Ok, I'm looking for someone who has lived with colverts and had them as part of your driveway. We cross a creek with 3 colverts buried in rock and when we have the heavy rains all 3 colverts fill almost to the top, but have not given in to the creek yet. When the rain is over the water level goes down and there is only a small amount of water that goes through the colverts. My concern is and I have not seen it happen is the colvert come flying out of the ground because of the water pressure. I suppose this can happen but I hope it does not. These colvert are plastic, black in color and are smooth inside. Does this make a difference? ???????