Collapses and blockages in sewer lines lead to overflows into nearby streams and basement backups.

For example, if the main drain has a blockage and filled with water, and someone unknowingly flushes the toilet, the positive pressure created by the flushing action had no where to go due to the blockage, in a conventional atmospheric vent the positive pressure can just be relieved, but not with an AAV.In some jurisdictions, they allow you to upsize the drain line in order to allow part of the drain to serve as a vent.Also, try to explore an option where a conventional vent can be implemented in the island, but creatively disguised as a support beam, a decorative pole or something.

Cash blockage?

Someone was clearly negligent here, however, I cannot prove responsibility and the blockage was found in unit 1.How would you go about charging the plumber bill?

That will usually clear the blockage and saves me from having to handle the snake (gross).

The danger you run into is that some of that calendar blockage you see could be owner blocks and not paying guests and there's no way to tell.

You know that and so does she.I would tell her she gets nothing for the hotel time during the actual work to repair the blockage (not the first repair) and that she owes you the full cost of the actual repair.

stick your hose or whatever in there and see how far it goes, then lay it on the ground above the pipe and you will see were the blockage is.dig it up, cut the pipe in half, and get the junk out of there. if it is black corragated 4 inch pipe, then you can get a coupling for 3 dollars at home depot and then wrap some duct tape around it. if its DWV pipe or SDR just go get a 4'' coupling for 3 bucks and slap that baby on there, glue is preferred but not needed, there is no pressure.if you are having trouble locating the blockage, try runnin the hose from the drain end of the line not from the gutter downspout end.hope it works, steven

The problem was that the powder laundry detergent (such as Tide) did not disolve completely and had actually cemented together at that exit point to form a partial blockage that interrupted the flow of the water but did not stop it.

Blockage could be caused by a multitude of things already named, as well as silly things like balls or dead birds, or even a collapse of the pipe upon itself somewhere underground.