I guess I should pipe up here since this is an area I have some experience
in. When we remove underground tanks for disposal, we throw a pile of dry
ice in prior to doing anything. The idea is that the CO2 released will
gradually fill the tank with a gas which does not support combustion. I
have never had to cut into an UST, the dry ice is added just for digging it
out safely. Cutting into one sounds like it could evoke the Darwin Effect.
Good luck.

John

"Offbreed" wrote in message
...
Ignoramus14003 wrote:

Even easier (and safer) would be to put down a hose from a compressor,

A compressor does not pump enough cubage. They are intended for pressure.

and let it pump air for a day, while at the same time trying to smell
the air coming out. I would think that if there is no perceptible
smell, including from an air sample from the bottom, there should not
be much risk of an explosion. But, better safe than sorry.

I get a numb nose and cannot smell anything after about the third whiff.
(No, not huffing. Gas mixed with 2-stroke smells different from straight
gas, and it's easy to get the cans mixed up after they've been sitting
for a few weeks.)