Linn County has revised the
"Is Modification to My Air Construction Permit Needed?" fact sheet and corresponding FAQ to incorporate updates made to 40 CFR Part 51 Appendix W. The fact sheet and FAQ have been revised to allow additional operation flexibility to change discharge styles without a permit modification for downward to horizontal, downward to vertical obstructed, and downward to vertical unobstructed discharge types. The FAQ is similar to Iowa DNR's recently revised document which includes the inclusion of additional scenarios.
These documents can be located at
http://www.linncleanair.org/Content/Business-Industry/Resources.aspx in the Permit Application and Compliance Assistance Forms table.