A water main break, a sewer repair, a new gas line — any trench dug through your property can leave the concrete above it sinking for years. Here is why trenches settle, who pays, and when lifting works versus a re-pour.
When a utility crew cuts a trench through your driveway or sidewalk, they remove the soil, do their work, and put the soil back. That sounds like the ground returns to normal — but it does not. The soil that goes back into a trench is loose, mixed, and full of air pockets. Even with mechanical compaction, backfilled soil is never as dense as the undisturbed soil around it, and over the following months it consolidates: the air pockets collapse, the soil grains settle together, and the surface above drops.
That is why settlement over a utility trench has a signature shape. Instead of a broad, even drop, you get a long, straight depression that follows the trench line exactly — a sunken stripe across the driveway, a sidewalk panel that dips in a straight line, a patio section that has fallen along one edge. If you can draw a straight line through the low spots, you are almost certainly looking at a trench, and the fix starts with understanding what is underneath.
The timeline matters. Most trench settlement happens in the first year, with the fastest movement in the first few months as the loose backfill consolidates under its own weight and the first rains work through it. After that it slows, but it does not necessarily stop: each freeze–thaw cycle and each wet season can squeeze a little more consolidation out of the trench, especially in the Salt Lake Valley's clay soils, which swell and shrink with moisture changes. Settlement that is still active after two or three years is a different story — it usually means something is still going on underground, and the most common something is a leak.
A water main break is the most dramatic version of this problem, and it works on your concrete in two ways at once. First, the break itself: a pressurized main can wash out a surprising volume of soil in a short time, leaving a void under the slab that the slab then drops into. Second, the repair: the crew excavates a large hole, fixes the pipe, and backfills — creating exactly the trench-settlement problem described above, on a bigger scale.
The damage often looks worse than a normal trench settlement because the washout can be extensive. You may see a sudden drop of several inches, a slab that has cracked or tilted, or a section that feels hollow when you walk on it. In the worst cases, the soil loss extends beyond the excavation itself — water under pressure finds its way along the pipe bedding and washes out soil well away from the break.
If a city main broke, document everything before anyone touches it: photos of the damage, the standing water, the excavation, and the finished repair, all dated. Then start with the city's claims process. Most valley cities have one, and whether the city pays for the concrete repair depends on the details — whose main it was, where the break was, and what the restoration covered. The same documentation habit applies to sewer work: a sewer line repair that leaves a sunken stripe across the driveway is the same problem with a different pipe, and the same paper trail is what gets it fixed at someone else's expense.
Settlement after utility work is one of the few concrete problems where someone else might pay — but only if you can show whose work caused it and whose responsibility the ground is. The rules of thumb:
Two practical notes. First, the line between city and private responsibility is usually the water meter — the city owns up to the meter, you own from the meter to the house — but that boundary varies, so confirm it with your water provider rather than assuming. Second, whoever pays, the paper trail decides it: dated photos before the work, during the excavation, and after the restoration, plus every work order and invoice. Without that record, a settlement claim a year later is your word against theirs.
Lifting works on trench settlement when three conditions are met: the backfill has mostly finished settling, the concrete is still in one piece, and there is no active leak underneath. The timing condition is the one people get wrong. Lift a trench slab too early — within weeks of the backfill — and the backfill is still consolidating, so the slab follows it down again and the lift fails. Wait several months, ideally through one winter, and the backfill has done most of its moving. A good contractor will ask when the trench was filled and will tell you to wait if the answer is "last month."
The method choice is straightforward. Polyurethane foam is the usual pick for trench settlement: it is lightweight, so it does not add load to backfill that is still consolidating; it is waterproof, so it resists the next round of water; and it cures in minutes, so the slab is usable the same day. Mudjacking also works and costs less per square foot, but the slurry is heavy — a consideration over soft backfill. The full comparison is in mudjacking vs. foam, and the pricing ranges are the standard ones: mudjacking $3–$8 per square foot, foam $5–$25 per square foot, most residential jobs $500–$3,000 total.
Re-pouring is the better call in three situations. The slab is badly cracked or shattered from the settlement, so there is no solid piece left to lift. The trench is still actively settling and you want to rebuild on a properly compacted base rather than chase the settlement with repeated lifts. Or the utility work will be repeated — a line that keeps failing is a sign the whole run needs replacing, and pouring new concrete over a pipe that will be dug up again is wasted money. If none of those apply, lifting is the faster, cheaper fix — and you can read the full decision framework in lifting vs. replacement.
This is the step that separates a fix that lasts from a fix that fails. A trench that keeps settling after a couple of years, or a slab that dropped suddenly, may be sitting over a leak rather than just loose backfill — and lifting over a leak fills a void that the water will simply reopen.
The warning signs are worth checking before anyone drills a hole: settlement that appeared suddenly or is worsening fast rather than gradually; soil that stays wet or soggy along the trench line even in dry weather; a strip of lawn that grows faster and greener than the rest; a water bill that jumped without explanation; or the faint sound of running water when everything in the house is off. A sewer leak shows up differently — persistent damp spots, a sewage smell, or unusually lush growth along the line.
If any of those fit, get the line located and tested first. Your water provider can check for a main-side leak; a plumber with a camera can inspect a sewer line. Our water leak guide covers the signs and the testing in detail. Once the leak is fixed and the ground has had time to dry out and stabilize, the lift will hold — because the cause is finally gone, not just covered up. And while you are at it, check the drainage around the repair: downspouts and grading that send water toward a fresh trench will restart the washout, so make sure roof water goes somewhere else.
Because the soil under it was dug up and put back. When a trench is cut for a water line, sewer line, or gas line, the excavated soil is backfilled into the trench — and backfilled soil is never as dense as the undisturbed soil around it. Even with mechanical compaction, backfill settles as it consolidates over months and years, especially after rain and freeze–thaw cycles. Any concrete poured over that trench — driveway, sidewalk, patio — follows the backfill down. See why concrete settles in Utah for the soil side of the story.
Usually within the first year, but it can keep developing for two to three years. The fastest settlement happens in the first few months, as the loose backfill consolidates under its own weight and the first rains work through it. After that, settlement slows but does not necessarily stop — each freeze–thaw cycle and each wet season can squeeze a little more consolidation out of the trench. If the concrete over a utility trench is still dropping after three years, the cause is more likely an ongoing leak than normal consolidation, and that is worth investigating before lifting.
It depends on whose line broke and where. If a city water main broke in the street and the repair damaged or undermined your driveway or sidewalk, start with the city's claims process — most cities have one, and they will want documentation of the damage and the repair history. If the break was in your private service line (the section from the meter to the house), the repair is generally the homeowner's responsibility, and your homeowners insurance may or may not cover it depending on the cause and your policy. Keep every photo, invoice, and work order — who pays is often decided by the paper trail. If you are unsure whose line it is, your water provider can tell you where the city's responsibility ends.
Usually yes, once the backfill has finished its main settling — which means waiting at least several months after the trench was filled, and ideally through one winter. Lifting too early means the backfill is still consolidating, and the slab will just follow it down again. The lift itself works like any other: foam or mudjacking fills the voids and raises the slab. The one exception is a trench with an active leak — lifting over a leaking line just fills a void that the water will reopen. Find and fix the leak first, then lift. Our water leak guide covers the signs of a leak under a slab.
Lift it, in most cases. The concrete itself is usually fine — it has simply followed the backfill down — and lifting restores the grade for a fraction of the cost of tearing out and re-pouring. Re-pouring makes sense when the slab is badly cracked or shattered from the settlement, when the trench is still actively settling and you want to rebuild on a properly compacted base, or when the utility work will be repeated (a line that keeps failing is a sign the whole run needs replacing). Compare both options in lifting vs. replacement.
Look for the water signs: settlement that appeared suddenly or is worsening fast rather than gradually; soil that stays wet or soggy over the trench line even in dry weather; a patch of lawn that grows faster and greener than the rest; a water bill that jumped without explanation; or the sound of running water when everything in the house is off. A sewer leak shows up differently — persistent damp spots, a sewage smell, or unusually lush growth along the line. If any of these fit, get the line located and tested before you lift anything. Lifting over an active leak is money down the drain, literally.
When a utility digs up your property for its own work — a main repair, a meter replacement, a service upgrade — it generally has to restore what it disturbed, usually to a reasonable standard: backfilled, compacted, and resurfaced. But "restore" and "make it like new" are not always the same thing, and restoration often means a patch, not a full slab replacement. If the restored section settles later, the question becomes whether the utility's compaction was adequate, which is harder to prove after the fact. Document the condition before, during, and after the work with dated photos — that record is what makes a follow-up claim possible. And if the settlement is on your side of the property line after a private line repair, the restoration is generally on you.
Related reading: Water leaks under slabs · Why concrete settles in Utah · Lifting vs. replacement · New construction settlement
Tell us what was dug up and when — trench line, water main, or sewer repair — and we will tell you honestly whether it is ready to lift or still settling.