Their are three zones of fluid in your hockey box. The top layer consist of all the floaties. A big frosty layer of TP, corn jiblits, ect. (use your imagination). The middle being mostly liquids and gases floating to the crust. This is the area where the tank is doing work and digesting the effluent. This area is also the largest in a healthy tank. The bottom, well that where "the shit hits the floor". All the heavy solids end up here til bacteria and other "good bugs" eat and work it down to a liquid brew.
In NC and other states tanks are two compartments separated by a baffle wall. This wall is designed to help keep the more solid stuff isolated til it has a chance to work off. The opening between the two is supposed to be in the fluid zone. About 2 to 4 inches above center if I remember right. The outlet end also incorporates a tee. Some where on both ends. The tee can also contain a removable plastic filter screen. Thus the reason for concrete or plastic risers in your yard, or you get to dig up the tee cover for periodic maintenance. Some home owners choose to chunk the tee filter, bad in my opinion. It's sole purpose is to catch and prevent solids from killing the leach field. I'd rather rinse A tee out than dig up or install a secondary field. A tee forces the flow to exit the tank at a predetermined height in the liquid layers. Its basically a sump that doesn't allow the whole tank to gravity drain. The pick up is several inches off the bottom and the outlet approximately 6 inches off the top. A precast tee is part of the tank and may or may not have the filter insert. Pvc tees are just that, a pipe placed during the concrete precast.
Back to the TP. To much of any non biodegradable product is bad, DUH HUH! Some is safer yes, but its all about volume. So the wife or daughter who clogs the thrown on occasion is slowly but surely killing your septic. So on top of the extra tp a much bigger expense is coming. TP and other things take up space. Space needed for a healthy liquid level. Also over the years a normal tank just needs pumped, solids do back up. So a build up floaties, too many solids, and not enough liquids.
You get a short circuited system that starts dumping waste your field cant handle. This reduces water absorption and thus you get the black tide. Just like your tank a yard can't readily break down certain deposits. Leach fields that can remain dormant for extended period have proven to heal themselves and break down the short circuited waste but who can wait a few yrs to take a dump? I do know a few people who rotate fields via a ball valve for this reason.
