Category Archives: Septic System Design

  • Sufficiency of Septic System

    Is The Existing System Sufficient For The House?

    Two factors determine whether a properly constructed septic system is able to effectively take care of all the wastewater coming from a household. These are 1) the size of the septic tank and 2) a properly constructed distribution system and its corresponding leach field so designed that it can treat the incoming wastewater.

    Sedimentation
    How can you identify if the septic system in place is large enough for the home? Georgia’s current policies need a septic tank to be a minimum of 1,000 gallons for a home having up to three bedrooms. For each added bed room over three you would add 250 gallons to the required tank size. The final number should then be increased once more by a minimum of 50 % if the house has a waste disposal unit, because that significantly adds to the amount of solid material the system should process.

    Ground Filtration
    In the 2nd phase of the treatment process the wastewater either flows or is pumped to a distribution system of perforated pipes buried in gravel-lined trenches in an absorption field. How big a field is needed, and where should it be positioned, to effectively treat the effluent the soil gets? That is identified primarily by four aspects: (1) how fast the soil can take in water; (2) the depth of the groundwater on the site (and any seasonal depth changes); (3) just how much water the system is anticipated to deal with every day; and (4) the topography of the land. The data from these 4 aspects are utilized to determine the total size of the drain field that is required for a particular property. Let’s talk about these factors in more specificity.

    Soil Percolation Rates.
    You have probably heard house inspectors or others refer to the “percolation rate” of soil. That term describes how quick water can be taken in by the soil, revealed as the time it takes for water in a test hole to decrease in level by one inch (minutes/inch). Soil engineers (or other persons accredited to do so by the County) can identify the percolation rate of the soil in the leach field.

    Soil Test

    soil test

    Percolation rates might vary between 5 inches/ minute and 90 inches/minute and still be within guidelines, depending upon other factors. The faster the soil drains, the larger the trench location (drain field) needs to be. This is since fast-draining soil is less dense, and has less ability to effectively filter huge quantities of wastewater. By enhancing the general size of the drain field, each square foot of ground is required to do less filtration and the wastewater can be adequately filtered by the larger amount of ground before reaching any groundwater.

    Depth of Underground Water Table.
    A soil engineer also identifies the minimum depth of the underground water table on the land. It must be identified that there is an adequate layer of soil in between it and the distribution pipelines to effectively filter out bacterial and viral pollutants before the wastewater rejoins the groundwater.

    Expected Water Usage.
    The size of the home, for figuring out the size of a septic system, is measured by how many bedrooms there are and the existence or absence of a garbage disposal system as discussed above. That will identify how many gallons each day a system is likely to process each day.

    Topography.
    The presence of rocks, trees, other homes, or neighboring waterways or wells have to likewise be thought about due to DHS guidelines. For example, drainfields have to be at least 100 feet from drinking water sources, 50 feet from streams or ponds, and 10 feet from water lines. If the property owner is thinking about purchasing equipment that uses well water, they will obviously wish to be particular that the leachfield was effectively laid out and constructed in order to protect their drinking water.

    As you can determine, this is a complicated process. Now that you have an idea of how a septic system works and the amount of information needed to plan for efficient processing of the wastewater.

  • Ground Filtration

    Phase II – Filtration

    In the first post in this series, the first stage of the treatment process was discussed.  Basically, the concept is that the wastewater from the plumbing systems exits the house via a pipe and through the power of gravity, flows into the septic tank.  Over a relatively short period of time, the waste becomes separated into liquids and solids.  After this the second stage of treatment takes place and what follows is an explanation of this second leg.

    For the second stage of the treatment procedure (the filtration process) the effluent flows from the septic tank to the leach (absorption) field where it is eventually soaked up and dealt with by the dirt. If the absorption area is uphill from the septic system, the water initially moves right into a separate storage tank called a dosing storage tank. A pump then relocates the liquid to the distribution system in the absorption field for handling by the dirt. If no pump is required, the effluent will merely leave the septic tank (via a pipeline developed to permit only the effluent to leave), and will then proceed via a pipeline to the absorption field. A typical absorption field houses a system of perforated pipelines buried in trenches. The bottom of the trenches are filled with crushed stones or a similar product to ensure that the pipelines do not become obstructed and to allow for equal distribution of the wastewater into the dirt. As the water “percolates” down through the ground, the soil itself functions as a filter removing damaging bacteria, viruses, etc. from the effluent, prior to it eventually entering the underground water system.
    There are numerous designs that can be utilized for the absorption field. Numerous ones consist of specific trenches as described in the previous paragraph, although they may be set in place in different ways as needed by the topography. Some systems might make use of a seepage pit instead, where the effluent empties into a large pit with a perforated or open-jointed cellular lining which permits the effluent to seep into the surrounding ground. These generally call for a lot less land area, however are only a good idea when normal absorption areas are not viable and also wells are not threatened. A specific home owner (or potential purchaser) ought to know specifically how the particular system on a lot is outlined, how it runs, as well as how to ideally keep it.

    This completes the basics of a septic system.