Sorry I have never cleaned a gravel driveway ...so i would not apply weedkiller.
Block paving is a "solid" surface so it's not licensed....due to run off....most driveways "drain" somewhere. So you have run off.
Flazasulfuron entering river courses will cause chaos with vegetation which will then affect wildlife. Hence the restrictions on it's use.
Did the instructor not cover this when you did your "weedkiller application training"?
Sorry I have never cleaned a gravel driveway ...so i would not apply weedkiller. ....Not sure what this means but I don't plan on cleaning gravel, just weed killing, and keeping it weed free as long as possible. And as gravel is a Permeable surface with soil under its fine.
As for block paving how exactly how is the run off going to occur? The bricks are not permeable but each brick has a channel with sand around it and soil underneath, and im not applying it with a hose. And you say most driveways have drains ? not sure about that probably just as many with soak aways which run into soil so no problem there so thats all driveways with soak aways ok .
flazasulfuron may be used in Amenity situations that are plant free. I dont think there's going to be a problem with this getting into drains as long as you stay a meter away from drains when spraying like they teach you chris
Did the instructor not cover this when you did your "weedkiller application training"?.......All you other comments were valid but this one well, I used to think you were all right, now I think your pink cigar smoker.