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Septic Systems


If a house is not connected to a municipal sewer system chances are it possess some type of septic system to treat and disperse the wastewater created by bathrooms, kitchens and the laundry room. Proper maintenance of these systems is necessary to avoid polluting ground water and the high cost of having to replace these systems.

Most septic systems possess the same general characteristics of an underground, enclosed septic tank and some sort of soil absorption system to allow the effluent to be released into the soil where it is treated by natural processes. (Cesspool will not be discussed because most jurisdictions greatly restrict or ban their use). Because the creation and operation of these systems is governed by established codes, your local health department is a very good source for information regarding your particular system, they may even be able to tell you who installed it and when.

The first component of a septic system that needs to be addressed is the septic tank. All wastewater from the house enters the septic. If the tank cannot be located, look for a sewer pipe exiting the house in the basement or crawl space. Outside of the house near the exit of the pipe is where the tank is most probably located. Some tanks have a 4 inch clean out or inspection port marking the top of the tank. Look for plastic piping capped with a square cap, the cap usually has a small square nub on top used to wrench open the cap. Some obvious signs of placement of the septic tank are depressions in the ground, a slightly mounded patch of ground, an area that is difficult to grow grass or an area where snow (if applicable) melts quicker. Septic tanks are usually rectangular in shape and can be made of concrete, fiberglass or steel. While fiberglass and concrete tanks may last up to 50 years, steel tanks may last ten years but have been known to collapse in five years. If a property contains a steel tank, a thorough inspection of the tank should be conducted. Depending on the size of the tank and number of bedrooms in a house septic tanks can range between 1,000 to 2,000 liquid gallons. Regardless of the material the tank is made of they each have the same basic components.

The purpose of a septic tank is to separate solid (sludge) from the liquid wastes (effluent) and lighter solids (scum). Bacteria in the wastewater digest the sludge and scum and liquefy the waste products into gases and water. The gases leave via a vent, normally through the roof of the house, while the liquid is then dispersed by the drainage system and broken down by naturally occurring bacteria in the ground. The solids are collected in the bottom of the tank where it is eventually pumped by a certified septic waste removal company. To accomplish the separation between solids and liquids, the septic tank has either baffles or a tee that allows the effluent to flow out while keeping the solids trapped in the bottom of the tank. Most newer septic tanks have an inspection or clean out pipe that will allow inspection of the tank. When looking down into the tank, the top of the tee or baffles should be visible. If they are not visible, it is possible that either they cannot be seen or they are covered over by the scum or wastewater. If this is the case, chances are the distribution pipe is clogged. This is a common problem with septic systems and a professional should be called to clear out the blockage.

From the septic tank, the effluent has to be dispersed of in approved manner. In almost all cases, the effluent is dispersed of into the soil where naturally occurring bacteria in the ground treat the waste. The three most common Soil Absorption systems are the Trench system (drain or leech fields), Seepage pits (dry wells), or Mound systems. A distribution box maybe found if more than one trench or seepage pit are required to equally spread the effluent to each part of the system. Depending on the geographical location, any one of the three types of systems maybe in place. A standard procedure to determine which system should be in place is the Percolation (perc) test. Very simply stated, a pit is dug in the ground and a known amount of water is introduced. The ground must absorb the water in a certain period of time. If the water is absorbed within the allotted time the ground is said to perc, meaning the soil is capable of handling the liquid produced by the septic system. If the ground does not perc either another location must be chosen or a mound system may be required to disperse the effluent. Whatever the circumstances, all three systems have the same purpose; to disperse the effluent in a manner that will allow the naturally occurring bacteria in the ground to break down the waste into safe substances.

The Trench system or drain field as it is commonly known is very simply a perforated pipe or pipes leading from the septic tank through a layer of gravel where the effluent can be safely leeched into the ground without contaminating groundwater supplies or adjacent bodies of water. Normally, these distribution pipes are beneath one to fifteen feet of backfill, the surface of this being the yard. Between the backfill is a barrier material sitting on top of between 3 / 4 and 2 1/2 inches of gravel. The distribution pipe runs through the middle of the gravel. All of this must sit at least four feet above water table or bedrock. The width of all of this is between one and three feet. (All of the above numbers vary according to local codes; call the local health department for more specific information).

Another popular type of soil dispersion system is the Seepage pit or dry well as it is commonly called. Leading from the septic tank is a distribution pipe leading into either a dug or bored well. The well is lined with either gravel or blocks with open joints. The bottom of the pit is covered with between six to twelve inches of 3 / 4 to 2 1 / 2 inches of clean gravel. Covering the well is a reinforced concrete cover with either an inspection pipe leading out of the top. (All of the above numbers vary according to local codes; call your local health department for more information). Dry wells are common on properties that have small yards or yards that back to cliffs or other obstructions that prevent the use of a drain field.

The third type of soil dispersion system is the mound system. These are used almost exclusively when the ground will not perc. This may be caused by either a high water table or a rock substrate that prevents purifying the wastewater completely. Whatever the situation, the mound system is created to disperse the effluent into a man made mound that is built above ground. Leading from the septic tank, the wastewater is carried into a chamber where there is a pump that pushes it into the mound. The top of the mound is crowned with a cap (usually underneath a layer of grass and top soil). Underneath the cap is a buffer of straw, hay, or fabric sitting on an absorption bed where the wastewater enters the mound. Although different companies utilize different methods, for the most part there is some type of fill or material that filters the effluent as it is pulled down the mound via gravity. At ground level is the earth is plowed to allow easier dispersion into the permeable soil underneath. A note about these systems: Routine inspection of the pump from the tank to the mound should be conducted. If the pump fails, the septic tank can fill and cause a backup. There should be some cover over the accessible chamber where the pump sits so that it can be inspected.

Proper use of your system as well as routine care and maintenance of your system are very important in getting a long life out of the systems require periodic pumping of the septic system every three to five years (more frequently for systems under heavy use). Be sure that the septic company chosen pumps both the sludge and the wastewater and will dispose of it in a proper fashion. Because prices will vary widely, it is recommended that a couple of companies are called and the prices are compared. Make sure that they will also inspect the inlet and outlet baffles or tees when they come to do the pump out. Have them repaired if there are any problems. Keep accurate records for all maintenance and repairs conducted.

If the following are followed, the useful life of the septic system can be greatly extended. It is important that the septic system location is known so that it may be monitored. Heavy vehicles should stay off of the system as they can cause damage to underground piping and components. Do not build over the drainage system nor plant trees or shrubs over it as the roots can clog drain lines. Rain water runoff from the house, spouts, sump pumps or any either water diverting devices should be kept away from the septic area to avoid overloading the system. Steps should also be taken to reduce sludge build-up in the system including; pumping of the tank, and avoiding the use of garbage disposal systems that introduce additional solids and greases that can clog the system. Garbage should be placed in the trash not down toilets or drains. This includes chemicals, paints, oils, solvents, acids, pesticides, or excessive cleaning solutions that destroy the beneficial bacteria in the tank, decrease sludge production and pollute groundwater. Lastly, take steps to conserve water, the less you use, the less that is entering the system.

The most common problem with septic systems is hydraulic failure. This means that the system can no longer purify the wastewater. Indications of this are strong odors emanating near the septic tank or soil absorption system. Sewage and effluent coming out of the ground and ponding are another indication. Dead grass in the septic area can be another clue. Finally, if sinks and toilets do not drain properly, plumbing backs up, or gurgling sounds start occurring in the plumbing, the system may be failing. If doubts arise whether the system is operating properly, call a professional, it is the home owner's responsibility to keep the system operating properly and health departments have the ability to penalize owners if their systems fail from neglect.