Look at the Professional Association of Therapeutic Horsemanship International website: www.pathintl.org/ The have a list of centers and what kind of programs they offer. The will also answer questions on the phone or refer you to someone who can.
Many of the centers have programs for at risk kids, especially the Equine Facilitated Psychotherapy (EFP) and Equine Facilitated Learning (EFL) programs. Some that come to mine are Touchstone Farm in NH, Great Strides in Md, Traverse in Fl, Legends in Tx, Dream Catcher in Ca, Hearts and Horses in Co, Windrush in Ma, Green Chimneys in NY and HorseMpower in Fl.
I have volunteered in this field for years and find it very worthwhile. Good luch and enjoy sharing your horse experience with this clientele.