How to Measure Hydrostatic Pressure in the Ground

Choose the location where you wish to measure hydrostatic pressure. Use the hand auger to drill a bore hole with a diameter larger than the diameter of the piezometer pipe. A 4-inch-diameter hole is suitable for a 2-inch-diameter pipe. Drill the hole to a depth of 12 inches below the proposed location of the piezometer tip. A hand auger is adequate to drill shallow bore holes up to 30 feet.

Use the water hose to clean the hole of slurry and rock cuttings. Pour sand to about 6 inches below the proposed piezometer position. The sand acts as a filter to allow the movement of water to the pipe.

Connect the cable to the piezometer. Lower the piezometer into position. Pour sand into the hole up to a point 6 inches above the piezometer tip. Seal the space around the piezometer with a mixture of one-to-one bentonite to sand backfill, or bentonite alone. Use the hand tamper to compact the fill.

Connect the cable to the readout box and switch on the readout box. Note the recorded readings. These are measurements of the hydraulic head at the tip of the piezometer in the ground. The hydrostatic pressure there equals the product of the hydraulic head, the density of water and the local gravitational acceleration.