reply to mepadre
Re: Sump Pump - Discharge riser freezing Here's what I'd be tempted to do:
Drill and tap a hole in the discharge riser just below the concrete ceiling level in the pump room. Get a vinyl or brass right angle fitting with NPT threads on one end and a hose barb on the other. Screw it into the hole you've just put in the pipe. Run clear vinyl tubing from that fitting back down to the pit.
When the pump is running, a small amount of water will recycle from the riser back down the vinyl tube. Once the pump stops, the top section of the riser (that's exposed to freezing temps) will drain back to the pit. The rest will stay full.
If you've got a lot of solids flowing into the pit, this might not work well due to the fitting getting clogged.