The leach field is a very important component of your septic system. A leach field is made from a series of perforated pipes (called leach lines) buried in shallow trenches full of gravel and covered by dirt. The leach field’s job is to dispose of the liquid waste water (called effluent) after most of the solids and oily or greasy material has been collected in the septic tank.
The effluent flows from the septic tank into the leach field where it percolates or filters into the gravel and soil underneath the leach lines. Natural bacterial action in the soil treats the wastewater as it percolates through the soil.
Over time, a layer of black, sticky substance builds up in the leach field trench under the leach lines. The biomat is made of microorganisms and bacteria and helps to filter and treat the wastewater as it flows through the trench. The microorganisms feed on the organic matter in the wastewater.
Biomat growth under the leach lines is a normal occurrence and is expected in any leach field. However, in some cases biomat growth can become too thick which slows the rate that the wastewater can seep into the soil. Infrequent septic tank pumping or abusing the septic system by overloading it or flushing chemicals or other materials down the drain can cause the drain field to clog and increase the thickness on the biomat.
When the drain field becomes too clogged to allow the wastewater to percolate into the soil fast enough, the septic system is on the verge of failure. Your sewer septic professional may be able salvage a failing leach field, but in many cases it will be necessary to expand the drain field or abandon a failed drain field and install a new drain field.
