Desperately need a chemist(?) to help me out of the hole I dug.

[IrishAyes]

How can I dissolve a clump of de-icing salt in the exit pipe for my clothes washer?

There was an ice jam in the trap, which can't be reached under the house because the clearance is so low nobody's crazy enough to crawl under there. When boiling water, vinegar and baking soda, and even anti-freeze didn't work on the ice jam, things really went south when I tried de-icing salt, which I had no idea would form an impenetrable clump on top of the ice jam. Even though I've mostly lived green and certainly regret my recent desperate measures, I did put a couple inches of very caustic drain cleaner on top of the clumped de-icing salt, which has done nothing to soften the rock salt clump in 2 days. I'm desperate because I can't find an answer and I can't afford a plumber!!

Putting heat on the pipe won't do anything to relieve the rock salt clump, and the pvc exit pipe is crammed up against the wall anyway, making me fearful of using too much direct heat. I was always afraid of heat tape because I've heard about it starting fires, but believe me, in the future if I can get out of this mess I'll be willing to risk heat tape rather than go through this again. I do learn from my mistakes, and this has been a doozy.

In the belief that this rock salt clump is in the section of pipe above the floor, I'd even be willing to try to cut the pipe off just above the floor, throw away the clogged portion, and refit an extension to restore the proper height. But that in itself presents hazards I'd rather avoid if possible. Of course I don't want to use a much thinner piece of conduit pipe to break off big chunks of the rock salt clump because it might well then fall down into the trap (once the ice melts on its own) and make an even worse problem. Best if I can find a way to dissolve the salt clump and flush it down gradually and safely.

If worse comes to worse, could I siphon off the present caustic drain cleaner and if necessary cut off the pipe down to where the rock salt clump starts, then take a titanium drill bit to it???? Bore through it so whatever might come loose would be in very fine particles? And then extend the exit pipe back to the proper height needed for operating the washer?