what to expect from tunneling

What to Expect from an Under-Slab Tunneling Project on Your Home

You have a leak under your home and are thinking about or have decided to do under-slab tunneling. The idea of the plumbers being able to reach the leak without demo-ing your flooring, tearing up your slab, tromping through your house, and making a pretty big mess sounds great. 

But what can you expect from this process? Will it be loud or messy? And how exactly do they do this thing? If you’re anything like me, you just want to know: What is about to happen at my home?

Anchor Foundation Repair Bryan College Station

At Anchor Foundation Repair, we understand what it’s like to have work done on your home and we don’t want homeowners feeling left in the dark on what to expect. We have tunneled under hundreds of homes in the Bryan, College Station, and Brazos Valley area and can tell you what the under-slab tunneling experience is like from a homeowner’s perspective.

This article will outline in detail what you will see, hear, and feel throughout the tunneling project around your home. 

Don’t worry, there should not be any smelling or tasting on your part during 150you being carefree and carrying on with your life by baking and eating blueberry muffins in your kitchen while we dig under your home. 

Consequently, I did have a blueberry muffin just before writing this article . . .

Major Questions About the Under-Slab Tunneling Process

questions about tunneling

Everyone always has some pretty basic (but major for you) questions about the under-slab tunneling process. Let’s fire off a quick Q & A session to get these out of the way. We do have more detailed answers about the under-slab tunneling big questions in another article too. These are the super-fast answers.

Q: How long will under-slab tunneling take?

A: This all depends on the length of the tunnel needed. The team can dig about 6 to 8 feet per day. It usually takes a certain number of days to dig, then ½ to one day less to backfill and finish up. So here’s a couple of breakdowns:

6 feet or less of tunnel = 1 day to dig + 1 day to fill = 2 days total

10 or so feet of tunnel = 2 days to dig + 1 day to fill = 3 days total ←average job

15 or so feet of tunnel = 2 days to dig + 2 days to fill = 4 days total 

20 or so feet of tunnel = 3 days to dig + 2 days to fill = 5 days total

Q: Will under-slab tunneling be messy?

tunneling work zone

A: It will not be messy inside your home. The whole point of tunneling is to keep the dirt and work outside and underneath the home instead of right there in your kitchen or bathroom with dirt piling up inside or holes in your slab. 

There will be a dirt pile outside of your home, either near the tunnel or on the driveway. The dirt pile will be bigger the longer your tunnel needs to be. We wouldn’t call it *messy* but just a work zone.

Q: Does anyone have to come inside my home during tunneling?

A: No, we do not have to come inside during most phases of the tunneling process. Again, that’s the whole point. You get to live your life in a relatively normal fashion while the majority of the work is in progress. When we are in the backfilling/mud-pumping stage, one person will need some access inside.

Q: Do I have to be at home during tunneling? Do I have to move out?

A: You do not have to be home during the work process. In fact, most people are not home during the tunneling process. We are used to working independently and homeowners trust us to do so. You do not have to move out of your home either. Tunneling allows you to get under-slab leaks repaired while mostly living as normal inside.

Q: Can I use my plumbing during under-slab tunneling?

repair plumbing under slab

A: Yes, you can use your plumbing while we are digging until we get closer to the leak, and then you will need to stop. A lot of times, you can just use one bathroom and avoid the other. Our team will tell you when you might need to cease using drain lines. You can still run water, you just can’t let it run down a drain until the leak(s) are repaired by the plumber.

We try to minimize any non-use time as much as possible by getting the plumber out right away to complete the repairs. Once the plumber has fixed the under-slab leak, you are free to use all plumbing fixtures as we work to fill in the tunnel.

Q: Do I have to coordinate with the plumbers?

A: Speaking of plumbers, we work with plumbers all the time to quickly and efficiently get the leaks fixed as fast as possible. We coordinate with the plumber of your choice to make things easier for you. We do check that the under-slab plumbing repairs have been done properly for under-slab environments.

why do I need a hydrostatic pressure test

We also run hydrostatic plumbing tests when working with unfamiliar plumbing companies. We want to make extra sure that all the leaks have been repaired effectively and that no new or undetected leaks pop up. We will not fill in your tunnel until we have verified that there are no further leaks under your slab.

Under-Slab Tunneling Step-by-Step Experience

The section will detail the day-to-day happenings that a homeowner will see and experience during the under-slab tunneling and under-slab leak repair process. We break down tunneling into 4 phases of on-site work:

Phase 1: Set up and planning

Phase 2: Digging and more digging

Phase 3: Plumbing Repair

Phase 4: Backfill and mud-pumping

dig test flags
Dig test flags

We do have a quick overview article about the tunneling process from our perspective as well, but this here article is more like what you will see with your eyeballs happening at your house.

Days before anyone ever arrives at your home, we would call 811 for a dig test. This is where people come out to mark any underground utility lines with those little colorful flags. If you already have a foundation repair job underway, this has likely already happened. But if you are just having tunneling for plumbing repairs, a dig test will need to be ordered.

Phase 1: Arrival, Set Up, and Planning for Tunneling

tunneling in Bryan college station

Most often, we will have two team members arrive for the initial setup and planning of a tunneling project. The workday typically starts a little after 8 am and the guys will arrive, unload some supplies, and begin to stage their work zone. 

There will be wheelbarrows, manual and electric shovels, extension cords, lights, and fans. Plywood is used to protect your yard anywhere a dirt pile or a main pathway will be frequented.

Oh, and the guys leave each day around 4 pm in case you are wondering. . . 

Making a Plan for the Tunnel

The under-slab leak or leaks may have already been located by a plumber or possibly a foundation repair team. If not, the leak location does need to be identified by a process of elimination using hydrostatic pressure testing so that they can plan the route of the tunnel.

We don’t just start digging all willy-nilly. We have a very specific and controlled plan to reach the leak location with the least amount of feet of tunnel possible. We absolutely do not want to dig a longer tunnel than we have to. It truly is hard work digging in expansive clay soils.

Phase 2: Start Digging and Then Dig Some More

what to expect from tunneling

Once a plan is devised, the team will begin the digging process at a starting point likely near one of the plumbing clean-outs on your property.

The leak could be close to the edge of the home as in this common scenario with a hall bath shown in the diagram. This could be around an 8-foot tunnel. For larger or more complex homes, the tunnel and leak could be much farther under the home. 

Starting the Tunnel

The initial start of the tunnel takes the longest. The team first begins digging straight down to get under the perimeter concrete support beam of the home. Once they dig under the beam, then they dig straight up on the other side of the beam to reach the bottom of the slab. 

The bottom of the slab foundation ends up being the ceiling of the tunnel. Using the slab as the ceiling creates the safest environment for the team and prevents cave-ins. 

Digging the Rest of the Tunnel

The tunnel will be a 3-foot by 3-foot square tunnel that runs along your drain line path to the location of the leak. The tunnel is surprisingly neat and square and the team can dig about 6 to 8 feet per day. The longer the tunnel gets, the more guys they need as they pass the dirt from one guy to the next every 5 or 6 feet or so to clear it out of the tunnel.

digging a tunnel

From a homeowner’s perspective, you will mysteriously see an ever-growing pile of dirt over one or more days of digging. One guy will be on the outside of the home taking dirt that is removed from the tunnel to the pile. The rest of the team is in the tunnel, digging and pushing dirt out. 

The electric shovels do make noise under the home, kind of like a jackhammer but muffled and not nearly as loud. It could still be enough noise to find slightly annoying so if you’re trying to do meditative yoga during your lunch break, this will not be the *most optimal* environment for that.

This phase will last as long as it needs to, in order to reach the plumbing leak(s) and a little beyond. Going slightly past the leak location allows the plumber plenty of room to move around and do the repairs efficiently.

Phase 3: Plumbing Repairs

repair under-slab plumbing by tunneling

Once we have uncovered all the leak locations by the tunnel. We coordinate with the plumbers to handle the next phase of repairs. We do not do the plumbing repairs ourselves because we are not licensed plumbers. Sorry, we can only be good at so many things. . .  

We do have some plumbers that we like to work with because we know for sure that they know what they are doing in an under-slab environment. But we can work with whomever you choose and coordinate things with them.

Normally, the plumbing repairs can take one day or less for one simple line break or 2 to 4 days to replace all the drain lines under a home.

Phase 4: Filling the Tunnel Back In

filling in a tunnel

When it’s time to fill the tunnel back in, it’s all hands on deck with a full crew. First, they are going to check for properly repaired under-slab plumbing and get to work putting the dirt back in the tunnel.

While dirt is being replaced, our team is also prepping for mud-pumping by placing PVC pipes in each section of the tunnel. Other team members will also begin sifting new topsoil that will be used for mud-pumping. So you’ve got guys putting dirt back, guys prepping pipes, and guys sifting dirt. A lot is going on outside your home at this time.

They will try to put as much of the old dirt back as possible, but certainly not all of it. The clay soil gets dry and clumpy and it doesn’t all go back the way it came out. There will be small pockets of air and spaces between the dirt clumps so we fill all of those voids in with something called mud-pumping.

More About Mud-Pumping

Mud-pumping involves injecting a pressurized flowing mix of topsoil, cement, and water (called slurry) to fill all spaces, as well as solidify and secure the previously tunneled area. The team uses the PVC pipes to pump the slurry throughout the tunneled area. 

slurry for tunneling

We have a whole article that talks about mud-pumping and slurry in more detail if you want to check it out.

The short version of mud-pumping is that it’s a key element of our tunneling services because how the tunnel is refilled is more important than how it is dug. We want the tunneled area to be stabilized and your slab fully supported after the excavation and plumbing repairs.

During mud-pumping, someone will need to enter your home and monitor the progress of the mud-pumping to make sure that it doesn’t get over-pumped. They are also running water in the plumbing lines to make sure that no other breaks are detected.

After backfilling and mud-pumping are complete, of course, the team will clean up the worksite. Clean-up includes excess dirt haul away, sod replacement, landscape tidying, and generally loading everything back up. It is always our goal to leave your home in great shape at the end of each day, as well as at the end of the full project.

How Will I Know How the Under-Slab Tunneling is Going?

Having a long tunnel dug under your home seems like an overwhelming project that you can’t really monitor or evaluate in progress. That’s why we want to make sure you know exactly what is going on. 

builder trend login

I mean, you can crawl in the tunnel yourself if you want . . . we can’t stop you after we leave for the day . . . but we have a better idea.

At Anchor Foundation Repair, we certainly understand that it feels a little out of control when you can’t see the work being done on your home. We have a solution for this feeling so that you can see progress through both photos and videos of what the crew does on (or really under) your home each day. 

Our premiere BuiderTrend communication system lets homeowners in on the repair process from a comfortable distance. You can see what’s up, without getting down in the dirt. Here’s an article that gives you all the deets on how BuilderTrend takes care of your needs during a project with Anchor Foundation Repair.