Here's the goal:

Geothermal open loop water-to-water system using well water and
discharging effluent to pond.

One option is to bury a 1" drain line below frost depth from building to
pond. Distance = 150'. Problem is the soil is very sanding and too many
obstacles to dig under.

Other option would be for effluent to feed a water feature near building
with a man made raceway to the pond. This would be easier and cheaper to
construct. Issue is preventing a freeze up where effluent leaves
building or ice accumulation that would eventually block flow.

I have to keep the drain line no smaller than 1".

Would a anti siphon device work? It would seem that such a device would
allow the last few critical feet of the line to drain when the water flow
is cut off.

Ideas? Suggestions? Improvements?

Thanks.