Literally Stumped

I have had footings dug for a small ground floor extension at the rear of my property.

In the corner between my neighbours garage and my property we have uncovered a large tree stump. The remains of a large pair tree which was approximately 3 meters high.

It is in such difficult position to dig out. I have dug out much larger tree stumps in the past but had the space around them to do it.

I have contacted a few tree surgeons to see if they could chip it down to where we can we can get at it but most of them have said it can’t be done.

A couple of builders have suggested it’s a long process to slowly chip away at it.

I am thinking of using a petrol jet wash to remove the dirt and then get at it with a chain saw.

Suggestions please welcome maybe you have been faced with the same problem?

do I need to remove the whole stump or just the. Bit that it’s the footing along with any roots?

Presumably it's well and truly dead and not going to sprout? Is there any way to adjust the foundation to avoid it? Either change the dimension of the extension or even bridge over it making sure you go deep enough either side. Might end up being cheaper (I'm not a builder)

Could you tackle it with an axe and a crowbar, or drill down into it with a brace and large diameter bit?

if you have a leaf blower, or a builders vac that can blow, you can put a steel tube to blow air, and set light to the side of the stump with some dry kindling.

use the air blower to enliven the fire and it will burn away surprisingly quickly.once you have a cavity, you can push the tube inside it. The blower need not be very powerful.

Arbortech wheel on a 4" grinder and 30 minutes.

Thanks for all the replies. I will let you know how I get on

I will try the chain saw and Axe to start with