40 CFR § 60.1450
How must I monitor opacity for air curtain incinerators that burn 100 percent yard waste?
June 9, 2020
(a) Use EPA Reference Method 9 in appendix A of this part to determine compliance with the opacity limit.
(b) Conduct an initial test for opacity as specified in §60.8.
(c) After the initial test for opacity, conduct annual tests no more than 13 calendar months following the date of your previous test.