Gov. Bob McDonnell said Tuesday that he plans to send a letter to Defense Secretary Robert Gates outlining his concerns with traffic congestion expected by the relocation of thousands of defense workers to the Mark Center in Alexandria by September.

“The Mark Center is a significant challenge,” said McDonnell on his monthly call-in show on WTOP, adding that he talked to Rep. Jim Moran, D-Va., after an inspector general’s report released last week said the Army was wrongly claimed that shifting thousands of defense workers to the new facility near Interstate 395 and Seminary Road wouldn’t cause significant traffic problems.