JCVO, Here in the US, emissions limits are dependant on gegraphic location and prevailing air pollution problems. If the plant is located in what is considered a severe non-attainment area the allowable limits will be exceeding low. Whereas, if the plant is located in an area that is not problematic, the limits will be set higher. Unless of course this is a new source, in which case the Regional EPA will mandate max. allowable limits and operating times. Either way, you will be pulled into the Emissions Reduction Management System which is a part of the Title V Air Permit which all plants are required to have and which is quite extensive and complicated.
If in the US, check with your Regional EPA office. They will have the answers you're looking for. They are only a phone call away.
Hope this helps.
saxon