D.C. Mun. Regs. tit. 20, r. 20-501
The Mayor shall require the owner or operator of a stationary source which emits more than one hundred (100) tons per year of any air pollutant to install, maintain, and operate, at the expense of the owner or operator, the stationary source monitoring devices necessary to enable the owner or operator and the Mayor to determine whether the source is being, or will be operated in compliance with all applicable air pollution standards, regulations, and laws. Monitoring information shall be supplied as the Mayor may require in accordance with § 500.1.
The owner of a major stationary source or major modification shall, after construction of the stationary source or modification, conduct the ambient monitoring that the Mayor determines is necessary, to determine the effect emissions from the stationary source or modification may have, or are having, on air quality in any area.
The owner of a major stationary source or major modification shall meet the requirements of Appendix B to 40 CFR Part 58 during the operation of monitoring stations.
D.C. Mun. Regs. tit. 20, r. 20-501