D.C. Code § 9-1201.04
Whenever any person desires to remove the paving stones, or to displace any other work done by the authority of the United States, for the purpose of laying gas pipes, or for any other purpose, it shall be the duty of such person to obtain a written permit from the Director of the National Park Service, and such person shall oblige themselves to replace the said work to the satisfaction of said officer, and within such time as he may prescribe. If any person shall place any obstruction on the streets, avenues, or sidewalks, so improved by the United States, such person shall pay the costs of removing the same, and shall be subject to a penalty of $10, to be recovered as other debts are recovered in said District, for each and every day the obstruction may remain after the Director of the National Park Service shall have given notice for its removal.
D.C. Code § 9-1201.04