Dug up my tank the other day to check the sludge level. Found a few issues.
This is my tank:
Found that the outlet pipe is not connected to the drain field:
Looking in, noticed the level is below the inlet baffle so water is dripping onto the surface instead of entering below:
Also, with the outlet inspection plate off, water level is well below the outlet pipe.
SO. I'm guessing that there's a leak/crack in the tank that's not allowing it to get up to level (after checking the morning after, the level had dropped off a bit more). The "soil" in the back is mostly blast rock and sand so I guess that's why nothing's ever shown up (other than the occasional smell when lots of water is used).
I'm not super concerned about it since it's probably been like this for years prior to us moving in 3 years ago. Also, there's not really any way to get machinery into my back yard (very steep slope on the back and the house is in the way in the front). Also, the town is hopefully going to be running sanitary sewer up into our neighborhood within the next 5 years.
So, this is what I'm thinking for a stopgap for now.
- use a flexible fernco fitting to connect the outlet pipe back to the drain field pipe (just in case I can get it patched up or if there's a lot of water used in a short period of time and it does manage to fill up)
- on the inlet side, make my own baffle with 4" ABS (elbow with a straight length down under the surface of the water).