UPDATE: Thanks again to all who responded to this thread! I now know more about septic systems than I ever wanted to!
Ultimately the system failed the inspection. It needs to be completely redone on a new site including a new leech field.
We are waiting on a quote for the new system, but due to the difficult layout of the yard and a pool which is directly in the way, we are probably looking in excess of $30,000.
The house is a short sale so we're waiting to hear if either the owner or the bank will fix it. If not I guess this house is out of the running ($1000 in inspections later).
Damn.