The septic system doesn't end with the tank. The drain field is where the effluent ends up after being processed in the tank. Here it percolates through the field until it has been processed sufficiently to re-enter the groundwater.
Damage doesn't occur overnight. Regular field inspections can help you spot trouble signs early. The earlier you spot an issue, the more likely it can be repaired.
The most obvious sign of a developing drain field problem includes the smell of raw sewage from the field, particularly after wet weather. You may also notice water pooling on the surface of the drain field, or the ground may seem much soggier than usual. Indoor trouble signs may include slow-moving drains or even overflowing drains. This occurs when effluent can't exit the tank and goes into an oversaturated and failing drain field.
Repair vs. Replace
Once a drain field problem is recognized, the next decision is whether the field can be repaired or if replacement is necessary. Generally, repair and restoration are preferred. Replacement can be difficult, especially if a new drain field site must be found as the old one is no longer usable.
Fortunately, full replacement is typically only necessary if the site has failed in a way that cannot be repaired. For example, if erosion has destroyed the soil structure or if groundwater or surface water movement nearby has made the site a permanent flood plain or wetland, it cannot be repaired. Otherwise, your field can be repaired so that it is restored to its former usefulness.
The method of restoration depends on the root of the issue along with its severity. Biological issues are the most common, and these are caused when the microorganisms in the field are out of balance. Clearing out the drain lines and the addition of additives to aid in healthy biological balancing will typically help. In some cases, the field may be too small for the tank, so adjustments to field size may be necessary.
Compacted soil for tree roots or driving on the field may require aerating the soil and repairing or replacing some of the lines feeding the drain field. If flooding from nearby irrigation or runoff is an issue, the necessary restoration may also include rerouting runoff water so it doesn't flow into the drain field and instead flows harmlessly to storm drain systems.
Contact a drain field restoration service if you are noticing issues with your system.