I have used several methods to rejuvenate septic leach fields.
The best solution I have found is to replace the leach fields with a new system. Leave the old system alone. Install a Y near both systems and put valves in. That way the new system is being used while the old system recovers. Then in 20 years or so when the new system fails all you have to do is turn a valve. Essentially you have an “A” and “B” leaching system. This is also the most expensive.
I have also found that installing a “Surge Tank” is very effective. One of the big reasons septic systems fail in multi-family is the effluent never stops running. A septic system is designed to have a big Flush of effluent twice a day. In the morning and in the evening. The leaching system should fill up and then drain away. Leaving several hours of dry time in between “Flushes” (pun intended). In MHPs there are so many people the leach field gets a constant trickle of effluent. That constant trickle allows the biomat to form and then slowly blocks the leaching system.
Surge-Tank-d1556.pdf (111.2 KB)
At one of my parks (we sold it last year), we had a lift station, gravity feed tanks, surge tank, and then out to pressurized leach fields. The surge tank was 1500 to 2000 gallons. The pumps would empty the tank and flood the leach fields. Then the leach fields could rest until the surge tank was full again. No more constant trickle. This also serves to aerate the leach lines, since the lines would be able to dry out.
I have also used treatments. They work ok. Depending on the problem. I have found that oil and grease “bait balls” work really well.
BIG TIME Blower/Aerator