A decade after the project was proposed, and almost two years after it was scheduled to be ready, Pennsylvania this month plans to start moving staff into its biggest, most expensive prison, the $400 million State Correctional Institution Phoenix.

Among state facilities, only the Convention Center in Philadelphia has cost taxpayers more, and still at issue is $23 million in fines related to construction delays.

Eight guard towers and utility buildings at the concrete complex just east of the aging Graterford Prison in Skippack Township, Montgomery County, have been granted certificates of occupancy after a series of contractor squabbles, inspection struggles, and final construction fixes in advance of the latest target completion date, Sept. 28. State officials said some prison staff will move to Phoenix in a few weeks.

Inspectors still are reviewing 3,000 electrical, mechanical, and architectural "deficiencies" in the 12 separate cell block buildings and at 12 other structures at Phoenix, said Troy Thompson, spokesman for the state Department of General Services. The state has no estimate for when all those buildings will be ready. The Department of Corrections expects to finish moving prisoners from Graterford to Phoenix by July, said Corrections Department spokeswoman Susan McNaughton.

The new prison, surrounded by rows of building-high barbed wire instead of a massive wall, adds program space and will have air-conditioning, a big change from the sweltering summers at Graterford.