I have a strange setup in the basement that consists of a pipe coming out of the cement floor, which then splits into two other pipes. One of them goes up and out to an area just under a basement window. The other just goes three feet into the air and stops, uncapped. Lately, during heavy rain there is water POURING out of the uncapped three foot pipe. It is clear water, not dirty, not swewer, but I have to fill buckets so that it does not soak the floor. I've included a pic but need to get this addressed ASAP. I have someone looking at it tomorrow, but any guesses would be welcomed. Thanks very much, and please view the attached photo:
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Could the uncapped pipe been a standpipe(drain) for a clothes washer?

It is a trap, so the short pipe is probably for a washing machine and the tall one is a "vent". Water does not flow uphill, so if it is coming out of that 3' pipe, it is coming from somewhere higher than that, and the downstream line is plugged so it cannot drain.

Agree with HJ, it's an old washer trap/vent. I wonder if it runs to an old dry well or grey water drain field? That would help explain why it backs up when it's raining.