Frequently Asked Questions - Septic SystemsSoutwick Sewer and DrainNote: The following information was prepared and provided by the Lincoln-Lancaster County Health Department Environmental Health Division.What is a septic system and how does it work?The septic tank receives liquid household wastes (soapy water from the laundry and bath, discarded food scraps and all body wastes) from the house plumbing. The solids settle to the bottom of the tank and the liquid passes into the seepage field. The solids in the tank are subjected to decomposition by bacterial and natural processes. The tank is large enough to accumulate substantial amounts of solids at the bottom while bacteria work to decompose the solid matter. Baffles, or tees, are provided in the tank to prevent floating solids or scum from entering the seepage field.Two different types of lateral systems are used in seepage fields in Lancaster County. The first type is the perforated plastic pipe used in a 2-3 foot wide trench approximately two feet deep with six inches of gravel below and two inches of road gravel above the pipe (Figure 1). Field tile is installed in the same manner. The second type is half-rounds (half moons) made of concrete or fiberglass which are used in 3-4 foot wide trenches three feet deep. Generally, two to four trenches from 60-100 feet each comprise a seepage or disposal field (Figures 2 and 3). Is a permit required to install a sewage system?Yes, a permit is required for the installation and construction of ALL individual sewage disposal system in Lancaster County. The permit fee is $200 and is obtained at the Lincoln-Lancaster Coutny Health Department.What about alterations, replacement of components or extension of a lateral?A permit is also required for ALL alterations or extensions to existing systems. A permit fee of $100 is required when the cost in labor and materials exceed $400. This permit is obtained at the Lincoln-Lancaster County Health Department.Is it necessary to have the septic system inspected?Yes, all new installations or repair work must be inspected and approved by the Lincoln-Lancaster County Health Department before being covered up.Note: All FHA, VA and most conventional lending agencies require the Lincoln-Lancaster County Health Department to approve the installation and location of both the individual sewage disposal system and water supply. What should I look for when buying a lot?Prior to buying a lot in Lancaster County, it is desirable to have a representative from the Health Department check soil maps, and sometimes the lot itself, in order to determine suitability of use. It is recommended that the lot be large enough for two seepage fields, in case of failure of the first field, or if additional laterals are required. The lateral field should be lower than the basement drain for gravity flow, but not located in a surface drainage area or depression.Are the soils in Lancaster County suitable for septic systems?About 0.4 percent of Lancaster County soils have only slight limitations for use of subsurface seepage fields. About 64.4 percent of Lancaster County soils have severe limitations and 30.2 percent are unsuitable for use of subsurface seepage fields.Severe limitations include dense clay subsoil, seasonal high water table or a combination of both. Some limitations may be overcome by providing very large seepage fields, filling, artificially lowering the seasonal high water table by provision of curtain drains, or otherwise providing improved drainage. Unsuitable soils include drainage ways, depressional areas, wetlands, quarries, very dense clay and high water table soils underlain by dense clay. Is my seepage field large enough?There are approximately 67 different types of soil in Lancaster County and water will infiltrate and percolate through them at different rates. Each of the various kinds of soils require a different size lateral field. Some soils are so dense that it is NOT practical to install a field large enough to accommodate the needs of the home on the lot.What about using a percolation test?The reliability of percolation tests vary with season and weather conditions, and generally only indicates if water will move through the soil. Percolation tests cannot be performed if the ground is frozen and are unreliable in drought periods. During wet periods, a margin of safety is obtained in the test. Soil map data is used to verify percolation tests results.How is soil map data used?Lancaster County was soil-typed in the early 1970’s by soil scientist from the U.S. Department of Agriculture Soil Conservation Service. Rough estimate percolation rates were derived for each soil type. When soil type data is superimposed over an aerial photograph, an idea of the suitability of a given parcel of land can be determined. Soil characteristics must be verified in the field by a percolation test.What is the life of a septic system seepage field?Seepage fields will last a long time if proper maintenance is observed. With time, the spaces between soil particles become clogged with suspended solids carried out of the septic tank in the effluent.How much water does an average family use?Average water usage varies from 60 to 125 gallons per person per day depending on the number of bathrooms and appliances, such as automatic washers, dishwashers, and garbage disposal units, and on the habits of the residents. For design purposes, an average of 100 gallons per person per day is assumed.Can I use an automatic washer? How many gallons of water can it use?Yes, all systems approved in Lancaster County are designed to accommodate an automatic washer. Depending on the make, an automatic washer uses between 37-48 gallons of water per load.Should I use a garbage disposal?Garbage grinders can be used in homes served by septic tanks and subsurface seepage fields. If they are used, solids may build up in the tank more rapidly a carry-out of solids into the field may be increased. This means that the tank may need to be pumped more frequently so that the life of the seepage field may be extended. The system will last longer if garbage is disposed in other ways.Is my septic tank large enough?The minimum size tank allowed in Lancaster County is 1,000 gallons for a one, two, or three bedroom house. An additional 250 gallons of capacity is required for each additional bedroom over three. It is recommended that a future basement, bedroom, or den be considered as a bedroom for design purposes of the proposed septic system.Can I put a line under a driveway?Lines under a driveway should be of cast iron, or schedule #40 PVC pipe, in order to prevent crushing. The trench should be sand packed to prevent sagging.Why should a lateral field be a minimum of 50 feet from a lake or stream?Contrary to popular belief, septic tanks do not accomplish a high degree of bacterial removal. With the lake or stream on a downhill grade, water naturally tends to seep toward the lake or stream. Seepage through fifty feet of soil will filter out most of the bacteria.Can I install a system on a hillside?Yes, if the lateral lines follow the contour of the land and a distribution box is used to assure that the effluent cannot flow directly to the lowest portion of the field. (Note: Contours are lines of equal elevation.)Installation problems will occur if laterals run downhill. The bottom of the lateral trench should be almost level, and not drop more than six inches per 100 feet. (See figure 4) What is a distribution box?A distribution box system ensures that each line receives ideally the same amount of sewage. This allows the entire seepage field to receive effluent.What about an aerated septic tank unit?These are systems in which domestic sewage undergoes aeration treatment similar to some municipal wastewater treatment plants. The effluent from these devices may be superior to that of the septic tanks in that the effluent is relatively clear and free of odor. However, effective removal of disease-causing organisms from the effluent of these devices has not been established. IF these systems were allowed to discharge to road ditches or to the ground surface, a more serious health hazard could result because the effluent no longer has the appearance and odor of sewage. For this reason, a lateral field or lagoon is required in conjunction with these treatment devices.Shall I use a cast iron pipe?Cast iron, or approved plastic, is required within 50 feet of a well and does a better job of preventing root penetration between the house and the tank. Breakage, due to settling around the tank after construction, is also minimized.What is the requirement on clean-outs and slope of the building sewer?A clean-out should be located for each 75 foot length of the sewer line and also at any changes in grades or alignments greater than 45 degrees. The slope of the building sewer should be 1/8 inch per foot minimum.Where should my well be located in relation to my septic system?It should be located so that the surface drainage flows away from the well and the septic system is downhill from the well.What is the required distance between a septic system and a well?The Lincoln-Lancaster County Health Department requires the well to be a minimum of 100 feet from the lateral field, 50 feet from the septic tank and 10 feet from the cast iron (or Health Department-approved plastic) sewer pipe. (See Table 1)How deep and far apart can laterals be?The bottom of the lateral trench cannot be more than five feet deep with a recommended maximum depth of three feet. Lateral trenches should have at least six feet of undisturbed earth between them.Is ventilating the field necessary?Not if the system is constructed properly. Building code regulations provide for removal of gases through the building sewerage system vent.Why are septic systems installed so close to the ground surface?Systems should be kept shallow because the top 18 to 30 inches of the soil is more porous and will percolate water faster than the clay that usually comprises the subsoil. Evapotranspiration is best at this level. Aerobic bacterial action also increases at shallower depths. Water rises to the surface by capillary action and is drawn into the root systems of plants. Moisture evaporates from the ground surface and leaves.What is the best time of the year to install a septic system?When the ground is dry so that the trenching process will not smear the sides of the trench.What precautions shall I take with a septic field?Know the location of your field and prevent heavy trucks and equipment from passing over it. Large hooved animals should not be allowed on the field in wet weather.Are any records kept on the location of the septic system?The Health Department has kept drawings of all legally installed systems in the City of Lincoln three-mile limit since 1967 and in Lancaster County since 1973.How can I determine the location of my septic system if no drawing is available?The field can usually be located in the fall because the grass over the field is greener or sometimes the grass will be drier. In the winter, a light snow may melt sooner because of the heat of the sewage in the tank and field. New systems are about 12 inches below the ground surface and a tile probe may be used to locate the lateral field and septic tank.Does a new septic system need an additive to start it?Some 1,200 products, many containing enzymes, are on the market for use in septic tanks and extravagant claims have been made from some. Past research has shown there are NO benefits in using additives.Will septic systems freeze?Shallow septic tank systems that are properly constructed will not freeze if kept in continuous service. The line between the house and tank may freeze if water stands in it. Shallow lines underneath driveways and other areas that are cleaned of snow may freeze under certain conditions.Should I plant a tree near the septic system?The roots of trees and shrubbery may be a source of trouble for perforated pipe or tile. They may enter the tile lines and clog them so completely that the liquid wastes are forced to the ground surface. When this occurs, a portion of the seepage field must be replaced.What can I do to prevent solids from entering the field?Pump the tank when needed and check the baffles to see that they are in good condition. The distribution box can also be checked to ascertain if solids are accumulating there.How often should a septic system be pumped?The heavier sewage solids settle to the bottom of the tank forming a blanket of sludge. The lighter solids, including fats and grease, rise to the surface forming a layer of scum. If the sludge is within six inches or the scum is within three inches of the bottom of the outlet device, the tank should be pumped. Checking the septic tank every year is good practice. For this reason, risers to the ground surface are recommended. Every two to three years would be a reasonable pumping interval (Figure 3).Should the tank be thoroughly cleaned?A septic tank should not be washed or disinfected after pumping. It takes several months for the bacteria in the tank to reach an optimum population, and if a small amount of sludge is left in the tank it will hasten their growth. Bacterial decomposition is the method by which much of the solids in the waster are converted to liquids and gases.Does adding yeast help?Under controlled experiments, yeast was found to be of no benefit.What about soaps and detergents?Soaps and detergents, bleaches, drain cleaners or other materials that are normally used in the household will have no appreciable adverse effect on the system. However, since essential organisms might be adversely affected by large doses of chemicals and disinfectants, moderation should be the rule. Advice from the Health Department should be sought before chemicals from a hobby or home industry are discharged into the system.What about cigarettes and other items?Cigarettes, paper towels, sanitary napkins and tampons, newspapers, wrapping paper, disposable diapers, rags and sticks will not readily decompose in the tank and are likely to lead to clogging.Should the water softener backwash be discharged into the septic tank?The backwash of a Zeolite softener has no harmful effects on a septic tank. However, studies have shown that the salt used in regenerating the ion exchange medium may adversely affect soil texture and hasten clogging of the field. The regeneration of a water softener adds large amounts of clear water to a seepage field and represents an added burden to the system.What about footing drains?Roof drains, foundation drains and drainage from other sources producing large, intermittent or continued volumes of clear water should NOT be piped into or over the septic field or absorption area.What corrective measures can I take to minimize septic system problems?Minimize the amount of water used. Decreasing the amount of water in the toilet flush tank by placing a brick in the tank will reduce the amount of water being used. Don’t take long showers. Take laundry out during wet weather conditions. Wrap insulation tape on hot water pipes to ensure that hot water is present immediately on turning on the tap. Install a curtain drain above the seepage field to intercept groundwater, or add more lines to offset loss of effectiveness of seepage lines with time.In new construction, low volume flushing toilet stools should be used. If my septic field is failing, what should I check?Check all toilets to see if the float valves are set properly and not corroded, to prevent water from constantly entering the field. Make sure all downspout runoff is diverted away from the seepage filed area. Fill in the sunken areas over the seepage trenches. Make sure no clear water discharged from sump pumps, air conditioners, or humidifiers enters the septic system.Does evaporation help?Evaporation and rainfall in this area are about equal when averaged over the year. Spring, when evaporation is low and rainfall high, is the critical time for system failure because the porous topsoil that overlay clay subsoils may already be saturated from snow melt and frost thaw. The annual potential evapotranspiration is about 44 inches, while average precipitation in Lancaster County is 30 inches.Why does my septic system fail only during spring?Seepage lines are warmer and the frost will leave the ground above them much earlier than the rest of the yard. Rainfall or melting snow then enters the lines and cause failure because the added water greatly exceeds the percolative capacity of the soil.Does rainfall have any effect on my septic field?Over 27,000 gallons of water fall on an acre of ground during a one-inch rainfall. Although there are a number of variances, approximately 70% of the water will soak into the ground. The area of your seepage field could receive about 2,000 gallons of water.Should I prevent my downspouts from running over my septic field?Approximately 500 gallons of water enter the ground from one side of an average house during a one-inch rainstorm. This should be diverted away from the seepage field area.What is a curtain drain?A curtain drain is not common in this area. It is similar to an agricultural field drain. It is constructed above the seepage field to intercept the groundwater moving laterally through the soil. It should be approximately SIX inches deeper than the seepage field and filled to within two to six inches of the surface with gravel. The downspouts and sump pumps can be hooked into this line if it is properly located.Why do I sometimes smell sewer gas in the house?Sewer gas may be coming into the house through dry traps in the sewer lines. The water in a trap used infrequently, such as a basement drain, may evaporate and allow sewer gas to escape into the house. These traps should be kept full of water. Another source may be an interior leak in the stack pipe.
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