There is a small pit (a round pipe or sleeve about 12" across and 12" deep) in the concrete basement foundation that is access to a back water valve. The cap of the back water valve is rectangular and the small spaces between the cap and the edges of the pit are sand. We have had a large amount of rain this year and water from the ground under the foundation is seeping up through the sand until there is about 4-5 inches of standing water in the pit. If I empty it out the water seeps back in again to the same level and stops. I believe it is due to the fact the ground is completely saturated with all the rain we have had this summer. The water is clear and not stagnant. There is already an external sump pump installed on the exterior of that same corner of the house that is functional. I need to find a way to seal off the ground between the edges if the pipe. I am open to any ideas or suggestions you may have.