sewer line replacement

Due to tree root problems, I've gotten a few estimates for sewer line replacement from my house to the curb.
I have two questions. 1) if it turns out that my existing sewer line is 6" clay pipe, is there anything wrong with the contractor inserting 4" PVC pipe through existing clay pipe for some of the installation rather than removing the existing clay pipe? The reason for doing this would be to avoid having to tunnel under a staircase that ascends in a direction perpendicular to the pipe and which is located above the pipe. By inserting PVC pipe through existing clay pipe, this could avoid damaging the staircase or causing it to settle. Is there anything wrong with inserting the 4" PVC pipe through existing 6" clay pipe in a problem section rather than removing the clay pipe altogether? None of the clay pipe would be used, since the PVC pipe would simply be inserted through it to avoid a problem area. Is this acceptable?
2) if the existing sewer line is made of metal (cast iron?) and there are no joints in it between the house and the location where it extends beyond the staircase (11 feet from the house), would there be any problem with the contractor attaching a PVC pipe to this location (11 feet beyond the house) rather than starting at the house itself. The contractor seemed confident that if the existing pipe is made of metal (cast iron?) and is good shape, and has no joints, that he could simply attach a PVC pipe to it with a solid connection (I think he said a 4 band stainless steel) and seemed confident there would be no chance of root intrusion at that connection. Is it true that with the proper connection of a PVC pipe to a metal pipe that there is no risk of root intrusion, or should I insist that the PVC pipe's connection should begin at the house (and take the risk of potential damage to the steps by having them tunnel under them.) I think the contractor may have talked about using a 4 band stainless steel connector rather than a rubber connector. As much as I'd like to save the steps, avoiding root intrusion is more important than saving the steps. Should I insist that the PVC pipe begin at the house or would connecting to the existing pipe be as solid in terms avoiding any potential root intrusion?
Thanks.
Jeff
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the s econd method with PVC is fine. that is how they do it in Philadelphia. it is perfectly legal here
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<<You might not like this response, but it needs to be said. Anything worth doing is worth doing right.>>
Ok, so I take it that your answer is NO to both of the 2 ideas with regard to the staircase issue. I'd like to know what's wrong with the first idea, since I'd still have a PVC connection from the house to the curb except that, in one section, the 4" PVC pipe would be pass through an existing section 6" clay pipe.
Thanks.
Jeff
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What you're wanting to do is called slip-lining. It's a common practice here in Houston and to be perfectly honest with you - on large piping projects (municipalities mostly) is extremely cost effective. However, the piping that is used is a very stiff walled polyethylene - is "hammered" down the line with sophisticated equipment, and prior to all that, the existing line is televised using GPS equipment so the damaged sections are excavated and replaced. I don't know how long or deep your sewer line is, but on a residence, I would replace the entire line. If nothing else, when removing the old 6" line using a backhoe, the roots will be disturbed and cleared away from the new line. In over 30 years of plumbing, I've never seen a *properly* installed PVC line take on roots.
As far as the size is concerned, you would have to calculate the fixture units to see if you can reduce to 4". Here in Houston, there are very few homes (even those with 4 bathrooms, 2 kitchens, wet bars, etc.) that would require a 6" line. I once had a customer who wanted an 8" sewer line (typical 2 bath, kitchen, w/d, etc.) I told them I would not install it because it would more than likely stop up over a 4" line. They thought I was crazy until I explained to them that with that much "barrel size" of the pipe, there was a good chance that the liquid would run around the solids and leave them behind in the pipe. Once they thought about it, it made sense. Good luck to you.
Jim Mc Namara

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When installing a new sewer line at my house, the goal is a complete 4" sch40 PVC mainline connection from the house to the curb, except that, in one small section, in which a concrete staircase is over the pipe, they're considering slipping the 4" PVC through through the existing 6" clay pipe (assuming the current outside line is 6" clay.)
The line within my house is already only 4" line, and 4" PVC is what they normally install around here for new residential lines as permitted by the code. If so, then slipping the 4" Sch40 PVC through existing 6" clay pipe is being considered for the problematic section where the concrete steps are located. The end result would be a completely-PVC connection from my house to the curb, except that one section of the PVC pipe would happen to have the old 6" clay pipe around it.
Would this be considered improper or is this acceptable?
Jeff
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You need to get that answer from the building code people in your area, because what counts is what they say when they come for the inspection before covering the pipe. In my area, it's 6 inch pipe to the house no matter what kind of pipe, and then 4 inch inside.
Tom J
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I see nothing wrong in slipping the 4" PVC through the 6" clay pipe as long as there is continuous fall on the pipe (since you're using it as the invert.) Hopefully there is nothing wrong with that section of pipe as it will save you time and money. Avoid any joints in this section (not knowing how long it is.) Just remember that the clay pipe you're looking at might very well be 4". The wall thickness of clay pipe is so great, that it may appear to be 6" - a very common error - even by some pro's in a hurry. For your sake (and the sake of not removing the concrete steps) I hope it is. :-)
Don't forget to install a cleanout plug at every 90 turn of direction and at least every 50'. Most people like to run 75' - 100' for their clean outs, but I've found that most places that sell cables to the homeowner come in 50' lengths. You might even consider a two-way cleanout about mid-line. Just a thought . . .
Jim

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<<Avoid any joints in this section (not knowing how long it is.) >>
Thanks again for the reply. Please clarify what you mean by avoiding any joints in this section. Do you mean not to do this if the clay pipe has joint(s) in that section, or do you mean to make sure the section PVC pipe inserted isn't two separate sections of PVC joined together?
Thanks.
Jeff
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No joints in the PVC pipe. If the section is over 20' long - you'll have no choice since you can purchase the pipe in 20' lengths.

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Are you sure about the 4 inch line (outside of the house) as I used to inspect main line sewer installations and all the house connections were 6 inches going to the curb ? It should be easy enough to check tho....go to the building dept. and / or plumbers for advise in your area. There may be building code requirements for this.
Personally, unless there is a compelling reason, I'd rather have 6 inch pipe outside the house. Inside homes tho, it's usually 4 inches.

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I see 6" being used here as well. that other old clay stuff is usually 5"
wrote:

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Alot of people have their lines augered out once or twice yearly for $100. a shot. At $200./year, say at a mere 5% interest, it would have a $4,000. capitalized value ($4,000. invested at 5% would produce $200./year). At a higher interest rate, the capitalized value would be lower.
So. if your excavation would cost more than that, you lose.
Everything in homes wears out eventually. Just like with cars. The issue is when it pays to do the replacement.
And if you have the stomach, you could spend $400. and buy the equipment to do it yourself..
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