This is the sewer pipe leak I previously mentioned in another thread, where the leak (or collapsed section) occurred under the slab and access from above is impossible (no spare tiles, and directly below kitchen cabinets etc...) so after much considerations I decided to go with the tunnel repair method.

So yesterday the project started. First the tunnel truck arrived. It has a giant 6" corrugated plastic pipe and a high pressure water jet.









Here is the cleanout that exits the house. The starting point. They manually dug a hole 3' deep or so, then they started the pressure jet and suction part.





Initially they used a pressure jet to wash off the soil (which is mostly sand) see the guy holding the jet.



Once the sand are loose the 6" black pipe is used to suck in the soupy soil, they kept doing it until the hole is about 3' deep.





I left for work after about an hour, but they continued with this and dug a tunnel about 20 feet in.

They then found a belly and a collapsed section of pipe and fixed those. I did not see the old pipes but they said they have pictures, and when I got home I took some pictures of their repair.







They are now waiting for the inspector to inspect, then they will shoot pressurized sand to backfill.

and my wallet is now $8000 lighter.



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Now some questions.

If you look at this picture:


I can see the purple primer, but there is another layer of something, is this glue? if so why is it blue? The glue I have is clear, is this the "low voc" glue?



The second question is regarding the layout of the new pipe. See the picture below. I know it is very dim but I brightened it as much as I can, and you can see a branch to the left (kitchen), then the main line goes to the right, but there is also a washing machine line further up.



it looks like they extended the main line to the washing machine line, but the 3" main bends to the right and they used a combo fitting. Now if I ever want to jet the line from the cleanout going upstream, I will always shoot up the washing machine vent instead of following the main bend to the right, correct?

Oh and they forgot to glue the CO riser and the CO fitting.





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Great pictures Sum.Technology in sewer line repair has come a long ways!I learn something new everyday.



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The blue glue is rain and shine or something along those lines. I use in on whirlpool piping because it matchs what they used at the factory.

Yes, you'll go up the washer drain instead of up the main line. In that case you'll need to pull a toilet to get to that section of piping.

What's holding up your house in the meantime before they backfill? Also - where's the guarantee that they pack the backfill in tight enough to actually hold that floor long term? I hope you get more than the standard tail light guarantee that most sewer cleaners give.

That said, I think it's pretty cool that they can do this now.

I would guess that if your soil is not sand, but rock or hard clay, or you are not in warmer places where the pipes are relatively shallow this method would not work?

I know many of you don't like the various *ROOTER* franchise companies but you know, I called around and most family owned or local plumbing and drain cleaning companies are not equipped with these types of tunnel rat trucks.

The city requires the repair contractor's engineering department to come and take a soil sample, and determine the compaction density of the soil/sand.

When they come backfill it, they are required to backfill with a pressurized nozzle to shoot sand back in at a density that is equal or exceed the original compaction density.

I will record the sand shooting part when they do it.

What is holding it up now? Nothing. It is standing "free willy".

Having said that, before I hired this company I also had a few other companies that came out and provided estimates and strategies. I asked about the possibility of structural collapse of the tunnel, and all of them told me that it will not happen because houses around here when they did this sort of tunnel, they were able to see what the foundation and the soil looks like, and they said a good percentage of the slab (sometimes 100% they said) were not resting on the soil below when they excavated. Most of the soil has settled after years and they are a few inches below the bottom of the slab. What's holding up the house are the foundation wall and pilings along the perimeter and some key interior areas.



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Wow, that's pretty interesting. Guess I should have asked what was holding up the floor over the tunnel, but you just hit that as well. That would just be one of those things I could never get out of my mind as I walk across the floor or lay in bed at night. Then again, I am somewhat of a worry-wort. Glad you're flushing again.

That is the frustrating part is that they told me after they did the pipe repair, they can schedule the inspector to come the next day and as soon as it's over they can backfill, total time from excavation to backfill will be two biz days unless there is unexpected conditions such as rain or other issues or bad inspection!

Now they excavated and repaired in one day. I asked today when is inspection and they said they have to get the engineering soil report back before they can call for inspection and THAT, is running 5 days late. So they said the earliest they get the soil report back is next Wed and will call for inspection Thursday and may be backfill next Friday. This means my floor will be standing free willy for 1 whole week!

This is like doing an open heart surgery and while the chest cavity is open, the surgeon decides to take a 2 hour long smoke break!!!

Thats amazing Sum, anyone willing and able to save me the trouble of a 20 ' tunnel under the house is going to be given a little leeway as far as the layout and glue job on the piping.

I am not complaining, for all I know the layout is exactly the way it was with the old piping.

I knew when I jetted the line a month ago, they sent a jet up this CO and before we knew it, water was pouring down from the roof, the jet went up the vent stack of the washing machine line and shot water up through the roof, of course, the standpipe in my garage also overflew as a result, and my garage floor was flooded with sewage water. I am wondering with this configuration, this will continue to be the problem. I cannot jet the line from this CO, unless they have a jet head that will only travel up a 3" line but not a 2" line. I cannot see this from the photo, but I am guessing they used a 3" combo with a 3x2 bushing to the washing machine line.

As for the unglued riser, I could fix it myself, I just need to get primer and glue from my "project house" LOL.

My favorite glue is the Christie's Red Hot blue blue.

hot glue may be used on wet fitting.Rain or shine which is blue too needs no primer so they used christy's hot glue.They did not forget to glue the co or riser ,we normally no not in a drive way area.They only used a minimum of hangars and did not stub them all the way to the pipe top,but is they are spraying back the fill not trying to compact it,guess they are good to go.Did not see a pic of the problem area before repair???

Lemon I see purple primer under the blue glue.

The sand HAS TO BE compacted to same or more density of the original compacted soil, that's why they need before/after engineering soil reports, there will be a truck here to shoot high pressure sand in at prescribed density.

What do you mean before repair picture? The problem area was 20' into the tunnel so there is no way to take before pictures by me since I was not there. They said they did take some pictures but I did not get them yet.

Lemon can you explain what you mean by do not glue in a driveway area? So the riser pipe is left loose at the bottom and top without glue? I have never seen that. What if it came loose and 2' of dirt fall into it?



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it is not just sitting there ,go ahead and try to kick it over or pull it apart.It will get cut to the correct height and then the fitting at the tee will be glued.the cap/co female never have.If the co mis laided on it's side it will get glue.if it is standing on top of the pipe.like to just pop them off cap and all.Sum saw the fernco on the old riser.How or when was it installed.



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Sum, thanks for posting. Very interesting!

Lemon, can you elaborate...I just walked outside and pulled up the riser. The riser pipe is sitting in the fitting and not glued, are you saying this is normal? I am totally confused.

No it will be glued at the tee.after the correct elevation has been determined.Will this be in cement, mulch ???If they glue it now.and strike it with the end of the equipment it could very well break the tee.left loose it would move not breaking the tee.I would not glue the female .Will the inspection include a water test?It would be much easier to install a test ball into the tee without the riser.



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North Carolina Plumber, I can't quite see the actual fitting they used where the main line makes a right turn, I think they used a 3" combo, and at the top of the combo they put in a 3x2 bushing to go up that washing machine line.

I wonder if there is another fitting that would allow the washing machine line to align straight with the main line, but will still makes it possible for a jet to go up and negotiate through the main line without travelling up the 2" washing machine line. Will a 3" 90 degree elbow with a "heel" inlet be a better fitting or no practical difference?

I don't think the inspection would include a water test. I was told during the inspection I don't need to be there and all it needs is their engineer to be present with their soil density report and pictures of before/after. If they needed water tests they will need access to the house which they don't.

How can they do a water test anyway? Wouldn't I need to pull all the toilets and plug all the drains with test plugs so they can fill water from the roof vent?

Well I might like to fill the dwv at least to the slab level.Not that any glue joint could be bad.They at least preformed a flow test after the repair???Fill all the fixtures run the washer at max load?

They told me to run my washer and flush my toilets the night after they repaired it and make sure "they all work"...but then again, why wouldn't they work? If there is a leak I am not going to be able to tell unless I crawl into the tunnel myself and feel the joints.

How would I fill it to the slab level, I mean how would I be able to tell when the slab level is reached? I would have to pull all the toilets and watch for the water level to rise almost to the brim of the toilet riser?

no shower drops?It would be below the cement level as the shower floor filled.The bath tub would begin to fill before the toilets over flowed.Install 3" test ball at the inlet of the 2 way co and fill the plumbing until the water backs in the shower.then look for obvious drips and release test. Wonder if the guy who keeps posing about sewer gas smell had this type repair?

Very good looking repair, small tunnel, pipe hung properly, WET SET glue and purple primer used. (Wet Set Blue Glue will set underwater if preped properly). Don't worry about the floor caving in unless you have a herd of elephants standing over the tunneled area.

PlumbCat TM 2003


Plumbermandan

Real cool pics. Not a job for the fearful.

There should NEVER be any need to jet upstream. That cleanout fitting is "okay" but only because it is so shallow that a plumber should be able to get his snake or jetter going downstream. Any deeper, and it could be a time consuming job to determine which way it is going. I, and many other plumbers, would ALWAYS install TWO cleanouts facing each other, rather than a single "two way cleanout fitting". The blue glue is probably "Red hot and blue" glue. Just a fast setting compound. I prefer it to the clear stuff.



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A good jetter would use a "directional jet" which has a side port. When it reaches a branch, if the port is facing away from the opening it "pushes" the jetter sideways into the opening. It takes some care on the part of the operator to make sure the hose does not rotate so the jet stays oriented away from the branch lines, or keeps it out of orientation until he nears the one he wants to go into.

hj because there was a break about 20' upstream of that CO, when water flows through it, especially with a full load of washing machine discharging, sand gets pulled into the pipes and deposited in various spots downstream of the pipe. That's how we determined there was a break to begin with, but unable to see what the break looks like because it was waterlogged and the camera always get near that spot, gets completely under water and things got real murky and not able to see anything.

So last time he put a jet from this CO up, and turned the jet on, the jet shoots water backwards and by doing this back and forth, he was sweeping the sand out of the pipe and pushing them into the city line. During this process the jet went up the washing machine line and flooded my garage, I think because by using a combo there, the washing machine line became the "main line" directionwise and the main line becomes the "branch".

Thank you Sum for all the great pictures as well as educating so many people as to what is possible today.

Vic

Sum.counting down the pictures at the start the eleventh.looking back to the wm branch the break was at the combo.The longer coupling they used and the accelerated fall is a mono-slab thing.The concrete guys broke it setting the rebar in the footing.want to bet ?love to see the broken pictures if you get them.I hate that they worked with dirt over them .but as said not a job for the weak hearted.

I once had to go under a grocery store, (a very large one), a couple of years after they had had a flood when the city opened an abandoned 6" fire main valve. The fill under the slab had washed away and/or settled to the point where there was 24" below the concrete. The only thing holding it up were the column piers every 30-40'.

i forget the name but they make slabs that are designed to be suspended. they dig out some dirt and put cardboard in its place


edit: ah ha! its a structural slab

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PLUMBERS "Protecting The Health Of The Nation"



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Swing the hammer softly?

Sum

That looks like some high quality work to me. I'd be interested in how tight the sand can be packed in the tunnel this is a problem as the pipe may eventually be supported by the sand if the metal supports corrode out. Probably not in our lifetime however. I would consider having some support under the pipes to suppliment the sand however I don't know much about the sand support.

Great post.

It is a post stressed slab, and you CANNOT drill, break, cut, or do anything to the slab once the cables are tightened.

Here, I would pump a "slurry" under the house. That is a low grade concrete soup, which dries quickly.

hj I did talk to them about pumping concrete to backfill. They said they did that up till about two years ago and now they use pressurized sand. They said the problem of pumping soupy wet concrete back in for a tunnel of this size is that often times it will end up encasing into concrete underground electrical conduits and copper pipes etc...and it makes it impossible for those utilities to be ever serviced. They also said when they used to pump concrete back in they have to bond that concrete to the old slab by doing rebar ties and stuff and now this is no longer done at least in Broward County.

I am curious as well as to how to compact the sand back to equal or exceed the original sand compaction. I am going to shoot pictures when they do it and post them here. also I have no idea whether the new sand will be shot inside at what kind of pressure, whether that itself could disturb the pipes. or whether the sand will completely fill the inside of the tunnel working it's way out, or whether it's is filling one layer at a time from bottom up. It seems like it has to fill from inside out.

I am just assuming that new sand will offer the same support as the original compacted sand. But it may not be a good idea to wedge in a few bricks under a few spots. I wonder if they would do it for me as I don't want to crawl in there myself...



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Did you have any sewer odor problems after the break in the line? I'm in Broward also and having sewer odor issues and I think there is a problem under the slab. Had a few smoketests done and made the repairs where smoke was found. The sewer odor began after the city jetted out line. YOur reply is appreciated!!!!

Slurry is not really concrete. It is mostly sand and gravel with some cement as a binder.



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Sum ever watch while they spray in ground pool walls?By controlling the moisture level in the sand and the velocity it is shot at they can make it like sand stone if they wish,just takes longer.Hj the slurry you speak of is how they fill the sink holes here.

Prudoco I would be the wrong person to help you I am just a DIYer seeking advise here from time to time, so I suggest you start a thread describing your problem and symptoms and let the pros here help you, the more specific questions the better.

But to answer your question no I did not notice any sewer odor, a break under the slab wouldn't cause odor in the house, even a break in the wall unless the wall is open I don't think would have odor. Good luck.

normally no oder under the slab but in walls ? yes

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PLUMBERS "Protecting The Health Of The Nation"

It has been 6 days since they did the work, the permit and inspection still not completed, they had trouble getting the city's attention and meanwhile I have a big hole waiting to be filled.

OK heard from the city today. They will not send out an inspector until the wording in the permit application is corrected. Apparently they did not like "sewer line repair" and wanted "domestic residential sewer line repair".

ARGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH



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In either case it will be wrong, since only the /building drain\ was repaired!!!drain inside sewer outside .Minus a lift station which is force main no matter where.

Sand usually doesn't need much compaction. Just blowing wet sand in to the top would do the trick. Almost a DIY. lol

Thanks for posting those pictures! Question, why cant you do anything to the slab once the cables are tightened? Is it due to the cable themselves, or is this more of a warning statement because something else may happen?

If you heart surgeon smokes, you have selected the wrong surgeon.

Regarding hanging the pipes to slab if house settled or slab moved that will not change the leveling of pipes, any idea ?