In which formation cannot a septic system be installed if the bottom is less than 4 feet from the top of the limestone?

The appropriate context for the question focuses on the installation of septic systems in relation to geological formations and their specific characteristics affecting drainage and wastewater treatment. In this scenario, creviced limestone presents challenges that make it unsuitable for septic system installation when the separation distance between the bottom of the system and the top of the limestone is less than 4 feet.

When the top of the limestone is too close to the septic system, it can lead to inadequate treatment of effluent, as the porous nature of limestone might allow contaminants to migrate into groundwater more rapidly than they can be naturally filtered. The 4-foot requirement serves as a safety measure to ensure effective filtration and reduce potential environmental hazards.

While granite, sandy loam, and clay may have their own considerations regarding septic installations, they do not have the same immediate concerns regarding rapid effluent migration into groundwater as creviced limestone does under the specified conditions. Each of those formations has distinct traits regarding permeability and drainage, which need to be evaluated, but the critical issue in this case specifically lies with the restrictions related to the proximity to limestone.