lists all contracts with the US govt. Your particular military base may have their own website with links for contractors and Small Business.
You must be a registered government contractor. Start the process at the link for Central Contractor Registration (CCR) on FedBizOpps. You must have a variety of identifying codes and designations including Dun & Bradstreet number. Registration is not hard to do, only tedious to grind through all the bureaucratic requirements, hit all the various websites, and make sure your information is consistent from place to place.
Then you can roll the dice at FedBizOpps. There are many many more small biz opportunities for Civil Engineering than other fields.
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering