Motmot Foundation Repair did an awesome job fixing this huge building from my apartment complex in San Antonio. I know you need to be very careful with commercial properties since this is a heavy structure but they handled it well and met my expectations. They also dug about 30 feet of tunnel so the plumber had access to the pipes for replacing them.
For every tunnel · Backfill & cleanup
Tunnel Backfill, Compaction & Cleanup After the Repair
A tunnel is only as good as the way it gets closed. Loose fill compresses under its own weight, the ground drops, and the slab or driveway over it cracks. We place backfill in compacted lifts so the void the repair needed doesn't turn into the next problem.
Plenty of crews will dig a tunnel and most will fill it back in. Fewer close it as a structural step. Loose or poorly compacted fill is why a repaired area sinks a year later, and by then the plumber gets the phone call, because the pipe is the only thing the homeowner remembers being touched. We treat the close-out as its own scope. Lifts placed and compacted to carry whatever sits above, spoil hauled, the site cleaned, and a written record of how it was done.
“Tunnel backfill and cleanup”“Backfill placed and compacted in lifts”“Spoil haul-off and full site restoration”
When you call us
The jobs that need a tunnel.
Backfill that settles later
Loose fill compresses under its own weight and under traffic. Compaction in lifts is what stops the area sinking after the repair.
Slabs and drives cracking over a tunnel
A poorly closed tunnel telegraphs straight up into the concrete above it. Proper compaction protects the flatwork.
Spoil and mess left behind
An open job site is a liability and a bad look. We haul spoil and restore the area.
Reopened access between trades
When a repair needs a re-test or a second visit, we stage the backfill so access stays available, then close it for good.
No record of how it was closed
We document the backfill so there is a record for the homeowner, the property file, or a warranty claim.
What you get
How we work with you.
This is the quiet half of every tunnel job. We backfill in measured lifts and compact each one so the subgrade carries the load above it, whether that is a slab patch, a driveway, a sidewalk, or landscaping. Spoil gets hauled, the work zone gets cleaned, and we document what was placed. If concrete or flatwork has to go back over the access, our own crews pour it. Here is the test that matters, and it isn't the invoice. Six months out, go stand on the ground over the tunnel after a hard rain. If it is still level with everything around it, the job was closed right.
SCOPE OF WORK
- Backfill placed and compacted in lifts to support the load above
- Spoil hauled off and the work zone cleaned
- Subgrade prepared for a slab patch or flatwork replacement
- Documentation of how the access was closed
- Flatwork and concrete replacement available through our own crews
How every bore is held
Velocity, precision, OSHA, quality control, and the standards behind them.
Tunneling is the slow, risky part of a plumbing or foundation job. We run it like a discipline, not a dig.
VEL
Velocity
Hand-tunneling is the slow part of any plumbing or foundation job. We staff the bore to the schedule and hand over an open, ready trench instead of billable hours spent waiting on a shovel.
PRC
Precision
We dig to the plan. Depth, width and pitch are shot before the first spade and verified as we go, so the pipe run or the pier lands where the drawing says.
SAF
OSHA safety
Cave-in exposure is real. We work to OSHA Subpart P excavation practice: protective systems, safe access and egress, spoil set back from the edge, water and air managed, and daily competent-person inspection.
QC
Quality control
Every bore is checked against the drawing for working width, clean floor and walls, and true pitch. Backfill goes in compacted lifts so the ground above settles right.
STD
Standards & compliance
Texas 811 is called and lines are located before we dig. We sell the access, not the licensed pipe work. Permits, locates and clean documentation come standard.
Why a foundation crew digs a better tunnel
We come out of foundation repair, and we've dug alongside plumbers for years, so we know how to dig it.
We know how a sewer line runs under a slab, where the belly usually hides, and how much room it takes to set a fitting and lie down to make a joint. So we open the bore wider at the repair, shore it, keep it dry, light it, and get out of the way. Years of watching the pipe work happen is what tells us how wide to make it.
- We open the work area wider where the repair is, leaving room to set, slope, and joint
- Shored, dry, and lit so the plumber works in a tunnel, not a hole
- We dig it and back-fill it; your licensed plumber does the pipe work
From locate to backfill
How an under-slab tunnel runs.
01
Locate & plan
We call Texas 811, locate utilities, and shoot the depth, width, and pitch the repair needs before a spade hits the ground.
02
Open the entry
A compact entry pit goes in at the chosen point, usually outside the foundation, so the floors above stay whole.
03
Tunnel to the work
We hand-tunnel to the pipe run, pier location, or access point, widening the bore where the repair happens.
04
Shore & hand off
The bore is shored and inspected, then handed off open, dry, and workable to your licensed plumber, foundation crew, or engineer.
05
Backfill in lifts
Once the repair passes, we place backfill in compacted lifts so the slab, drive, or walk above settles correctly.
06
Clean & document
Spoil hauled, site restored, and the access and backfill documented for your file or warranty.
LICENSING & SAFE DIGGING
In Texas, plumbing repairs are regulated by the Texas State Board of Plumbing Examiners, which issues Tradesman, Journeyman, Master, and Inspector licenses. Motmot sells under-slab tunneling and access excavation, and partners with your licensed plumber for the pipe repair. Before any dig, Texas 811 is contacted at least two business days ahead so gas, water, and utility lines are located first.
Industry FAQ
Backfill & cleanup tunneling, questions answered.
Because loose fill settles, and when it does, the slab, patio, or driveway above it cracks or sinks. Compacting in lifts builds a subgrade that carries the load, so the repaired area stays level and the dig disappears instead of coming back as a callback.
Yes. We remove the excavated soil and clean the work zone as part of closing the tunnel. The site shouldn't look like a job site when we leave.
Often, yes, if the access was dug safely and we can verify the repair is complete and the bore is sound. Call us and we'll take a look.
Yes. Where a slab section, sidewalk, or driveway had to be removed to dig, our concrete & flatwork crews replace it on a compacted subgrade so it sits right.
Yes. We document how the access was closed so there is a record for you, a property file, or a warranty.
From real jobs
What this access looks like on real jobs.
Need under-slab access? Tell us the run.
We'll scope the tunnel, dig it to plan, shore it, and back-fill it clean, so your licensed repair goes in smoothly and the floors above stay whole.
Now booking free inspections in Central Texas.
Free inspection request
Tell us what you're seeing.
We'll call to schedule, usually within one business day. Prefer to talk now? (210) 816-0034.
- 60–90 minutes on site, including the elevation survey
- Written summary whether or not repair is needed
- No-pressure pricing with firm numbers, no same-day-only discounts
