I can't speculate on what that "14 inch limiting factor" is.
I do know that if you want to install a proper, working septic system you need to have it professionally designed and reviewed; that may require the assistance of a soils engineer. To get the permit for such it will require a perc test. Here in the county I'm in, Mecklenburg, North Carolina, they require traditional core borings. However, the next county north, Iredell, requires pits to be dug with a back hoe: it's a far more invasive and costly test. The result of the test will determine the needed amount of drainfield, the tank size, and the size of the home that the system will support.
In the aborted attempt I mentioned, we made the permit application, hired a GC to manage the process, and he got the backhoe operator. The county septic guy did the testing with the open pits. Then he drew a rough map with all the required setbacks, etc., which were pretty severe. Our designed system required 240' of double stack T&J panel in a 36" deep trench, 24" wide...and if that wasn't enough, you need an identical drain field called "the repair field" for when the first one fails. So, we needed 480' of double stack T&J panel in those trenches and a certain distance between them. That would only support a 2000 square foot 3 bedroom home which was too small for us on this half acre lot. The owner had a dual listing on the lot, for a custom 2800 square foot 4 bedroom home "to be built". She also had the soils work done but not with a permit, so she knew in advance what the limitations were. That's why we got every penny back including our costs with the GC, the soils engineer, and the permits.
So, hire your own, talk to the town or county...