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Sewer pipe under concrete driveway

24K views 7 replies 3 participants last post by  justdon 
#1 ·
We are remodeling, adding a bathroom upstairs where there was no plumbing prior. The designer located the bathroom on the opposite side of the house from the side sewer and existing sewer outlet. We are too far to redesign, so I am thinking of adding a sewer outlet to the other side of the house by drilling through the basement floor and running the sewer pipe under the double car driveway concrete slab to connect to the existing side sewer.

What are my options and how expensive would this be? Will I have to break up or cut the concrete or is water drilling under the slab a viable option? If I use the water jetting method of laying the pipe, will it compromise the driveway support? If we use this method, once the pipe is in, is there a void created by the jetting? The side sewer is about 4 feet deep at the point where it would meet up with the new pipe so the run would not be a problem.

I think this option would be preferrable to running a pipe across my livingroom ceiling or dropping my ceilings to make space for plumbing to connect the new pipes to the old sewer outlet or running the outlet on the exterior of the house, as my contractor suggested.

Is it o.k. to have 2 sewer outlets connected to a side sewer?

Thanks.
 
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#2 ·
Using a soffit or dropped ceiling to traverse the living room would work if it can be done in an aesthetically pleasing manner. If using plastic pipe then noise could be a factor.

Going outside can work if you really have enough drop. What is your frost line and what is the total distance (not straight line) you need to go? Don't know if horizontal drillers will guarantee no settling - you really need to see who has what technology in your area. Slope of the line should be 1/4" per foot so if you have say a 72 foot outside route the pipe will be 18 " higher at the end so your 4 foot deep pipe will only be 30" deep.

I'm a little confused about your yard grade. Is your basement floor level with your driveway and 4 feet above the existing sewer line that is on the other side of the house?

I would first attempt to route through the basement ceiling area using soffits as needed to hide the pipe in finished areas.

Oh and you would bring the new and existing DWV lines together somewher before you connect to the city sewer and yes that's ok.
 
#3 ·
We live at about 30 foot sea level in the NW. Frost line is not much of a consideration since we rarely see extended periods of cold.

The basement where I would install the outlet is ground level and at the same grade as where the existing side sewer is buried. The sewer run would be anywhere from 30 feet to 50 feet, depending on where I locate the outlet in the basement. The existing side sewer is buried 4 feet deep at the lowest grade on my property. We just had it dug up and repaired so I know exactly where it is located and how deep it is. If I only need 1/4 inch per foot of run, then I only need a 7.5 to 12.5 inch drop? I have that, easy.

The consideration now is whether I can burrow a sewer line under my 2 car wide concrete slab and have the slab retain its integrity, or install sewer lines overhead in the living space in an aesthetically pleasing manner. I'm hoping the outside option is cost effective.
 
#4 ·
Check carefully as to whether there is a way to route the line in the basement - even if only part way (enough to avoid the driveway) before going out. Usually you can find a way to route it along a beam, wall, or ductwork. Even if you have to take a few turns and not take a direct route to get from the new stack to the existing sewer it will be easier (and therefore cheaper) unless you have a lot of finished basement to go through (even then it can be pretty straightforward to add a soffit).

Or to put it another way, what is stopping the GC from routing the line through the basement? You've got the full height of the basement to work with so what's in the way that he can't go around or under? Do you have any drawings or pictures of the basement showing location of new stack, existing sewer and any basement doors, walls, posts, beams, ducts, windows and stairs?
 
#5 ·
Actually, the GC was terminated for a variety of reasons that will probably be discussed in court someday. Another GC isn't on board yet so I'm trying to think around this problem before another hair brained idea is suggested.

I don't have adequate drawings of the basement, but the house was built in 1926 as a small cottage, then remodeled by many different owners. Now it's about 3500 sf. approx 25 x 50. The new toilet is in one corner of the top floor, the outlet is in the other corner of the basement. There are structural beams running both directions in the main and basement that prevent straight runs, floor joists that run the opposite direction from the direction the run needs to go and doors in the basement that could prevent the run from crossing midway through the basement. My ex GC said he ran into a problem with head room trying to run it through the basement.

Our first problem is a beam in the livingroom that runs across the ceiling. The toilet was placed on the opposite side of the beam from the outlet, therefore, the run needs to go either straight down the exterior wall, to the basement ceiling and find it's way out, or frame it into my living room, aesthetically.

I may be able to run the line down the wall and bump it under a structural beam that is between the main floor and basement ceiling. That puts the pipe pretty low. It would then cross the width of the basement ceiling (approx 25-30 feet) then turn and run most of the length of the house (approx 30-40 feet) to meet up with the original outlet. (The designer couldn't have possibly put this toilet in a worse spot). That's sounds doable except the basement is a main through way into the house from the garage, the ceiling is very low, about 6ft 4in, there are 6x6 beams, and exterior and interior doors.

I was thinking that too many turns in a sewer run would be a problem. Just more chances for leaks and clogs, etc, not to mention a problem if we ever want to make the basement into living space. I really think going outside and digging a trough and then turning and going under the driveway slab would be the least obnoxious looking. I will use the 1/4 inch per ft measurement and take a look this weekend to see what might work for the basement option.

Thanks.
 
#6 ·
Tough one. All you can do is check out various paths and see which one will work the best. Once you get to head bumping height and below try to keep the route along walls, beams or ducts.

If your ceiling height is 6'4" in the basement it would be pretty tough to finish out. Most places it would be against code.
 
#7 ·
Yes, if I wanted a shop or hobby room or something like that, the basement would offer good space. Definately not to code, though. The basement is very utility, so exposed pipes aren't too big of a deal. I'm going to measure this weekend and see if we have the headroom inside that could work. I guess my ex GC can't really be trusted with a tape measure, so it's best if I take a look. Once I'm across the doorway, the route to the outlet should be easy.

Thanks.
 
#8 ·
whats to keep you from dropping straight down next to the wall where this new bath is,,,then cut a narrow trench in your basement concrete floor and lay it 'straight' to your existing line under the floor level?? WITH proper clean out just above basement floor??
 
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