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mhamel 12-22-2012 10:36 AM

2'x2' Hole in basement floor, sewer line access?
2 Attachment(s)
So we've been in our new home for a few months now (built in 1950), and I've found that there is a 2'x2' hole in our basement floor, it was under a small pallet that neither we, nor our inspector looked under.

My first guess was that this was cut to access the sewer line, but then I noticed that there appears to be a concrete patch running the length of that wall, so maybe it's drainage related? The concrete floor only appears to be a couple of inches thick, and there is a rotting wood frame around the edge of the hole. Upon visual inspection I don't see brick or tile in the hole.

During our home inspection, we found slightly elevated radon levels, so we've been thinking about adding a radon reduction system, but now I'm thinking this is probably the culprit. I thought covering it with plastic might be the best bet--I'm thinking access to these pipes probably isn't a terrible thing. At the same time I want to make sure I don't create a situation that causes the pipes to deteriorate.

Anyone have any insights as to what this could be, or what I should do about it? I found the thread below that shares some similarities, but I want to be sure.

Fireguy5674 12-22-2012 01:17 PM

From the limited amount of information that can be gleaned from the picture and description I am guessing this is where your sewer line exits your house. The line which is perpendicular to the basement wall appears to have a check valve installed in it. I cannot tell from the picture if that line continues or dead ends in the hole. The only other thing I can think of is that valve could be some sort of a pressure release device. Looks like a check valve. The concrete which has been removed and replaced seems to be in line with the other side of the Y in the sewer line. Where does your sewer stack come out of the floor to go upstairs? I don't think I would get in a hurry to fill this area with concrete. If you have only lived there a few months you have not experienced a full cycle of wet/dry conditions which may give you more clues why this is there. If you are concerned about radon and want to cover this hole I would replace the rotted lumber, build a cover with plastic backing and seal it up.

mhamel 12-22-2012 04:40 PM

3 Attachment(s)
Well I dug around a bit, and the perpendicular pipe does appear to be capped-off. I've also taken a couple of better shots of this possible check valve.

I've attached a drawing of my basement layout, as you said, I assume that the other side of the Y does go to the sewer stack, but that's on the other side of the basement-- so I still have no idea why the concrete appears to have been patched.

Fireguy5674 12-23-2012 08:15 PM

The valve definitely appears to be a check valve. Its is oriented to stop flow from coming back into the basement. The plastic plug in the end would seem to be a later addition because everything else is cast iron or galvanized. Why it is there is a mystery to me. Many possibilities. Why did they patch the concrete? Your guess is as good as mine. I still would not cover this area with concrete until I had given it some more time. Seal it up as suggested and leave it unless there is a pressing need to fill it in.

JoeD 12-23-2012 09:49 PM

That is definitely a check valve. The fact that it is on the end of the line means it is doing nothing. Maybe left over from something that has been removed.
It also looks like one used on water supply line. Why it is on the drain is strange.

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