40 CFR § 60.2971
What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard waste?
June 9, 2020
(a) Within 60 days after your air curtain incinerator reaches the charge rate at which it will operate, but no later than 180 days after its initial startup, you must meet the two limitations specified in paragraphs (a)(1) and (2) of this section.
(1) The opacity limitation is 10 percent (6-minute average), except as described in paragraph (a)(2) of this section.
(2) The opacity limitation is 35 percent (6-minute average) during the startup period that is within the first 30 minutes of operation.
(b) The limitations in paragraph (a) of this section apply at all times except during malfunctions.