I use a brass hose barb fitting at the drain and add a short (12") pc of good plastic tubing to the fitting to get the drain water away from the valve and avoid getting gravel, fines, etc in the valve.  All sitting in a couple feet of washed gravel as a base, then empty 4" PVC (acts as a heat riser) all the way up to about 2 ft above ground level. Drill a pipe-sized hole in a 4" PVC cap, saw it in half and seal to top of 4" PVC riser with silicone or similar caulk/sealant.

On more recent installations of hydrants and cattle waterers I've been installing a foot valve/curb stop type shutoff so in case something goes wrong I can turn it off without shutting off water to the house or other fixtures.