D.C. Code § 9-401.14

The portable asphalt plant purchased under the appropriation for repairs of streets, avenues, and alleys for the fiscal year 1913, may be operated under the immediate direction of the Mayor of the District of Columbia in doing such work of resurfacing and repairs to asphalt pavements, in the repair of macadam streets by constructing on such macadam streets and asphalt macadam wearing surface and in the construction of asphaltic macadam surfaces on concrete base, as in his judgment may be economically performed by the use of said plant; provided, that at no time shall more work of resurfacing and repairs be done with the portable asphalt plant than can be accomplished with the single portable plant owned on March 4, 1913, by the District of Columbia.