Hole in basement floor


  #1  
Old 12-28-16, 10:24 PM
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Hole in basement floor

I have a12 inch diameter hole in my basement floor filled with rocks. There is pvc around the edge of the circle. After a lot of melting outside recently some water appeared in the hole.

It looks like it was covered before the basement was finished with a sheet metal cover, which looks to have been removed when it was finished. I can't use the cover now because the framing is in the way.

I just bought the house a month ago from the original owner, it's about 13 years old. There's no odor coming from the hole and the rest of the basement is bone dry.

The sump pump is on the opposite corner of the basement and sealed. There is also radon mitigation installed in another spot which seems kind of pointless now with this hole just sitting there.

What on earth is this hole for? Can I buy some pvc for a cover and cut it to diameter, sealing it with silicone?

Here's a pic:

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https://goo.gl/photos/4gwwSdoSLovH4eTa8


Thanks in advance for any suggestions.
 

Last edited by ray2047; 12-29-16 at 12:31 AM. Reason: Add image.
  #2  
Old 12-29-16, 05:29 AM
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Your neighborhood probably has a high water table. If you fill the hole, you don't know where the water will appear.
 
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Old 12-29-16, 05:45 AM
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It's got to be a secondary location for a sump. Judging by the size of the patch I the concrete, they allowed space for a 18" basin, but must not have used it for some reason. I wonder if this is the basin they used instead. Polylok 3017-12C 12" Round Septic Distribution Box or Drain Basin

I think I would dig out the rock and investigate further, see if drain tile is connected to it, see if it's connected to your sump somehow... when the sump comes on does the water level lower?

But to answer your question, yes, you could silicone a cap over it. How long it will remain waterproof is anyone's guess. Personally I don't think it's a good idea for the framing to cover the edges of the lid. Those sill plates should be notched to allow the cover to be taken off easily. You could also see if a cap from the link above would work, although it may not be low profile.
 
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Old 12-29-16, 07:35 AM
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Thanks for the replies.

So I dug some of the rock out and found a 4-6" diameter capped black pipe with water sitting on top of it. Is this a sewer clean out? Or was it possibly a stub for a shower?

Here's the pic:
https://goo.gl/photos/QyH5b43jvfkG7qKC6

I'll try to dig down a bit further tonight when I have some time and figure out where the water is coming from i.e. the pipe or from under the foundation somewhere else...

I'll try pulling the cover off the sump pit and seeing if it's dry. If not, I'll try running the pump to see if it pulls any of the water away from the hole.
 
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Old 12-29-16, 07:44 AM
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Assuming you had decent relationship during the sale you might see if your realtor could pass along a note through selling realtor. Might save a lot of guesswork.

I've never seen anything like that before!
 
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Old 12-29-16, 07:53 AM
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I've never seen anything like that before!
It's seen in areas near bays & canals as I said, with high water tables.
 
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Old 12-29-16, 09:59 AM
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Donoli2016, what purpose does it actually serve then? Since there is water sitting on top of the pipe cap, i dont believe it is connected to the drain tile?

The house is near a bay (1 mile or so), but the land is very high above bay level. The community is called bay highlands.
 
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Old 12-29-16, 02:57 PM
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sublimer, who knows what they did over the years or where that pipe goes? Maybe you can get the plumbing plan from the building dept or find the architect. Also, who knows, why they called it the Bay Highlands & if it's truly highlands.

When we moved from Brooklyn to the suburbs, there was a similar hole & my parents filled it never to be seen again. I don't know who advised them. Some years later, I lived near a canal & there were many houses with a hole that filled when during high tide. Personally, I wouldn't fill the hole yet. Try to get some info. Ask some neighbors if they have the same thing.
 
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Old 12-29-16, 04:15 PM
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sublimer-

After a lot of melting outside recently some water appeared in the hole.
My bet would be what XSleeper mentioned. I wonder if it is a floor drain connected to drain tiles outside. In other words, itís not connected to the sewer system but itís connected to the storm water handling system, and when they finished the basement they decided to just cover it up.

I have 4 drains, one in each corner of my unfinished basement, each drain connected to the underground gutter system. It all drains to daylight. Sometimes on an extremely hard rain I get some water backup out of one corner drain.

I donít know how you figure out if itís a drain though. If you had something outside that drained to daylight I guess you could add a slow flow of water to that hole and see if it came out the other end outside. Thatís how I traced my drains. But I know you have to be careful because your basement is finished.

But as donoli says it might be best to find out more before you cover it up.

Maybe if you go through some really good hard rains without a problem you would in fact be OK to cover it up.

Thatís a tough one IMHO Ė but Iím sure no expert.
 
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Old 12-30-16, 09:49 AM
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Thanks again for the responses.

I opened the covered sump pit last night and to my surprise it was bone dry...dust on the bottom. There is one drain tile pipe leading into the pit.

Why would there be standing water in the gravel 1" under the slab at this point opposite corner of the sump pit, but the sump pit is bone dry?

Sounds like my drain tile may be clogged or I possibly have a broken pipe...any thoughts?

I also sent the old owner a message to see if they could tell me at least what the hole/pipe is for.
 
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Old 12-31-16, 06:30 AM
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A complete basement sump pump system has drain tile going all around the perimeter of the foundation, either inside or outside.

This will intercept water seeping in from the outside anywhere around the foundation except through cracks in the foundation wall above slab level.

Not all sump pumps have this. A sump pump all by itself will "protect" the basement floor only for a few feet around it, the radius depending on the porosity of the soil under the slab.

If you pour a lot of water on the floor will the water flow towards this hole?
 
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Old 12-31-16, 09:20 AM
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Why would there be standing water in the gravel 1" under the slab at this point opposite corner of the sump pit, but the sump pit is bone dry?
Because the water table is higher in that corner.
 
 

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