Q.How Deep Do Horse Chestnut Roots Go?
I am planning to put a Horse Chestnut sapling into our yard that I hope to grow from the conkers of an old one nearby. I have to choose the location. Near the planting location we have the buried pipes for our septic field. My question is how close can I plant the sapling to the field while making sure the roots don’t interfere with the pipes? Will the roots start going deep, or will they spread out just under the surface?

Certified GKH Gardening Expert
Unfortunately, the root system on this tree is considered invasive in most areas, here. I would avoid putting them within 50 feet of anything that you don't want destroyed.
When you do find a suitable spot, this article will help you to care for the tree: