Pasa, the effluent flow to alternating leach fields should be alternated annually. Each leach field should contain 2 monitoring and ventilation ports. The ventilation ports provide a conduit for atmospheric oxygen to enter the aggregate in the leach field thereby allowing oxidation of the clogging mat that has formed at the gravel/soil interface. The oxygen also allows for an aerobic environment in the resting field where aerobic microbial digestion of the organic matter that has escaped the septic tank can occur.
The indigestible sludge, which accumulates in the septic tank should be removed when the measured sludge depth is 1/3 the liquid depth of the tank. I recommend that the septic tank outlet tee be fitted with a septic tank effluent filter. JWA