Read Ebook: Sewage and Garbage Disposal on the Farm by Rockey J W John Wesley Simons Joseph Winslow

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Characteristics of sewage 1 Protection of water sources from household wastes 2 Septic-tank systems 2 Operation of a septic tank system 2 Selecting the site 4 The house sewer 4 The septic tank 8 Building a concrete tank 11 The effluent sewer 13 The disposal field 13 Disposal methods in tight or wet soils 14 Care and maintenance of septic tanks 17 Effect of drain solvents and other materials 17 Protection against freezing 17 Septic-tank troubles 18 Grease traps 18 Disposal of drainage from fixtures other than toilets 19 Cesspools 20 Privies 21 Care, and maintenance 22 Chemical closets 24 Disposal of garbage and trash 25

TO INSURE healthful living, domestic wastes must be disposed of. Primitive wanderers and too often present-day tourists deposit their wastes promiscuously and move on when the surroundings become foul. This is impractical in built-up communities. Therefore, in most cities and in some rural areas sanitary codes regulate the disposal of wastes.

CHARACTERISTICS OF SEWAGE

Household sewage ordinarily consists principally of human excrement, toilet paper, garbage, dish water, and other wash water from the various plumbing fixtures and floor drains.

Many kinds of bacteria, at times disease-producing ones, are contained in the discharges from the human body. Epidemics of typhoid fever, dysentery, diarrhea, cholera, and other water-borne diseases may result from the pollution of the water supply with sewage. Pollution is carried by water moving underground, as well as by water flowing on the surface. This is especially true in limestone regions, where underground channels and rock crevices permit water to flow for considerable distances with little filtering action. Sewage used for fertilizing or irrigating crops may contaminate vegetables or the udders of cows and thus spread disease. Anthrax, cholera, and parasitic worms may be present in the surface drainage from fields and barn lots. It is wise to regard all sewage as dangerous and to dispose of it promptly in a sanitary manner, so that disease germs will not pollute the water supplies or be spread by flies, animals, or man.

This subject is discussed at length in Technical Bulletin 675, Sewage Irrigation as Practiced in the Western States.

PROTECTION OF WATER SOURCES FROM HOUSEHOLD WASTES

Under most farm conditions a safe place for the disposal of wastes is in the upper 3-foot layer of soil, where the action of bacteria tends to render it harmless. Tile disposal fields, such as are used with septic tanks, and earth-pit privies accomplish this if the water table remains several feet below the surface and if the location is remote from water supplies. Cesspools and other types of pits do not ordinarily confine contamination to their immediate vicinity and are not recommended except for special conditions.

Sewage or other wastes discharged into abandoned wells or other pits that reach to the water table or below it are almost certain to contaminate the ground water.

It is generally poor practice, and often illegal, to discharge wastes into surface streams. Streams do not necessarily purify themselves in 50 feet, 100 feet, or some other stated distance, as is commonly believed. They do tend to purify themselves over long distances through the action of sunlight, aeration, and other factors but may not be safe for domestic use for many miles below the source of pollution. Clear, sparkling water is not always safe drinking water. Streams in agricultural communities are subject to many sources of pollution and they are likely to become more contaminated as they merge into larger streams.

SEPTIC-TANK SYSTEMS

Septic-tank systems, if installed and maintained properly, provide the most sanitary method of sewage disposal for farmhouses equipped with running water.

Ground water or rock close to the surface, lack of sufficient fall for the sewage to flow by gravity, and too small an absorption area for the effluent limit the satisfactory operation of a septic tank. When these conditions exist, special advice should be sought from a competent local sanitary authority. Adverse soil conditions can be overcome if sufficient fall and space are available.

The five essential parts of a septic-tank system are the house sewer; the septic tank; the effluent sewer; the distribution box; and the disposal field. In special cases a grease trap is added. To facilitate inspection and repairs it is good practice to keep in the house a chart showing the location of the tank and other parts of the system.

A septic tank does not necessarily purify the sewage, eliminate odor, or destroy all solid matter. Its purpose is to condition the sewage or domestic waste by bacterial action, so that it can be disposed of in a more satisfactory manner.

OPERATION OF A SEPTIC-TANK SYSTEM

A tank that is too small may fill up with solids in a short while, because sufficient time is not allowed for breaking them down by fermentation, or the sewage may be pushed right through into the disposal field and clog it.

The effluent may contain even more disease germs than the original sewage, and though it may be as clear as spring water it is far from pure and may cause foul odors if discharged or allowed to pool on the surface of the ground.

The final disposition of the effluent into the upper layer of the soil exposes it to the action of aerobic bacteria. These bacteria, unlike those in the tank, need air and cannot work in saturated soil or live much more than 3 feet below the surface of the ground. The "living earth," or upper stratum, teems with these bacteria, which convert the dangerous sewage and disease germs into harmless matter and thus tend to purify the effluent if it remains long enough in the top layers of soil before seeping into the subsoil and thence to the ground water. Effluent discharged deep in the soil does not receive the benefit of this purifying action.

Several types of septic tanks are in common use. The one described in this bulletin is the single-chamber type, which can be built with or without siphon. This should meet all average farm needs where there are not more than 16 members in the household. It would be advisable to consult the authorities of the State agricultural college or local health department as to their recommendations because frequently local conditions and larger establishments require special installations.

SELECTING THE SITE

First install the tile disposal field where there will be least danger of polluting water supplies, at least 100 feet from water sources if possible and always at a lower surface elevation. This is of greatest importance. Even though selecting a more distant location would result in greater initial cost, it would be a good investment as protection against diseases that might result from pollution of water sources. The site should slope away from the house and away from the source of water. Gentle unshaded slopes free of trees or shrubbery are best. Root-free locations are important because the open-jointed tile cannot be "rootproofed." Porous, well-drained, gravelly, or sandy soil allows greater purification. Do not have the disposal field in vegetable gardens, under roadways, in swampy land, in muck soils, or in areas having rock substrata sloping toward the water supply. Allow sufficient area, where available, to enlarge the field later if needed.

The septic tank may be close to the house, but a more distant site would reduce the likelihood of odors if leakage occurs. The tank should also be kept 50 feet or more from any source of water supply and at a lower elevation. It should not be placed under driveways, pavements, or flower beds, as these would make it not readily accessible for periodic inspection. Care should be taken to insure that surface drainage from the area around the tank will not reach the vicinity of the water supply.

THE HOUSE SEWER

Material

Vitrified salt-glazed clay or well-made concrete sewer pipe and cast-iron soil pipe are the standard materials for house sewers on farms. Asphalt-impregnated fiber pipe, of a type designed especially for house sewers, appears to be satisfactory for this purpose. Cast-iron soil pipe with leaded joints should be used when the sewer is within 50 feet of a well or suction line from a well, within 10 feet of any drinking-water supply line under pressure, within 5 feet of basement foundations, or when laid beneath driveways with less than 3 feet of earth covering the pipes. When within 15 feet of large trees or shrubs, the sewers should have root-tight joints.

Size

For house sewers, 4- and 6-inch pipes are generally used. Where a 4-inch pipe is used, cast-iron is commonly recommended. Grades with little fall require larger pipes. The large sizes are also less liable to become clogged. Clay pipe is made in pieces 2 or 2-1/2 feet long, whereas fiber-pipe sections are 4 feet long and cast-iron pipe 5 feet long, so that there are fewer joints. The minimum number of joints is desirable, as there is less danger of stoppage.

Alinement

Run the house sewer in a straight line and avoid bends whenever possible. Slight changes in direction may be made with one-sixteenth or one-eighth bend fittings. For sharper changes of direction a manhole or distribution box may be used. Changes in direction of more than 45 are not recommended unless a manhole is provided. Clean-outs are desirable within 5 feet of the septic tank where tanks are placed more than 20 feet from the building and the sewer line is not buried deeper than 4 feet.

Establishing Line and Grade

The trench for laying the sewer is usually dug after the septic-tank excavation has been completed and the elevation of the tank inlet determined. A simple method of setting guides for the excavation is illustrated in figure 2.

Digging the Trench

Start digging the trench at the tank end, so that rain or seepage will have an outlet. Rounding the bottom of the trench to the shape of the pipe and hollowing out basins for the "bell" ends allows the pipe to rest firmly throughout its full length, permits full calking of joints, and relieves the strain on them.

Laying the Pipe

Begin laying the pipe at the tank with the bell end uphill. Joints in clay-tile pipe are commonly made with portland cement mortar or grout. Where root-proof joints are essential, sulfur-sand compounds may be used or copper rings provided and used with cement-mortar joints. Asphalt-mastic compounds, however, are more satisfactory. For cast-iron soil pipe, lead is the standard joint material.

After the hub is pushed into the bell, oakum is packed with a calking iron or a piece of wood solidly and evenly in the joint to a depth of about half an inch to center the hub end in the bell and to keep the joint filler from getting inside the pipe. Oil, grease, or dirt on the joint surfaces should be removed, as it will prevent joint material from sticking. Figure 3 shows the different jointing methods.

Bituminous, sulfur-sand, lead, and other commercial joint compounds are poured while hot into the joint from a ladle , and when the work is well done they form a joint that is practically root-proof. They are more expensive than cement mortar.

For molding hot compounds, a clay dike, or funnel, built about 3 inches high around the triangular opening at the top of the jointer greatly aids in the rapid and complete filling of the joint space. A hot joint must be poured continuously, otherwise a seam may develop between successive pourings.

Bituminous compounds make a slightly elastic joint. A joint in 4-inch pipe requires about 3/8 to 1/2 pound of compound and in 6-inch pipe about 1 to 1-1/2 pounds.

Sulfur-sand joints are hard and inelastic. The compound is made by mixing together equal volumes of ordinary powdered sulfur and very fine clean sand, preferably the finest quicksand, and then heating the mixture until the sulfur melts. A 4-inch joint takes about 3/4 pound and a 6-inch joint about 1-7/8 pounds of the mixture. Commercial sulfur-joint compounds also are available.

Soft pig lead or old scrap lead is suitable for lead joints on cast-iron pipe. About 3/4 pound per inch of pipe diameter is generally required for each joint. The lead is hot enough to pour when it begins to char the paddle used to skim off the impurities. When it cools it must be calked tightly to take up shrinkage. The calking should be uniform around the entire joint and should stop when the lead is tight. Heavy pounding or continued calking may crack the bell of the pipe.

It is easier to get good, joints when the pipe is in a vertical position. Therefore, two lengths of pipe are frequently joined and are then laid as a single unit in the trench. In using terra cotta pipe, this procedure may be followed only when the joint is made with a mastic compound. Cement-mortar joints cannot be used in such cases.

Before filling the trench, the sewer should be tested to detect possible leaks. Earth free from rubbish and large stones should then be tamped around and about 1 foot above the pipe.

THE SEPTIC TANK

Flow Through the Tank

Slow, undisturbed flow through the tank is necessary for the separation of solids and liquids and for bacterial action. Submerged inlets and outlets or baffle boards reduce disturbance. A submerged outlet prevents scum from passing out with the effluent.

The single-chamber tank without a siphon, shown in figure 4, is easy to build, inexpensive, and entirely satisfactory in most instances. In very tight soils or for large installations a siphon and sometimes two chambers are advisable.

Size

The tank should be large enough to retain the sewage at least 24 hours. The size should be determined by the largest number of persons that may live in the house, rather than by the number actually living there at the time the tank is built. The additional cost of a large tank over a small one is relatively little. If there is any question as to which of two sizes should be built, it is wise to choose the larger. The dimensions recommended in the table in figure 4 are based on an average production of 50 gallons of sewage per person per day.

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