How is a Septic System's Feasibility Determined?
Feasibility of a septic system for a lot starts in much the same way as with a full design, with soil investigation and testing.  A suitable number of percolation test holes and deep observation pits are dug in the area of the proposed leaching system.  Many counties require a total of four observation pits and two percolation tests.  This requirement allows for two deep observations pits and one percolation test to be dug in the area of the primary leaching system and two deep observation test pits and one percolation test to be dug in the area of the reserve leaching system. These soil observation test pits and percolation tests supply the constraints for the design and construction of the septic system. Typical design constraints include the maximum depth of the septic system leaching fields and the rate at which water moves through the soil.

The data collected during the soil investigation and testing is then used to determine the minimum size of the septic system that must be illustrated on the subdivision plans.  To complete the septic system feasibility plans, an approximate house location, driveway, and well, are shown in relation to the septic system. In addition, these plans also show the required size of the system and demonstrate that all required setbacks are met.  The septic system feasibility plans do not supply installed elevations, detailed grading, or installation details.