D.C. Mun. Regs. tit. 25-B, § 1601
1601.1 An outdoor storage surface for refuse, recyclables, and returnables shall be constructed of nonabsorbent material such as concrete or asphalt and shall be smooth, durable, and sloped to drain.
SOURCE: Final Rulemaking published at 56 DCR 5245 (July 3, 2009).