Seems a little expensive just to get them to go away. How about security showing them the door unexpectedly and sending their personal effects to them afterwards in a box via USPS?
Reassign those living in Northern Virginia to satellite offices in Hagerstown, Maryland (and vice-versa).
After two weeks sitting in beltway traffic the resignation letters will come flooding in.
Yeah—I’d give them the option—a buyout or the pension they have earned to date.