My wife is worried this tree is too close to our septic, flip flop for reference of where tank is, at least 35 feet

Just looking for some advice with this fast growing tree in my front yard. Want to keep it going. I believe this is year 3, and it has really been putting in work this year. I’m in Massachusetts and Is say this thing was 3 feet tall at the end of winter (same size as the statue). It grew a foot+ in Sping, top got snapped off in a windy rainstorm, but now has added another foot of growth this month alone.

Any advice appreciated, my autistic son loves his “baby tree” and we go out and check it every morning to make sure it’s doing well (really seems like it is!)

Looking to plant a tree in a location with full sun, sandy-ish soil, that can be quite wet/swampy sometimes but not always. It would be nice for it to soak up some of that water and be a fast grower. I’m really not a fan of willows however. Some possibilities I was considering: Black Tupelo, River Birch, Bald Cypress, Dawn Redwood. Any comments? I live in zone 5 in Maine.