I can't craft either of those two buildings. Looking through FNEI there isn't even a recipe for them.
I'm using a bunch of mods that change recipes (Bob's, basically all of Angel's, AAI Industry, etc.), so it might be possible that the recipe got broken or one of them removes it intentionally. If so, I can't find out which one.

If you're using Angel's, Angel's Flare Stack and Clarifier replace those. You can still access them through an Infinity Chest though.

Though in my case, I still have the recipes appearing in What is it used for?.