D.C. Mun. Regs. tit. 21, r. 21-2202
Any enforcement action under the Act shall be commenced with a written notice of violation or threatened violation issued to the owner, operator, or any other person deemed appropriate by the Director, except as provided in § 2204 and in § 2207.2.
The notice of violation or threatened violation shall identify the violation or threatened violation and may require the person to take the corrective measures the Director considers reasonable and necessary.
The notice of violation or threatened violation need not be denominated "Notice of Violation" or "Notice of Threatened Violation"; Provided, that the body of the notice makes clear that the person is presently "in violation of or "out of compliance with" the Act or regulations, or, that failure to take the corrective measures directed, will constitute a violation of the Act or regulations.
A notice of violation or threatened violation shall be served on the person or his or her authorized agent in person or by certified mail return receipt requested. If the person fails or refuses to accept certified mail, the notice of violation or threatened violation may be served by regular first class mail; Provided, that the following occurs:
If a person objects to a notice of violation or notice of threatened violation on the grounds that the action directed is not necessary or appropriate from a technical, engineering, geophysical, or other scientific perspective, the person shall file a written statement including the grounds for his or her objections within fifteen (15) calendar days of service of the notice, or any other longer time period as the Director may specify.
D.C. Mun. Regs. tit. 21, r. 21-2202