"We're hoping the first year to do between 15,000 to 20,000 people over several weekends," Bates said. "And I hope that number grows."
But opponents say the idea demeans the thousands of Pennsylvania residents who lived there as well as the landmark court case over alleged inhumane treatment of Pennhurst residents that led to the closure of it and similar institutions across the country.
Bates said he became involved with the project, originally called "Pennhurst Institute of Fear," about 10 months ago.
The purpose of the attraction, he said, is to "bring the family out, let them run through the haunted house, listen to them scream."
The Pennhurst Memorial & Preservation Alliance, however, called the idea a "travesty" and urged a boycott, saying a haunted attraction at Pennhurst "portrays people with disabilities in a demeaning and degrading fashion."
"Demonizing people with disabilities as a profit-making entertainment is [and should be] offensive to everyone," the group said.
The historical marker outside the site says more than 10,500 Pennsylvanians with developmental disabilities lived at Pennhurst between 1908 and 1987. But a class-action lawsuit in 1974 alleged that residents were beaten by nurses, strapped to beds, or ignored, left naked, alone and drugged.
In 1978, a federal judge ordered the 1,230 residents moved into community-living arrangements in the Philadelphia region. Three years later, the U.S. Supreme Court agreed, saying mentally disabled people could not be taught to live up to their potential in large, isolated institutions and that confining them there was unconstitutional.
Similar lawsuits around the country ordered the dismantling of state institutions.
Bates also noted that 95 people are being hired to work at the attraction, and local hotels, stores, and other businesses will benefit.