40 CFR §63.9991

1. (a)You must meet the requirements in paragraphs (a)(1) and (2) of this section. You must meet these requirements at all times.
   1. (1)You must meet each emission limit and work practice standard in Table 1 through 3 to this subpart that applies to your EGU, for each EGU at your source, except as provided under § 63.10009.
   2. (2)Before July 6, 2027, you must meet each operating limit in Table 4 to this subpart that applies to your EGU.
2. (b)As provided in § 63.6(g), the Administrator may approve use of an alternative to the work practice standards in this section.
3. (c)You may use the alternate SO2 limit in Tables 1 and 2 to this subpart only if your EGU:
   1. (1)Has a system using wet or dry flue gas desulfurization technology and an SO2 continuous emissions monitoring system (CEMS) installed on the EGU; and
   2. (2)At all times, you operate the wet or dry flue gas desulfurization technology and the SO2 CEMS installed on the EGU consistent with § 63.10000(b).