My house was built in 1940. I recently pulled up the floor and subfloor in the basement and noticed this basement pit. There was about 6 inches of water in the bottom which I drained. Below that is a layer of what I think is home-heating oil. Maybe the house used to have an oil tank inside that leaked (it now has an electric boiler). I removed most of the oil; below it is clay soil. The pit is about 3 feet deep. The short pipe comes from the garage floor drain (I think). The 90 degree pipe goes to the sewer system (I can hear it). This pit has probably not been opened in at least 30 years. There are no signs of flooding or water damage in the basement.
My questions are:
- Is the idea behind this that water drains down through the clay soil? If so, maybe the oil was blocking it, that's why there was the accumulation in the pit?
- Is the pipe to the sewer system for overflow should the pit fill with water and not drain quickly enough through the clay?
- Should I be thinking about putting a sump pump in the pit?