I lived in my current house for five years. Location is Chicago suburbs. I never had an issue until last summer, in a bad summer storm I had my basement flooded due to failed sump pump and failed backup pump. A licensed plumber came in and opened the sealed pit (due to radon) and installed two new pumps, he did not re-sealed the pit. Five months later, one month ago, I noticed a horrible odor, coming out directly from the pit. I flushed the pit with a garden hose and 3 gallons of bleach, the older went away only to come back the following morning. I examined the bottom of the pit, nothing unusual, the water is dark grayish, and some water trickling from the drainage opening into the pit, I collected a sample, it looks clear, does not smell too bad. I bought a new lid and completely sealed the pit, the smell is still there, maybe stronger! two PVC pipes come out on the pit cover, each connected to each pump, they drain outside the house separately, additional galvanized smaller maybe half inch pipe come out, goes into the ceiling then I do not know where, not traceable. I have full finished basement with floor tiles and with radiant hot-water heating, it is working fine, no visible leaks. I have a bathroom next to the pit, it is used often, I also flushed it with Clorox. Next to that I have an ejector pump which is completely sealed, no odor. And the furnace room there is an additional pit with sump pump, it has a cover but not sealed, seems to be working fine, no odor.No leaks no clogging no odor anywhere else in the house. I do not have a septic tank, the village has well maintained main sewer lines. One interesting observation, it is when I disconnected the pumps, the water level filled up above the drain opening inside the pit and covered it, the odor miraculously disappeared for one day, then came right back when I restarted the pumps and the water level sank below the opening!! the check valve is see-through, the water color is grey-ish. The check valve is only installed on the main pump.I placed food coloring on all the sinks and showers and toilets, the color in the check valve remained the same. I do not know how to proceed, any advice? If you need any further clarifications, please ask Thank you in advance.
