The scheme involves running the Royal School of Military Engineering's 881 ha estate in Kent and Surrey, as well as providing skills training to the army's engineers.
A consortium led by Carillion Defence Training and a team including Mowlem, WS Atkins and defence contractor Hunting are fighting it out for the project, which was launched in 1999. A shortlist was originally expected last year.
One bidder said the delay was caused by the military's determination to ensure that the scheme was delivered effectively. "We cannot afford to get it wrong," he said. "That's why everyone has been so cautious during the project."
The PFI contract will be for a minimum of 10 years, and could be extended to 25 if a capital works programme is started on the estate.
Bids must include plans to rationalise and develop underused and underoccupied parts of the estate, which houses the leading military-scientific school in Europe.
The estate comprises 13 sites totalling 800 ha in the Medway towns in Kent and eight sites totalling 81 ha at Minley, near Aldershot.
The successful PFI consortium will be required to deliver and manage military training in construction-related disciplines.
It will take over trade and career development courses currently taught at the construction engineer school, based in the Medway towns.
The consortium will provide 100 courses for 2700 students a year, covering trades such as civil engineering, M&E engineering and building services.
The courses will provide trade training for carpenters and joiners, electricians, fabricators and mechanical fitters. The PFI partner will also offer a variety of technical courses.
Career development courses will train military engineers to become clerks of works, military plant foremen, professional engineers and project managers.
The project brief requires the successful consortium to budget for teaching and support resources. The winner will be invited to buy and manage parts of the estate and provide facilities management for parts retained by the school.
Debut, Citex, Amec, Carillion, Laing, Mowlem and Interserve are vying for the scheme, which will include the upgrade of 20,000 Ministry of Defence bed spaces and ancillary accommodation.
The winner is due to be announced next autumn.