My septic system's leach field is not able to absorb the liquid that comes out of the septic tank any more. It flows out of the pipes in the leach field and surfaces in the grass. Based on the reading I have done (the "Septic System Owner's Manual" by Lloyd Kahn which is very good) there is a chance of recovering from this problem by installing an aeration system.
An aeration system pumps air into the septic tank, thereby encouraging the development of "aerobic bacteria". The aerobic bacteria need air to survive, and are more voracious eaters than the an-aerobic bacteria that are typically present in a septic tank without air pumped into it. The idea is that the aerobic bacteria will clean up the fluid in the septic tank and then they will also make their way into the lines of the leach field, clearing away the "bio-mat" that has formed over the years. This bio-mat is the thing that is clogging up the leach field, preventing it from doing its job.
Anyway, there are quite a few air pumping systems out there that are designed to be installed into an existing septic system. My question is, does anyone have experience with installing such a pump to deal with this type of problem, and if so how effective was it at clearing up the problem? Is it worth the investment? For some reason these systems seem to cost around $1,000, which seems a lot for what is basically just an electric air pump.
Update: I had the air pump system installed in April 2011, so let's see how it works..! It is an aero-stream unit which sits near my outside electric outlet and there's a plastic tube that is buried a few inches and that goes into the septic system via the outlet riser and down into the liquid. It pumps a lot of air in, the liquid churns around and bubbles continually. So far, I can say that the septic liquid is no longer foul-smelling. It has almost no odor any more. The level of liquid varies, depending on rainfall and water usage. Sometimes it comes to the top of the riser, at other times it's about 10 inches below the top. If this system works, I'm expecting that the level of liquid will fall gradually. This means that the lines are being cleared of gunk. Time will tell... I'll try to report back periodically.
Update June 30 2011 The level of liquid in my tank is about 18 inches below the top now. Very encouraging so far. Mind you, the Spring wet season is behind us, so it could just be due to the water table being lower in the summertime. Also my family was just out for a couple of weeks on vacation which took all the load off the septic.
Update Aug 20 2015 The aeration unit helped a lot but by itself wasn't enough. I ended up digging (by hand) a new "overflow trench" from the tank outlet. I used 3/4" gravel plus a piece of perforated plastic drainage pipe at the bottom. The trench was about 2 foot deep and 30 foot long and ended at a large flower bed which is slightly downhill from the septic tank. With the aeration unit plus this new overflow trench my septic tank is working well enough to not need replacement. The aeration unit ensures that the effluent that sometimes drains into the overflow trench is not foul smelling. This has been working for a few years now. Overflow will happen during periods of high usage such as lots of showering/dishwashing. It's not perfect but it's good enough.