Your almost done.
That pit is for a sewer pump. Those pipes you call a trap are actually the sewage pump ejection line connected to the pump vent- the one you are holding is the pump line to the future pump. The vent should be tied in on or above the first floor as you suggested. The sewage pump needs a 2" vent, so those two pipes will run independently to the pump basin(once the 90's are cut off). Not sure why the plumber has them looped together.
That pit is for a sewer pump. Those pipes you call a trap are actually the sewage pump ejection line connected to the pump vent- the one you are holding is the pump line to the future pump. The vent should be tied in on or above the first floor as you suggested. The sewage pump needs a 2" vent, so those two pipes will run independently to the pump basin(once the 90's are cut off). Not sure why the plumber has them looped together.