tunneling under a driveway

[Point37]

i am looking to put a 3/4" conduit under my driveway for a wire for a electric driveway gate opener...i tried to do it this past weekend but failed when i hit an obstruction about 10' in (i have to go about 18' total)...i'm using 3/4" steel pipe and i'm down about 3.5' to 4'...i have a piece of solid bar formed to a point welded onto a 3/4" nipple with a coupling after that with a 5' section of steel pipe then another coupling and a nipple on the other end to hammer on...i think i am going to try the same method again a little higher in the hole at a different angle to hopefully miss the obstruction and use a jackhammer this weekend to make it go faster...the only jackhammer bit that i found that was flat enough at the local home depot rental office was a grounding rod driver...i don't want to use water cause i don't want to undermine the driveway and have it sink...i'm a little afraid to use a pneumatic mole cause of the shortness of it and it being able to ricochet and come up through my driveway plus i don't know where to rent one in my area...anyone have any better ideas or ideas that can be improved on?

[Fred]

I have water jetted successfully but understand your reluctance. Three to four feet sounds awfully deep, try boring a bit higher and with persistence your good technique should be successful as long as subsurface conditions are not too rocky.

[Point37]

Point37, you are most likely hitting fill "junk" that is below the actual concrete slab of the driveway. Most driveways will have fill under the slab, that was used to fill in the hole, or old broken up concrete from the previous slab...things like tat. It could be large rocks, debris, etc. And.....the bottomside of a slab driveway are usually not uniform, meaning that concrete slab could be 4 inches thick in some spots, and 5 inches thick in other spots, and 6 inches thick in other spots.

You are headed in the right direction, but you may have to go slightly deeper...and keep adjusting your input rod, to back off from obstacles, and try a different angle.

I did this 6 years ago, but I only had to go under a 4 foot wide sidewalk.....so world of difference in distance.

thanks TWilight...yea it's an asphalt driveway that was laid down on crushed stone...there was no previous driveway or house there before but there was a trailer home...i cleared the lot and had the house built...they temporarily stripped off the loam and used fill under the driveway...my pit is 3.5 to 4 feet deep so i'm def not hitting the driveway

I have water jetted successfully but understand your reluctance. Three to four feet sounds awfully deep, try boring a bit higher and with persistence your good technique should be successful as long as subsurface conditions are not too rocky.

thanks Fred...yea i think my next shot is going to be a little higher and off at a different angle but i will have to figure out a good way to support a 27lb jackhammer as well as keep the pipe being driven in steady

[ZDR1]

If it is asphalt I would cut the asphalt put my pipe in for wire and cement the patch.

[jtomelliott49]

Ditto to Zdiver. I did what you are doing about 25 years ago, but I had gravel driveway. I had to go under a sidewalk and a couple four inch wide by about ten inch deep edgings. I used a six foot tall chisel type tool. Looks like a giant nail. About one inch or so diameter steel chisel on one end and tamping head on the other. Best tool I have ever bought for yard/driveway work. Are you putting in a Mighty Mule gate opener? Otherwise known as EZ Gate? BTW, I would rent a trencher if I had it to do over. Too old for that manual labor.

[Point37]

Thanks guys...the driveway is somewhat new so I won't be cutting it which is why I'm looking for tunneling ideas...I think I'll stick with my plan...little more work but def cheaper


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[GaryL]

I can only speak from my own experience here doing the same thing. It was an impossible task with all the rocks hidden under ground in my area. I finally gave up the plan of tunneling and cut the dam asphalt to lay the wires in conduit and then replaced most of the asphalt pieces and patched over the cut lines. When my brother did the same job at his house he used the water jet which did get him through but as you mentioned, the tunnel caused the asphalt to sink and he ended up patching it any way.

It seems to never fail. I ran electric out to my new steel building 130 feet just last year. Rented a trencher and ran the cable in 1 inch conduit. Wishing now that I had also added a telephone wire while doing it. We live and we learn that hind sight is always 20/20!

GaryL

[Joemama]

I think at the depth that you are at 3.5' to 4' the chance of washing out is very low, if you were to use a water jet.
Joe

[ZDR1]

Call the utility and have the underground lines marked out for free and have a contractor bore the hole.

[ZDR1]

811 In Your State | Call811 This will save you a few bucks if you hit the fiber optic line for the east coast and it is not marked properley.