[snmhanson]

I have a 170' run of 2" schedule 160 conduit that we had installed a few months ago for pulling a poly gas line through. The conduit runs adjacent to a retaining wall before sweeping under the large footing and then across our driveway to a firepit. I recently tried to suck a pull string through with my shop vac and had no luck - there was absolutely no flow through the pipe. After some troubleshooting with a long fish tape I came to discover that there is a clog near the middle of the pipe. I believe it is mud and dirt that got caked in the sweep that goes under the wall and I think it is a pretty significant clog as trying to rotate and jab with the fish tape didn't clear it. I also tried sucking on one side with the shop vac and blowing on the other side initially with a leaf blower that fit perfectly into the end of the conduit and then with my air compressor and it didn't clear it either.

After exhausting my options I have resolved to hire a company to come out and do a private locate to determine exactly where the clog is so I can dig up the pipe and clear it. It is going to be expensive and a total pain though as I'm going to have to either dig through our gravel drive or behind the wall where there is significant drain rock and irrigation pipes. So, as a last resort I am coming here to see if any of you smart people on this forum have any ideas as to how I could clear the pipe. Any ideas on how I might be able to accomplish that?

Thanks!

Matt

 

[rjniles]

Adapt a garden hose fitting on one end and try water pressure. If it is mud, that should soften it up. Once you get water flowing you should be able to get a fish tape into the pipe and pull a rag back through.

 

[snmhanson]

I'll give that a shot. The conduit drops about 20' from end to end - it is fairly flat at each end for ~60' and the drop is over the middle ~50' and I believe the clog is at the bottom of the drop where the sweep it. Would it make any difference whether I attack this from the lower end or the upper end? The clog is closer to the lower end, but maybe the upper end would provide a little gravity assistance? I do have a spigot with hot water at the lower end as well, but not sure if that'd make a difference when it comes to mud and dirt.

Thanks,

Matt

 

[rjniles]

I would put the water in from the high end and let gravity assist. Hot water would also be a good idea.

 

[joed]

Mud in a sealed conduit system would indicate to me the conduit has failed.
If you want to attack it, I would do it from the lower end. Anything you flush will wash back out the lower end by gravity.

 

[snmhanson]

I do think there is a good chance that the pipe failed, but the contractor who backfilled and ditched and ran the remaining pipe said he is pretty certain that's not the case. My only thought it is that the sweep was left open in a ditch for a while and we had a fair amount of rain during that time that filled the ditch up with water. I think it is possible that sediment flowed into the sweep and then it wasn't cleaned out before the run was finished. I should have been on the contractors about this more, but I didn't realize the potential issue at the time. Of course you would think that they should have known to cover the open end of a pipe and to check that it's cleared before making the connections... In any case, I want to try everything before having the locate done and digging into our driveway or behind the wall.

Matt

 

[joed]

Can't hurt to try cleaning. It will save you a lot if work if it clears.

 

[tribe_fan]

They make these attachments for the hose.
https://www.homedepot.com/p/Husky-M...VS73ACh2STApfEAQYAiABEgKbA_D_BwE&gclsrc=aw.ds

 

[rjniles]

You said you have Sch 160 conduit, Sch 160 is irrigation pipe not conduit, it is very thin walled and could be collapsed by carelessly back filling. If you can not wash out a clog and need to dig, I would run a snake in from both ends and take measurements. You should be able to determine where the problem is located.

 

[snmhanson]

OK, so I attached a PVC fitting to the top and connected a hose. After it pressurized I let it sit for a while and there was still just a bit of water running through it. However, there was a small leak at the connection which I assume is why it was running. Once I gave up on that and disconnected the hose there was quite a bit of back pressure. Seems that the air would have escaped to some degree into the surrounding ground and I would not have had that back pressure if the pipe was cracked or broken. I'm going to try the same thing from below next and then run a fish tape from each end just to see if things may have loosened up. I wish I had an actual snake I could run but it would have to be at least 75' long to reach the blockage from the bottom and 100'+ to get to it from the top.

I did previously try to run the fish tape from each end to try to pinpoint the clog, but when I measured it out from each end there was a fair amount of overlapping so I couldn't get closer than probably ten feet. I assume that is due to the tape bunching up a bit in the pipe. Also, the pipe is pretty thin walled class 160 gas sleeve - not sure if that is the same as schedule 160 or not. It is yellow and designed to run gas lines inside of. It is possible it collapsed, though the excavator was pretty good about bedding all of the conduit runs and providing a good layer over the top before back filling.

This is so frustrating as this firepit has been a long time coming and it would be great to have up and running as we have been stuck at our house for the most part. Thanks for all the help and ideas. I'll keep plugging away at it.

Matt