Secondary containment requirements are addressed by the Environmental Protection Agency (EPA) through the Resource Conservation and Recovery Act (RCRA) contained in title 40 of the Code of Federal Regulations (CFR) part 264, the 2006 Uniform Fire Code (UFC) in standard 60.3.2.8.3 and in the 2012 International Fire Code (IFC) in 5004.2.
You should check your visa endorsement for the period of your stay in Zambia. Although you are allowed 90 days per calendar year the immigration officer will not normally endorse the full length of time upon entry and you will be required to extend the stay at the nearest immigration office.
He can also go to Thai Embassy in Vientiane and get a tourist visa good for 60 days and he can extend it once for 30 days, or he can apply for two tourist visas and use the first one for 90 days then do a border run and come back using the second tourist visa for an additional 90 days.