AMEC is preparing for its callup papers for a £100 million project to redevelop Catterick Garrison in North Yorkshire for Defence Estates.
Project sources said this week the firm had taken the capital works prime contract to build living and works accommodation for 5th Battalion Royal Electrical and Mechanical Engineers and 3rd Close Support Medical Regiment.
Amec fought off rival bids from Balfour Beatty and Laing.
Fourth bidder Skanska pulled out of the running last year.
The source said: 'There is no formal agreement between Amec and Defence Estates but the other two bidders have been told that they have been unlucky this time round. Barring any last minute hitches, this deal is only going one way.'
The deal also involves building mess facilities, infrastructure and garaging. Work is due to start later this year and is set for completion in 2006.