Slight sewage smell in basement and sump pump
I am Guessing this a sewage pit/ sump Based on the size and that there are 2 pipes and in that case it should be sealed and there should be a gasket under the lid. I have seen pits with a float and a stick that were not a tight seal and when a toilet flush or running water there was a smell until the pump kicked in. I installed a internal sensor that measured the distance to the water level where the stick was and eliminated the smell totally by sealing but they still had a high level indicator.