I live in an old house built in 1937 with a crawl space. We have had numerous issues with the kitchen drain line leaking under the house. The first 10' or so of piping is above ground and then it disappears underground to meet up with the main sewer pipe. I would like to replace the underground part with PVC and connect to an available drain nearby from the washing machine. The problem is with the under-house beams and such is that I don't think I can make a straight shot from the existing drain to where I wish to tie the new line. I would tie into the existing vertical piping from the sink, run about 10' horizontal with the correct drop, add a vertical riser of maybe 12" and then continue the horizontal run with the correct drop to the tie in for another 10'. Since water seeks its own level, I can't see an issue with this and it seems to me like another P-trap. I would like any plumbers thoughts on this as whether this is done in practice. Thanks in advance for any help.