Which factor does NOT affect the reliability and interpretation of the soil percolation test?

The reliability and interpretation of the soil percolation test are influenced by various factors that can directly impact drainage capabilities and soil characteristics. The shape of the test hole is not a significant factor affecting the outcomes of these tests.

Percolation tests are primarily concerned with how well water moves through the soil, which is greatly influenced by factors such as the soil profile, type, and structure, along with the size of the test hole and the soil's saturation level. The shape of the hole, whether it is cylindrical, rectangular, or otherwise, does not alter the fundamental interaction between the water and the soil particles in terms of drainage performance.

While there may be some considerations regarding uniformity in testing methodology to ensure consistency, the percolation performance remains the same regardless of whether the hole is round or square, making it less critical in the context of reliability and interpretation. Therefore, focusing on the characteristics that directly impact water movement illustrates why this factor does not play a significant role.