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Improving Household Wastewater Treatment

Septic Tank System • System Management • Assistance with Septic Systems

The most common form of farmstead on-site wastewater treatment is a septic tank system. A properly designed, installed, and maintained septic tank system minimizes the impact of that system on groundwater and surface water. State and local regulations specify how wastewater systems must be designed, installed, and maintained. Act 402 of 1977 regulates Arkansas Department of sewage systems, and it's administered by the Health.

Septic tank system

In this system, wastewater flows from the household into an underground septic tank and goes through the following process:

• The waste components separate ­ the heavier solids (sludge) settle to the bottom, and the grease and fatty solids (scum) float to the top.
   
• Bacteria partially decompose and liquefy the solids.
   
• The more liquid portion (effluent) flows through an outlet into a distribution box and out into the soil absorption field.
   
• The absorption field is usually a series of parallel trenches that contain perforated distribution pipes surrounded by gravel.
   
• The effluent leaks out through holes in the pipe, then down through the gravel and into the soil.
   
• The soil filters out the remaining solids and pathogens (disease-producing microorganisms), and the dissolved substances slowly move through the soil down to groundwater.

Figures 1-2 below illustrate this process.

Can my septic system contaminate my well?

If septic tank effluent flows into an area with a shallow water table, it might not be adequately purified before entering groundwater. A similar problem can happen where the soil is too thin over rock to treat the septic tank effluent well. If inadequately treated septic tank effluent enters groundwater, your well water supply and that of others nearby can be contaminated. In this case, you might unintentionally "recycle" this poorly treated septic tank effluent into your home with your drinking water supply. With proper safeguards, recycling of untreated sewage can be greatly reduced or avoided.

System management

Location of system

It is important that the location of the septic tank system is known. A drawing that shows the system in relation to the house is recommended. This can be very helpful when it is necessary to locate the system for maintenance.

The system should be located downslope and at least 100 feet from any drinking water source. If an existing system is closer than 100 feet to a drinking water source, it doesn't mean that the water source is being contaminated. However, it is important that the system be properly maintained to avoid problems.

Tree roots can enter septic system lines and cause plugging. Lines should not be placed near trees, and trees should not be planted near lines.

Maintenance

The most common maintenance effort is to routinely have the septic tank pumped out. This is done to keep the sludge and scum from building up to the point that they flow into the absorption field and stop up the pipe and gravel bed. The frequency of this pumpout for most systems is usually every four to six years. This period can be shorter if there is a lot of wastewater produced from the household, especially if a garbage disposal is used.

Figure 2 shows a method of measuring the septic tank scum and sludge accumulation to determine if a pumpout is needed. The sludge depth is measured with a wooden stick that has cloth securely attached to about four feet of its length. The stick is pushed to the bottom of the tank through an access port and held in place for about three minutes. When the stick is removed, the sludge depth will be shown by black sludge particles on the cloth. If the sludge depth is one-third (33%) of the depth of the septic tank, it is recommended that the tank be pumped out. The bottom of the scum layer is determined with a similar stick that has a small (6" x 6") board attached to one end. The board end of the stick is pushed through the scum layer by feeling the resistance difference when it goes into the liquid below the scum. The board is then pulled up until it hits the resistance of the scum layer bottom. A mark is made on the stick at the soil line before making the next measurement. The same process is used to mark the location of the outlet bottom on the measuring stick. If the distance between the two marks on the stick is less than three inches, then the tank should be pumped out.

This measuring effort should be done each year. Unfortunately, it is a nasty job and most homeowners are unwilling to do it. Because of this, it is important that a record of pumpout dates be kept in order to be sure it is done every four to six years to avoid problems. When absorption field becomes plugged, it is easily recognized, but it may be difficult to fix ­ prevention is certainly the best option.

Damage to the septic tank and absorption field can occur from traffic or wheel loads on the system. Vehicles and farm equipment should not be driven over septic tank systems. No driveways, concrete surfaces, or asphalt should be placed over a septic tank or absorption field.

Do not try to correct the problem of sewage surfacing above the absorption field by placing more soil in this area. This does not fix the system, and it will only be a matter of time before it surfaces again.

If tree roots have stopped up a drain line, they will probably have to be removed mechanically. This usually requires the services of a plumber with roto-rooter type equipment. Once roots are cleaned out, it may be possible to discourage their regrowth by periodically adding copper sulfate to the distribution box. The copper sulfate label should have a dosage recommendation, but if not, contact the county health department for a recommendation. Some references suggest applying 2 pounds per 300 gallons of tank capacity up to two times per year. However, this should be checked against the copper sulfate label or the county sanitation recommendation. A more permanent solution would be to remove the problem tree(s). If the homeowner wants to keep the trees, it may be possible to just trim back the problem roots. This might be done by using a backhoe or similar equipment to cut the roots back between the drain line and the tree. There is a risk of losing the tree, but it may survive if only a small percentage of the tree root volume is lost.

Limiting household wastewater

Reducing the volume of wastewater entering the treatment system is important because less flow (volume) means better treatment, longer system life, and less chance of overloading the system. Reducing the volume of water entering the system will improve the treatment by increasing the time the waste spends in the system, thus providing more time for settling, decomposition, and contact with the soil.

The quantity of water used depends upon the number of people using the dwelling, how water is used, and maintenance of the water supply system. Average water use in rural households is 75 gallons per person per day. Installing low-use water fixtures along with individual awareness, concern, and conservation efforts can greatly reduce the household water use.

Consider the following ways to minimize water use:

• Eliminate nonfunctional uses, such as flushing toilets to dispose of tissues or other wastes that should be handled as solid waste. Turn off water between uses and fix plumbing fixture leaks.   
   
• Consider which actions use the most water. Toilet flushing usually ranks highest. Low-flow models could decrease water use by more than half. At least consider filling a plastic bottle with water and putting it in the toilet tank to reduce the water required to refill the tank after a flush. The bottle size will vary, but a one-liter drink bottle may be a possibility. There are also commercially available devices available for putting in the toilet tank.
   
• Bathing and clothes washing are next in order of water use. For bathing, consider such reduction options as installing low-flow or controlled-flow shower heads, which give good cleansing with less water. Taking shorter showers and running less water in the tub (especially children) may seem minor, but they don't require any expense ­ only changes in habits.
   
• For clothes washing, use a suds saver and run full loads. Front-loading washers use much less water. When running small loads, be sure to use the reduced water level setting.
   
• Modern efficient plumbing fixtures offer the potential of substantial reduction in residential water use and wastewater generation.
   
• A household water softener that reduces water hardness may be a significant user of water. Proper adjustment and timing of the softener's regeneration mechanism can reduce excessive water use.
   
• Keep in mind that your awareness of your family's water use and how each of you can reduce it is as important as the use of water conservation devices.

Some rural households have been plumbed so that sink, tub, shower, and wash water do not go into the septic tank. This wastewater is usually released from a plastic pipe that is run to the edge of the yard or into a road ditch. Even though this reduces the wastewater entering the septic system, it is a violation of state law. All household wastewater, including these sources, are defined as sewage and are required to enter the septic system.

Reducing unnecessary solids in wastewater

The reduction of solids entering the septic system can extend the time between pumpouts and avoid other system problems. Consider the following recommendations:

• Minimize garbage disposal use. Garbage disposals contribute large loads of solids to wastewater and also require additional water for flushing down the sink.
   
• Do not put items down drains that may clog septic tanks ­ fats, grease, coffee grounds, paper towels, sanitary napkins, tampons, disposable diapers, cigarette butts.
   
• Do not put toxic substances in drains ­ solvents, degreasers, acids, oils, paints, disinfectants, pesticides. This does not include using bleach to disinfect laundry or to wash clothing worn for pesticide applications. Normal household cleaning chemicals and occasional use of drain cleaners should not significantly affect the system.
   
• Do not use chemicals or additives to clean or "sweeten" your system. At this time, there is no conclusive evidence that these products improve the septic system operation.

Avoiding unnecessary water flow into the system

Don't allow water that doesn't need treatment to add to your waste volume. This would include water from basement floor drain sumps, foundation drains, and roof gutters. Divert surface water and runoff from driveways and other surfaces away from the well and also away from the absorption field.

Assistance with septic systems

If you suspect that your septic system is backing up or your distribution system is clogged, contact a plumber or a septic system service company for suggestions. If extensive repairs are required, it is recommended that you contact the county sanitation for information on necessary permits or approval procedures and requirements.

Work Sheet