D.C. Code § 9-203.03

(a) Where the highway plan shows: (1) a street as 90 feet wide, the Council may accept a dedication of land no less than 60 feet wide; (2) a street as 120 feet or more wide, the Council may accept a dedication of land no less than 90 feet wide; provided, that in both clauses (1) and (2) of this section the persons dedicating the land agree to establish building restriction lines to correspond with the width of the street as shown on the highway plan.
(b) An application to dedicate land to establish a minor street that would not meet the requirements of § 9-203.04 shall be accompanied by a document signed by the Mayor, stating that the Mayor has authorized the nonconforming street width or building-line setback.
(c) When the Council makes street construction a condition for the dedication of land for street purposes, the Surveyor shall not record a dedication plat until DDOT has issued a written statement (“DDOT Statement”) that:
(1) The owner of the property to be dedicated has constructed the street improvements in accordance with the Council’s conditions, DDOT’s standard and specifications, and any plans required and approved by DDOT; and
(2) The owner of the property being dedicated has signed a document, which shall be attached to the DDOT Statement, that indemnifies and holds harmless the District and all of its officers, agents, and servants against any and all claims or liability arising from or based on, or as a consequence or result of, any latent defects, act, omission, or default of the owner of the property, his employees, agents, servants, contractors, or subcontractors, in the performance of, or in connection with, any work required, contemplated, or performed in connection with the construction of the street.