If the new prison planned for Southeast Washington turns out as Mayor Marion Barry has described it, it would be unlike anything else in the country -- a 700- to 800-bed facility designed not to warehouse prisoners but rather to treat problems that experts agree are closely related to crime: drug and alcohol abuse.

But corrections experts, while they applaud the city's intention, question whether it can succeed. They base their doubts on various factors, from the high cost of effective treatment to the difficulty of trying to treat anyone in a prison setting.

"I hate to say it would never work," said Bill Wilkey, chief of the prisons division of the National Institute of Corrections. "But there are a lot of questions."

Currently, no state or federal institution targets the substance abuser, according to Wilkey and Curt Toler, chief psychologist for the Federal Bureau of Prisons. In fact, no institution even attempts an intensive treatment program for substance abuse for more than a handful of inmates, corrections experts say.

The biggest reason is the cost of a treatment program, which usually amounts to an extra $10,000 a year per inmate, beyond the roughly $10,000 to $15,000 it costs to house them, according to Joan Petersilia of the Rand Corp., who has studied corrections programs for 15 years.

Cornerstone, a much-praised program on the grounds of Oregon State Hospital in Salem, costs a staggering $40,000 a year for each of its 32 inmates -- $26,000 a year more than the cost at three state prisons from which it draws.

Without that kind of investment, enormous though it seems, corrections experts warn that the public can expect little success from a prison program. "Experience with this population has shown if you throw a little money in, you get nothing back," said Gary Field, director of the Cornerstone program. "If you thrown a lot of money in, you get a modest amount back."

Thus far, the Barry administration has not talked about spending that kind of money. City Administrator Thomas Downs said "we know it will cost more than a traditional bed," but the city hopes to keep down the cost by using staff and other resources of treatment programs located next door on the grounds of D.C. General Hospital.

Hal Williams, special assistant to the mayor, told City Council members Wednesday that the administration has not yet come up with an estimate of the cost of operation.

It's the lack of discussion about the probable costs that lead some like Alvin J. Bronstein, executive director of the National Prison Project for the American Civil Liberties Union, to conclude the mayor's treatment facility will not be offering much treatment.

"It'll be just like the D.C. Jail," Bronstein said. "He's glossing it up with a fancy title but it won't be any different."

"I look at the words 'treatment facility' as a little bit of sugar that the mayor is putting on the notion that he is placing a prison in that neighborhood," said City Council Chairman David A. Clarke.

City officials say they hope a prison planning firm will help them answer such questions as how much the prison will cost to operate, who will be sent there, what sort of treatment will be offered, whether it will be voluntary and whether the prison will draw together inmates who share chemical dependency problems but present different security risks.

Williams said the city is figuring on a medium-security prison, but could conceivably include maximum- or minimum-security units.

Many statistics support the mayor's conviction that drug treatment programs are needed. About 65 percent of those arrested for crimes in the District and given urinalysis tests are shown to have used drugs. More people are imprisoned in D.C. correctional institutions for drug violations that any other type of offense. As of last June, fully 26 percent of the District offenders in prison were charged or convicted of drug offenses, according to the D.C. Department of Corrections.

In Barry's view, those figures mean "we are facing a drug epidemic in this city" and the corrections system must try to tackle it head-on.

"We cannot simply keep warehousing prisoners and ignore the problem that a lot of these people have," said Downs. "If you don't attempt to solve it, they come back, and then you pay some more . . . . A system that doesn't try anything is bound to fail."

That was the predominant view around the country in the early 1970s, when drug and alcohol programs reached their apex in state and federal prisons. But with rising prison populations, the federal and state prison systems began diverting funds from these efforts to pay for routine supervision.

The federal government, for instance, turned its two hospitals for offenders with histories of alcohol and drug abuse at Lexington, Ky., and Dallas-Fort Worth, into everyday prisons.

The District was part of the trend, according to Bronstein, closing an alcohol treatment facility at Lorton Reformatory and reopening it as a general-population prison.

Studies helped fuel the massive move away from treatment. Petersilia said researchers "came up with very little evidence to show that people who had participated in those types of programs behaved any differently from those who had not participated," though she questions whether the studies were detailed enough to reach that conclusion.

The federal Bureau of Prisons now makes no pretense that it is correcting its inmates' drug and alcohol abuse habits. "From my perspective, the amount of money and resources it would take to have an effective program are probably prohibitive," said Toler. If the primary goal is to treat the offenders, he said, "they should be sent to a treatment facility."

Prisons in the federal system offer some limited programs that range from self-help groups to stress therapy, on the theory that "a little bit of treatment is certainly better than nothing at all," Toler said, but "we're very realistic about what they're going to accomplish."

The question of whether drug and alcohol treatment programs can work at all in a prison setting is still very much a matter of debate in the corrections field.

Counselors at least can be sure that they have their subjects' attention and time in a prison program, according to Mark Moore, a Guggenheim professor of criminal justice at the Kennedy School of Government at Harvard University. On the other hand, corrections experts agree that the environment is wholly artificial and robs the inmate of the very control over his life that he is supposed to be learning in a treatment program.

Mimi Silbert, who runs the Delancey Street Foundation Inc., a respected community-based program in San Francisco, said she believes treatment is nearly impossible in a prison setting. "You can't do it in a secluded environment," she said. "That's just an absurd assumption."

Others, like Moore and Petersilia, are less willing to write off programs within prison walls. But Moore argues for a strong focus on "after-care" once the inmate has been released, "otherwise the investment could conceivably be wasted." Toler favors programs that begin near the end of an inmate's sentence and continue past his release date.

However the District structures its effort, "I think they would be pressed to come up with dollars enough to support a meaningful program," said Petersilia. "If they could, I think that would be a laudable goal."