"Manhole" cover in basement, moving water at bottom?

[sjb1]

I've just moved into a home in Minneapolis built in 1956, and there is something I've never seen before in the basement - there is a hole in the floor several feet deep covered by a piece of metal resembling a manhole cover. Around the outside of the hole it starts spelling "Minneapolis" before the rest is covered when somebody redid the floor of the basement.

When you pick up the cover, the sides of the hole appear to be made out of clay, like it was originally some kind of barrel or cylinder placed there. At the bottom of the hole there is a gap of 3-4 inches between the clay sides and the ground underneath. The ground looks like a mixture of concrete and gravel, and I can see some metal wire mesh sticking out as well.

When I first looked at the home and when I did the inspection, the ground at the bottom of the hole was damp, but there wasn't any water sitting there. I will note that it had been raining quite hard all day when I checked during the inspection. Now, several days since it last rained, there is a stream of water flowing through the bottom of the hole. The hole is near the foundation wall of the house, and the direction of the water is from the foundation wall towards the center of the house (see diagram).

I have two questions:
1. What in the world is this?
2. Do I need to do anything with it?

Any help is appreciated!

I think my pictures and video are too big to upload but here is a link to the items in my Google drive - https://drive.google.com/open?id=0B-p09AjIszR8REJmWHpVcXZCMlU
If I should be sharing these in a different way please let me know.

 

[frodo]

looks like a sump pit or area drain for foundation water.

you did not have the mechanical systems inspected by a third party before buying ?

damn,,,contact old owner and ask,

or, shove a sewer camera in that line see where it goes..i would have had the realtor pay for this camera inspection..
it is pricey

 

[sjb1]

I did have an inspection done, and even had a concrete/foundation guy come look at it. The inspector had no idea what it was and had never seen anything like it before, the concrete guy thought it must be some sort of drain and thought I should just fill it with concrete. There wasn't water flowing through it when either of them looked at it though.

Would there be any harm in filling with concrete or any reason I shouldn't do that?

 

[frodo]

I did have an inspection done, and even had a concrete/foundation guy come look at it. The inspector had no idea what it was and had never seen anything like it before, the concrete guy thought it must be some sort of drain and thought I should just fill it with concrete. There wasn't water flowing through it when either of them looked at it though.

Would there be any harm in filling with concrete or any reason I shouldn't do that?

i would not, untill i found out where it went.

have a plumber with sewer camera take a video.

then go from there. my opinion

 

[SHR]

Common in many older Minneapolis homes. Follow Frodo's advice.

It seems your "inspector" was as competent as most in the Twin Cities area: They have no idea of how to inspect a home. They are really good at cashing checks though.

 

[sjb1]

Frodo - how big does the hole need to be to fit a sewer camera? From what I can see there's only a 1-2 inch space there. It doesn't seem like a smooth pipe interior that you could easily thread a camera into. I can open the area up a bit more tomorrow to get a better view though.

SHR - If you've seen something similar in the Minneapolis area, could you hazard a guess at what the original purpose was?

 

[Mr_David]

Any Pictures ?????

 

[sjb1]

Any Pictures ?????

My pictures were too big to attach directly, can you see them at this link? https://drive.google.com/drive/folders/0B-p09AjIszR8REJmWHpVcXZCMlU

 

[SHR]

In the many homes I have seen them in, it appears to be similar to a sump basin that drains directly in to an opening in the main drain line from the home. Seems like a real bad idea...

 

[sjb1]

In the many homes I have seen them in, it appears to be similar to a sump basin that drains directly in to an opening in the main drain line from the home. Seems like a real bad idea...

Well it seems like that's correct. I dug out a bucket's worth of clay from the hole and discovered a pipe leading away from the drain that connects to the main drain line after 2-3 feet. I stuck a short camera snake down there and verified that when I turn on water in the sink I see water coming down the main drain line.

I also found what looks like a clay pipe, probably 6-8 inches diameter that is likely the source of water coming into the hole. (picture 8 in the link).

https://drive.google.com/drive/folders/0B-p09AjIszR8REJmWHpVcXZCMlU

A neighbor thought the clay pipe might be coming from an external french drain system around the house, which would make sense. My thought at this point would be to cap the line attached to the main drain, and put a sump pump in the hole to pump out any water that accumulates down there. However I'm still concerned about the 60 year old external french drain system that could break or clog at any point...

SHR, In the houses you've seen this before how did they deal with it?

 

[SHR]

I was never in the home to deal with the manhole, so I always left them alone. I always had other issues I was hired to be working on.