Therefore, the bottom 12 inches of the sidewalls and the bottom of the hole should be scratched or scarified with a sharp, pointed instrument such as a knife. Nails driven into a 1 x 2-inch board as shown in Figure 3 will do a good job of scarifying the hole to provide an open, natural soil into which water may percolate. Remove all loose soil material from the bottom of the test hole. The gravel can be contained in a nylon mesh bag as shown in Figure 4 in order to be removed after the test is performed and used for additional percolation tests. Distinguish between soil saturation and soil swelling.
Saturation means that the voids between soil particles are full of water.
This can happen in a short time. Swelling is caused by intrusion of water into individual soil particles. This is a slow process, especially in clay soils, and is why a prolonged soaking period is necessary for some soils. Carefully fill the percolation test hole with clear water to a depth of at least 12 inches above the soil bottom of the test hole. Use a hose to prevent the water from washing down the sides of the hole or add the water directly into the percometer as shown in Figure 6 .