By doing a perk test. Something the home owner can do. Dig a hole somewhere in the root zone, fill it up with water and let it drain. Fill it up again and time how long it takes to lower in inches. Half an inch or less in 60 min is slow, 1/2" to 1" is nomal, faster than 1" is highly porous.
In your case you will need to determine if the drainage is normal for your area or compacted. If you do a search worded, The Soils of Maine, you should find a (miscellaneous report 402) from the University of Maine. It will have a wealth of information on the soils in your area.
Your soils vary quite a bit. If you want, you could pm me the address of the tree's location and I could have my wife try and pull up that location's specifics. So much of what is going on is soil related. It can help to understand what you have.