My house was built with a deep basement such that the weeping tile was about 3 feet below the line to the sewer. The basement floor was cut to install a sump to pump groundwater to the storm sewer. After a serious flood I raised the floor by adding crushed rock and then a new concrete floor over this. On one half I raised the floor 3 feet and on one side by 1 foot. This is because the house is a side split. Most times the ground water level is below the old floor but during heavy rain the water level can rise above the lower new floor level even with 6 sump pumps. I think this is because the water is coming from the weeping tile into the sump. Would sealing the sump below the old floor cause any problems? I would still have the sump above the old floor to the new floor level (1 foot) to pump out any water during high rain fall events.