Clogged 3/4" Gray PVC conduit

[socallly]

Hello All,

I built a block wall with 6' x 18"colums that my entry gates are mounted to. I installed 3/4" conduit taped on both ends. I went to install the light and found the pipe is blocked with concrete down at or above the 90 which is 16" below grade.

Iv´e tried jamming a piece of 3/8th rebar, using 4000PSI pressure washer, air compressor and whatever else I could find that would fit.

I hope the pipe didn't come apart inside the column but the more I try and fail it seems this might be the case.

The attached picture shows the column on the right side of the driveway with the light on top (For looks Right Now).

If anyone has some idea's, short of tearing down the column please let me know?

Thank you,

 

[srs]

Can you come in from the other end with a small "snake"?

 

[socallly]

I tried a snake with a cutter bit but it wouldn't go past the bend in the 90.

Thanks,

 

[srs]

Looks like you (or the company who did the stone work) will have to start digging. At least it is below grade so you won't damage the nice looking stone. I'm thinking you have a pretty good size footer due to the large gate so this can be a royal PITA to chip out part of the footer. Good luck to you sir!!! Keep us informed here (with pictures please) how things are progressing.

 

[inveresk]

Nice looking gates.

 

[tcartwri]

It's probably frozen water, not concrete. Can you wait for the thaw?

 

[dave1949]

If I understand it, you are working from the top down? The conduit must exit the concrete somewhere 16" below grade. Have you dug that end up and tried working on it from that end?

Very nice gates!
Dave.

 

[Gator6x4]

Very nice looking gates and entry. Have you considered checking on the rental availability of a 3-4 inch round diamond tipped hole cutting tool like those used by plumbers to cut holes for pipes in block/concrete walls. Depending on how thick the footer is at the 90 degree turn point you may have to drill 2-3 inches and then chip out the core to gain access to the 90 degree bend so you can remove it. You should then be able to snake or fish the wire up to the light. I don't think I would even consider tearing down the column.

 

[socallly]

Inveresk, Thank you.

Tcartwri, The PVC isn't frozen its 50ºf today.

Dave1949, I've tried top and bottom for approach, the problem is if I shove something in from the bottom it either snags on the bell end of the 90º or is not rigid enough to knock free the obstruction. I appreciate the comments on the gates!


Gator6x4, Thanks,I will look into the mentioned tool. The footing is 24" square x 28" deep the PVC 90º's out mid footing. You did give me a idea, I could core drill like you said except go thru the PVC then use direct bury cable run that from the exposed PVC end to a junction box.

Keep it coming Guy's.

Thanks,

 

[teg]

:confused2: sand blasting through a hose from the bottom??? :confused2:

 

[Craig Clayton]

Pour Hydrochloric acid down the conduit at a 50% that will eat out the cement. when it is clean flush with lots of water. There is sometimes a cause why cement falls down a sealed conduit 1 minor accident or 2 somebody was upset about ?.
Craig Clayton

 

[blackie65]

cut a long piece of fish tape and stick it in a drill. Work it from both ends...this sometimes helps break things up.

 

[socallly]

Craig,

Will the acid eat the pvc also?

 

[BillBeyer]

Just curious as to what type of 90 did you install in the base of column? Long sweep 90 or standard 90?

 

[Craig Clayton]

I use to work in construction as a electrician and have had conduit filled by causes unknown. The 50 % hydrochloric acid is strong and maybe be difficult to get unless it comes from a chemical supply company. Battery acid H2SO4 sulphuric acid is similiar and will eat the lime out in the cement. It will produce Carbon Dioxide gas and water the Baking Soda at any time can be poured on to neutralize the reaction. Wash with water and wear a full face shield. The PVC will stand 50% HYDRO acid but do not leave it on for ever. All our chemical lines in the plant are PVC and they handle strong acids for years.
Craig Clayton

 

[socallly]

Bill,

Standard sweeping 90º, see picture

 

[socallly]

Ok with all the suggestion I've gathered here, my plan of attack for this weekend will include the following.

1) Attach length of fish tape to drill.
2) locate, purchase and pure acid.
3) if all fails try to core drill a 2 or 3" Dia hole in footer to get to the conduit.

I would try the sand blast method, if I owned one.

Thank you,

 

[hr3]

I use to work in construction as a electrician and have had conduit filled by causes unknown. The 50 % hydrochloric acid is strong and maybe be difficult to get unless it comes from a chemical supply company. Battery acid H2SO4 sulphuric acid is similiar and will eat the lime out in the cement. It will produce Carbon Dioxide gas and water the Baking Soda at any time can be poured on to neutralize the reaction. Wash with water and wear a full face shield. The PVC will stand 50% HYDRO acid but do not leave it on for ever. All our chemical lines in the plant are PVC and they handle strong acids for years.
Craig Clayton

Yeppers this works every time,, I too have had to do it in the past.. The last time we it happened it took 2 days to eat it's way through..

 

[DiskDoctr]

Yeppers this works every time,, I too have had to do it in the past.. The last time we it happened it took 2 days to eat it's way through..

+1 for HCL. Look for Muriatic Acid. The fumes are bad and will burn your nose, throat, etc, so don't breath it.

It will make the cement in the concrete brittle.

Good luck.

 

[Craig Clayton]

To DiskDoctr
As I understand the problem the cement plug is inside the conduit and we want to make the cement brittle in the conduit. Then flush with lots of water.

Craig Clayton