Willows are a little different, but most trees do not live long if you pile up dirt on their trunk & burry their root system - I would plan on losing the tree.
Sounds like you have things worked out pretty good, but why bother? /forums/images/graemlins/smile.gif Water runs to the lowest point, so might as well leave it there.
Where I live, there are _real_ issues with drain fields. You don't want to tamper with one whatsoever or draw any attention to one. The officials get real inspection minded. I would not wish to mess with a working curtain drain, or put more water into it. You might well be reverse-flooding the curtain drain until the pump can catch up with all the water you are feeding it - which appears to be a lot. You could saturate all the ground by the red line....
It's funny, on here I see people wanting to dig a pond in a sand front yard, and then you see others with a natural pond & go through all sorts of work to pump the water uphill & around & over.....
Guess we humans are just never happy with what we have. /forums/images/graemlins/smile.gif
(I have 200 acres of farmland & we had 4" of rain in under 3 days. The county ditch is running full because they had 5" of rain uphill from me. So my several miles of underground tile is mostly running backwards, adding more water to my fields. Probably lose 10% of my harvest this fall from the water ponds. I know a lot about drainage. Water always goes downhill. We think we can change that, & can sometimes influence it a bit. But can't make major changes.)
--->Paul
