Branch line standing water (solution?)

[ATM]

I've had an issue with the first floor powder room running into the floor drain trap by the furnace rather than the main line for a number of years (probably has been going on since the house was built in the mid-80s). My temporary solution was to run a bucket of water through the floor drain one a week or so to clear the sludge (it goes down the main line without issue as I pour water down the furnace trap. After having some other plumbing work done yesterday I had them investigate. Using a camera down the clean out on the branch line from the powder room he found that the line has standing water and isn't graded properly to the main. He first proposed busting out the concrete floor and relaying pipe with the proper fall. However, since the vertical drop from the 1st floor joist is near the back wall of the basement I asked if he could just cut and cap the vertical and reroute the 3" line to the main stack on the back wall. He thought that was a good idea and quoted me a price to do so. Any issues with doing it this way? (Sorry for no pics, I can add later this evening if that helps).

 

[Jadnashua]

Pictures would help clarify the situation. Generally, as long as you maintain the required minimum slope (0.25"/foot) and if the changes of direction don't exceed a certain value (don't remember right now), you can do this. If the changes of direction exceed that magic value, it can still be done, but you'd need to add a cleanout so that you could have success using a snake (it won't go around that many corners!).

 

[Sponsor]

 

[ATM]

Here as some pics of the current situation. Idea is to run the new line on the back wall to tie in with the main stack. They're planning to reroute the supply lines on the utility tub