I know that soil testing is a big part of septic design, but I'm not exactly sure what they're looking for. Is it just about drainage, or are there other factors like soil type and depth that matter? I'm also curious about how many test pits are usually dug and whether the process is disruptive to the property. If you've had soil testing done, I'd like to know what to expect and whether the results ever lead to major changes in the system design.