Septic Problems: Drainfield
Septic tank problems can be the source of drain field problems.
The drain field disposes the waste water goes
as it flows from the septic tank. It is also refered to as the leachfield or disposal field. The water can also
flow to a mound, a seepage bed, or a seepage pit . The general and technical name for these methods of dispersing the wastewater
from the tank is the soil absorption system. To start, the most common type is the drain field or leach field.
RIGHT: cross section of a typical drainfield.
The primary treatment of the sewage occurs in the septic tank. The clarified effluent is discharged to the
drainfield where it is applied to the soil for final treatment and dispersion.
The typical drain field is made of several 3'-4' wide shallow trenches filled with gravel and perforated pipe.
The pipe
distributes the waste water throughout each trench. A drain field will perform a very long time if an effective septic aerator
is installed and the system is maintained following best industry practices.
The Biomat formation is caused by the process of wastewater entering your leach field, drain field, mound, seepage bed,
or a seepage pit. The wastewater feeds the biomat. The biomat (biological mat) is comprised of a black, jelly-like material that
forms on the bottom and then on the sidewalls of the drain field trench. It is composed of anaerobic (lacking oxygen) microorganisms
and their mucus) that fill in the voids between the soil and rock particles. They live on the organic material wastewatter flowing
from the septic tank. The biomat clogs the soil pores so it slows the absorption rate of the trench into the soil below the drain
field.
The biomat grows along the trench bottom first and then upwards along the trench walls. Because it is less
permeability than clean soil, the incoming wastewater will accumulate over the biomat and flow across the trench bed to an area
where there is minimal or has no biomat. Eventually the biomat will cover the bottom of the trench and grow up the trench walls
as also.
In the soil along the outside of the biomat of a non failing or
problem drain field the aerobic soil bacteria (microorganisms that consume organic materail and need oxygen) digest and break
down the biomat. By design, these two bacteria types work simultaneiosly,
controlling the thickness of the biomat and balance each other
and alow the waste water flow to keep up with the daily flow.
Drain field problems
On the left is the natural progression of a drain field that is moving through stages of failing.
Aerobic(needing oxygen) soil bacteria
cannot consume the biomat at the same rate as the biomat grows. Many factors can contribute to a drain field becoming saturated.
Failure to pump the tank regularly, soil compaction, or abuse by a homeowner are some of the reasons a septic system fails.
When the drain field is saturated the anaerobic bacteria in the
biomat feed on the organic matter in the wastewater. This allows the biomat to grow thicker and decreases the dispersment of a
effluent into the drain field.
Test Your Drain Field for Potential Problems
Lush lawn or dead lawn or soft wet and spongy spots over your drain field orover the tank are signs of
septic
problems. A simply way to check the drain field's absorption capacity is to perform a hydraulic load test.
With the septic tank cover removed, run about 80 gallons of water into the tank and watch how long it
takes for the water to drain into the drain field. You may see the tank levels come up from the normal tank level which is even
with the bottom of outlet pipeI is expected. The level may rise up to 1 inch,
if the field is functioning normally and doesn't have biomat growth. If functioning normally the tank should
return to normal levels within ten minutes.
The biomat is a living organisim it's balance can be disturbed. Septic tank problems can cause excessive organic
material to feed the biomat organisms. This can cause excessive growth and reduce the ability of the waste water from the septic
tank to flow through the biomat and enter the soil. In a saturated condition the aerobic soil bacteria cannot thrive and the
breakdown of the biomat by aerobic soil bacteria will no longer occur.
The image on the right is a failing drain field caused by septic tank problems. The biomat has grown around the
pipe not allowing the effluent to flow through the drain field. The flow into the drain field will be greater than the flow through
the biomat. This will result in excessive ponding in the trenches, backflow into the septic tank and into the home.
Water surfacing above the septic tank or over the drain field. These wet spots will result in lush grass growth and you will
be in septic system failure.
Failing drain field problems
The organic material in a septic system break down when anaerobic bacteria consume the organic material in sewage.
By definition, anaerobic microorganisms can only live in an oxygen free environment.
Adding a controlled septic aerator will encourage the growth active aerobic bacteria to treat the effluent.
These Aerobic Bacteria is the fundamental reason controlled septic aeration is superior. Aerobic bacteria are much far more
effective then anaerobic bacteria. Aerobic bacteria (oxygen loving) are 30-30 times more efficient than anaerobic bacteria.
When oxygen is provided by a controlled septic aerator,
The aerobic bacteria in the waste decompose organic material and consume oxygen from the water.
The higher the dissolved oxygen the controlled septic aerator can introduce the more aerobic bacteria can thrive to consume
organic material.
Data has determined anaerobic bacteria only break down 30 to 40 percent of solids in a septic tank.
Aerobic bacteria break down 90 to 98 percent of solids.
Installing a controlled septic aerator to your system enables aerobic bacteria to digest organic waste in the tank.
The aerobic bacteria also travel into the drainfield, where they digest the biomat. They now can survive in the drain field
because the effluent flowing to the drain field has dissolved oxygen in it.
Controlled Septic Aeration Can Pay for Itself by Reducing Pumping Frequency
It is typically recommended that septic tanks are pumped every 3-5 years. A failing system may require
pumping several times per year. Adding a septic aerator to a septic tank, will allow the standard pumping of every 3-5 years
Septic tanks without aeration break down approximately 30%-40% of the organic solids. Adding controlled septic aeration breaks
down 90% or more of the organic solids at a much quicker rate.
