recommend best way to pipe sink/washing machine in basement

[jasesun23]

Hi. Need advice on the best/correct way to set up pipe the following situation. Ive included 2 pics below.
My old sink/metal cabinet setup was completely rusted so I removed it. Upon inspection of the pipe it was rusted going down in the drain pipe so I removed all of it. It just lifted out of the drain on the floor. So now I'm left with setting it up and running some pipe.
Background - this drain does not seem to go to the septic tank as all the other waste pipes do. You can see the septic line 4 feet above. I believe this goes to a dry well under the driveway. It is a 2 inch pipe that a 2 inch donut fits into snugly.
The old setup there was the black flexible drain pipe from the washing machine that went directly into the piping,just below the p-trap for the sink. Also there was a heavy black hose going up 7 feet and ending in the beams below the ceiling. I'm assuming this was some form of a vent (however it was not venting out side)

Idealy I'd like to drain right into the pipe as opposed to the sink if that;s possible/allowed.
I plan on putting a counter top from the shelves on the right all the way to the washing machine on the left. Then cut out a section to put a drop in plastic laundry sink. I'd rather not cut another hole into it to run the washing machine's drain pipe into the sink but will if necessary.
I believe the yellow line in the pic (drain into sink ) is okay. Would the green line or the black line be acceptable, directly into the plumbing either above the p-trap or below.

Lastly how would I correctly add a vent to this system. The old way was just a rubber hose going up to the ceiling. Do I need a vent?

[jadnashua]

Are you planning to retain the drywell? Eventually, the ground gets plugged up with lint and soap scum and can't absorb water at a decent rate, plus, in some places, it's illegal.

But, that isn't a p-trap, it's an S-trap. You may or may not need a vent line to the drywell, but having it terminate in the same room is just a waste.

My mother's house had a similar situation. WHat I ended up doing was installing a Liberty pump designed specifically for this application and running it into the main line to the septic system. The pump is small enough that it fit right beside the sink. We ran the outlet of the WM into the sink, and the sink drained into the tank of the pump, then the pump's float switch turned on and pumped it to the drain.

[jasesun23]

Jim thanks for the replying . I was planning on using the 2" pipe to the drywell. Did not want to tap into the main line just yet and it seems to be emptying okay. I got this recommendation from someone else - empty the washing machine drain into the sink and add a studor vent about a foot or higher than the sink on than drain pipe. Something like the picture below

[cacher_chick]

The purpose of a trap is to prevent sewer gas from coming back into the building. The purpose of a vent is to prevent the fixture's trap from being siphoned.

If your laundry is not connected to a sewer or septic system, there is really no reason for it to have a trap or a vent.

[Hammerlane]

If your laundry is not connected to a sewer or septic system, there is really no reason for it to have a trap or a vent.

good point

[hj]

Without a "vent" that system is NOT going to drain unless the drywell is so "loose" that the air trapped in it can escape through the ground, and a Studor vent would not help it one iota.

[Tom Sawyer]

Dry wells around these parts have not been legal for many years and......when it plugs up, and it will, you better hope you are home and in the basement when the washer starts to dump all over the floor.

[jasesun23]

This is my parents house and I agree with everything said about drywells. From childhood I can remember the first one completely clogged up. That was about 15 -20 years ago. This one is probably on its last leg as well. I will let them know when then time comes to tap into the septic drain system with a pump and close off that drywell. Thanks for the help guys.