Nasty areca roots

I am trying to dig up and remove a few old ( approx. 10 yrs ) clumps of Areca Palm roots next to my lanai. Over last 2 weeks was able to use my loppers & 14" chain saw to get down to about 14 " above the ground. Chain saw isn't hacking it anymore nor the loppers nor shoveling ( roots spreading out, found digging futile ).

Was wondering if anyone out there knows of some kind of liquid I could pour over this tangled root, to sort of disintegrate it over time and make digging easier.

If it was in the middle of my backyard I'd simply pour gasoline over it and burn the roots out, but can't do that here, have come to enjoy the lanai over the years ! ( smile )

My neighbor says he has a 20 " chain saw and is willing to have at it, - but am holding him off for now. Am afraid even that will not eliminate the underground tangled web of roots.

Will try to add a photo or two,..appreciate any ideas.

I have about 12 large clumps of Areca Palms. Many years ago my wife planted them along the side of our house as a privacy fence. They grow fast and are difficult to maintain. I think i will try the salt first. I have a 180 gallon reef tank and will try watering them with the waste water.

I cut down one clump of areca palm that was in a awkward spot last summer. I cut the trunks level with the ground. It kept trying to reprout but I just kept at it and it gave up the ghost later that summer. The roots quickly decomposed.

Hello, I wanted to follow up on these comments and see how it all turned out for everyone

I kept cutting mine down and pouring weed killer on it. Even tried to burn it with a propane blow torch from lowes. It kept coming back so I had my landscaper grind the roots out.

Will these plants/roots push up or incroach on patio pavers? I have an area that I want a privacy fence/hedge and it is right next to my patio and don't want to damage it.