Resources for the Community
Septic Systems: Proper Care and Concerns by Kit Rosefield and updated by Rebecca Ng, Deputy Director of Marin County Environmental Health Services First, know that all septic system have a number of different components. Even a standard gravity system has at least four components that play a role in the performance and longevity of the system: the source, the treatment tank, the leachfield, and maintenance and monitoring. The source may be the most important component. Your household’s water use and waste habits can make all the differ- ence. Maintenance of plumbing fixtures, landscaping, and how you treat the area above and around the system will determine how well and how long your system will perform. The most prevalent cause of system failure is hydraulic over- loading — too much water. Whether from excessive water use in the home or leaky plumbing fixtures, excessive water flow not only washes solids through the tank but saturates soils in the drainfield, preventing oxygen transfer to the microbes whose job it is to finish cleaning up the wastewater constituents. Another major cause of failure is solids overloading . The only solids that should go down the drain are human waste and used toilet paper. Anything else, such as packaging, per- sonal care products, and even facial tissue, should go in the waste basket. On the kitchen side, garbage disposals are not a good thing for septic (or sewers for that matter) as they put slowly decomposing solids into the system. Powdered laundry detergents are another source of unwanted solids as many brands have fillers that do not readily break down. All these unwanted solids inevitably have to be pumped from the tank and hauled to disposal. It’s a much quicker trip to the trash can and direct to the land fill. Improper planting of landscaping can ruin a system as roots may work their way into the septic tank, drainrock or drainpipe and plug things up. Maintaining vegetation on and around system components will allow ease of service and pre- vent root intrusion, and promote oxygen transfer to the soil. On the same note, driving, parking or allowing livestock to be atop system components will compact soils and slow down or prevent needed oxygen transfer to the soil. They can also cause damage to the disposal field by crushing trench laterals and distribution pipes. The treatment tank (septic tank) is not only a separation device, but an anaerobic treatment unit. Almost all tanks these days have two compartments. The inlet compartment is where wastewater from the home enters through an inlet fitting, which facilitates separation of solids. The lighter materials, such as fats, oils, and greases along with unwanted synthetic fibers, float to the surface and form a “scum layer.” At the same time, heavier solids, such as dirt from washing clothes and vegetables, and fillers from powdered cleaning products,
settle to the bottom forming a “sludge layer.” These two layers develop at whatever rate you put things down the drain: The less down the drain, the less frequently you need to have your tank pumped. It’s that simple. Larger tank size or capacity may increase the ability to store and digest sewage constituents. Typically septic tanks require pumping once every 3-5 years. Between the two layers of solids in the inlet compartment is what’s referred to as the “clear zone,” where separated liquid is subject to anaerobic degradation. An internal baffle in the tank holds the solids back and through a mid-depth passage allows separated water to flow through to the outlet compart- ment. The water then flows from the outlet compartment via an outlet fitting (or even better: an effluent filter) and into the “soil treatment area” (drainfield). When properly functioning, these processes of separation and degradation represent from 25% to 40% of the wastewater treatment. Note: Systems that are subject to waste from folks who need extended medications, such as antibiotics, heart medication or chemotherapy, may need more rigorous maintenance. Never put old unwanted medication down the drain as these materials are toxic to the system and will kill the natural biology . The drainfield (leachfield) is actually a soil treatment com- ponent. Good soils affording adequate retention time will clean most or all of the wastewater constituents that the treatment tank leaves behind. The soils draw oxygen from the surface and help the natural bacteria clean up the wastewater as it flows through the drainrock into the surrounding soils. If the soils are too compact or swell because of clay or other restricting materi- als they will become saturated and the natural bacteria will die off. On the other hand, if soils are too porous such as sand, the wastewater races through the biologically active zone directly to the ground water with little or no treatment. If a treatment tank is not properly maintained, or if water moves too quickly, solids will carry through to the soils and plug up the pores. This is when things stop working and wastewater backs up. With all that said, you see why maintenance and monitor- ing is a critical component of your system. Having an Onsite Service Provider (Qualified Inspector) check your system every year or two will not only help head off any problems before they start, but will help you know when tank pump- ing, plumbing repairs, or other maintenance issues need to be addressed. If you have a system with one or more pumps, rou- tine maintenance and monitoring is even more critical. One thing you can do to help yourself and/or a service provider, is by installing water tight risers over the septic tank openings to allow for easy access for service and maintenance. Improperly working septic systems contribute to a larger problem: impairment of the Tomales Bay watershed, includ- ing local swimming holes and Tomales Bay itself. Wastewater leaving a septic tank into an improperly designed or sited drainfield moves quickly to springs that make up the water- shed. At the same time, many systems dug deep into the “allu- vial zone” of the creeks and streams, do not allow adequate soil
135
50 th Anniversary
Made with FlippingBook - Online Brochure Maker