Hugel bed near water well?

There's a natural slope/trench near our well pump, about 15ft away. It's already at a slant (slants away from the well), and looked like an easy dig. After about 3 feet down and water started pouring in, so I covered that portion back up so it wouldn't flood because it was pouring at a good flow. Then I thought "is this good for the water below, will it have an affect on my drinking water?"
I have no idea, does anyone think this would be OK to have a hugelbed here? Planning on logs, following branches/twigs from pruning season, leaves, compost, grass clippings, composted horse manure, goat/chicken mixed with old hay. Our well is 400 feet. I figure if this won't work I can use it as a giant vermi pit. Thank you.

I wouldn't put fresh manure in it. I'm curious what others think

Matu Collins wrote:I wouldn't put fresh manure in it. I'm curious what others think

Thanks Matu.
This is my second bed, but the first that I've actually had to dig. The other issue I'm finding is that now I have a 4 foot deep trench with mounds of clay based soils on both sides.
Would covering the compost material with this soil be counter productive if I wanted to plant something in a month or so, due to the heavy clay?
I don't know if I should cover it with the clay soil (I'm talking play-dough type of clay!), or is there something better I could do with these clay mounds (vermiculite, peat moss and organic matter perhaps to break them up and make more usable)? Then I'll have the hugel bed, plus two more in a years time if I can till in lots of organic matter. Decisions, decisions!

If your drinking water well is properly cased and at a depth of 400 feet the likely hood of nitrate infiltration from a bed is probably very low. Denitrification occurs in groundwater at the oxic/suboxic interface usually well above the 400 foot depth. Plant uptake is an important factor as well, a group of nitrate loving plants can easily treat for nitrates as demonstrated in constructed wetland basins for septic waste.
A well log of your well probably exists and would show what the well driller encountered as he drilled to the 400 foot depth. The water flow you have encountered now might be a seasonal flow and decrease later in the year.
I guess I would have a concern about where that first water flowed to and the distance it travels before it gets to my neighbors. It might be a non issue depending on plants, distances, rate of flow, soil type and nearest receptor whether that's another well or body of water/stream.

You could always just plant daikon radish and leave 'em in there