On Mon, 06 Aug 2007 09:54:59 -0700, Too_Many_Tools
wrote:

On Aug 6, 11:47 am, Don Foreman wrote:
On Mon, 06 Aug 2007 13:21:17 GMT, RoyJ wrote:
Won't work unless it is an old, out of tune carburated beater.

It does work with a carbureted riding mower. Takes about an hour per
hole, though.

The 95% oxy 5% propane subterranian boom works a lot faster. I
don't know why the mix is so oxygen-rich, but that seems to be what
works in practice. Ignition is done with a robust and fairly powerful
spark, a piezo-popper apparently is not sufficient.

Cong tunnels were cleared with ethylene oxide/air explosions, it isn't
a new idea. Dispersed local overpressure pulse (as opposed to higher
but much more localized overpressure from HE) and flash heat are what
does the job.

Expect divots. You may also get the occasional ballistic rodent.

This may not work as well as you hope it will.

If the tunnel is among tree roots, it can kill a tree you want.

If the tunnel bisects a natural gas line, you may have an interesting
side effect.

Years ago a neighbor used this approach...and the tunnel was along
side his house...the gas mixture leaked into his house and the hot
water heater ignited the mixture..the neighbor and the house suffered
ill effects....the gopher lived.

TMT

There are always cases where a particular procedure is inadvisable.
The propane-air method definitely does work where appropriately used.
Devices using it are commercially available. I'm not making it up
and I didn't invent it.

From many previous posts, I do not read SteveB as a Darwin award
candidate. Your neighbor clearly was.