Part 6

E shows a section of grouted joint, well rounded out, strong, and tight.

F shows the use of a pipe jointer for pouring a hot filler. The pipe jointer may be an asbestos or rubber runner or collar or a piece of garden hose clamped around the pipe leaving a small triangular opening at the top. The jointer is pressed firmly against the hub, and any small openings between the jointer and pipe are smeared with plastic clay to prevent leakage of the filler. A clay dike or funnel about 3 inches high built around the triangular opening greatly aids rapid and complete filling of the joint space. The filler may be a commercially prepared bituminous compound or molten sulphur and fine sand. The former makes a slightly elastic joint; the latter a hard unyielding joint. With good workmanship both kinds of joint are practically water-tight and root-proof, and cost about the same as cement mortar joints. The filler is heated in an iron kettle over a wood, coke, or coal fire. It should be well stirred, and when at a free running consistency should be poured with a ladle large enough to fill the joint completely at one operation. As soon as the compound cools the jointer is removed. Sulphur-sand filler is made by mixing together dry and melting equal volumes of ordinary powdered sulphur and very fine clean sand, preferably the finest quicksand. A 5-inch sewer pipe joint requires from three-tenths to nine-tenths of a pound (according to the kind of pipe) of sulphur, worth 3 to 5 cents per pound, and a like quantity of sand. From ½ to 1½ pounds of bituminous filler are required for a 5-inch pipe joint.

G shows section of finished joint.

H shows the use of a pouring ladle in making lead joints in cast-iron soil pipe. This pipe is in lengths to lay 5 feet, and the metal of the barrel is ¼ inch thick. The joint is yarned with dry jute or oakum, as described above, and is poured full with molten, soft, pig lead to be afterwards driven tightly with hammer and calking tools. About ¾ pound of lead for each inch in diameter of pipe is required. Prepared cements of varying composition have proved effective and, as they require no calking, are economical. Among the best is a finely ground, thoroughly mixed compound of iron, sulphur, slag, and salt.

I is a homemade pipe jointer or clay roll for use in pouring molten lead. A strand of jute long enough to encircle the pipe and the ends to fold back, leaving an opening at the top, is covered with clay moistened, rolled and worked to form a plastic rope about 1 inch in diameter. The jointer gives the very best results but must be frequently moistened and worked to keep the clay soft and pliable. The jointer shown in F is frequently used for pouring lead joints.

Obstructions in house sewers are frequent. Among the causes are broken pipes, grade insufficient to give cleansing velocities, newspaper, rags, garbage, or other solids in the sewage, congealing of grease in pipes and main running traps (house sewer traps), and poor joint construction whereby rootlets grow into the sewer and choke it. Good grade and good construction with particular care given to the joints, will avert or lessen these troubles. The sewer should be perfectly straight, with the interior of the joints scraped or swabbed smooth. When the joint-filling material has set, the hollows beneath the hubs should be filled with good earth free of stones, well tamped or puddled in place. It is important that like material be used at the sides of the pipe and above it for at least 1 foot. The back filling may be completed with scraper or plow. No running trap should be placed on the house sewer, because it is liable to become obstructed and it prevents free movement of air through the sewer and soil stack. Conductors or drains for rain or other clean water should never connect with the house sewer, but should discharge into a watercourse or other outlet.

Where obstruction of a house sewer occurs, use of some of the simple tools shown in Figure 20 may remedy the trouble. It is not likely that farmers will have these appliances, except possibly some of the augers; but some of them can be made at home or by a blacksmith, and most of them should be obtainable for temporary use from a well-organized town or city sewer department. The purpose of the several tools shown is indicated in the notation.

=The tank.=--The septic tank should be in an isolated location at least 50 to 100 feet from any dwelling. This is not always possible, because of flat ground, but in many such instances reasonable distance and fall may be secured by raising both the house sewer and tank and embanking them with earth. Cases are known where tanks adjoin cellar or basement walls and the top of the tank is used as a doorstep; in other cases tanks have been constructed within buildings. Such practices are bad. It is difficult to construct an absolutely water-tight masonry tank, and still more difficult to make it proof against the passage of sewer odors.

In Northern States, particularly in exposed situations, it is desirable to have the top of the tank 1 to 2 feet underground, thus promoting warmth and uniformity of temperature in the sewage. In Southern States this feature is less important, and the top of the tank may be flush with the ground. Every tank should be tightly covered, for the reasons above stated and to guard against the spread of odors, the transmission of disease germs by flies, and accidents to children.

Considerable latitude is allowable in the design and construction of septic tanks. No particular shape or exact dimensions can be presented for a given number of people. One family of 5 persons may use as much water as another family of 10 persons; hence the quantity of sewage rather than the number of persons is the better basis of design. Exact dimensions are not requisite, for settlement and septicization proceed whether the sewage is held a few hours more or a few hours less. As to materials of construction, some form of masonry, either brick, building tile, rubble, concrete, or cement block, is employed generally. Vitrified pipe, steel, and wood have been used occasionally.

A plant for use all year round should have two chambers, one to secure settlement and septicization of the solids and the other to secure periodic discharge of the effluent by the use of an automatic sewage siphon. The first chamber is known as the settling chamber, the second as the siphon or dosing chamber. The siphon chamber is often omitted and the effluent is allowed to dribble away through subsurface tile, as illustrated in Figure 16. The latter procedure is not generally advised, but may be permissible where the land slopes sharply or has long periods of rest, as at summer houses and camps.

The septic tanks shown in this bulletin are designed to satisfy the following conditions:

1. Water consumption of 40 gallons per person per day of 24 hours.

2. A detention period of about 24 hours; that is, the capacity of the settling chamber below the flow line is approximately equal to the quantity of sewage discharged from the house in 24 hours.

3. Where a siphon chamber is provided, its size is such that the dose of sewage shall be approximately equal to 20 gallons per person; that is, the capacity of the siphon chamber between the discharge and low-water lines is roughly equal to the quantity of sewage discharged in 12 hours.

A simple one-chamber brick tank suitable for a household discharging 180 to 280 gallons of sewage daily is shown in Figure 21. A small two-chamber tank constructed of 24-inch vitrified pipe, suitable for a household discharging about 125 gallons of sewage daily, is shown in Figure 22. A typical two-chamber concrete tank is shown in Figure 23. Excepting the submerged outlet, all pipes within the tank and built into the masonry are cast-iron soil pipe with cast-iron fittings. Vitrified or concrete sewer pipe and specials are generally used, as they are frequently more readily obtainable and a slight saving in first cost may be effected. Cast iron is less liable to be broken in handling or after being set rigidly in masonry, and the joints are more easily made water-tight. The submerged outlet is midway of the depth of liquid in the settling chamber. The inside depth of the siphon chamber is the drawing depth of the siphon plus 1 foot 5 inches.

The following table gives the principal dimensions with quantities of materials for four sizes of tank as illustrated in Figure 23:

Dimensions and quantities for septic tanks

--------+--------+--------+-------------------------------------------- |Quantity| | Settling chamber. | of |Capacity| Number | sewage | below +-------+-------+-------+----+-------+---+--- of | in 24 | flow |Length.| Depth.|Width. | W. | X. | Y.| Z. persons.| hours. | line. | | | | | | | --------+--------+--------+-------+-------+-------+----+-------+---+--- | Galls. | Galls. |Ft. In.|Ft. In.|Ft. In.| In.|Ft. In.|In.|In. 5 | 180-280| 240 | 4 0 | 5 0 | 2 0 | 6 | 2 0 | 4 | 6 10 | 320-480| 420 | 5 0 | 5 6 | 2 6 | 6 | 2 3 | 4 | 6 15 | 520-680| 620 | 5 6 | 6 0 | 3 0 | 8 | 2 6 | 5 | 8 20 | 720-960| 860 | 6 0 | 6 6 | 3 6 | 8 | 2 9 | 5 | 8 --------+--------+--------+-------+-------+-------+----+-------+---+---

--------+----------+------------------------------------------------ | Quantity | Siphon chamber. Number |of sewage +-------+--------+--------+----+----+----+------- of | in 24 |Length.| Depth. | Width. | A. | B. | C. | D. persons.| hours. | | | | | | | --------+----------+-------+--------+--------+----+----+----+------- | Galls. |Ft. In.| Ft. In.| Ft. In.| In.| In.| In.| In. 5 | 180-280 | 5 0 | 2 8 | 2 0 | 3 | 4 | 15 | 18-1/4 10 | 320-480 | 8 0 | 2 8 | 2 6 | 3 | 4 | 15 | 20-1/4 15 | 520-680 | 8 8 | 2 10 | 3 0 | 4 | 4 | 17 | 20-1/4 20 | 720-960 |10 0 | 2 10 | 3 6 | 4 | 4 | 17 | 20-1/4 --------+----------+-------+--------+--------+----+----+----+-------

--------+---------+---------+--------+--------+---------+------------- |Quantity | | | | |Reinforcement | of | | | | | in top slab Number | sewage | | | | | (strip of of | in 24 |Concrete.| Cement.| Sand. | Stone. | heavy stock persons.| hours. | | | | | fencing). | | | | | +-------+------ | | | | | |Length.|Width. --------+---------+---------+--------+--------+---------+-------+------ | Galls. | Cu. yds.| Bbls. |Cu. yds.| Cu. yds.| Ft. | In. 5 | 180-280 | 3 | 4-1/2 | 1-1/3 | 2-2/3 | 10 | 32 10 | 320-480 | 4-1/4 | 6-1/4 | 2 | 3-3/4 | 14 | 39 15 | 520-680 | 6-2/3 | 9-3/4 | 3 | 6 | 15-2/3| 47 20 | 720-960 | 8 | 12 | 3-1/2 | 7 | 17-1/2| 56 --------+---------+---------+--------+--------+---------+-------+------

=Siphons.=--Reference has already been made to the vital importance of air in sewage filtration. If the spaces within a filter or soil are constantly filled with water, air is excluded, and the action of the filtering material is merely that of a mechanical strainer with its clogging tendency. The purpose of a siphon is twofold: (1) To secure intermittent discharge, thus allowing a considerable period of time for one dose to work off in the soil and for air to enter the soil spaces before another flush is received; (2) to secure distribution over a larger area and in a more even manner than where the sewage is allowed to dribble and produce the conditions of the old-fashioned sink drain--namely, a small area of water-logged ground.

Three types of sewage siphon are shown in Figure 24. In all, the essential principle is the same: A column of air is entrapped between two columns of water; when the water in the chamber rises to a predetermined height, called the discharge line, the pressure forces out the confined air, destroying the balance and causing a rush of water through the siphon to the sewer. The entire operation is automatic and very simple. The siphons shown are commercial products made of cast-iron; they have few parts and none that move, and the whole construction is simple and durable. The table (fig. 24) lists stock sizes adapted to farm use. Manufacturers furnish full information for setting their siphons and putting them in operation. For example, take type 2, Figure 24: (1) Set siphon trap (=U=-shaped pipe) plumb, making E (height from floor to top of long leg) as specified; (2) fill siphon trap with water till it begins to run out at B; (3) place bell in position on top of long leg, and the siphon is ready for service. Do not fill vent pipe on side of bell.

The overhead siphon, type 3, Figure 24, may be installed readily in a tank already built by addition of an outlet sump. If properly set are handled, sewage siphons require very little attention and flush with certainty. Like all plumbing fixtures they are liable to stoppage if rags, newspaper, and similar solids get into the sewage. If fouling of the sniffing hole or vent prevents the entrance of sufficient air into the bell to lock the siphon properly, allowing sewage to dribble through, the remedy is to clean the siphon. Siphons are for handling liquid; sludge if allowed to accumulate will choke them.

=Submerged outlet.=--The purpose of a submerged outlet is to take the outflow from a point between the sludge at the bottom and the floating solids or scum. The outlet in Figure 23 may be readily made of sheet metal by a tinsmith. Wrought iron or steel pipe with elbows or light lead pipe may be used, the pipe being set in the concrete and left in place. Sometimes a galvanized wire screen (¼-inch mesh) is fitted over the inner end to prevent large solids leaving the settling chamber and possibly clogging the siphon or distribution tile. If a screen is used it should be easily removable for cleaning.

=Manhole frame and cover.=--The frame and cover shown in Figure 23 are stock patterns made of cast-iron and weighing about 250 pounds per set. The cover is 21 inches in diameter; it is tight and, on account of its weight, is unlikely to be disturbed by small children. The frame or rim is about 7 inches high and 31 inches in longest diameter. If desired, light cast-iron cistern or cesspool covers obtainable from plumbing supply houses, homemade slabs of reinforced concrete (see fig. 25), or wooden covers (see fig. 21) may be used.

=Overflow.=--The purpose of an overflow is to pass sewage to the distribution field should the siphon stop working. The overflow (fig. 23) is a 3-inch riser pipe with top 3 inches above the discharge line and the bottom calked or cemented into the side outlet of a =T= branch. The run of the =T= branch should correspond with the size of the sewer from the tank to the distribution field. If this sewer is 4-inch pipe, a 4 by 3 inch =T= branch is used, the 4-inch spigot end of the siphon being calked or cemented into the branch, as shown in Figure 23; if the sewer is 5-inch, a 5 by 3 inch =T= branch is used and connected to the siphon with a 5-inch to 4-inch reducer (in vitrified specials the equivalent is a 4-inch to 5-inch increaser); if the sewer is 6-inch, a 6 by 3 inch =T= branch is used and connected to the siphon with a 6-inch to 4-inch reducer.

=Concrete work.=--Before excavation for the tank is begun, two wooden forms should be built for shaping the inside of the settling and siphon chambers. In most instances the ground is fairly firm, so that the lines of excavation may conform to the outside dimensions of the tank, the back of the walls being built against the earth. The forms may be made of square-edged boards, braced and lightly nailed, as shown in Figure 26. The forms should have no bottom. If it is desired to lay the sides and covering slab in one operation, the top of the forms must be boarded over. All pipe and manhole openings should be accurately placed and cut. The faces of the forms may be covered with paper or smeared with soap or grease to facilitate removal later.