D.C. Mun. Regs. tit. 24, r. 24-217
If a pre-Act vault is partially abandoned and partially retained under § 215.2(c), application shall be made for a permit to abandon. The provisions of § 215.3 shall apply to the portion maintained.
When an owner has notified the Mayor in writing of the abandonment of a vault, rent shall be charged until the Director has verified the abandonment.
Specifications for abandonment shall be secured from the Underground Locations Section, Department of Public Works. No rent shall be charged for any existing vault abandoned by December 31, 1969.
When an owner wishes to abandon a vault constructed after July 1, 1969, the provisions of this section regarding abandonment of vaults constructed before that date shall apply.
When abandonment is in connection with subway construction, the execution of an agreement between the owner and the Washington Metropolitan Area Transit Authority transferring full responsibility to the latter agency shall relieve the owner of all responsibility, including rent; Provided, that the owner notifies the Director in writing, and furnishes an executed copy of the agreement.
D.C. Mun. Regs. tit. 24, r. 24-217