Q&A: How can the shipper know when DOT 406 bulk fuel cargo tanks are empty?

I read through your internet article USDOT Requirements for the Shipment of Empty HazMat Packagings thanks for posting it.

I have a couple of questions on behalf of the US Army Europe.

Military cargo tank - Diesel Fuel

Situation: We have DOT 406 Bulk Fuel Cargo Tanks that must be returned to numerous Army bases across the USA from Europe. The tanks have contained fuel and have been completely drained (including pipes, pumps and removal filtering systems) according to the manufacturers technical manuals. There may be “Crevice” residue fuel trapped in pipe connection seals that is undrainable. We will use military vessels to get them back from Europe to the nearest port in the USA. The tanks will have onward shipping by commercial trucks to their final destinations in the USA. We find no examples or provisions in the 49 CFR 171-173 that define “Cleaning/Purging” certificates or statements. We want to make sure that the “Cleaning/Purging” certificate statement we prepare here in Europe is acceptable for commercial carriers in the USA to authorize them to carry these Bulk Fuel Cargo tanks as a Non-Hazardous Material shipment.