Work on the largest prison in Pennsylvania, which general contractors from Chicago and Atlanta had promised to complete last year, blew through another deadline Oct. 24, and state officials now say it will open more than a year behind schedule.

The concrete housing stacks at State Correctional Institution Phoenix, built to replace the 1920s stone Graterford complex nearby as the main detention center for Philadelphia-area inmates, is not expected to open until at least January, the state Corrections Department now says.

Walsh Heery Joint Venture, the Pittsburgh-based group overseeing work on the Phoenix complex in Skippack Township, Montgomery County, is liable for $35,000 a day in damages for failing to complete its 2012 contract on schedule, according to state general services officials.

"They are 339 days behind schedule," and the contractors owed $11.9 million, as of Oct. 25, Troy Thompson, spokesman for the state General Services Administration, told me.

Brian McGinty, operations manager for the Walsh Heery partnership, and other officials at the parent companies Walsh Construction Co. in Chicago and Heery International Inc. in Atlanta haven't responded to my inquiries.

Pennsylvania had agreed to pay the partnership $349 million, including change orders. Design and project management costs, including expenses from arrangements that were aborted before the current deal, take the total cost to about $400 million.

The state granted Walsh Heery a bad-weather delay last year and would give another if there were "conditions beyond the control of the contractor" keeping Phoenix from opening, spokesman Thompson added.

But no new extension has been granted, and officials were at a loss last week to explain the failure to open. "This has not been the most favorable contract in terms of the performance of the contractor," Thompson said.

Local officials are wondering, too.

"I have no idea what the hell is going on," said State Rep. Mike Vereb (R., Collegeville), whose district includes the Graterford and Phoenix prison sites. "I'm obviously concerned."

Vereb said neighbors had complained about night lighting from the complex and other construction-site problems.

"We don't know the reasons" for the delay, either, Skippack Township Manager Theodore Locker Jr. told me. "It's a quandary."

Phoenix includes two clusters of freestanding, cross-shaped cell units east and west off a central fork-shaped building, plus a separate unit for women, and one for prisoners sentenced to death. Contractors have graded the site to improve drainage and provide for extensive concrete foundations, and planted trees atop earthen berms, screening the property from neighbors.

Skippack Township sewer managers want to know when their system will be called on to replace Graterford's antiquated water-treatment works, which has been cited for needed improvements by state environmental officers.

Phoenix is designed to hold nearly 4,000 inmates, a few hundred more than Graterford, which is expected to be decommissioned once Phoenix is fully operating, though the state could continue to use the older site for a time.

State Corrections Commissioner John Wetzel told me last year he inherited plans for Phoenix from the Rendell administration after Gov. Tom Corbett named him to the post, which he has retained under Gov. Wolf.

Wetzel said he was initially skeptical of the need for Phoenix. Nearly 50,000 Pennsylvanians are now incarcerated in the state system, down slightly from nearly 52,000 at its peak in 2012, amid a nationwide trend to incarcerate fewer people.

But Wetzel said he came to support the project after advocates convinced him the more efficient new facility would save taxpayers millions, costing $70 an inmate a day to operate, down from about $100 at Graterford, and potentially freeing resources for staff and programs.

Phoenix is the second-most-expensive building complex built by the state, after the Convention Center in Philadelphia.

215-854-5194@PhillyJoeD