Saturated hydraulic conductivity (Ksat) testing is required in North Carolina when seeking a reduction in the required vertical separation between a septic system trench bottom and a unsuitable soil feature by pre-treating wastewater effluent; or, if you are attempting to justify a higher long-term acceptance rate (LTAR) for wastewater disposal on a particular site. Saturated hydraulic conductivity is a quantitative measure of a saturated soil's ability to transmit water when