Beech Tree Survivability after root pruning

[OscarArt]

Hello Everyone,

I am usually a lurker in these forums. I purchased a home and have been taking care of several trees that have been severely disregarded for what seems a couple of decades. Your advise has been very useful so I hope you can help me once more.

I am looking to install a retaining wall about 13 feet away from the center of the beech tree trunk. The tree is on elevated ground (3 feet). At the end of it all, the wall backfill will take up up to 9 feet away from the tree trunk (not center).

My question is how much of the root system can I compromise while digging in? The tree trunk is approximately 46" in diameter.

 

[ATH]

That is a big Beech... Beech don't take well to root damage. Older trees don't take well to root damage.

I'm trying to picture what you are doing. Do I have this right?:
*Tree on hill
*13' (downhill) from the tree you will be building a wall
*The area between the tree and the wall will be filled with soil
*at 9' from the trunk, the soil depth will be 0", then get progressively deeper towards the wall

Do I have that right?

How high is the wall going to be?
What are you backfilling with? (using a looser backfill will certainly be a big help)
What is your native soil like? (rocky, sandy, clay, etc...)
What % of the root system will this impact? (just on one side, wrapping around the tree, etc..?)