DIY sewer line replacement (partial) ?

[JLM34]

Well I'll go ahead and revise my question based on what I found. I had approx 120 feet to run this line. 2.5" every 10 feet would be a 30 inch drop overall, plus my starting point I would think has to be at least 6-8" underground. So after finding the tie in point, I don't think it's going to be quite deep enough to pull this off with that long of a run. So my two options I believe are to either go the other way, which would involve chopping up some concrete AND tapping into the city sewer ($$$$), or go the same direction I was going to originally and use a pump. The sewer pump I've found can be bough preassembled in a 30" deep basin meant for underground burial. a 4" inlet and 2" outlet. Again, this is kitchen sink/dishwasher and laundry water only. Pipe those two things into it and run pipe out of the discharge around and tie in to the sewer. Cap off the old drains. Cut vent pipe in the wall, cap it off, and tie new lines back into it (it goes out the roof). My question: Will deep freezes make this system inoperable or will each cycle of the pump empty the basin??? The pump I found will pump water 18 feet straight up. It does not specify how far horizontally it will go. I will try and keep the pipe as level as possibe. Should I run 2" pipe all the way around to increase the pressure in the pipe? I'm not sure if this pump with each cycle will be able to completely flush out the line or not. What do you guys think?

 

[Leejosepho]

I had approx 120 feet to run this line. 2.5" every 10 feet would be a 30 inch drop overall ...
I don't think it's going to be quite deep enough to pull this off with that long of a run.

If you had only half of that, it would still be fine as long as there were no sags in the new line.

... my two options I believe are to either go the other way, which would involve chopping up some concrete AND tapping into the city sewer ($$$$), or go the same direction I was going to originally and use a pump.

A pump is the very last thing you would ever want to do here. Gravity requires no equipment or power to run it, and it never fails to work! Again, your connection at the other end of the house is already low enough for dish water and wash water to gravitate over there even after its route gets slightly altered.

 

[Sponsor]

 

[JLM34]

Well, I see what you are saying. Yes, there is enough drop right now for it to flow, but right now it just cuts straight across the house under the slab so its only maybe a 60 foot run over to tie in. The way I would have to do it based on how my whole property is situated would require me to go all the way around the house and I'm looking at more like 130 ft going that route. And the first 50 feet or so is uphill - not a lot uphill, but still uphill. A pump isn't ideal for me, but it's not a concern either. I've had pumps in a house with a basement and they were very reliable. I'd rather have a pump than maybe chance it with doing all that work and not having enough fall and having issues with things backing up. At least with a pump I won't have any backup issues (I hope). Seems a properly sized pump would force everything through that pipe sufficiently without any backups. Right now I just think the pipe would almost have to be level - otherwise by the time I get around to tie it in I'm going to be lower than the sewer line - then I'd have to go UP into it to tie in - I don't think that sounds too good.

 

[Jimbo]

A pump does not solve the problem. It will just raise the sewage from a deep location to the drain, but there must be proper gravity drain from that point all the way out. A pump will not move sewage 120' through a non-sloped line.

 

[JLM34]

A pump does not solve the problem. It will just raise the sewage from a deep location to the drain, but there must be proper gravity drain from that point all the way out. A pump will not move sewage 120' through a non-sloped line.

I had a sump pump in a basement in a prior home that took the water straight up vertically 8 feet and pumped it another 80-100 feet horizontally..and this was a pretty inexpensive sump pump I bought at Lowe's..not all that powerful. I've seen specs on several sewage pumps stating the maximum horizontal length it would pump is 140+ feet. I can at least keep the pipe level.

 

[JLM34]

http://www.**************.com/Buying-Guides/Sewage-Pumps-Systems-Buying-Guide/11

Their example on pump selection is for a 7 food static head (minimum water level in basin to highest point in discharge pipe), and a 200ft long discharge pipe, which is the length of the pipe from basin to final exit where gravity takes over. I'm not sure why you claim a sewer pump can't pump sewage down 120' of relatively flat pipe. Unless I'm misunderstanding what I'm reading. I'm obviously not claiming to be the know it all on pumps, just relaying the information as I read it.

 

[Leejosepho]

Well, I see what you are saying. Yes, there is enough drop right now for it to flow, but right now it just cuts straight across the house under the slab so its only maybe a 60 foot run over to tie in. The way I would have to do it based on how my whole property is situated would require me to go all the way around the house and I'm looking at more like 130 ft going that route. And the first 50 feet or so is uphill - not a lot uphill, but still uphill.

Your trench will be deeper to keep the pipe falling where ground level runs up hill, of course, but there will still be fall between point A and point B (between the connections at one end of the house and at the other) as long as the fall of your new line begins at point A and is not interrupted before arriving at point B. I understand your concern about the new line being longer because it must go around the house rather than straight through underneath, but you will still have the same overall fall and the line will still drain as long as it is all bedded on one plane.

After your trench is dug, and I would be renting a trencher to do that as long as you will not be trenching across any power, gas or phone line ... then use a water level or transit to determine exactly how much fall you have available between point A and point B. Next, measure the length of each leg of your new line's journey around the house, and then assign each leg its proportional amount (per foot) of fall ...

... then install each leg to those specs and drain a sinkful of water ...

... and if that line does not drain, I will buy you a pump!

Believe me, you have all the fall you need to run your new line around the house.

Edit: Be sure to use the more-expensive, long-turn sweep 90s at the corners to get a smooth flow, and I suspect the code requires them anyway.