From documentation left with our house we know that our sump pump used to empty into the sanitary sewer. In the early 90’s the home owners took advantage of a city grant that paid for moving the drain to the storm sewer. We assume that the pictured drain pipes were installed at that time. We have a receipt that indicates the work was done by a professional plumber and we suspect that it was probably inspected by the city at the time.
In the lower right of the picture, the drain leaves the front of the house toward the storm sewer. Our front yard slopes downhill, so this level should be comfortably above the level of the storm sewer itself. From the upper left corner of the picture the pipe continues through the ceiling to the back of the house where it drops fairly directly into the pump.
Question 1 - What is the purpose of the upside-down U bend and the split into two separate pipes which then rejoin halfway down the wall?
Question 2 - If I were to simplify this pipe, is there something that might go wrong?
I've asked two different professional plumbers who were in the house for other reasons and neither had any ideas.