Help me understand the potential impacts to structural integrity if a tunnel is dug to repair sewer line. The break is 12' from the nearest outside wall, so the tunnel will be at least that long, and however deep and wide is usual for access.

This same spot was accessed via holes jack-hammered through the floor about 7 years ago (rant about bad remodels and shifty plumbers saved for another post). I am being told that they don't like to access below-the-slab plumbing that way anymore, and want to tunnel under.

While the interior access mess was considerable, I have to wonder what removing all of that base material beneath my slab will do, if I allow the tunnel. How do they compact the soil back when they are finished?

I would get another plumber's opinion. That sounds like lots of extra expense for no good reason.

I wouldn't worry about opening up a hole big enough for one man to work.

Be prepared it's going to be a bigger hole than you're thinking to get under and around the grade beam.

We typically excavate a tunnel that is 3' x 3' to the location of the drain line failure. This makes it large enough for any plumber (and helper if need be) get under the slab and make the necessary repairs.

The most important part of tunnel work is putting the dirt back the right way, and hand packing certainly does not qualify. After returning the excavated fill, we mud pump the remaining voids and any nearby voids that may have occurred due to settlement or erosion from the leak. The slurry is a mix of Portland Cement and sifted topsoil that is injected at approximately 400 PSI. It travels extremely well filling all the nooks, crannies, and crevices and hardens up like sandstone to keep everything nice and tight. Make sure drain lines are secured to bottom of the slab with appropriate pipe hangers as the slurry will weigh in at close to 90 lbs per cubic foot.

The biggest advantage: the mess stays on the exterior of the home and doesn't disturb any flooring, furniture or belongs.

Saw this method used at a neighbor's home. Probably 3 ft wide and 5 feet deep. The depth may be less as they get further under the slab.

I can't imagine a 3 foot gap would put any undue pressure on the slab and as long as it gets packed in shouldn't be a problem in the future.

I would also get another opinion.

Has the "exact" location of the break been marked? What is above it - inside the house? What kind of flooring do you have?

Tunneling is normally a better option if tearing up or changing the flooring is not a good option. or you cannot get access from above. Maybe the break is right under a vertical wall etc. If you have a stained concrete floor or something that you cannot replace or match then tunneling is usually a good option.

If you can do a repair on the flooring or it is carpet then popping a hole in the top to repair the break is normally going to be a lot cheaper.

No matter what method you choose I would get some more opinions and make sure the break is accurately marked. You can get pictures or video from the plumbers camera snake. They also have a locator that they set right above the snake and it tells them when they are right over the top of it.

It is easy to jump on the first estimate when your house and routine are disrupted. And if you do tunneling make sure someone like Anchor Foundation fills the hole. Filling it back under pressure is the key to the entire thing.

Koko Chingo said:

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Has the "exact" location of the break been marked? What is above it - inside the house? What kind of flooring do you have?

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We know exactly where the break is...right where it was previously repaired, bottom left concrete patch is where the locator indicates the current issue:



We had a prior break in the line where it went through a beam. The company that repaired it went through the floor on both sides of the beam to connect new line. The new break is at one of those connection points, directly under the existing patch in the concrete. At the time, our remodeling contractor was on the hook for the repair costs, as the repair work unearthed several lazy and not-to-code things that his plumbing sub had done that likely caused the break, so my mantra was to do everything necessary to make sure we never had to go through this again, no matter the cost. We ran all new line to the septic tank, had new and additional clean outs installed, etc.. My suspicion is that there was something not quite right about that connection they made, that broke and/or leaked enough to encourage the massive root growth that appeared in the line.

Busting through the floor is a little tricky, as that end of the house is several feet above grade due to the slope of our land, resulting in the need to dig down ~5 feet, through compacted base, to reach the line.

How long ago was the first repair done? Is there any warranty or other opportunity to go back on that contractor?

Went through a break on new work at my home many years ago. When we finally got the 'broken' pipe out it was obvious a joint had no adhesive. Dry fitted and left.

In my world we find every way possible to make any repairs without any tunneling of this type. By the time we deal with confined space restrictions and other safety related issues it's not worth the time and expense.

On a bit humorous side- can't imagine tunneling up under a slab burrowing through sanitary waste that leaked. Good grief- some poor guy.... Especially when you're under there and the whole line empties on you after u remove last of the fill.

Most breaks don't result in quite a mess like that. Occasionally we'll run into something that Mike Roe and Dirty Jobs would've been proud of.

Figured it must not be that bad normally or you may not be able to pay enough to get someone to do it.

Most of the breaks I've seen are water lines not waste. I have a very experienced construction manger working for me who's kitchen drain line broke last year and that's the first residential drain I've heard of that I can remember.

The first repair was seven years' ago. My daughter spent the holidays that year camped out in the living room for three weeks.

Since then, we have had continued issues in the line, and I called the same company every time, and have a stack of invoices showing their work. Over the past 16 months I asked them to camera the line three times, trying to figure out why we have constant problems, and they said there were no issues in the line. One time they said I should consider replacing the older toilets in the home, suggesting that the old ones didn't flush with enough force to move the waste.

Due to the history, I am waiting on a repair quote from this company, hopeful that they will give me a break, since there is documented evidence of ongoing issues every year since the first repair. On the other hand, I am torn, as I am not sure I can trust them to get it right this time.

I can play devil's advocate, and cite the reputation of North Texas soils, the fact that my house is surrounded by massive oak trees and their roots, etc.. I know what their arguments are likely to be against taking any part of the blame.

Since this room is vacant now (one of my two at A&M), going through the floor wouldn't be much of an inconvenience - and 'convenience' to the homeowner seems to be the top argument for tunneling.