Alternative small waste water treatment systems are considered acceptable unless?

The acceptance of alternative small wastewater treatment systems is closely related to the depth of impervious formations. When impervious layers are found at shallower depths, there is an increased risk of surface water contaminating groundwater, as the wastewater may not be adequately filtered or treated before reaching these layers.

In this case, the presence of impervious formations at a depth of 10 feet signifies a potential obstacle for effective wastewater treatment. Wastewater systems rely on the natural filtration processes of soil to treat effluent, and shallower impervious layers can impede this filtration, possibly leading to the leaching of pollutants or pathogens into the groundwater.

Having impervious formations at a depth of 5 feet would pose a significant concern, as this is relatively close to the surface where wastewater effluent may be present. Conversely, if impervious formations are deeper than 10 feet, there is typically more soil available for natural treatment processes, which is less likely to pose a risk to groundwater quality.

Thus, alternative small wastewater treatment systems are considered acceptable unless impervious formations are found at a depth of 10 feet, indicating the limitations in the ability to effectively treat the wastewater using natural soil processes.