Some ground just isn't fit to build on. Organic topsoil, soft clay and old fill full of junk will settle under concrete no matter how good the pour is. We dig the bad soil out, haul it off, and replace it with compacted fill or gravel that will hold.
Soil Removal in Boise for Slabs, Driveways and Pads
The soil under a slab or driveway does most of the work, and nobody sees it. When a garage floor cracks in a spider web or a driveway sinks along one edge, the concrete usually wasn't the problem. The material under it was too soft, too wet, or full of something that rotted and left a gap.
We remove unsuitable soil and replace it in Boise, Nampa, Caldwell, Meridian, Kuna and Middleton. Most of these jobs start one of two ways. A builder or engineer hits bad ground during the dig and needs it fixed before forms go in. Or a homeowner is replacing a slab that failed and wants to fix the cause this time, not just the concrete.
Signs the Soil Is the Problem
A few things point to the ground rather than the concrete. Cracks that keep growing, one side of a slab dropping lower than the other, or a hollow sound when you tap it. Water that pools in the same low spot after every rain. A patio or walk that has tipped back toward the house. Those usually mean the material underneath settled, washed out or was never right to begin with. New concrete poured over the same soil tends to repeat the problem within a few years.
Soil That Shouldn't Stay Under Your Project
Topsoil and sod
Topsoil is great for grass and bad for concrete. It's full of roots and organic matter that break down over time, and the ground drops as they do. On most slabs, driveways and pads, the sod and topsoil get stripped off first. It can be stockpiled for landscaping later.
Soft or wet clay
Clay holds water. Wet clay pumps under a loaded truck and can't be compacted until it dries, and in parts of the valley it can stay soft for weeks in spring. When there's no time to wait, the soft layer comes out and gets replaced.
Rocky caliche fill
Around Meridian, Nampa and Kuna, some lots were built up with fill full of broken caliche chunks and rock. It leaves voids and won't compact evenly, so a slab sits on high spots and bridges over gaps. Caliche left in place, undisturbed, is often hard and stable. The trouble starts when it's been broken up and dumped back in as loose fill.
Old fill with debris in it
Older lots in Boise and Caldwell sometimes have fill with brick, wood, concrete chunks and trash buried a few feet down. Wood rots, voids open up, and the surface settles years later.
How Deep We Dig
We dig until we reach firm native soil or the depth your plans call for. On new homes and commercial work, a geotechnical engineer often writes a soils report that sets the depth of over-excavation and what fill goes back in. We follow that report. On a residential driveway or patio, we probe the ground, dig out the soft and organic material, and show you what we found before we backfill.
What Goes Back In
The replacement depends on what's going on top:
- Structural fill for building pads and areas under footings
- Gravel base such as pit run or road mix under slabs, driveways and RV pads
- Topsoil where the area will be lawn or garden
Fill goes in layers and gets compacted at each lift. See our soil compaction and backfilling pages. For lawn areas, we can handle topsoil spreading too. Lift thickness depends on the material and the compactor, and a soils report will often set it. Dumping all the fill in at once and rolling the top only firms up the surface, which is how a lot of these sites got into trouble in the first place.
Groundwater and Irrigation Season
Near the Boise River in Eagle and Garden City, groundwater can rise once irrigation water starts running in spring. A hole that was dry in March can have standing water in May. Soil that looked fine during the dig can turn soft once the water comes up. We plan around that, and on some sites it changes what fill makes sense.
If the Soil Might Be Contaminated
Ground that smells like fuel or oil, or sits near an old heating oil tank, a shop floor drain or a spot where vehicles leaked for years, needs a different process. That soil usually has to be tested by an environmental consultant and handled under specific rules before it can be dug or hauled. We don't handle hazardous material. If you suspect a problem, tell us before work starts and we'll talk through next steps with you before anyone touches it.
What Soil Removal Costs
The price comes down to how much soil has to come out, how far it has to go, and what replaces it. Gravel base and structural fill cost more than the dig itself on many jobs. Access, soil that's too wet to work, and debris that raises dump fees add to it. We price the expected depth up front and explain what happens if the ground is worse than it looks.
Topsoil Removal
Topsoil is the dark, organic layer on top, usually the first several inches. It's good for lawns and gardens and bad under concrete, because it keeps breaking down and settling. Before a slab, driveway, patio or building pad, we strip the topsoil off the footprint. If it's clean, we can stockpile it on site to spread back over the yard later, or haul it off if you don't need it. Tell us which you'd like when you ask for an estimate.
Why Hire Ultimate Excavation LLC
Bad soil is hard to price until it's open, so trust matters on these jobs. Our reviews call Tanner a man of his word, and if a dig turns up more than we expected, you hear it from him before the price changes. We're an Idaho registered contractor (RCE-65836) with a 5.0 rating on Google. Call (208) 697-2429 or request a free estimate.
