Thinking of a birch, red maple and norway spruce to kind of repeat the other trees in the yard. ... you can't get much more invasive than those.

leach fields are not deep, and almost any large plant will have roots that get into the leaching tubes and clog them.

Can you mark the extent of the field on the pictures?

Would a tree with a tap root work better around a leach field? I don't have one, so I don't know what restrictions are imposed, but maples are notorious for near surface roots with red maple being a water lover.

The leach field starts at the front corner of the house and runs toward the back of the property. The area we will be planting is about 100ft deep (from the road to the leach field) and 100ft. wide...we don't want to plant anything else directly in front of the house. hope that helps!

Would a tree with a tap root work better around a leach field? I don't have one, so I don't know what restrictions are imposed, but maples are notorious for near surface roots with red maple being a water lover.

Now weeping willows anywhere near that field.

Don't even worry about tap or other types of roots. Tree roots grow wide and shallow out from big trees. Its amazing they hold themselves up in fact. While my young (2 year?) Oak may want to grow a tap root 3 feet down I don't believe the structure at maturity to be significantly different than sugar maple. The difference in surface root prone vs not is about a foot in average root branch height. Want to see some roots go to a river bank and look at all the shallow roots on the trees being washed in.

Far as keeping the roots out of your septic field, look at the mature spread of the tree and plant it just a little further than that far away. Where the branches won't grow out over your field. Adjust further if you're growing a tall narrow oak or 100 foot tall dawn redwood which might only get 40ft wide.

Sure you could go further but in my experience digging around my yard there is no point since ts easy to dig outside the drip lines of any of my major ash trees. There just aren't that many roots there.

Plus, thinking about the time dimension, them 60 foot spread trees are darn near 60 years old!

Septic Tank Materials: a steel septic tank rusts away, first losing its baffles (which lead to drain field clogging) and eventually rusting at its bottom or sides. The rate of rust depends on the soil conditions and soil acidity and other factors. A concrete septic tank can have a very long life, in excess of 40 years, except for cases of poorly-mixed concrete or possibly acidic soils which may reduce that span. Plastic or fiberglass septic tanks can expect to have a similar life unless they are mechanically damaged.

Here is a link that might be useful: Where I copied that Italics quote from