About a year after we moved into our house, our drains quit draining properly. I opened the cover to our septic tank and discovered that the floating sludge in the tank was blocking the inlet pipe. I used a mattock and punched the floating sludge down into the septic tank and everything was fine... for about a month. But the problem kept re-occurring at the most inopportune moments. The solution was always the same... open the septic tank (blecch), and use the mattock to move the sludge away from the inlet pipe.
Today I decided to fix this once and for all. I surmised that something was wrong at the septic tank outlet... causing the water and sludge in the tank to raise to a problematic level. I dug up the outlet cover and peered into the tank. Yep, something was amiss. The outlet baffle was cocked upward, keeping the effluent in the tank about 3 to 4 inches higher than it should be. (see photo above)
|before the fix|
The pipe from the septic tank outlet to the leach field had settled into the soft ground about 3 inches (while the septic tank stayed put on solid undisturbed ground). The fix was to cut the old elbow out with a battery powered sawzall, add 3 inches to the vertical portion of the outlet pipe, and reattach a new elbow.
|after the fix|
This allowed me to reset the horizontal outlet pipe to be truly level. Everything seems to be working fine now. Some septic systems have an inlet baffle, and I might someday have to add one of those... but for now, I'm going to see if this works for several years without an inlet baffle. For what it's worth, you never want to operate a septic tank without an outlet baffle, as this would fill up your leach field with floaters. Here's what the working outlet baffle looks like now (notice the water line in the septic tank is 3 to 4" lower than before).
I found this web site to be a great septic system debugging resource: http://www.inspectapedia.com/septic/tanktees.htm