prevent supply loop

I noticed that most of my fuel is currently consumed because trucks are traveling across the map to dump stuff (dirt, rocks, slag) at the designated dumping area at the beach.
To save some gas I build a loose storage on the one side (only import allowed) where I gather the ressource and a loose storage at the dumping area (only export allowed) and connected them with a conveyer belt.
So far so good because the conveyer belt is doing most of the work, but then I noticed that some trucks travel the whole and long way back from the the loose storage of the dumping to the losse storage where the ressources are gathered.
Setting export/import routes has no impact on this behaviour.
Can you please implement a flag at the loose storage which indicates that ressources are marked for export at the dumping area only pls? I think this would solve that problem.

I think you should look at the video of JDplays on youtube about advanced logistics.

Place mining tower at end point, set dump zones in mining tower area, set export from storage to mining tower. now any emptying of the lose storage has to be done to the mining tower to dump there.