I need to have a sewer line repaired and one of the options is to tunnel
under and the spot is about 5 feet from the exterior wall.
The company provided an estimate to dig using a "vaccon truck". Did a
search and cannot figure out what this is, is this a mini-horizontal
After the line is repaired, they said they will back fill with a
"non-exacavatable flowable fill". What type of material is this? Is it
plastic? If they run into a footing, do you know what is a standard
procedure? Break the footing there to get through, or go under the footing?
Will the back fill material be able to fill the void ABOVE the footing line?
I think you misheard. I'm sure they referred to a vacuum
excavator. Here is some information:
Flowable grout is cement and sand with a high water content. It
is usually made up to test between 600 and 900 psi. It does not
require compaction and will fill up spaces just as water would
avoiding settlement and voids.
(top posted for your convenience)
Keep the whole world singing . . . .
DanG (remove the sevens)
I did some search and found one reference where one guy was selling a
"vaccon truck" here is the link:
may be it's some high tech stuff? I will call the company to find out. I
just want to make sure it's not something that will chew up the bottom of my
house and cause a sink hole...
If they tunnel under the house, and go under the footing, there will be dirt
above the footing line that they need to exacavate to access the pipe which
I don't think they can they can back fill because you can't back fill "up".
I am not sure I am saying this right, but without some sort of pump to pump
dirt upward how can they back fill the void below?
When you're in Rome, top-post like the Romans.
I think the excavation probably will be some kind of hydro-excavating.
Picture a BIG pressure washer and a BIG wet-vac and you get the idea.
Won't damage pipes, roots, concrete. Sink-hole? hmmm. Ask them if their
insurance will cover cracks in your floor or tile.
DanG's guess is as good as mine, I think you'll find they can back-fill
"up" just dandy. My concern would be the "non-excavatable" part. If
they fill their hole with a big concrete blob, you're never going to be
able to get back under there the next time this happens. What then?
Flowable fill is a material made by a ready mix company and delivered in a
mixer truck. It consists of sand, water, fly ash and a small amount of
cement. It has a high water content and is very flowable. It's designed to
achieve more strength than compacted dirt and is 100% compacted once it
sets. It's usually designed to be excavatable with power equipment.
Will it expand after being apply? What is the chance of it cracking the PVC
pipe as it cures?
So after it sets it's like concrete, in the event more repair is needed they
will need a slugehammer?
My wife vetoed it. Did not want to:
(1) Ruin the tiles - no replacement.
(2) Have "yuck" or cockroaches coming up the kitchen floor.
(3) Deal with dust and debris from the digging.
(4) Remove/Replace cabinets that are sitting on the problem spot.
She rule the kitchen so I have to fix it from the outside.
biggest concern about tunnel under footing would be that your footing is
putting all the soil under it in
compression from the weight of the house. when you tunnel under, x square
feet of footing soil will have
that compression removed, thereby transferring load to the footing to each
side of the tunnel. if the soil under
the footings is already of questionable stability, you might get some
if you were going through the foundation wall, the concrete could probably
absorb the load change without problem.
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