How to Grade Over High Water Tables

Create a sloping bank away from the future structure's foundation using a motorgrader or bulldozer. The grade's percentage of slope depends upon the amount of space between the structure's foundation and nearby street. Small spacing requires a steep slope, such as 20 percent, whereas larger areas can have smaller slopes, such as 3 percent. Each job site is unique, based on its available spacing.

Grade the structure's intended base area to an almost perfectly flat surface with the motorgrader or bulldozer. This flat surface will ensure a level beginning for the structure's foundation.

Install drainage piping within the soil that will reside beneath the structure's foundation. Ensure that any water discharge outlets are properly placed at the slope's edge, allowing the high water table's water to flow out to the street's municipal drains.

Install a sump pump for moving the water through the drainage system. Locate the sump pump on the outside of the structure's foundation to allow access for repair and replacement. The drainage and sump system effectively lower the water table for the immediate area.

Verify that the graded slope is still intact after installing the drainage for lowering the water table. Run the motorgrader or bulldozer across the sloped area again. Any areas that require a cut and fill with soil will be obvious as the machine's blade moves across the surface. Add soil to any accidental holes made by the drainage installation. Smooth out any soil uplifts with the machine's blade.