If he's not going to go willingly and has not been court ordered, I'm not sure what the options are.
In my son's case, he had just turned 17 and had finally agreed to sign himself into an adolescent rehab. Here in Michigan, there is such a grey area, as 17 is considered an adult by the law, but it is considered a juvenille/adolescent by the medical and rehab places. He went into a short term place, where the game plan was to keep him for 21 days while we looked for a long-term placement so he could go directly to the long-term facility from the rehab place. The facility released him on day 12 and he was arrested that very night on a drug related felony.
It took a few weeks to get the long-term placement in place, but he did agree to go, as he knew he had run out of options. We were able to find an adolescent dual-diagnostic (psychiatric and sub abuse) secure (yes, locked) facility. I had made countless phone calls to hospitals, rehabs, agencies, etc. and was finally able to find this one. We went through our county's MHMR agency and they put us in contact with an agency that worked with them for placements. He was evaluated (once in their office and once in our home) and after filling out countless forms, they actually put him in through social security. It was based on his income (which was 0) and most of his residential was paid for. They did ask us to fill out financial forms, and based on our income, gave us an amount they thought we could afford. We disputed this amount and were able to get them to lower it to a more manageable amount.
His facility was part of a larger program, but he stayed in a wing comprised of 12 boys. They lived together, made their meals together, cleaned up together, had meetings together, etc. It was based on the philosophy that they would hold each other accountable. They did go to school on the grounds there with other groups, but that was really their only interaction. As time went on and one of the boys would reach a certain level, they were sometimes given approval to attend the local public school (transported via van by the facility) and were able to work outside of the facility. This was a process though - they had to earn these priviledges.
My son was there a total of 10 months, until his 18th birthday, and actually we were told that since he had entered the program, he could have stayed after 18 until they felt he was ready. They did feel he was ready though, and he came home and attended outpatient therapy and group sessions for sub abusers.
I only relay our story to let you know that help is out there, but unfortunately, even in that instance he had to want the help. Many of the boys in his program were court ordered though, so they didn't have that option. Once my son signed himself in, however, he was also locked in with the agreement (by now, through the courts as the judge only agreed not to throw him in prison if he completed this program) that he only be released once the director of the facility felt he had completed their program and was ready.
Check with your state or county MHMR agencies. Contact rehab programs and find out if they have any secure (locked) programs.
My heart goes out to you. I know what a hopeless situation it is to watch your child self destructing and not being able to stop them. Substance abuse encompasses everyone around the addict.
Big hugs,
Deb