We have an older home that has new subdivisions built around us at higher grades. The problem is that when it rains or the snow melts, the water follows the slope downhill in the ditchline and causes our sump pumps to run like crazy! We live in an area where there are no storm drains, only ditches to carry the water away. The soil is clay and the water seems to follow the underground, gravel-lined, ditch located main sewer lines until it reaches the residential sewer lines running to each house. It then follows the gravel filled "underground water roads" right the base of our foundation causing the sump pumps to fire like crazy.
The idea that a plumber had given us is the dig out around the sewer cleanout in our yard down to the virgin soil. They remove the gravel and replace it with bentonite. I guess this is a clay like substance that hardens when exposed to water and will prevent water from flowing through it. They use the stuff to line the bottom of ponds to keep the water from draining out. So the idea is to build a "clay dam" to prevent the water from reaching the house and will prevent it from following the path of least resistance(at least the path to our house). It will continue downgrade following the underground sewer main in the ditch and should keep our sump pumps from running like crazy for weeks on end. When I say crazy I mean all 3 pumps run like every minute or so 24-7...This is causing me to lose a lot of sleep and I am looking for any help/advice I can get.

Thanks so much!!