It doesn't look me as though a disposer will be a good idea under your sink, even if you can manage to shoehorn one in. There doesn't appear to be enough height between where the drain line emerges from the back wall, and the bottom of your sink. If the bottom of the grind chamber and the disposer discharge tube is lower than the drain line, the disposer won't discharge waste and drain properly. Even if you run the disposer long enough and pour enough water down the drain to clear it of food waste, you'll still always have water sitting in the bottom of the disposer. In the short term, it will function, but unless the disposer drains completely after each use, it's going to have a short life.

1. Basically, yes, but every situation is different, so it may not be that simple 2. You will have to use a Studor vent or vent loop under the sink. 3. Cost varies too much by location to make a guess on that. Plumbers aren't cheap. 4. Yes.

Thank for the reply. Before calling a plumber this morning, the 2nd floor called and told me that the standing water in her sink was now gone. I went up there and turned on the hot water on the 3rd and 2nd floor. Meanwhile, down in the basement, I could hear what sounded like chunks of ice hitting the elbow at the bottom of the waste riser. Now that that's the drains are all fine, I think I have a related problem. This morning, after going into the basement while running the hot water, I could see a puddle of water under the riser pipe. There was dirt in the puddle and the dirt was in a path down the foundation wall. On top of the foundation wall, there was a bunch of wet dirt. (I'm pretty sure the dirt has always been there from the fire stop material and dust and whatnot. Directly above the dirt on the top of the foundation is the hole in a 2x4 where the PVC riser runs up through the back exterior wall of the house, and then through the roof. The wood around the hole is wet with moisture, and some of the insulation I put in that hole around the pipe to stop a draft was moist too. Is it possible that the PVC waste pipe had standing water in it from the blockage (whatever it was) and froze and cracked overnight? The temp last night dipped to 15 degrees Fahrenheit and stayed below 25 until 10:00 this morning. This riser pipe is in an uninsulated exterior wall on this 1940's house, and vents through the roof. Any help would be appreciated. Thanks, Nick

It should be no problem at all. Standard drain plumbing pieces are available to accomodate most configurations. Merely a shorter horizonal pipe coming from the wall to the trap will probably do the trick.