1. (a) The owner or operator shall not cause or allow visible fugitive emissions or visible stack emissions for any ferrous foundry installed prior to or on May 12, 1971 to exceed an average of 20 percent opacity for any continuous 6-minute period.
2. (b) Opacity shall be determined in accordance with Env-A 807.

Source. #10315, eff 4-23-13m (from Env-A 2403.02); ss by #13694, eff 7-22-23