D.C. Mun. Regs. tit. 17, r. 17-401
The licensed operating engineer shall be responsible for the safe operation and maintenance of all equipment in his or her charge.
The operating engineer licensed under this chapter shall personally inspect all equipment in his or her charge at least once every twenty-four (24) hours when the equipment is in continuous operation.
When the equipment is in operation for a period or periods of less than twenty-four (24) hours duration, the licensed operating engineer shall personally inspect the equipment at least once during each period of operation.
The continuous presence at all times of a steam or other operating engineer duly licensed in the proper class by the Board of Examiners for Steam and Other Operating Engineers in the District of Columbia shall be required for the operation, maintenance, or supervision of the operation or maintenance of high-pressure steam boilers as defined in this chapter.
If the engineer-in-charge is on the premises and within call, he or she shall be deemed to be in continuous presence for the purpose of this section.
D.C. Mun. Regs. tit. 17, r. 17-401