I have a small shop behind my house that is on a location that is not accessible to connect to my house septic tank/system. I have a toilet and sink in the shop, I was considering using a 500 gal fiberglas tank as the septic tank and running feeder/distribution lines as with a normal concrete tank.
However, I am not quite sure how to position the inlet and outlet pipes into the tank. I think I remember the inlet pipe needs to be positioned higher than the outlet pipe. Any assistance on this will be helpful. But basically I would like to know how to make the fiberglas tank work as a does a concrete tank.

I found a fantastic resource, "How to build Septic Systems", which includes the use of fiberglass septic tanks.

Everything from performing a Site Evaluation, to Soil Density and correct Slope.