Hole underneath foundation in crawl space

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Old 08-24-13, 09:37 PM
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Hole underneath foundation in crawl space

There is an area of my foundation that seems to be missing concrete. During the rainy season, water pools in the dirt under the hole. The "missing concrete" is right where all of the pipes exit the house. Can I just mix up some concrete and fill the area? See attached pics.
 
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Old 08-25-13, 03:33 AM
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THAT's all the footing you have???? Amazing. Or is it just in a small area where the pipes are? Most often footings are up to a foot deep depending on your location. 4" is lacking in support. Having water pool in there is not a good sign and packing concrete may not solve the problem. Can you access the outside of the footing where the pipes are located? Fixing it from the outside will ensure a better water retardant factor.
 
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Old 08-25-13, 06:14 AM
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I'm pretty certain that that area used to be resting on the ground. The water has washed away the soil. I think you need to address the water problem first otherwise any repair will probably be undermined again.
 
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Old 08-25-13, 02:20 PM
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The 6" deep footing is fine for most of western side of WA, here. Appears they beveled the top edge for some reason.... You have a major leakage problem in the buried drain line as it exits under the foundation. Need to dig/inspect/repair to stop the settlement from the water packing the sub-soil, glad you probably have steel rebar (2) in the footing if as new as the DWV pipe.

Gary
 
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Old 08-25-13, 10:36 PM
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You have a major leakage problem in the buried drain line as it exits under the foundation
Yikes!!!!! Please explain. What is a buried drain line? It seems like it's not a leak related to my indoor plumbing since water only enters after a lot of rain.

I googled buried drain line and it sounds like a downspout from the roof that gets buried underground. There is definitely no downspout there. The closest one is probably 10 feet away, and that drains into a pipe buried in my backyard that slopes away from the house.

The house was built in 1994. I have no idea if there is steel rebar. I can see remnants of the wood forms on the lip of the footing.
 
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Old 08-26-13, 05:04 AM
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Normally a weeping tile is set along the bottom of the foundation to drain away any water that collects there....... I've never worked in your part of the country but assume that's what Gary is referring too. He should be back later to confirm
 
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Old 08-26-13, 06:20 AM
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I suspect it's an outside water/drainage problem. Make sure all your gutters and downspouts are clean and working properly to carry the water well away from the home. Make sure the ground outside the problem area is sloped to direct any surface water away from the home.

Garry in WA could be right about your houses main drain (sewer) line. If it is broken or if there's a hole in it the dirt under your foundation could be entering the pipe and get washed away creating a mini sink hole. If you go under the house during a big rain you should be able to get a better idea as to what's causing the problem.
 
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Old 08-26-13, 09:48 AM
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Here is a pic from the outside of the house. Nothing seems obvious to me.
 
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Old 08-27-13, 12:29 PM
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I replaced a wood post under a beam in a house due to soil settlement, 2" longer. Crawling around the post to attach cap fasteners, I looked over at the foundation wall with my light, WOW. The soil under the footing was 6" low of supporting, tapering to grade 7' each way= 14' of low soil. Told my house-flipper GC about it and he sent a crew in to spread a yard of pea gravel under it and out past the surrounding area including the low pier pad. Hide it all, with little support other than looks. The plumbing waste pipe- similar to yours, may have been leaking at a union/fitting (possibly not even glued- if work was done by my boss at the time, lol) saturating the dry soil; back-filled by hand from the plumber. When soil is wet, it settles/compacts due to gravity (good trick before pouring a concrete slab). It can all stay there in the same volume- just lower now from compaction. Capillary wicking can spread the water to the surrounding soil, even many feet above the leak. IMO, the pipe is leaking between the elbow fitting pictured and the side yard. To check, drape some plastic across the yard on the bark, tape to the concrete wall to get as slope for drainage away from the house, a foot high or so. Check underneath for water pooling after soaking house with hose for 20 minutes.

You could run a clean-out snake in the access on the side of house (if that ties in), or hire a plumber with a drain camera to check (also identifies location). DIY digging/visual inspection is much cheaper (plumber last resort)...

Gary
 

Last edited by Gary in WA; 08-27-13 at 12:35 PM. Reason: sp
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