Repairing void under concrete slab (conditioner, heat, drain, plumbing)

[TMBGBlueCanary]

I did some yardwork this past weekend and notice that there is a void under the concrete slab my heat pump sits on. It's in an area where you can't see it with normal use of the yard, so I never noticed it until I went to do some work in that area.

I need to fix it and am trying to figure out the best way. I think maybe filling it in with some fill dirt (it's a pretty big hole--so deep that I can see the buried cable (as in internet and TV) wire exposed) and then foam jacking the rest might be the route to take, but I wondered if anyone had any other ideas. I am just trying to piece together how to fix it by finding what I can find online.

Also, I can't figure out why that area is eroded away in the first place and I need to fix that as well. It's up against the house and near the drain spout, but I have plastic tubing from the drain spout to the fence line so the water shouldn't be draining in that area (unless the damage was caused by water from tropical storms/other large storms we've had in this area in the past couple of years that the gutters and spouts couldn't handle... I confess, I haven't been in that area for a couple of years because I didn't mulch around the until for a couple of years). The gutters are clean by the way (do that every year).

[Pitt Chick]

We had the same sort of damage... from chipmunks.
We hired a local company that pumped a slurry underneath the slab.

[TMBGBlueCanary]

Originally Posted by Pitt Chick

We had the same sort of damage... from chipmunks.
We hired a local company that pumped a slurry underneath the slab.

As sore as I am from all the yardwork this weekend, I am tempted by this option. What kind of company does this? A concrete company I would assume.

[K'ledgeBldr]

I don't think "mud-jacking" is worthy in this particular scenario.

HP/condensers sit on a relatively small concrete pad- just dig it out enough so you can pack it full of dirt. Then look at the immediate topo around the area; is it pitched away from the house? If not, this needs to be corrected.

Since you can see the buried cables inside the void, its a pretty safe bet that the "hole" is actually the trench that was dug for the utilities. It is pretty common since the dirt just gets "pushed" back over the trench and not "packed" into the trench.

[TMBGBlueCanary]

Originally Posted by K'ledgeBldr

I don't think "mud-jacking" is worthy in this particular scenario.

HP/condensers sit on a relatively small concrete pad- just dig it out enough so you can pack it full of dirt. Then look at the immediate topo around the area; is it pitched away from the house? If not, this needs to be corrected.

Since you can see the buried cables inside the void, its a pretty safe bet that the "hole" is actually the trench that was dug for the utilities. It is pretty common since the dirt just gets "pushed" back over the trench and not "packed" into the trench.

Thanks. I know little to nothing about this kind of repair. Give me a plumbing issue, small electrical fix, anything like that inside the house any day of the week, but when it comes to the outside drainage and such, I am not civil engineer. I only noticed it this week because part of my yardwork was repairing pavers that were also loose and wiggly from erosion.

It is a small concrete pad and I think you are exactly right that it's the trench the wires were buried in. The odd thing is, that trench is pretty old (I've lived in this house five years and they were there when the previous owners had the place). But we did get some bad storms in that time including a couple of hurricanes.

There is a slope to the yard, leading away from the house. So things drain properly in that regard. But I remember in those bad storms there was too much water to drain properly.

[K'ledgeBldr]

Just keep this in mind-

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