# Tunnel/sewer replacement job



## Epox (Sep 19, 2010)

I have a job to start next week at a very historic home. This was Robert H. Goddards home. It also had living quarters for Charles Lindbergh_. 
4" _CI sewer pipe in one portion of this home is deteriorated. 
I estimate roughly 25ft. under slab. This is an adobe home with very substantial footings though the drain appears from what little I saw to pass under footings.
I've never attempted anything such as this so am looking for suggestions on excavation as well as replacing material once new line is installed.
I know some in here do this very regularly.
Thx in advance.


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## justme (Jul 4, 2012)

about 4 laborers and make sure they have the short shovels with about 6 home depot buckets.lol


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## Adamche (Feb 10, 2012)

Can you use hydro excavation?


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## BigDave (Mar 24, 2012)

Hire a company that does this type of excavation daily. Digging around
under a slab is NOT day labor kind of work. Make sure the tunnel is roomy
enough to work in, or your labor estimates go right down the toilet (pun
intended). Secure the new piping so that the backfill process does not
affect the fall on the system, nor the settling that comes after. Always
mud pack (wet backfill) to ensure compaction and all material removed
goes back in the tunnel. If done properly, a four inch "cap" will end up
on top of the entrance pit. This eventually settles to grade after 4-6 mo.
Enjoy your time down under, keep fresh air moving at all times. Your
gonna love it


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## justme (Jul 4, 2012)

The best way to back fill is with flowable fill if that is possible , by coring a few holes on top of the tunnel and pumping the flowable in.


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## justme (Jul 4, 2012)

Dave is right about using a professional company to tunnel if their is one available in your area . Here in the D/FW there are companies and that is all they do is tunnel and dig.


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## U666A (Dec 11, 2010)

BigDave said:


> Hire a company that does this type of excavation daily. Digging around
> under a slab is NOT day labor kind of work. Make sure the tunnel is roomy
> enough to work in, or your labor estimates go right down the toilet (pun
> intended). Secure the new piping so that the backfill process does not
> ...


I was taught to allow 1" of settlement for every foot of excavation. 4' hole would be backfilled 4" high. Sound about right?


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## Cuda (Mar 16, 2009)

Is pipe bursting or pipe lining not an option or maybe there are too many tie ins?


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## Epox (Sep 19, 2010)

I'm not aware of any tunneling company's locally. I pondered air jetting but feel the dust and atomized hydrolic oil in the air might prove harmful. Water jetting of course makes it a really wet experience so in this case I'm toying more with the idea of a bosch hammerdrill and spade bit. Man running the drill and 2 hauling material out. They can rotate.
Drilling through the floor would not be acceptable in this instance I'm sure, not only that I'd have to hire a pumping crew but after line tracing it might turn out that I'm under closets etc so will keep that in mind.
I could process the removed soil material to the perfect moisture content and hand pack it back in but again that would be labor intensive.


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## BigDave (Mar 24, 2012)

U666A said:


> I was taught to allow 1" of settlement for every foot of excavation. 4' hole would be backfilled 4" high. Sound about right?


The rate or amount of settle would depend on compaction. But I've heard
the inch "rule" before as well. The main thing you want to avoid (here
at least) is backfilling dry clay and have it start swelling with say,
spring rains. If you choose what some folks call the slurry method, then
you darn sure better choose a pro with liability. I heard of this process
fracturing a slab if not done right.


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## Epox (Sep 19, 2010)

Cuda said:


> Is pipe bursting or pipe lining not an option or maybe there are too many tie ins?


From what I could tell it is very likely to have multi tie-ins as well as at least one turn and possibly more. I will camera and line trace the line first day.


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## Epox (Sep 19, 2010)

BigDave said:


> The rate or amount of settle would depend on compaction. But I've heard
> the inch "rule" before as well. The main thing you want to avoid (here
> at least) is backfilling dry clay and have it start swelling with say,
> spring rains. If you choose what some folks call the slurry method, then
> ...


You're right about the clay. Back in my concrete days we seen occasionally where a clay ball would swell and heave the concrete.
We would bust the concrete up, dig out the clay ball and recompact.


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## 504Plumber (Jan 26, 2011)

If you can find a company to hydro tunnel it that would be the best way, I'm finding hand dug tunnels are dug to suit the size of the illegal digger. Hydro tunnels are a bit sloppier but we use chest waders to keep somewhat clean. As far as hangers we use all stainless. 3/8 stainless drop in anchors, 3/8 stainless rods and 3/8 stainless underslab repair hangers. Pray to god the plumbers that installed the pipe ran it a good bit under the slab, if not you're in for a world of fun chipping concrete to make your tie ins.


This is the type of hanger we use, once installed the pipe isn't going anywhere during backfill.


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## Cuda (Mar 16, 2009)

I will tell you some of the tools I use for the digging and moving part. A air powered clay spade is light and make quick good trenches, way faster than any electric tool can do.
Dirt conveyors (which can be rented pretty cheap) most are around 20 feet and really speed up the right job.

The air spade tool you can put in the ground and it just makes the dirt bubble up making it easy to shovel if you keep it in or very near the ground there will be no dirt cloud to deal with and times improve drastically over a digging bar. And you won't hurt anything that is unforeseen.


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## BigDave (Mar 24, 2012)

504Plumber said:


> I'm finding hand dug tunnels are dug to suit the size of the illegal digger.


This is true :laughing: :laughing: :laughing:



504Plumber said:


> This is the type of hanger we use, once installed the pipe isn't going anywhere during backfill.


Nice lookin' work, THAT'S what I'm talking about


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## 504Plumber (Jan 26, 2011)

BigDave said:


> This is true :laughing: :laughing: :laughing:
> 
> Nice lookin' work, THAT'S what I'm talking about


The tunneling company we normally use doesn't come out unless its 15ft or more, the last couple have been 10. Those have been some of the most annoying tunnels, it's bad enough to be in that confined of a space for that long, but to be in an even smaller space.... Lets not mention you can't even stretch out when your leg starts cramping.

And thanks! I have plenty of pics in my tunnel thread. We haven't done too many recently but I think we have a few coming up.


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## DesertOkie (Jul 15, 2011)

Sounds like you need a pipelining demo.

No way you would get my fat azz in a tunnel like that. I did one no problem but every time a speck of dust fell from the concrete I almost sh!t myself. NEVER again... unless it's biiiiiiiiiiiiiiiiiiiiiiig money


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## johnlewismcleod (Apr 6, 2012)

While there's an outside chance that with a really good crew and optimal soil conditions you could get this dug out and rebuilt in a very long day, even with the best of luck you couldn't get it back filled.

Most likely you're looking at several days with an open tunnel (two minimum), so remember to build a small levee around your tunnel opening and cover it with plywood at night.

It's a big time loss if it rains and fills your tunnel with water :yes:


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## justme (Jul 4, 2012)

johnlewismcleod said:


> While there's an outside chance that with a really good crew and optimal soil conditions you could get this dug out and rebuilt in a very long day, even with the best of luck you couldn't get it back filled.
> 
> Most likely you're looking at several days with an open tunnel (two minimum), so remember to build a small levee around your tunnel opening and cover it with plywood at night.
> 
> It's a big time loss if it rains and fills your tunnel with water :yes:


Most of the time its not the rain you have to worry about , its the old broken pipes you have just exposed that will fill your tunnel up. What we used to do was slope the excavation to where sewer water would flow to the pit outside of the beams and put a pump with a float about a foot deeper than the rest of the hole.


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## johnlewismcleod (Apr 6, 2012)

justme said:


> Most of the time its not the rain you have to worry about , its the old broken pipes you have just exposed that will fill your tunnel up. What we used to do was slope the excavation to where sewer water would flow to the pit outside of the beams and put a pump with a float about a foot deeper than the rest of the hole.



Tunneling live sewers sucks peanuts :thumbdown:

That's when you use OS's special pricing schedule x 2 :whistling2:...and do just like you said :yes:


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## justme (Jul 4, 2012)

One other tip always and I mean always turn the customers water off and flush all the toilets after the water is off before you are under there replacing the pipe. The customer doesn't think about where the **** is going lol


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## Epox (Sep 19, 2010)

The house will be empty with exception to the House cleaner and handyman. The owners are from Texas so keeping control of the water should be easy enough. Plus there are 2 septic tanks they think, and I saw 4 sets of cleanouts exiting the building so we should be able to shut this end of the house down.
The initial entry is from a basement. The access to under floor is gained through a 20" by 20" hole about 5 ft. off of basement floor. Rain shouldn't be an issue.


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## TallCoolOne (Dec 19, 2010)

I do this type of work daily

Either reline it or jackhammer up the slab

I am not a fan of tunneling, and the reasons are:

After you tunnel and backfill, Give the house or building about 5 years and it will have foundation issues due to not being able to back fill properly

If you do tunnel you need to have a structural engineer come out and suggest places where piers need to be added

I am fan of jackhammering and going after the pipe, or if it is a straight run then just re line it.

If you have a transistion, such as a 4 by 2 Wye then cut the 2" opening into the liner:thumbsup:


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## Epox (Sep 19, 2010)

We have 2 company's here that pump concrete or flowable fill under problem slabs. Both are owned and operated by engineers. I will give them a call. I agree this has to be done right.
I think the best way to go at this job is from the outside in, instead of through the basement.
There are no reliner's in our area. And I've never done it much less seen it done. Can relining make turns if there are any? I'm thinking it does have a turn or 2.


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## Cuda (Mar 16, 2009)

lining can take bends, and branch lines can be cut back in by using a robotic cutter, they can travel in 4" lines. The camera work is the most important to plan the job out and jetting may be needed just to get it clean enough to not miss something with the camera. Pipe bursting can also break the cast and is another option.


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## bulldozer (Jan 11, 2009)

You need to send cuda a plane ticket and let him knock it out for you!


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## justme (Jul 4, 2012)

Cuda said:


> I will tell you some of the tools I use for the digging and moving part. A air powered clay spade is light and make quick good trenches, way faster than any electric tool can do.
> Dirt conveyors (which can be rented pretty cheap) most are around 20 feet and really speed up the right job.
> 
> The air spade tool you can put in the ground and it just makes the dirt bubble up making it easy to shovel if you keep it in or very near the ground there will be no dirt cloud to deal with and times improve drastically over a digging bar. And you won't hurt anything that is unforeseen.



I love the dirt conveyor idea, I bet the guys I worked with that were digging would have loved it too.


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## Piper34 (Oct 10, 2011)

I never tunneled a repair according to this thread it sounds pretty common but I can't imagine it being easier than saw cutting and chopping it also pretty much guarantees a good backfill but in my area I've never even heard of it . LINY. No wonder we live on 90% sand


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## Epox (Sep 19, 2010)

Well it took 4 days hand digging what ended up being 32 feet. Bout an hr to run the pipe and apprx. cple hrs to verify perfect grade, hand and support piping.
First day into this I realized the outside drain has negative grade. I upsold replacing an additional 15 ft. to a c/o but upon investigating realized a combo'd in line has negative grade connecting within 2 feet of my connection from the building. Which means it's either fix both drains or do nothing. Explained to owner and waiting for a decision. These people can easily afford this but will have to see what they allow me to do.


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## mytxplumber (Jul 28, 2013)

*Tunnel/Sewer replacement job*

The problems with tunneling in some areas here are when the trunk line or branch line runs through a beam and is wrapped by hot and cold water lines. The other problems we run into a lot of the homes here have foundation issues and the house has been raised which creates back fall on part of the line going through a beam or being pulled up by the riser going to the fixture it is serving. I have seen houses here in the North Texas area where the ground heaved and the loose soil where the plumbing was replaced was pushed up and looked like a rollercoaster ride when you camera the repairs. I have also dig up some tunnel jobs that the ground heaving or foundation lift just destroyed the hangers and piping because of bad backfilling. Don't get me wrong there are jobs where you have to do what you have to do and we will tunnel on certain jobs. but when tunneling you have to know the soil and the areas you are working in really well. We always get an engineer to sign off on any tunnel job to minimize liability. We also offer pipe lining services if we get into a problem with a beam we can line it to. Some of our jobs are followed by a void fill from foundation companies needing to level the structure. This is another concern you need to know about before a tunnel job. If the foundation company is just going to do a void fill or if they are going to be raising the structure with the void fill that is another. We always ask our customers about what happens after the repairs. So often here your customer is fixing the home to sell the property. They have talked to a structural engineer an he said fix the plumbing first and then they would look at the foundation again later. Under slab repairs are not for the faint of heart.


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