WASHINGTON -- A proposed change to the U.S. Tariff Act could drastically change the way carriers report cross-border movements of tanker containers to U.S. Customs and Border Protection.

CBP is reconsidering how it monitors "chemical residues" -- even in trace amounts -- left at the bottom or attached to the walls of tank trucks and related containers.

As a result, there could be a lot more paperwork (and, of course, costs) for liquid bulk carriers when they cross the border.

Since 1994, CBP has held that a steel container filled with a chemical when exported could be entered as empty when imported back into the U.S., notwithstanding the residue of chemicals remaining in the containers.

The reasoning behind the rule was that it is extremely difficult for a carrier to completely pump a tanker clean of certain residues, and the amount left over is usually minuscule anyway.

Now, the border agency says that allowance is inconsistent with its treatment of other commodities (such as 'petroleum slops' from vessels) and that in order to ensure the "safety and security" of CBP officers who examine them, re-imported containers with chemical residues should no longer be manifested as 'empty.'

Re-imported' tankers could soon no longer be
reported as 'empty' when crossing back into the US.

Petroleum slops, for example, would be manifested as ‘‘crude oil residue" and such substances of foreign origin must also be entered as imported merchandise.

Since the gross weight of most residues cannot be determined until generated, carriers would then have to estimate the quantity of residue left in the tank and have their broker prepare a formal Customs entry under the Harmonized Tariff Schedule for it.

That could be tricky, considering electronic manifests have to be submitted between half an hour and an hour in advance of the unit reaching the port of entry.

If there's a mechanism for a more precise report upon arrival at the border, CBP suggests the entry should be amended.

CBP makes specific note residual chemicals being covered by the Toxic Substances Control Act (TSCA) under the jurisdiction of the Environmental Protection Agency. As such, "the safety of CBP officers coming in contact with the containers is unnecessarily put at risk if they are under the mistaken impression that the containers are empty."