Sewage pump for mother-in-law unit


  #1  
Old 05-02-16, 10:28 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
Sewage pump for mother-in-law unit

I'm building a detached MIL unit in my back yard. The MIL's main waste line will tie into the waste stack in the main residence, which exits the basement floor. This is a run of 60'. However. the point where the waste line exits the MIL is about level with the cleanout at the bottom of the basement floor, so I can't use a normal gravity sewer.

So I need a sewage ejector, and I have very little context for understanding the difference between a $500 unit and a $7,000 unit. The MIL is a small studio, with a 3/4 bath, kitchen sink, and washing machine. How do I decide what kind to get?

I also have questions about configuration. Do I put the ejector immediately outside the MIL, have it pump waste vertically a couple feet, and then have a normal gravity sewer line from that high point to the house? Or should I use the ejector to set up essentially a pressure sewer system for the entire 60' distance from the MIL to the house? I have seen both configurations but can't find any info about when to use each (probably because I don't know the right nomenclature).

Thanks much!

PS: In case someone suggests tying into the side sewer rather than the waste stack in the house: the reason this isn't an option is that where I live (Seattle), the county will charge you a $10,000 hookup fee if you connect a detached dwelling to the side sewer anywhere after the cleanout.

(x-post from Help with sewage ejector: what kind, and what configuration? - Plumbing Forum - Professional & DIY Plumbing Forum)
 
  #2  
Old 05-02-16, 11:04 PM
P
Temporarily Suspended
Join Date: Jul 2008
Location: NY
Posts: 10,265
Upvotes: 0
Received 0 Upvotes on 0 Posts
I didn't know about the $7,000 version. I lived in a place with an ejector pump & it needed to be replaced twice in 7 years. I'm in another place now, also with a pump & there hasn't been a problem in 3 years. It was replaced 4 or 5 years ago.

How cold does it get there? Could low temps affect the pump, if you put it outside?

I can understand that you don't want to pay $10,000 for the connection but I would be nervous about running sewage into the house only to send it out again.
 
  #3  
Old 05-03-16, 05:25 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,392
Received 2,327 Upvotes on 2,069 Posts
I have a twin tank septic system with a pump that moves everything to the leach field. It's currently in it's 14th year on the original pump. I've had to replace two float switches but that's a relatively minor expense.

In all cases with an ejector pump I pump it all the way. There is no simple lift where it dumps into a gravity flowing line. Parts of the run may operate by gravity by coincidence but it's primarily pumped the whole way. So, if you have a 2" outlet from your pump I'd run 2" all the way to where it ties into your main drain stack and becomes a true gravity flow. You will also want to consider the flow volume coming out of your pump. Don't fall into the trap believing that bigger is better. If you move too much too quickly it can cause a backup problem in your main house if the gravity system cannot take the waste away fast enough. There is no harm if it takes several minutes for the ejector pump to empty the sump.

In your case it's impossible to comment about the prices your seeing since we know nothing about what you are considering or even if the $500 and $7'000 units are an apples to apples comparison. The vast difference in price makes me think they are not and are two vastly different systems.
 
  #4  
Old 05-03-16, 12:15 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
It depends on the slope and the addition your building.. If its a slab addition then a lift system in the home will not work as the outlet will come out above grade..

You would then need to put it outside. This way it will be deep enough for the slope..

We do the e/one low pressure ejectors here.. This is the type I would suggest..

Note: This video is for reference only... Also the system shown is a large unit for this home. Your would be a lot smaller...

( Also have you considered or have the room for a small septic system?)

https://www.youtube.com/watch?v=LWYPbzg8knw
 
  #5  
Old 05-03-16, 01:25 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
Pilot Dane - Thanks for the info. I think I was using the terms "ejector pump" and "grinder pump" interchangeably, which is where my confusion about price points came from. The grinder units are not only different, but a LOT more expensive.

With respect to flow rate--that's a point I hadn't thought of. However, the 2" run would tie into a 4" vertical waste stack that runs straight out the basement floor to the side sewer, so I'm assuming that won't be an issue.
 
  #6  
Old 05-03-16, 01:31 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
Pulpo - It doesn't get too cold here. The frost line is 18" and the entire pump and reservoir would be below that depth.

I would be nervous about running sewage into the house only to send it out again.
Is there a particular risk or concern that you have in mind here?
 
  #7  
Old 05-03-16, 03:44 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
The grinder units are not only different, but a LOT more expensive.
Grinders and ejectors do the same thing .. The only difference is head they can overcome..

Did you read my post below?
 
  #8  
Old 05-03-16, 04:34 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
lawrosa - Thanks for the reply. To answer your questions: It is a detached dwelling, not an addition, and the pump will have to be outside--there's no place for it inside. Also, I'm really not considering a septic system, for a variety of reasons including cost and space constraints.

You would then need to put it outside. This way it will be deep enough for the slope.
I'm not sure what you mean here--can you clarify? In my case, the detached building's outlet is about 2' below grade, and is about level with the point in the main house's waste stack where it would tie in.

It sounds like you're suggesting using the pump to create a pressure sewer for the whole 60' run. I'm curious, why is that preferable to using the pump to elevate the waste just enough to use a gravity sewer the rest of the way?
 
  #9  
Old 05-03-16, 05:21 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
In my case, the detached building's outlet is about 2' below grade, and is about level with the point in the main house's waste stack where it would tie in.

It sounds like you're suggesting using the pump to create a pressure sewer for the whole 60' run. I'm curious, why is that preferable to using the pump to elevate the waste just enough to use a gravity sewer the rest of the way?
Youll need about 1' 1/2 to pitch pipe properly from detached building to the main home..

You need a low pressure system that will not need to be pitched...

If leaving the detached building at 18" below grade for frost then when it gets to the main home it will be at about 3 ft below grade..

So if the outlet is even with the tie in, how will that work?

Unless I am missing something..

Lets tacklke this another way...

Show me what unit( gravity lift) your thinking about putting outside and I will tell you why it will not work...
 
  #10  
Old 05-03-16, 10:34 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
Here's what I was envisioning. Forgive the crude drawing.

Name:  IMG_20160503_222849.jpg
Views: 2091
Size:  15.3 KB
 
  #11  
Old 05-04-16, 02:39 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
And the reason for the two different pumps is what your drawing shows...

How will your service that pump?
 
  #12  
Old 05-04-16, 10:00 AM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
What do you mean, two different pumps?

And re: servicing the pump--how does anyone service any sewage pump? Take the cover off, I guess...? I don't really understand what you're asking.
 

Last edited by dlukas; 05-04-16 at 10:58 AM.
  #13  
Old 05-04-16, 12:41 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,392
Received 2,327 Upvotes on 2,069 Posts
You need to make sure you plan for and include a way to service the pump. If the pump dies with the pit full how will you get the pump out and install a new one?

Union fittings are often used on the outlet and placed high enough that it can be reached from the surface. A rope is tied to the pump so you have a way of lifting it out. Float switches are attached to a vertical piece of PVC that is just stuck into a fitting at the bottom with the wiring going up to the top before heading down to the pump so the switches can be serviced. Then you need to make provision for your wires and wiring connections. Electrical connections are generally not permitted inside the sump so you need a gas tight seal where the wires exit to a box where connections can be made... always keeping in mind that those wires may need to be pulled and new ones run in their place.
 
  #14  
Old 05-04-16, 01:34 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
Your drawing shows a verical lift pump. The top of that elbow needs to be 18" below grade per your postings.

And these type pits/pumps have a wired plug that comes out the top. These are not hard wirde.

How will you wire it?
If there was a way then if the pump failed you will be digging 3 ft to access the lid and to access the pump..

Your municipality will never allow it...

[ATTACH=CONFIG]65827[/ATTACH]

What do you mean, two different pumps?

And re: servicing the pump--how does anyone service any sewage pump? Take the cover off, I guess...? I don't really understand what you're asking.
You seem a bit upset..

Possibly you have in your mind that your going to do it your way do to cost or some other reason. You can try and let us know the outcome..

The low pressure systems ...

Have the lid flush at ground level
The discharge is side mounted.
No pitch is needed for discharge.
Electric is hard wired
Pump pulls out easily with rope and reinstalls the same with leak free drop on connections..

Its your home do what you want. You came and asked a question. Im a plumber 30 plus years and gave you my answers to the best of my knowledge...
 
Attached Images  
  #15  
Old 05-04-16, 02:00 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
lawrosa - Not upset at all; I was just confused by your previous reply, as it was kind of vague. Your follow-up was very helpful though, thanks. So was Pilot Dane's. I very much appreciate both of your help.

Follow-up question though. The MIL waste outlet is 24" below grade. Doesn't waste flow into the top of the pump unit? So if the pump unit (say, this one) is 24" tall itself, then I'm already stuck digging down 4' to install or uninstall it, right? Is there some way around this? I feel like I'm missing some key piece of info here.
 
  #16  
Old 05-04-16, 02:32 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
Doesn't waste flow into the top of the pump unit?
No.. The waste enters a side port...

So if the pump unit (say, this one) is 24" tall itself, then I'm already stuck digging down 4' to install or uninstall it, right?
That unit is a top discharge. As stated you need a side discharge low pressure type unit..

Did you watch the video I posted below on how the low pressure units install?

The only way Your type of unit you linked to would work is if some type of man hole was dug to service the unit... And I have never seen that for ejectors...

But the e/ones and other brands like it are made this way...

I have done this job many times...

https://www.youtube.com/watch?v=FflBw7vqg4g
 
  #17  
Old 05-04-16, 03:02 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,997
Received 85 Upvotes on 77 Posts
I am not sure you can get enough pitch.. A cheaper solution would be a zoeller style side discharge..

They have risers as an accesory..

You need permits anyway so why not just call local plumbers in your area and get a few estimates...

https://www.plumbingsupply.com/zoell...s.html#outdoor
 
  #18  
Old 05-05-16, 09:02 PM
D
Member
Thread Starter
Join Date: Mar 2015
Location: United States
Posts: 42
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks, that's very helpful. I'll research Zoeller. I already have my permit issued, but planning to consult with a local plumber too. I just wanted to have a game plan first.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: