boring under a concrete pad, am I crazy?

[The Cobbler]

I am planning a garage build in the spring. I plan to run cold water & sewer to it . about the only place I can run the sewer is underneath a 10' concrete patio pad. there is trench about 2' wide full of clear stone from the footing to the underside of the pad . I don't want to break up the patio , I really want to go underneath. I also have to be min. 4' below grade .

Here is my thought on how to achieve this.
core drill thru the basement wall from the inside , take a leght of 2" sch 40 pipe with a coupling on the end of it with some sort of bullet tip. anchor a heavy brace to the basement floor and use a porta power to push the 2" pipe thru the soil ( clay) once I am past the pad there will be a dug hole where the pipe will exit . once the steel pipe has come thru I am hoping it will have little resistance because the coupling has made the bore larger than the pipe. I would follow the bore pipe with 2" abs and cut off the steel pipe in pcs as it exits from under the pad.
I would do the same to run the water line, but a smaller pipe, probably 3/4" to run 3/4 pex.
am I crazy or could this work ( other than if I hit a rock LOL)

 

[pstnbly]

Give it a try, the worst you can do is fail and have to dig. I've done similar, but have left the pipe open and cleaned it out later.

 

[The Cobbler]

..... I've done similar, but have left the pipe open and cleaned it out later.

that probably would be an easier push because the dirt has a place to go .

I could use 2" galvanized pipe and leave it in there

 

[Bib Overalls]

You can't simply push the drill pipe through the soil. You have to remove the dirt at the face of the drill pipe for it to advance.

For this coming summer my wife has already put me on notice. She wants a yard hydrant on the other side of the concrete garage apron. My plan is to use a well point and wash my way through.

 

[Chitown_hillbilly]

Directional Boring is all the rage down here, seems like those guys are popping up on every corner right now. They aren't really that expensive, and for what your talking about I don't think it would be that tough of a job.

I don't know for sure, but what you propose doesn't sound very likely.

 

[justme-]

gotta be careful of the well point idea with regards to the run off, both at the beginning of the hole and under ground. It's possible to undermine the surface much more than one realizes, especially if the water flow is higher than the ground speed of the nozzle.

A solid bullet point like the OP is suggesting will create a lot of resistance - the dirt you're pushing through has to go somewhere. a solid point is going to push out in all directions creating enormous resistance to that. A hollow pipe uncapped would be much easier to push as mentioned.
Push a little then back it out and clean it out and repeat. Oh, and hope you don't find any large rocks. Even better would be a long auger - like this guy did(youtube)

 

[CNGsaves]

OP since you have patio covering the surface area where you want to enter basement, that plan to bore out sounds fine. The one worry I'd have is to be sure you don't have water pressure problem from outside against wall that now would have way to get into basement when you core drill out. Is that totally dry soil, and you don't have water drainage problems in the area?? Thus, no high water table issues??

For only 10 ft, I like your McGyver idea of 2" PVC pipe that sounds like your plan for undersized sewer . . . . right (this liquid only for urinal in garage and sink)?? I like the auger idea and just keep pushing pipe as it eats away soil in front of it. Threaded rod could be jerry rigged to power the auger bit just in front of pipe. If room in basement a single 10 ft stick of PVC would be ideal if it reached your manhole dug in ground outside.

If the first one works well, then I'd go another 2" PVC that would have PEX for both hot and cold out to garage !!

Be sure to plan cleanout access on basement side for sewer. For the PEX I'd include way you could blow out lines with compressed air if Canada winter so cold that your depth is not enough to protect from freezing. Good luck.

 

[The Cobbler]

.... be sure you don't have water pressure problem from outside against wall that now would have way to get into basement when you core drill out.

For only 10 ft, I like your McGyver idea of 2" PVC pipe that sounds like your plan for undersized sewer . . . . right (this liquid only for urinal in garage and sink)?? I....If room in basement a single 10 ft stick of PVC would be ideal if it reached your manhole dug in ground outside.

If the first one works well, then I'd go another 2" PVC that would have PEX for both hot and cold out to garage !!

Be sure to plan cleanout access on basement side for sewer. For the PEX I'd include way you could blow out lines with compressed air if Canada winter so cold that your depth is not enough to protect from freezing. Good luck.

the 2' of clear stone drains water into weeping tile & into main sewer. that wall has delta wrap on it, I would parge the wall from the inside ( block wall) and drill a few weep holes from the cavity to the ouside so any water that did come beside the pipe would wick back outside. parge the insode and it should be good for my lifetime. 2" is undersized but all I'm running is a wash sink . and yes, a clean out in the garage & one inside would be installed.
also plan on rigging up a air blow-out so I can drain the line if needed . I think I'm going to run only cold water & install an on demand electric heater in the shop. electrical & other wiring will be from another location, that can be trenched right up to the house .

 

[Cyberbear]

Even though it's only a 10 ft. run, this sounds like an ambitious under taking. If you are considering using plastic pipe for the drain, I'd be concerned about deflection of the plastic not going where you want it, and what about the typical 1/4" per foot drainage pitch ??
In any case good luck, and let us all know how it works out for you.

 

[DangerousDan55]

I bored under my 10 foot drive when I was running electrical to my shop. Its started out good for the first 2 feet, but then I hit clay. OMG!!! Spent two 10 hour days getting through. I used PVC with teeth cut on the end & a water hose trying to wash out the clay. Worked just a little bit. Tried hammering the PVC, pull it out to clear it & hammered it again. PVC gets perty flimsy the further you get & can start to change direction on you. Finally took my 1500 lb electric pressure washer, took the gun off, installed a stainless steel tubing section, hammered down the end to make a fan pattern. Then I ran it down the PVC pipe & worked the tubing in&out cutting the clay. Also driving the PVC in & out. Mind you that the pressure washer line was Very Easy to handle. It did not go crazy like a lose fire hose. But dont try it with a realy high pressure gas driven washer.. you may get injured.
Well I got through & I did miss my target on the other side by about 8-10 inches to the side & lower. I tried to bore from the other side of the drive also trying to intersect the tunnel bore. They missed each other but I was close & I kept changing my angle until my water that had acummulated in the trench all of a sudden started flowing through to the other side of the drive. Oh yea, two days of water washing I had a lot of water in the trench. I would have to pump it out many times. Otherwise I would have had to be laying on the ground & working with the stuff all under water. Which I still did a lot.
Yea, two 10 hour days ALL DAY LONG!!!
Well, I did have help from our dog sometimes.

 

[Big Bad Dad]

You need to have existing utilities marked. It would not be fun to bore into a buried power or gas line.......

 

[BRIANBB]

I would just call the local irrigation company and pay them the $500 to run their borer/auger thru there. In the end you would be money ahead.

 

[gazza]

Here is another way to do it. Using a timber box and a hammer drill, I had to bore a 1" hole through a concrete foundation about 3' thick.
If you set up a box in the trench you can easily apply pressure to the back edge of the box using levers, you still need a few different lengths of boring bars, maybe some pipe to make up the distance you need.

 

[mustangfan]

I own a farm and had to run a new water line to one of my barns and it had to get to the back side of the barn from the house. The plumber came out and dug the trench on the front side and then dug a trench on the back side. He then went down in the trench and pushed a 1.5" pipe through the dirt from one trench to the other. It was about a 40' push, and then when the pip came out the other side he proceeded to feed the plastic inside the steel pipe. He had a cap on the end of the steel pipe.
Going under a 10' wide slab should be a piece of cake as long as you don't have any big rocks in your way!!!

 

[volleyball]

Maybe another way of approaching this is to dig a trench at the far end where it is going to come out. This will be needed anyways but it will give you a reference point of what material you have in the ground and at what depth. If you hit a boulder, you may have to rethink everything. Once that is done, put a perfectly vertical post that goes above grade.
Drill an eye hole in the foundation wall so you can see the post from indoors. This will give you a visual reference line. In the basement, drill through the wall where you want. Then using an auger bit, drill trough the clay. You might have to spray water to soften it but hopefully not. When you reach the end of the bit, add an extension ,and drill further. Keep on adding extensions until you get through. The above ground site hole will keep you in the right direction along with using a level to get the correct drain pitch.
I would have smaller diameter augers and once say a 1" made it through, then up the diameter and repeat. A decent SDS drill should have enough power.

 

[nutjob]

Here's 2 solutions to look at:

http://www.bulletmole.com/

http://www.borit.com/

I have not used these products but they might help you with ideas.


Kevin

 

[JACDes]

They make a tool for this, it's called a horizontal auger

Most real plumbing outfits have one for this exact purpose.


See if you can rent one.

 

[machsnell]

dont use pvc use a metal pipe and leave it in place. Make a point on it and be ready to do some hard hammering. PVC will bust against the clay

 

[CNGsaves]

Couple of above might work for OP, but remember he's going OUT from basement since he doesn't want to disturb the 10 ft patio outside at surface level.

Horizontal auger would be great if "bearing groove" could be rigged on front of PVC pipe so OP can go through in one pass and just leave pipe in . . . thus push pipe as auger digs. Might be able to rig shop vac to be sucking dirt out of pipe as it goes through . . . maybe a T with shop vac attached. Would need a seal where rotating rod went through driving the auger. When all the way through, dis-assemble bit on outside end in man hole 4 ft down. On basement side, would pull back drive rod / disassemble. Sealing up that hole from basement side will be biggest challenge.

* * * * * * *
For anyone else doing outside horizontal bores, here's machine that plumbers/landscapers likely have called the Trench Mole (made by company PortaMole) powered by gasoline engine.

Above is mini version of larger horizontal drillers like Ditch Witch or Vermeer.

That TrenchMole looks slick as it drops into a short trench to drive the bore. For installing sprinkler systems under a driveway, that machine looks great if it could be rented.

 

[homebuilt burner]

My father has the boreit tool refered to above. We have used it a few times with mixed results. On his farm I have used it to bore as far as 80 ft. It worked well, very hard work and accuracy is an issue. At my house in town I wasn't able to go even 5ft due to soil conditions. It will depend on what is down there. Gravel and stones are not very helpful from what I have found. The boreit unit will move small stones out of the way if the surrounding soil is soft.

 

[The Cobbler]

thanks for all of the comments, tips etc. Hopefully I can get something worked out. will post updates in the nicer weather