CHICAGO (CBS) — More than a year into a program to train jail inmates a useful skill while providing a service to the community, Cook County Sheriff Tom Dart said the effort is “an outrageous success,” and is expanding.

In late 2013, Dart’s office began using inmates in the jail’s boot camp program to do a dirty job at no cost to taxpayers, by having them tear down abandoned buildings across the Chicago area.

“This thing has been such an outrageous success. We’ve doubled it. We now have two crews of inmates out working on buildings. We’re probably going to have a third one before the year is out,” he said as a crew of inmates tore down a building in Dolton. “One of the buildings was a 36-unit townhouse; a two-story townhouse development that had been vacant for decades.”

He said the program has become more targeted, focusing on demolition of neighborhoods where those living in occupied homes nearby get the most benefit, losing eyesores that drag down property values.

“If there’s a block that is otherwise stable, but with one house on it that is a wreck, if we remove that, all the property values go up exponentially,” he said. “Very smart people who work for me, they’ve identified the ones where you get the biggest bang in the community.”

Dart said another benefit of the RENEW program is inmates learn skills they can use to get a job once they’re released. He said some have had job offers as a result of the initiative.