The heck is going on here?

[Mattilac]

So check this out:

It's kinda funny, but obviously a problem that needs to be addressed. I have no idea what's going on. This is the dirt ground just outside my garage foundation, backfilled 5 months ago. In fact, I discovered this yesterday when I went to move my telehandler back inside the foundation. As I drove onto this dirt strip between the asphalt driveway and foundation, the wheels just dropped into the ground. Fortunately I was able to self-recover using the boom. But now I'm left with this super squishy ground. It literally feels like I'm standing on a waterbed.

For reference, here's a photo from back when we did the backfill:



We put the same dirt back in around the foundation. Did not compact it besides hitting it with the excavator bucket to pack it in while moving along, and driving the skid steer over it a lot. (We did properly compact the fill inside the foundation, since that's getting a slab at some point.)

It always felt like solid ground up until yesterday (when I moved the telehandler as mentioned above). Now it's a sponge.

So what causes this? Water in the ground? How to remedy?

 

[egdede]

My knee-jerk reaction is water, and you need to run some drain-tile to daylight (lower elevation). But seems if it were water, you'd know, you had a shovel in it! It is weird because you'd expect enough water to cause that would not cleave the way it did when you shoveled.

 

[Drill Sergeant Arc]

I saw this same thing about ten years ago when using a backhoe to dig a square footing in a rather swampy area. The ground was like a peat bog and the hoe cut it out like jello, it was like a 5 foot square hole that jiggled when the bucket hit it. There was a water content like a wet saturated sponge because it was summer. It would have been like a swamp in winter.

It’s right at the point where adding more water would turn it to mud. A phase transition so to speak.

 

[Sumboodie]

Crost coming out?

 

[gizardlizard]

Dude that’s crazy. Never seen anything like that.

 

[Chris705]

Crost coming out?

Frost coming out….. I agree the surface layer is frozen enough to support your weight…. Otherwise it would be a muddy mess if the ground was above freezing. Looks like about 12” or so of frost.

 

[niget2002]

There's other videos on YouTube of super saturated ground like that. The one I remember most had grass and when they stomped one side it made a wave across it.

Have you had a lot of rain lately? If not, it's time to start looking for a busted water pipe.

 

[jack stand]

Dig it out at least at the traffic doors and replace it with crushed stone (2" +/-). And if you can daylight some drain tile that would be great.
The video looks like fall. Did you quit for the winter and leave a rough grade that would direct runoff to this area?

 

[kj_mustang]

Guessing there is a layer of clay or other impervious soil under the fill and water is trapped in that layer.

 

[firebirdparts]

You live in a place where there is actual soil. That's good news in itself, although I admit that cold weather is what causes it. Where I live, the carbon in the soil gets converted to CO2 and we just have clay. It's not really great to use real soil as backfill. You need more drainage.

 

[Renegade1LI]

Almost looks like water trapped by a layer of frost and can't drain.

 

[racecougar]

What is under the soil in the backfilling photo? Almost looks like dumped extra concrete. As others have said, that sure seems to be a drainage issue. It will need to be dug back out and corrected.

 

[Mattilac]

Thanks for everyone's input. To answer a few questions:

Have you had a lot of rain lately? If not, it's time to start looking for a busted water pipe.

Not much rain or snow lately or even this whole winter. In fact I think it is the lowest snow total in many years.

No water pipes in this area...

Dig it out at least at the traffic doors and replace it with crushed stone (2" +/-). And if you can daylight some drain tile that would be great.
The video looks like fall. Did you quit for the winter and leave a rough grade that would direct runoff to this area?

Does 1-1/2" recycled material (crushed concrete, brick, asphalt, etc) work? I have a couple yards worth on hand.

The video is from yesterday. The photo is from this past fall. I took a break for the winter after the foundation was placed and backfilled. Starting to make plans to frame it this spring. Discovered this issue yesterday.

Guessing there is a layer of clay or other impervious soil under the fill and water is trapped in that layer.

You might be right. We excavated a lot of clay/sand while digging for the foundation.

What is under the soil in the backfilling photo? Almost looks like dumped extra concrete. As others have said, that sure seems to be a drainage issue. It will need to be dug back out and corrected.

Yea you are seeing a bit of extra concrete that got splattered around. Otherwise it is just virgin soil/clay under the footing.

---

It seems the consensus here is poor drainage, which makes sense. I wonder if I should just dig and replace the soil with stone to a certain depth, or really dig it out and install some pipes or something?

 

[MoonRise]

Dig it out and do it right.

Crushed gravel down low (compact it at least somewhat, otherwise you WILL end up with some settling), then some drain pipe (aka 'weeping tile' in Mike Holmes speak ) with the 'sock' around it, all sitting in a good layer of crushed stone (again compacted at least somewhat). Then put some geotextile cloth on top of the crushed stone (otherwise the dirt just ends up down IN the stone gaps and kind of defeats the whole purpose of the spaces in the crushed stone layer being able to drain water down and away) before you put your top layer of dirt on everything. Except don't put dirt there right in front of what looks like the bay door openings, since you will probably want to have concrete or asphalt to drive on from the paved driveway area into the building through the bay doors. So leave all gravel there in front of the doorways. You can always scoop out some gravel if you need to.

The drain pipe has to have the correct slope/pitch and has to drain the water AWAY from the structure and foundation. Either to daylight (away from the structure!) or to a drain pit (aka "DRY WELL") that is located AWAY from the structure.

And make sure that your grading around the building is NOT directing water towards the structure, but is pitched AWAY from the building in all directions.

 

[dfiler2]

Around here we call them "frost boils" they can occur in the middle of the road, they are caused by the ground being thawed on top but still frozen a couple feet down and water is being held on top of the frozen ground.

 

[dcg9381]

I have a home that's built like that.. Sorta a 3/4 basement. Along all the concrete there is a tar paper vapor/moisture barrier, so we can't get water in from the soil. All long that foundation line we have a french drain that is property sloped.

 

[Rusted Nut]

Run into this a lot in construction, we call it pumping. Water/moisture. The only fix is get rid of the water or channel the water somewhere else. Then dig it up and replace with good fill. Dig down to solid ground, then place about 8” of 2” to 4” quarry spalls, the fill the remainder with crushed rock of other suitable fill.

 

[NUTTSGT]

We had a spot like that when we tore out our old concrete apron in front of the station.

We wanted to dig it up, put stone in and compact it. We got overruled by the Chief and poured concrete right over it.... whole apron, one piece of rebar. Yeah now wonder it looks like **** and cracked to hell.

 

[wssix99]

That is definitely soil liquefaction: https://en.wikipedia.org/wiki/Soil_liquefaction

Lots of great comments above. It looks like the fill here is different than the surrounding soil -> backfilling with the original material from the trench should also help.

 

[Brly]

Run into this a lot in construction, we call it pumping

Yup, pumping is what we call it too.

 

[Dan in Pasadena]

Glad someone finally called it by the right name^^^

You don't mention there being a drain in the bottom of that trench but if you had one it would have to flow someplace. It's paved right up to the trench so water has flowed into it and has no way out. I'd suggest excavating the soil and either installing a French drain (if there's somewhere you can let it drain without tearing up even more pavement) OR after removing the fill, backfill with slurry - usually a one sack or sack and a half mix then pave over it to match the existing. If you're unfamiliar, slurry will dry to the equivalent of professional compaction.

There's no other way unless you remove the fill, allow it to dry, backfill and compact to 95%, have it tested, pave over it, yada, yada.

 

[545_days]

I’ve seen an old Ford tractor sink out of sight on soil like that. The exhaust stack sticking out of the ground was the only sign it was there. in that case it was ground water flowing through sand that kept it liquified. Losing the tractor was foolish. They drove over the area that was pumping until the top layer broke up and down it went like a sinking ship. The driver didn’t even have to spin the wheels to dig in.

 

[jives]

The end of our driveway is like that. The gravel driveway was poorly constructed 12 years ago, but only over the past couple of years we have gotten the liquefaction effect near the end of winter. Our plans to have it dug out and replaced by stone/gravel was thwarted when the guy we contracted with never showed up. This summer I will do it myself. In the meantime we use a 10 x 10 perforated heavy duty plastic stall mat ove rthe area.

 

[NUTTSGT]

Looks like you have an excavator on site. I'd be digging it out and replacing it with stone/gravel.

If there's a drainage issue, now is the time to take care of it.

 

[Mattilac]

Should I dig all the way down to the foundation footing (4' deep) or just to a certain depth? Seems like a ton of stone if going all the way down, but perhaps it's necessary.

I'm all for a french drain and will plan on installing one. Might as well go all the way around the foundation if I can. But it's a little tricky because this property is so flat, it could be hard to slope it all to daylight.

 

[Rusted Nut]

Get rid of the water, then dig down to where you find solid ground. If you place large (2” to 4”) rock on the bottom, that give any residual moisture somewhere to go, and also help bridge any soft spots.

 

[Mainiac Mat]

Years ago I worked a short time in public works, where I learned that almost all road problems are the result of inadequate base prep.

A decade later, when we put our 900' private drive in, the road paving standard required excavation and gravel back fill to a minimum depth of 12" AND NO ORGANICS. There are stretches where we had to excavate 3' deep and the total cost of the gravel fill alone was $11K (in 2006 dollars). We paved 2" of hot top base and deferred the final 1" top coat until the property was fully developed... and 16 years later, still haven't done it. But we've had no stress cracks, no potholes, no damage of any kind.... because the base (and drainage) were done so well.

For construction, there's a test called bearing ratio that measures the ability of the earth to carry weight. That test has to be run "soaked" as water decreases the load bearing ability of the soil.

So my guess is that you can either 1.) excavate and fill in with sand, and then put loam and grass above that. And/or 2.) put in drain pipe to remove the water.

 

[nateo]

Ooh, I've got a story too!

A few years back we were rebuilding our site waaaaaay up in the highest arctic. We started work in June when the snow drifts were still 8' high, but thanks to 24 hour sunlight as soon as we cleared the snow down to bare tundra things started melting, and fast! We had made ourselves a gravel pad about 20' x 20' for our building and noticed the whole thing was moving like a water bed. You could even get big ripples rolling across it if you jumped a little. After a day or two of continued melting and draining, everything settled down nicely.

We buried some foam under the gravel and that coupled with the shade provided by the building itself has kept the ground frozen well enough that our structure hasn't tipped over yet!

 

[jives]

Suggestions to get rid of the water, increase drainage, and so forth are spot on, but in many cases impractical or not possible unless using a pump. Dig out, pack with appropriate stone/gravel, use geotextile, be done.

 

[backupbeeper]

I’ve seen an old Ford tractor sink out of sight on soil like that. The exhaust stack sticking out of the ground was the only sign it was there. in that case it was ground water flowing through sand that kept it liquified. Losing the tractor was foolish. They drove over the area that was pumping until the top layer broke up and down it went like a sinking ship. The driver didn’t even have to spin the wheels to dig in.

Yeah we almost lost a bobcat tracked skid steer like that . At a job site near Augusta Georgia .

The ground was fin a little soft but no big deal until you had driven over the same spot four or five times and then broke through the top crust .

Then it was just jello .

We were way back in the woods working on some artesian wells .

We hooked three new 3/4 ton 4wd diesel pickups to the bobcat and were able to pull it out .

 

[ZRX61]

Years ago I worked a short time in public works, where I learned that almost all road problems are the result of inadequate base prep.

71 Freeway in LA developed a ****-ton of potholes this month because of the rain. News showed CalTrans workers dumping out bags of asphalt mix into water filled holes that were 3in deep... They did have some clueless jackwagon with a leaf blower who was supposed to be blowing the water out of the holes, but he really didn't have the first ******** clue what he was doing. He'd fail the boot/piss/heel/instructions test

 

[olytdi]

I had that exact problem on my shop site prior to building. The building site had three huge craters where tree stump/roots were removed. Think 25 ft wide craters 3 ft deep. These filled with water from the ground and once filled they were filled with pit run, became exactly like your video -- squish squish, wave wave.

What we did:

Dug a three foot + deep trench around the building site sloping to the low side. Lined the trench with filter fabric. Laid 4 inch perf pipe in the bottom. Filled trench with 2 inch round rock to about 1 ft below grade keeping the pipe at the bottom. Folded the filter fabric over rock filled trench and "sewed" the folded pieces together every 2 ft or so with zip ties. Then back fill to grade. Trench immediately started to drain about 5 gallons/min and did so for days.

Once the trench no longer was moving any water, we dug out the stump craters, lined them with geoteck, and refilled the craters with gravel. We used a vibrating roller compactor over and over for a couple of days. Then we let it sit for 3 months. It became hard as concrete.

Finally, we graded the site level with rock, roll/vibrate/compacted it again and again prior to building the post construction building. Final pour was 5 inches of fiber reinforced concrete with rebar about 4 months after final grading with rock. It's been a year now and not a single crack yet in the shop. I expect some (I've never really seen a crack-free pour) but nothing is evident yet.

The key was drying it up by giving the water somewhere to go (not just initially, but ongoing), compacting, and waiting for everything to dry up and lock down.

Last thought: I find drain pipes with socks to be utterly insufficient. If you're going to put in a drain trench, do it right -- pipe on the bottom of a trench lined with high-quality filter fabric, filled with clean drain rock, sealed over and knitted.

 

[nadogail]

IMHO, John Macadam solved this problem when he invented the Macadam Road.

If you can build a perfect base, in theory asphalt paving would only need to be a paper thin layer to keep the base layers dry.

 

[Grokew]

Dig it out at least at the traffic doors and replace it with crushed stone (2" +/-). And if you can daylight some drain tile that would be great.
The video looks like fall. Did you quit for the winter and leave a rough grade that would direct runoff to this area?

"Daylighting", at first I thought it meant digging and exposing the foundation in order to install the drain tiles, then found out that there are two uses for the term. Installing windows or light pipes, and Digging with a hydro-vacuum excavator. That's interesting.

 

[duga]

On the West coast we call that pumping. Usually caused by fill placed but not compacted properly. That provides space in the fill dirt for water to later occupy. Like others have said, it has to be pulled out and either compacted properly (can't compact saturated dirt) or just base rock/gravel it.