What is placed at the bottom of each perc test hole before filling it with water?

In a percolation test, it is crucial to establish the drainage characteristics of the soil in a potential leach field. Placing 2 inches of gravel at the bottom of each perc test hole is essential because it creates a stable base that allows for accurate measurements of water infiltration rates. The gravel provides a consistent medium for water to flow through, helping to measure how quickly the water dissipates into the surrounding soil. Additionally, the gravel ensures that the bottom of the hole is not affected by soil compaction or clogging, which could skew the results of the test.

This practice aligns with established methods in septic system evaluation, ensuring that the data gathered reflects the natural absorption capacity of the soil above and around the gravel, facilitating suitable site evaluation for septic system installation.