In which type of ground are perc tests not allowed?

Perc tests, or percolation tests, are conducted to evaluate the drainage characteristics of soil, which is essential for the design of wastewater treatment systems like septic systems. In this context, fill or disturbed ground is not suitable for perc tests because the soil’s natural properties have been altered through the process of excavation, compaction, or the addition of soil materials.

When ground is disturbed, its ability to infiltrate water can be significantly compromised, leading to misleading results from perc tests. This can occur because the structure of the soil may have changed in ways that do not accurately represent its original drainage capability. As a result, when planning for wastewater management, it is crucial to test undisturbed soil to ensure that assessments reflect true hydrological conditions.

Loamy soil, unsettled terrain, and frozen ground have specific characteristics that may affect the results of percolation tests, but they can still be tested under certain conditions. For instance, though frozen ground presents challenges, it is often more related to timing than to the fundamental nature of the material itself. Unsettled terrain could be evaluated if properly stabilized, while loamy soil is generally regarded as acceptable for perc tests due to its balanced texture and drainage properties.