Start with enlarging your area. A couple of feet will not give a plant enough room given the surounding area is roots. Try first raking the soil away to see the roots. You may find as under my maple tree the root mat is only 6-8 inches deep. If so use the heaviest shears, metal work ones work and cut a hole in the mat.

Second purchase a spading fork. The tines will make it easier to dig.

3 go back to your first method but be aware that roundup really needs to go on the foliage.

i'd do a lasagna method to make good soil or truck in some loam/compost to start off then lasagna it. depends how big an area though i suppose

Thanks for the suggestions. I have a spading fork I've been trying. You know it's bad when that won't even go in.
I've seen in other posts folks have warned against putting soil on top of tree roots cuz they say it causes the roots to move back up to the top of the soil, especially maple trees that are shallow rooted which is what I have on one end, so one doesn't gain anything. I do have access to a bunch of compost. Maybe that would help get something started. The whole area is more like 4 feet wide, not 2 feet. It's the back 2 feet that is rootbound.

well, seems like a great job for a maddox - one of those pickaxes with a flat end. those things are insane. i've chopped through 4 inch stumps and granted it took some intense swinging it works. itd work for roots - chop right through em. just need to put some muscle into it. im glad it's such a small space. i'd definitely use a maddox!

RoundUp is never to be used in the soil. It works by being absorbed by the foliage and translocated TO the roots. Applying it to the soil is totally against label directions.

I am cutting the roots with shrub cutters as I dig them up as I haven’t got the muscles to swing a pick axe. Whatever way it’s a laborious task, 4th day, 8 bags of rubble and now getting to the roots ! I would give up but the mature hedge plants are waiting to be planted !