Can I burn away a rotten fence post in the ground?

Question

One of the posts for my fence rotted away underground to where the post above ground could be simply pulled out. I fixed a ring with some lag bolts to the top of the remaining post (which is about 3 inches below ground level) and used a 7 ft pry bar to try to rip it out of the ground, but it turns out that the cement for the post was connected to the foundation of the house, so it's not going anywhere.

Beneath the initial rot, the post is still strong, so I can't break it up and pull the pieces out. I can't get tools like my drill deep enough to cut into it either. Maybe there's some tool purpose-built to drill/cut into the post, but I'm sure it'd be more expensive than I'd like to take care of a single fence post. The only other option I can think of is burning the remaining underground post away, or at least enough to compromise its structural integrity enough that I can pull it out.

Is there any concern / risk with doing this? The surrounding area is just dirt / concrete -- no grass or plants. The ground is extremely dry, though the fence post has naturally absorbed a bit of water in order to rot like this. The exterior wall above the hole is stucco. There's nothing flammable except for the fence post. I presume I should be using wood/similar based fire starters rather than gasoline given the plethora of gasoline-fire-starting mishaps documented well across the internet :)

Answer 1

Drill it out.

If your drill (or drill bits, or drill bits + extensions) won't do the job, rent or purchase one that will.

Even if the gas line WASN'T right there, the heat from burning it out would damage the concrete you are evidently trying to save.

When you replace it, use concrete or heavy steel below ground, and only switch to wood above ground, if at all. While "ground contact rated" pressure treated wood is supposed to last, one suspects that overblown life claims are rarely collected on (do you have a collection of the little tags on the ends of the lumber filed away with what project they were used on to be used as evidence for your warranty claim when your 40 year lumber rots out in 20? Neither do I. And if I did, I wouldn't remember where they were in 20 years if I hadn't thrown them out in the meantime. Also the lumberyard I bought them at went out of business 10 years ago...)

Answer 2

Is that a gas meter and gas line ?

Know this: if you pour gasoline or any other flammable liquid in the hole and then light it, there will be a combustion EXPLOSION. Which will destroy your gas meter, which will destroy the wall to the neighbor and you home.

The fence post was probably 3 feet deep.

1- use a 2 feet chain saw stick it vertically in the hole first *have firm stand and good grip) then turn it on and cut the remaining fence post in pieces. The chain might be EOL after that. Since the chain saw is in the hole when running, it wont jump on you.

2- now use a demolition hammer (electric is fine) to knock off the concrete in the hole, find a 24 inch or 36 inch shaft length and chisel away.