Andrus, too, if we got too frustrated. But fortunately, we didn't have quiet rooms or locks on our doors. I remember touring one of those lock up places with my parents and I watched some screaming kid get dragged off to a quiet room, and it totally freaked all of us out. That's why we went with Andrus. (Little did I know that I would end up in a place far worse than any lock up or childrens' home a few years later.)
I could have sworn there was a place across the street from us called Summit, but maybe it was Sun-something instead. Like Sundown, sunset, sunridge... not sure. It's possible it was Summit, and they moved. All I know is, we were scared shitless of the kids across the way. We thought they were all thugs and super violent. Of course, I'm sure none of that is true, since I never even met anyone from over there. It was all based on stories and rumors.
Interesting, but there definitely seemed to be more than your usual amount of residential treatment centers, group homes, lock ups and childrens' homes in that area. The lock ups sucked, but the group homes were pretty sweet, if you could get into one. Even though we had quite a bit of freedom to fuck around and get into trouble at Andrus, and the house mothers for the most part were pretty damn cool, most of us were aiming to get into a group home if we could.
I guess this doesn't really help with your summit specific question, but more addresses (vaguely) the kind of things going on in westchester and the surrounding counties when it comes to RTCs and the like. It kind of has its own vibe up there, as most of the places in that area were originally orphanages at the turn of the century, and later became RTCs or group homes for runaways and abused foster kids. I thought I would chime in since I spent 8th and 9th grade up there, and most of the time, a kid who was in one place knew a whole lot of mess about a bunch of other places in the county, since we might know someone in another center, or we toured a place, or spent some time there ourselves. I wish I could remember more, sorry.