In the very long fuel pipelines a foam pig can not make the whole journey to the cargo's delivery point, so the different grades of gasoline, diesel, and blends

In the very long fuel pipelines a foam pig can not make the whole journey to the cargo's delivery point, so the different grades of gasoline, diesel, and blendstock are pumped sequentially back-to-back with no physical separation, resulting in many barrels of intermediate off-spec fuel that is designated transmix and segregated upon arrival. Inside the tank terminals I had to witness and certify the pigging after each parcel loaded, when one chemical was done and the line needed to be cleared and volumes accounted for before filling with a different chemical. Among many other more or less toxic things. Measurement training was not easy in the full-scale industrial environment but you can't really lead as well in the micro-scale activities without it.