BAS do have non-science posts - as well as the ones you've mentioned there are cooks, IT and communications people, doctors (but sorry no nurses at present), carpenters, mechanics, electricians, plumbers and possibly a few more I've forgotten about. Most of the above need some kind of qualification in their field. There are also people called Base GAs - that's general assistant - who deal with waste etc. on base.
The people you've heard of who are involved in cleaning up Antarctic waste for BAS and the South Georgia govt. are employed by Morrison Construction. They are mostly people who work in construction services eg. carpenters, mechanics, steel erectors, etc. A large proportion (although not all) of them have worked for BAS in the past.
If you're really interested in working in the Antarctic, it's worth getting in touch with BAS - the folks in Personnel are very friendly. Website is www.antarctica.ac.uk
Hope this is useful, Sue