Trenchless Sewer Pipe Repair: Should You Do It?

In the last post, I talked about trenchless repair methods for fresh water pipes and why it’s not a good option at this time if you have fresh water leaks.

Today, I’m going to continue the discussion as it applies to sewer lines.

Directional Boring

I ended the last time explaining a bit about directional boring so let’s start there.

While directional boring is something I might recommend for water pipes in a yard, I would not recommend it ever for sewer pipes — outside or inside.

If you recall, with directional boring a bore pit is dug at both the entrance and receiving ends while a machine drills a line into the ground sideways.

There are still the problems that could occur with directional boring under a slab — blind drilling making it nearly impossible to see potential obstacles like concrete beams, roots, rocks, construction trash pits, etc. But there’s also no way to ensure sewer pipes will have the fall required for the pipes to work properly.

Sewer pipes are designed and installed to work with the power of gravity allowing water and refuse to flow downhill out to the city’s lines. And if the lines don’t have a proper fall, you’re going to get stoppages.

Sure you fixed the leak but now you have constant stoppages, so what did you really accomplish? The lines still need replacing.

Pipe Bursting

Along the same line as directional boring is pipe bursting. Again a large machine is brought in and pits are dug at an entrance point and an exit point.

A bursting head that looks like a missile has the new pipe attached to its back end, fed into the entrance hole, and then pulled through the existing sewer line. The back end of the bursting head is larger than the existing pipe so it breaks the original line leaving the new pipe in its place.

Sounds good, right?

Here’s the problem with pipe bursting. First of all, while it’s technically trenchless there is some excavation that still needs to be done to create the two pits.

And next, whatever the host pipe is doing, the new pipe will do. What if the host pipe is bellied, dipping, or back-falling — falling the wrong direction — or there’s a break in it so it’s not joined the right way?

There’s also the same issue with debris, roots, or anything underground that will throw off the pipe causing it to not have the proper fall.

Another thing to consider is if there are any utility lines near the sewer line. With the bursting process, the old pipe is forced out and pieces could hit and possibly damage nearby utility lines like gas or water.

Additionally, the new pipe comes on a roll and flexible so it has some give, much more than PVC. And because of that give there’s still the question if it’s going to have the right fall.

In the end, pipe bursting is a horrible plan. I was involved in a few pipe bursting jobs at other companies before I started In-House, and they were nightmare jobs. And I’ve heard from other companies who have pipe bursting machines, they very rarely do any pipe bursting repair jobs.

CIPP – Cured In Place Pipe

Next up we have sewer pipe lining aka CIPP aka cured-in-place-pipe.

This is similar to the epoxy lining with fresh water pipes. There are a couple different methods to do this type of repair but basically a sock-like tube is filled with an epoxy resin and is shot into the damaged pipe. The resin is then cured in place with warm water or air, hence the name, and a new “pipe” is created inside the existing pipe.

But we run into a similar problem here as we do with pipe bursting. If the process works as it is meant, whatever the host pipe is doing the new “pipe” will as well.

However, the process doesn’t always work as it is meant to. Sometimes the new pipe doesn’t adhere to the old pipe so it ends up still leaking. We’ve also had to go in and pull out the liner because it was actually crinkled up in the line.

Back in 2005, we subcontracted to one company in town to do 10 jobs to see if this method worked — because we wanted to if it did.

Five of the jobs they couldn’t do because they couldn’t even get the liner into the pipe. And the remaining five, we had to redo because it didn’t work. Either it didn’t adhere to the inside of the pipe, so it didn’t stop the leak. Or it caused stoppage problems. Different jobs had different problems. There were just so many different and potential problems with this method that we don’t recommend it.

Everybody thinks CIPP sounds fantastic, including me. But in reality, it just doesn’t work.

Most Promising – Flood Grouting

Flood grouting is currently used for pool repair, but I have high hopes for it as a possible trenchless option for residential sewer leaks.

The process involves two different liquid chemicals, both environmentally friendly. After the lines are cleaned with high pressure water and plugged, it’s filled with the first liquid. The liquid seeps into the surrounding ground through the existing leak.

The liquid is continually pumped into the line until the levels stabilize when it’s then pumped out of the line. Then the second liquid is pumped into the line which exits the pipe through the leak. It hardens and creates a sandstone-like material outside of the pipe that plugs the hole or crack causing the leak.

The nature of the sandstone-like material means it won’t shrink or expand after it hardens. And because the leak is repaired from the outside, there is no restriction for water and debris flowing through the pipes.

The biggest problem with this that I foresee is if the liquid doesn’t exit the line properly. And to get the liquid out of the line requires a lot of head pressure.

Currently we can’t get the right head pressure to make that happen in a residential home. We’d have to fill the sewer lines up to the roof to get the kind of head pressure in order to force the liquid out of the lines.

And we just can’t do that in a residential situation. It would flood out of the sinks, tubs, and toilets.

We could potentially block them with test balls but test balls blows up. And if you have a system full to the roof and a test ball blows, all that is going all over the house. It’s too risky.

I was really excited when I found out about this process. Especially when it comes to cast iron. This could provide a viable temporary option to buy homeowners some time until they can replace the whole system.

I repeatedly contacted the only company doing this in Texas at this time, and it took them four months to reply. That’s when and how we found out about the required head pressure.

Also until we can test it, we don’t know if it will work and if it will stay repaired.

So while this seems like it has the most potential for trenchless sewer leak repair, it is not something I can recommend at this time. But there is some promising technology that may work in the future.

Why Are There Trenchless Repair Companies in DFW?

So what about all the companies in Dallas/Fort Worth claiming they can do trenchless repair? In some cases, it’s a tactic to get your business.

I know of several companies in the area who bought pipe bursting machines at a low cost so they can call themselves trenchless. Then once you’re in the door, so to speak, they explain why it’s not the best option for you.

Similarly for CIPP. I have first hand knowledge of a company in DFW that spent more than $200,000 to do it — training and equipment, etc. Within six months of starting it, they scraped the whole project.

Several other companies, including the one we use to recommend for fresh water epoxy repair, spent thousands of dollars on equipment for CIPP sewer repair, but ultimately it did not work. The stuff ended up sitting in a warehouse for a long time.

Call In-House For Questions

Trenchless repair sounds like a great idea. But right now it’s just a great idea. At this time, though, the only trenchless repair I would recommend is directional boring for fresh water pipes in a yard.

However, my staff and I will continue to keep an eye on the options and investigate any promising ones.

And until then, we are happy to discuss a repair plan that will work for you if you think you might have a leak.

As always, we’re available by phone and email. You can call us at 972-494-1750 anytime. Or email service@inhouseplumbingcompany.com, and we’ll get back to you as soon as possible.