The Difference Between Pipe Bursting and Traditional Digging

When a plumber or contractor is replacing a broken sewer line runs under a porch or tree or such, he’ll sometimes have us just do the pipe bursting part of the job.  He’ll do the rest.  It can be very efficient for all involved.  When we are going to do a pipe bursting job with a contractor we’ve never worked with before, we try to help him understand that just about everything is going to be different.  Even when we succeed in getting the main points across, the full value of pipe bursting is hard to realize until you’ve been through a whole job and managed it well.  Pipe bursting is considered a trenchless or no-dig technology, but there is still excavation.  It is more less-trench than it is trenchless.  It is key to the final result how you manage that excavation.  Even if the contractor is happy with the result, we are not if the result is less than it could have been.

We recently did a job for a plumber where this was the case.  The plumber himself is a great guy who has overcome a lot of hurdles since the economy tanked and he had to change directions entirely and reinvent his company.  I have a lot of respect for all he’s done.  He’s done it mainly through a determined pushing forward when others would have given up.  His techs know this and they also have that push.  You know what I mean?  These guys are great in an emergency because they will invent the solution while they’re chin deep in the problem and they never give up.  But…

Pipe bursting is not just another way to replace a broken sewer line.  It is a completely different way to run an drain replacement job.  If you want to reap the full benefits of the technology, almost everything about your approach to install a new sewer line is different.  When you do traditional excavation, whatever your plans are from the start, it is easy to accommodate unexpected issues which may arise.  Let’s say you are going to replace a 150’ sewer lateral.  Maybe you plan to get an early start and get it all excavated and the new drain pipe installed in one day.  If you’re stuck in traffic, your equipment won’t start right away, you run short on material, or whatever, you just keep digging until it’s time to stop for the day.  So instead of replacing all 150’ of the old clay or cast iron sewer pipe, maybe you just get just 100’ of new drain pipe in instead.  You can easily make adjustments at any time.  Pipe bursting is not like that.  The plan is not easily adjusted.  When you start, it is all in or all failure.  So the plan is not just a suggestion.  It is well thought out, well executed, and must be adhered to.  If you have an 8 hour window to work in and it takes 8 hours to fuse pipe, prepare the holes and pipe burst the line, if you’re stuck in traffic, equipment won’t start, or you’re delayed for any reason, you’re not going to get it in anything.

Traditionally, it’s the excavation that is the limiting factor on a new sewer line installation.  So if you’re a plumber replacing the old clay, terra cotta, orangeburg, cast iron, or whatever drain pipe, you probably wanted someone to dig fast and give you plenty of room to work in.  That meant the bigger the excavator the better and big trenches with big piles of dirt running along them. The client just had to understand that a mess comes with replacing his sewer lateral.  With pipe bursting we know exactly the size of the holes we need before we start.  That means we can now manage what was unmanageable before.  With limited and precise excavation we can manage the excavated dirt with plywood set on drop cloths.  We don’t have to move the excavator a lot so we can work off of boards to protect the landscape from damage.  A smaller excavation means we can crib our equipment off of the sides easier and with less cribbing and so keep the bursting head better aligned in the center of the pipe.  With a small hole, it is also easier to manage any groundwater which might be there with a smaller pump and less mud.  Finally, a smaller hole is quicker to backfill and clean up around.

On this recent job the plumber was going to replace his client’s broken cast iron sewer line from the curb to the basement.  The line went under the front porch.  We gave the plumber a photo of his client’s front yard with a diagram of the 4’ x 3’ pit we wanted to mount our equipment in by the curb.  Inside he was to open up a 1.5’ x 3’ pit for the new pipe to enter.  Unfortunately, his job foreman never got that information and so he did not know what to expect.  When we arrived we found a full size backhoe on the job had dug a 2’ wide trench from the curb back 20’ up the lawn.  The trench was full of groundwater, the pump had quit, and all was one big muddy mess.  The basement work had yet to be started.

We quickly saw that for the best stability we would need to move our pipe bursting equipment inside.  We broke up the floor and dug the basement equipment pit ourselves.  We asked the foreman to have his excavator backfill most of the lawn so there would be soil on the old cast iron drain piping to give it the needed stability during the pipe bursting.  However, his excavator, who also didn’t understand pipe bursting, convinced him that backfilling before the new sewer piping was in place was pure heresy and wouldn’t do it.  With a lot more work on our part, which wasn’t part of the deal, we pulled the new HDPE sewer line into place.  But the yard was all ripped up and the plumbers were working in mud to make the final connections.  There were muddy footprints all around the trench.  We tried to explain to the foreman what should have been.  But of course, he was a good guy who always pushed through and he was busy doing that now.  Besides they didn’t know better and were content that the new piping was now run under the porch.  They thought that was what pipe bursting was all about – change out the part of the sewer lateral that they couldn’t reach by digging.

For us though, it was sad to see all that work when you know what could have been, and at less labor too.  Pipe bursting is not easy.  It is hard work with heavy equipment, cable, and cribbing which needs to be moved around.  There’s little time to squander.  That’s all the more reason to think and plan before you “make tracks”.  In carpentry the expression is to measure twice, cut once.  In pipe bursting you need to plan twice, work once.  If you have a good plan there’s still plenty to be done.  You don’t have to make more work for yourself, only to end up with poorer aesthetic results.  It is not just a version of traditional excavation.  It is a completely different trade.  Once you understand how it all works, then you’ll grasp what the technology allows you to manage that you couldn’t manage before – and then you have to do that with a real discipline.  Think twice, work once.

John Galligan
Pipeshark
3/23/14