Drilling Under Sidewalks/Driveways

[JFletcher]

...w/o an excavator. I've seen several methods, from shoveling out dirt (sidewalks), to pressure washing/blasting (messy), to hammering in conduit (has its own pitfalls). Is there a bit made for this that could be chucked into a corded drill? istm a 5' bit (an older one) made for drilling walls would work well, provided you cleared it out every now and then. This is remodel work done well after the possibility of laying conduit is an option. I'm not drilling thru rock, mostly loam>red clay. Also, I just need to lay down one maybe two runs of UF, or limited energy landscaping lighting: I dont need a huge hole.

There has to be something out there made for this that doesnt cost a fortune/take forever/require subbing out.

 

[kwired]

For loose types of soil probably is best to pound or wash your conduit or sleeve into place, as the hole will fill back in behind a drilling bit.

For firm soils like you have I don't see why you couldn't drill it. You would need to clean out frequently with auger type of bit if the auger isn't full length of the bit. Otherwise a short auger on a long shaft or extension is like putting in a screw type in anchor for guy wires or mobile home tie downs if you don't clean out frequently.

 

[Smart $]

For loose types of soil probably is best to pound or wash your conduit or sleeve into place, as the hole will fill back in behind a drilling bit.

For firm soils like you have I don't see why you couldn't drill it. You would need to clean out frequently with auger type of bit if the auger isn't full length of the bit. Otherwise a short auger on a long shaft or extension is like putting in a screw type in anchor for guy wires or mobile home tie downs if you don't clean out frequently.

Depends on design I think. With a constant pitch fluted auger, it will at some point pull itself all the way thru without clearing itself of spoils. An auger with variable-pitched flutes that clears the spoils faster than augers penetrates at the tip should work... but finding one???

 

[Smart $]

In the mean time, perhaps one of these, drill from both sides, and/or with a shaft extension...

https://jet.com/product/detail/f3b5...fvSHWJB8-UW8Z5cg6Zpw9Uhx2_QgY0z0u1hoCU8bw_wcB

NOTE: Definitely NOT a recommendation. Especially if one expects it to live up to the description.

 

[mike_kilroy]

check out log home supplies; they sell LONG drill extensions for reasonable prices. I believe mine was 3' extension for my 18" 3/4" dia drill - like we did when we built our home, often 3' steel bars are driven into the holes drilled vertically down thru multiple logs every 4ft along wall for stability. If I had any clue where mine is now 25 yrs later I would offer to loan it to you!

 

[ActionDave]

The problem with drilling under a sidewalk is you need a hole big enough, two feet down, to work in.

 

[junkhound]

pressure washing/blasting (messy)

Big wet/dry shop vac is your friend

lots of rocks and cobble here, 4000 psi/4gp or larger PW only way to go.

Local poco even uses a big vacuum truck to dig holes in the street with big PW.

 

[kwired]

Local poco even uses a big vacuum truck to dig holes in the street with big PW.

That is what most directional boring contractors use to find existing buried utilities - One call marks them, but that is allowed to be off by 18" and they generally will not tell you the depth - this is a CYA for them if you hit it and it wasn't at the depth they said it was, so if they want to know exactly where something is they use high pressure water and a huge vacuum to remove some dirt to expose whatever they are looking for. Can find a communications line by only making a small diameter hole - if one call marks were right on horizontally.

 

[junkhound]

Yeah, out here, am not even sure Potelco owns a track hoe <G>.

Saw them 'digging' a 4 ft by 6 ft by 6 ft deep hole with just PW and big vac truck, 1T truck mounted crane to set the sidewall steel and temporary cover, etc. .

 

[JFletcher]

thank you for all the replies/suggestions. today we went back to a job where we laid conduit before... HO wants more out in front yard. Next time we do it, I'll put a stick or two extra of 1" PVC under driveways/sidewalks to save myself the aggravation of digging the same trench multiple times. :rant: