The washing machine waste is coming back the pipe and onto the floor, the pipe is clear other than plastic in the middle half way down should it be there to slow the water down?

the pipe is clear other than plastic in the middle half way down should it be there to slow the water down? You put a blockage into the stand pipe and are now wondering why you are having backups? I assume you put the plastic in the pipe hoping to slow down the force of the flow because you were already having backups. Is that correct? First thing is to retrieve the plastic you jammed in the stand pipe. Next, answer my questions and I'll come back with a solution for you. Cheers, Tom

Nothing was put in to the pipe it looked like plastic but after the use of a pressure washer a load of muck came out and everything is OK thanks.

We thank you for the update. Tom