Reactivation of the Army's famed 29th Infantry Division has spurred plans for almost $22 million in new or expanded military facilities in Virginia and Maryland, a National Guard spokeswoman said yesterday.

The 29th Infantry Division, reknown for spearheading the American invasion on Omaha Beach on D-Day 40 years ago, again will be composed of Virginia and Maryland National Guard units.

A $2.1 million headquarters at Fort Belvoir in Fairfax County tops the list of the 19 buildings needed for the light infantry unit. Dormant for 16 years, the 29th is being reassembled from existing guard units and is scheduled to include 10,800 soldiers by the summer of 1986.

Listed as "top priority," the Fort Belvoir headquarters is now being designed, Guard spokeswoman Capt. Phyllis Barnes said.

Eighteen other buildings also will be constructed under a still undetermined timetable, she said.

The reactivated unit hastened the long-studied expansion of three major facilities in Virginia and two in Maryland, National Guard spokesmen said. These renovations include:

* A $5.7 million, 600-man Aviation Brigade headquarters armory in Edgewood, Md.

* A $1.7 million, 2nd Brigade headquarters armory at Fort A. P. Hill, near Fredericksburg, Va.

* A $1.5 million, 29th Division Artillery headquarters armory at Byrd Field near Richmond.

* A $1.1 million, 2nd Battalion 115th Infantry armory in Chestertown, Md.

* A $1.3 million, 1st Battalion 111th Field Artillery armory in Newport News, Va.

Barnes said 13 other facilities also will require renovations, expected to cost $7.6 million.