PERC test, at least in Aderson County, Tn, are only required IF the wrong type of soils ar at the 4 foot depth of a core sample. The health dept comes out with a manually operated core sampler to determine this at the tune of $500.
A mannually operated core sampler! This is a classic case of "bringing a knife to a gun fight". I've said it once or a million times, they dont call this part of the state Rocky Top for nothing. That manually operated core sampler made it about 8 inches before the guy told me I'd have to have a soil map done.
What's a soil map you ask?
A soil map is where you get to hire an engineer to come out and, with a powered core sampler, to take a core sample. Then he sends the results the Health Dept, who in return, sends you a report on what type of septic system must be installed, or if you need the additional PERC test.
Moral of this story:
If you plan on building a house in an area that requires a septic tank and drain field, hire the engineer first to do the soil map.
P.S.
I called an engineer Friday and left a message. Waiting for call back. Dis gonna be fun!