This should help for question #1
As I'm not a plumber to answer #2. Are the two toilets shown are existing? Is one of them on the horizontal 3" near the floor joist and the other run between the floor joist?
Each washer needs it own drain should both dump water at the same time.
The two toilets that come into the header are existing from first floor. They are nowhere close to this area. The setup is like this from left to right:
- 2" drain for existing washer
- 3" drain for 2 existing upstairs toilets
- 3" trap vent
If actually serving toilets, choose a grinder pump, rather than an ejector pump. However usually only basement toilets feed the sealed basin to get pumped, and the main floor waste does not get pumped. Your diagram does not show what feeds the basin.
Yes, the pump would be for 2 additional basement toilets, 2 additional basement sinks, and 2 additional basement showers.
Actually I'm glad you said that about the grinder pump. I was going to do a regular 4/10hp Liberty ejector pump that does 2" solids. Then I saw that they also have provore grinder pumps. The smallest Liberty grinder I can find is 1hp.
So just to confirm, I asked Liberty to recomend a pump for my setup. They recommended the 4/10hp regular pump that I had in mind. But I asked them why they didn't recommend the grinder. The first thing they asked was if I have a septic system. I do have a septic tank and a cesspool. So they said they dont recommend the grinder for septic systems because it grinds everything down and doesn't allow the solids to separate from the liquids properly when arriving into the spetic tank. They said this leads to the mixture going into the cesspool before having enough time to biodegrade and separate since its mixed with the liquid, and can eventually create a film in the cesspool on the sand, sort of like slime on the bottom of a pond, how it doesnt drain properly.
I dont entirely agree with this idea. First off, I've seen cesspools get this film even without grinder pumps. Usually the cesspool people will fix this by sucking most all the liquid out of the cesspool leaving a little bit, and then they'll add sulfuric acid and it eats the film away down to the clean draining sand, then wallah. Or, they'll also try to "airate" the sand, which I never let them do because I feel it's a scam. All they do is empty their truck into your sand that is not supposed to be filled with crap. Under the film is clean draining sand and they are making a mess of it by doing so.
So the questions are, does the good outweigh the bad in regard to the two different style pumps? How fast can this film happen if it does in fact happen faster with a grinder? Isn't it worth getting a grinder pump over a regular pump to avoid the headache of a tenant throwing rags, tampons, diapers, wipes and all other non-flushables. I just dont understand because wouldnt you think ground up sewage biodegrades faster than logs of turds? But then again I'm not a turd expert. Maybe having the cesspool pumped a little more often is better than having to fix a regular style pump everytime someone does something stupid?
So I'm leaning toward a grinder unless someone can shed some light and make sense of what the manufacturer said.