Plumbing is a system of piping, apparatus, and fixtures for water distribution and waste disposal within a building. This
chapter covers the basic water supply and water distribution systems, the theater of operations (TO) water supply and water
distribution systems, and the sewerage system. Plumbing also includes the installation and maintenance of these systems. When
architects design a building, they prepare a set of prints and a set of specification sheets detailing the types and quality
of materials to be used. Plumbers use the prints and specifications to layout and plan the project. 1-1. A water supply system receives, treats, and moves water to a water distribution system. Water may come from a stream
or lake, a deep or shallow well, or a reservoir which collects surface water. The water supply system purifies and pumps the
water into a storage tank. After the water is purified, it is released into the distribution system. The distribution system
is an arrangement of connected pipes (called a run) that carries the water to its destination. This system usually has a means
of heating some of this water. 1-2. See Appendix B for information on construction plans, prints, drawings, and plumbing and heating symbols. 1-3. A plumber should be able to install a complete water supply system by using a plan together with standard and special
detail drawings and a BOM. A standard detail drawing will show the water heater and standard storage-tank connections. The
plan will show the type of piping by size and fittings (see Appendix B). 1-4. For more information on utility- and building-waste system plans, see Appendix B. 1-5. Prints are used for structures and equipment in water supply and water distribution systems. The type of print depends
on whether the unit is constructed or if it is a package unit to be assembled in the field (see Appendix B, paragraph B-8). 1-6. The designer (architect) or draftsman usually prepares a BOM (DA Form 2702) when preparing the original drawings. However, if no BOM accompanies the field prints, the plumber must compile it. Appendix C gives instructions for preparing a BOM. 1-7. The main water supply system provides potable cold water at the main at a pressure that meets National Plumbing Code
standards. The water service main for the plumbing installation Ts into the main water supply. The plumbing system must provide
enough water for normal use at each outlet. 1-8. Fixture supply risers take water from the main supply to the fixtures on each floor level. Each fixture supply riser
must have a diameter large enough to supply water to all the fixtures it connects. The size is determined by the design load
for the riser (refer to Appendix D, Tables D-3 or D-4). 1-9. Cold-water systems may use galvanized-iron or galvanized-steel pipe, copper tubing, plastic pipe, brass, cast iron,
galvanized, wrought iron, or other approved material. The material used depends on the— Amount of water to be supplied. Water pressure. Corrosion factor for different types of pipe in different temperatures. Cost. Availability. Water pressure and friction loss through the length of the pipe. Number and kinds of fixtures installed (fixture demand). Number of fixtures in use at a given time (factor of simultaneous use). Type of flushing devices (refer to Chapter 4). 1-11. When a liquid flows through a pipe, layers move at different speeds, with the center layer moving fastest. This resistance
to flow (called friction loss) varies with different types of pipe. Pipe friction, in turn, causes a drop in water pressure.
In a small pipe, this friction loss is overcome by increasing the water pressure. If higher water pressure is not possible,
increasing the pipe size can reduce friction loss. See Appendix D for friction loss in different types of pipe. 1-12. In a water supply system, water hammer occurs when flowing water is stopped abruptly or cannot be compressed, causing
the flowing water to slam against the valve with the same amount of pressure as applied to the water system (such as when
you flush a water closet, the water closet's tank completes the filling action, and the control valve in the tank closes). 1-13. The effects of water hammer are noise from rattling pipes and sometimes leaky pipe joints, both of which can be eliminated
easily by installing a device called a expansion chamber to slow the water in the plumbing system. The expansion chamber shown
in Figure 1-1 is capped at the upper end causing it to fill with air, not water. Air, unlike water, can be compressed. Therefore, when
the water flow is stopped abruptly, the air in the air chamber works like an automotive shock absorber relieving the slamming
action against the valve. Install expansion chambers in the water supply system on both hot and cold service lines at each
major fixture within a structure. Figure 1-1. Expansion Chamber Construction 1-14. Expansion chambers can be purchased or fabricated. Figure 1-1 shows an example of a constructed expansion chamber. The type of pipe and the dimensions used are not critical, but ensure
that the section identified as the riser is at least 6 inches long. 1-15. Pressure in the main usually ranges from 45 to 60 pounds per square inch (psi). If the pressure is over 60 psi, a
pressure-reducing valve must be placed in the water service line at its entry to the building. The size of the water service
pipeline, the rate of use, the length of the line, and the outlet height in the system control the pressure available at the
outlet. If the water pressure is less than 15 psi, use a tank and a pump or other means to provide pressure. If the water
pressure is over 80 psi, use an approved pressure regulator. 1-16. The minimum practical size for a water service line is 3/4 inch. This size should be used even when calculations
indicate a smaller one. Calculations for factoring loss of pressure in complex systems are beyond the range of this manual.
For simple systems, use approximate figures to find the pipe size. Tables D-1 and D-2, Appendix D, give capacities and psi for galvanized-steel/iron pipe, copper tubing, and plastic pipe. Use these tables combined with
the maximum fixture demand and simultaneous use factor to determine pipe sizes. 1-17. Maximum Fixture Demand. The maximum fixture demand in gallons per minute (GPM) is the total amount of water
needed to supply all the fixtures at the same time. Estimate the maximum fixture demand by counting the number and types of
fixtures in the plumbing system. Table 1-1 gives the maximum fixture demand for different fixtures. Table 1-1. Fixture Demand (in GPM)
Plumbing is a system of piping, apparatus, and fixtures for water distribution and waste disposal within a building. This chapter covers the basic water supply and water distribution systems, the theater of operations (TO) water supply and water distribution systems, and the sewerage system. Plumbing also includes the installation and maintenance of these systems. When architects design a building, they prepare a set of prints and a set of specification sheets detailing the types and quality of materials to be used. Plumbers use the prints and specifications to layout and plan the project.
1-1. A water supply system receives, treats, and moves water to a water distribution system. Water may come from a stream or lake, a deep or shallow well, or a reservoir which collects surface water. The water supply system purifies and pumps the water into a storage tank. After the water is purified, it is released into the distribution system. The distribution system is an arrangement of connected pipes (called a run) that carries the water to its destination. This system usually has a means of heating some of this water.
1-2. See Appendix B for information on construction plans, prints, drawings, and plumbing and heating symbols.
1-3. A plumber should be able to install a complete water supply system by using a plan together with standard and special detail drawings and a BOM. A standard detail drawing will show the water heater and standard storage-tank connections. The plan will show the type of piping by size and fittings (see Appendix B).
1-4. For more information on utility- and building-waste system plans, see Appendix B.
1-5. Prints are used for structures and equipment in water supply and water distribution systems. The type of print depends on whether the unit is constructed or if it is a package unit to be assembled in the field (see Appendix B, paragraph B-8).
1-6. The designer (architect) or draftsman usually prepares a BOM (DA Form 2702) when preparing the original drawings. However, if no BOM accompanies the field prints, the plumber must compile it. Appendix C gives instructions for preparing a BOM.
1-7. The main water supply system provides potable cold water at the main at a pressure that meets National Plumbing Code standards. The water service main for the plumbing installation Ts into the main water supply. The plumbing system must provide enough water for normal use at each outlet.
1-8. Fixture supply risers take water from the main supply to the fixtures on each floor level. Each fixture supply riser must have a diameter large enough to supply water to all the fixtures it connects. The size is determined by the design load for the riser (refer to Appendix D, Tables D-3 or D-4).
1-9. Cold-water systems may use galvanized-iron or galvanized-steel pipe, copper tubing, plastic pipe, brass, cast iron, galvanized, wrought iron, or other approved material. The material used depends on the—
Amount of water to be supplied.
Corrosion factor for different types of pipe in different temperatures.
Water pressure and friction loss through the length of the pipe.
Number and kinds of fixtures installed (fixture demand).
Number of fixtures in use at a given time (factor of simultaneous use).
Type of flushing devices (refer to Chapter 4).
1-11. When a liquid flows through a pipe, layers move at different speeds, with the center layer moving fastest. This resistance to flow (called friction loss) varies with different types of pipe. Pipe friction, in turn, causes a drop in water pressure. In a small pipe, this friction loss is overcome by increasing the water pressure. If higher water pressure is not possible, increasing the pipe size can reduce friction loss. See Appendix D for friction loss in different types of pipe.
1-12. In a water supply system, water hammer occurs when flowing water is stopped abruptly or cannot be compressed, causing the flowing water to slam against the valve with the same amount of pressure as applied to the water system (such as when you flush a water closet, the water closet's tank completes the filling action, and the control valve in the tank closes).
1-13. The effects of water hammer are noise from rattling pipes and sometimes leaky pipe joints, both of which can be eliminated easily by installing a device called a expansion chamber to slow the water in the plumbing system. The expansion chamber shown in Figure 1-1 is capped at the upper end causing it to fill with air, not water. Air, unlike water, can be compressed. Therefore, when the water flow is stopped abruptly, the air in the air chamber works like an automotive shock absorber relieving the slamming action against the valve. Install expansion chambers in the water supply system on both hot and cold service lines at each major fixture within a structure.
Figure 1-1. Expansion Chamber Construction
1-14. Expansion chambers can be purchased or fabricated. Figure 1-1 shows an example of a constructed expansion chamber. The type of pipe and the dimensions used are not critical, but ensure that the section identified as the riser is at least 6 inches long.
1-15. Pressure in the main usually ranges from 45 to 60 pounds per square inch (psi). If the pressure is over 60 psi, a pressure-reducing valve must be placed in the water service line at its entry to the building. The size of the water service pipeline, the rate of use, the length of the line, and the outlet height in the system control the pressure available at the outlet. If the water pressure is less than 15 psi, use a tank and a pump or other means to provide pressure. If the water pressure is over 80 psi, use an approved pressure regulator.
1-16. The minimum practical size for a water service line is 3/4 inch. This size should be used even when calculations indicate a smaller one. Calculations for factoring loss of pressure in complex systems are beyond the range of this manual. For simple systems, use approximate figures to find the pipe size. Tables D-1 and D-2, Appendix D, give capacities and psi for galvanized-steel/iron pipe, copper tubing, and plastic pipe. Use these tables combined with the maximum fixture demand and simultaneous use factor to determine pipe sizes.
1-17. Maximum Fixture Demand. The maximum fixture demand in gallons per minute (GPM) is the total amount of water needed to supply all the fixtures at the same time. Estimate the maximum fixture demand by counting the number and types of fixtures in the plumbing system. Table 1-1 gives the maximum fixture demand for different fixtures.
Table 1-1. Fixture Demand (in GPM)
1-18. For example, what is the maximum fixture demand for a plumbing system which consists of the following 14 fixtures: 2 water closets, 4 lavatories, 2 showers, 3 urinals, 1 slop sink, 1 laundry tub, and 1 floor drain? Use Table 1-1 and the following steps:
Step 1. Multiply the number of each fixture by the GPM of that type fixture (from Table 1-1).
Step 2. Total these figures.
1-19. The result is a maximum fixture demand of 313.5 GPM.
NOTE: Use the fixture demand (313.5 GPM) with the simultaneous-use factor to select the pipe size.
1-20. Simultaneous-Use Factor. The simultaneous-use factor is the percentage of fixtures potentially in use at a given time (Table 1-2). It is an estimate of the total demand on a water supply system, expressed as water supply fixture units. Simultaneous-use factors decrease as the number of fixtures in a building increases. Use the formulas in Table 1-2 to determine simultaneous use factor.
Table 1-2. Simultaneous-Use Factor
1-21. If a table for the simultaneous-use factor is not available, estimate the probable demand by computing 30 percent of the maximum fixture demand in gallons.
1-22. Continuing the example in paragraph 1-18, the 14 fixtures would have a simultaneous use of 42.72 percent (round up to 43 percent). Since the fixture demand was 313.5 GPM, the water service line must have a capacity of 43 percent of 313.5 (110 GPM). What size of pipe would be needed for a 60-foot long pipeline with a pressure at the main of 45 psi (refer to Appendix D, Tables D-1 and D-2)?
Step 2. Read across (left) to the psi column and establish the given as 45 psi.
1-23. Either 1 1/2-inch galvanized, copper, or plastic piping would be large enough for the water service line.
NOTE: Remember, the minimum practical size for a water service line is 3/4 inch. This size should be used even when calculations indicate a smaller size.
Main Water Supply Line
1-24. The main water supply is a pipe, usually hung from a ceiling, with branches connected to serve the fixture risers. This supply pipe has the same diameter as the water service from the main and is centrally located to provide short takeoffs to the fixture supply risers throughout the building. To reduce friction loss, lay the main supply piping as straight as possible. The main supply pipe must not sag or trap water. It should be graded slightly, up to 1/4 inch per foot, dropping toward the water meter. At the low end of the grade, place a drip cock or stop-and-waste valve for draining the pipe in the winter. A drainpipe may be needed to carry the wastewater from the opening in the valve to a floor drain or sump. If it is impossible to grade all the piping to one point, all parts that cannot be centrally drained should have separate drip cocks or stop-and-waste valves. The main supply pipe must be well supported to take its weight off the fittings and to prevent leaks.
Fixture Supply Risers
1-25. Use reducing Ts to connect fixture supply risers to the main supply. Run the risers through the interior walls of the building. Tighten all the joints before the partitions are finished. Use pipe rests or clamps to support vertical-fixture supply risers at each floor level. (Fixture supply risers must not depend on the horizontal branches for support.) Horizontal-fixture branches should be well supported and graded upward toward the vertical-fixture supply risers.
1-26. Install gate valves in each vertical supply riser, so that a section can be repaired without shutting off the water to other sections. Small gate valves on the supply to each fixture allows for shutting off the water for faucet repairs.
TESTING FOR LEAKS
1-27. Inspecting for leaks is important. A leaky joint wastes water and causes costly damage to the building. In new construction, test the entire system for leaks before the floor and partitions are closed up. When performing this test, use the water pressure from the main that feeds the system. While the system is under pressure, inspect each joint for moisture. If a leak is detected in a joint, tighten the joint or replace it by cutting the pipe and connecting a new section with a union. When working with copper soldered joints or plastic solvent-cement joints, drain the pipe and then connect the joint. Copper compression joints can be tightened or replaced.
DISINFECTING THE PIPING SYSTEM
1-28. After installation or repair, clean and disinfect plumbing pipes and other parts of a water supply system carrying drinking water before use. Flush the system to remove dirt, waste, and surface water. Disinfect each unit with a chemical such as a solution of hypochlorite or chlorine.
1-29. Under average conditions, use the dosages (in parts per million [ppm]) in Table 1-3. The chlorine dosage required to disinfect a unit depends on the—
Table 1-3. Chlorine Dosage
Table 1-4. Volume of Water Disinfected (By Pipe Size)
1-30. Use portable gas chlorinators to apply the liquid chlorine. Chlorine cylinders should not be connected directly to the mains because water may enter the cylinder and cause severe corrosion, resulting in dangerous leakage. A solution of hypochlorite is usually applied by measuring pumps, gravity-feed mechanisms, or portable pipe-disinfecting units. Use the following steps to apply disinfectant:
Step 1. Flush all sections thoroughly at a velocity of at least 3 feet per second (fps) until all the dirt and mud are removed.
Step 2. Plug all branches and other openings with plugs or heads properly braced to prevent blowouts.
Step 3. Insert the disinfectant into the mains through taps or hydrants at the ends of each section.
Step 4. Bleed out any air trapped in the line.
Step 5. Add the predetermined chlorine dosage as the main slowly fills with water.
Step 6. Continue feeding until the water coming from the supply end contains the desired amount of chlorine.
Step 7. Keep the chlorinated water in the unit for 24 to 48 hours.
Step 8. Flush the main until the water contains only the amount of chlorine normally in the supply.
Step 9. Analyze samples daily for bacteria until the analyses show no further need for disinfection. If the samples are unsatisfactory, rechlorinate.
MAINTENANCE AND REPAIR
1-31. Galvanic corrosion (resulting from a direct current of electricity) occurs in a plumbing system that includes two different kinds of metal pipe, such as galvanized pipe and copper pipe. See Chapter 3 for reducing and repairing corrosion.
1-32. Hard water contains a large amount of calcium and magnesium compounds, which prevent soap from lathering. This forms a scum that slows the flow of water. The scum deposits harden and form scale. See Chapter 3 for reducing and removing scale.
1-33. Water supply lines may freeze when exposed to temperatures below 32 degrees Fahrenheit. Outside pipes must be buried below the frost line. In northern zones, this is 4 feet or more. If the building temperature falls below freezing, inside pipes may also freeze, causing the pipe to break at the weakest point. Use the procedures in Chapter 3 to thaw frozen pipes.
1-34. Water mains are usually cast iron, 8 inches or more in diameter. If the main is less than 8 inches in diameter, taps should be 2 inches or smaller. Use Figure 1-2 and the following steps to tap the water main:
Step 1. Dig to expose the pipe at the point where the tap is to be made. Dig as close to the top of the water main as possible.
Step 2. Clean all dirt and rust off the pipe at that point.
Step 3. Place the gasket of the water-main self-tapping machine on the pipe, and set the saddle of the machine on the gasket.
Step 4. Wrap the chain around the pipe, and tighten it to clamp the water main self-tapping machine to the pipe.
Step 5. Remove the cap from the cylinder of the machine, and place the combination drill and tap in the boring bar.
Step 6. Reassemble the machine by putting the boring bar through the cylinder and tightening the cap.
Step 7. Open the flap valve between the compartments.
Step 8. Start drilling the hole by applying pressure at the feed yoke and turning the ratchet handle until the drill enters the main.
Step 9. When the tap starts threading the hole, back off the feed yoke to prevent stripping the threads.
Step 10. Continue to turn the boring bar until the ratchet handle can no longer be turned without extra force.
Step 11. Remove the tap from the hole by reversing the ratchet. Then, back the boring bar out by turning it counterclockwise.
Step 12. Close the flap valve between the upper and lower compartments.
Step 13. Drain the water from the cylinder through the bypass.
Step 14. Remove the cap and drill tool. Place a corporation stop (Figure 1-3) in the boring bar, ensuring that the stop is closed.
Step 15. Repeat steps 6 and 7.
Step 16. Turn the ratchet handle to thread the corporation stop into the pipe.
Step 17. Repeat Step 13.
Step 18. Remove the cap from the cylinder, and unbolt the boring bar from the corporation stop.
Step 19. Remove the lower chamber from the pipe.
Step 20. Inspect for leaks.
Step 21. If the corporation stop leaks, tighten it with a suitable wrench.
Figure 1-2. Tapping the Water Main
1-35. Curb and meter stops control the water entering the building. Figure 1-3 shows this installation.
Figure 1-3. Curb and Meter Stops
1-36. After tapping the water main and inserting the corporation stop, install the curb stop in a suitable position. It is usually set in a cast-iron stop box to provide easy access in the water service between the curb and the building.
1-37. The stop box has a variable telescopic length for use on different grades. When the water service is copper, join the curb stop to the service piping with a compression joint. After installing the curb stop, run the water service line to the building and through the building wall to the inside of the basement. The water service line can be laid in the same trench as the sewer. The bottom of the water pipe at all points should be at least 12 inches above the top of the sewer line. The water pipe should be placed on a solid shelf excavated at one side of the common trench with a minimum clear horizontal distance of at least 12 inches from the sewer line. It must be placed in the ground at a level deeper than the maximum depth of frost penetration.
METER AND METER STOP
1-38. After running the water service lines through the side of the building and closing the holes around the service pipe with waterproof cement, install the water meter and meter stop.
1-39. The meter stop is a ground-joint valve, which controls and shuts off the flow of water into the building. Place the meter stop as close to the service pipe entry as possible.
1-40. The water meter, installed near the meter stop, measures the amount of water used in the building.
1-41. Often the meter and stop are placed in a meter vault that replaces the stop box at the curb. In this case, place a stop-and-waste valve in the line where the water service enters the building.
1-42. The hot-water system consists of a water heater and a piping system. This system runs parallel to the cold-water pipes running to the plumbing fixtures (faucets) where hot water is desired. A standard detail drawing will show the water heater and standard storage-tank connections. The water heater is fueled by gas, oil, electricity, or possibly solar energy.
1-43. Water heaters are classified into four categories: range-boiler, gas, oil-burning, and electric. See Chapter 5 for water heaters.
1-44. The pipes used in hot-water systems are similar to those used in cold-water supply systems. Old hot-water systems used wrought-iron or steel pipe. Newer systems use chlorinated polyvinyl chloride (CPVC) plastic pipe, since CPVC resists corrosion. Copper is the most commonly used piping for distribution.
1-45. To size the hot-water main supply lines and the risers, follow the same procedure as for basic water supply, paragraph 1-10.
1-46. Installation begins with a water-heating device and the main supply line from that device. Grade the hot-water supply to a centrally located drip cock near the water heater. Water for the fixtures at various levels throughout the building is taken from the main hot-water supply by fixture supply risers. Each of the risers should have a valve.
1-47. Buildings with a large floor area or with several floors need the supply of hot water to the fixture as soon as possible after the tap is opened. In a one-pipe system, such as that used for cold-water supply, a lag occurs from the time the hot-water tap is opened until the water travels from the water-heating device to the tap.
1-48. To overcome this time lag, use a two-pipe, circulating-water supply system (Figure 1-4). Hot water passes from the water heater through the main fixture supply risers and returns through a line to the water heater. This looped system circulates the hot water at all times. Warm water tends to rise and cold water tends to fall, creating circulation. The water within the loop is kept at a high temperature. When a tap is opened, hot water flows from the hot-water supply riser into the branch and out of the tap. The cold-water filler within the hot-water storage tank (water heater) has a siphon hole near the top of the tank. If reduced pressure occurs at point A, the siphon hole allows air to enter the cold-water filler. This breaks the vacuum and prevents back siphonage of hot water into the cold-water distribution system.
Figure 1-4. Circulating Hot-Water System (Two-Pipe)
1-50. This circulating supply system (Figure 1-4) is an overhead-feed and gravity-return system and is likely to become air-locked. An air lock prevents circulation of the hot water. Since air collects at the highest point (B) of the distribution piping, the most practical way to relieve the air lock is to connect an uncirculated riser to the line at that point. The air lock is relieved when a fixture on the uncirculated riser is used.
MAINTENANCE AND REPAIR
1-52. Fire protection for buildings of fire-resistant construction is provided by fire hydrants. These are usually located at least 50 feet from each building or from the water distribution system within the building.
AUTOMATIC SPRINKLER SYSTEMS
1-53. Automatic sprinkler systems are used for fire-resistant structures only when the value, the importance of the contents or activity, or the possibility of a fire hazard justifies a sprinkler system. Buildings of frame and ordinary construction that are more than two stories high and house tops will be protected by automatic sprinkler systems.
1-54. In a TO, there is always a chance the Army may have to take over the repair and operation of a municipal water system. Although most systems will be similar to those used in the US, problems can be expected in obtaining replacement parts and operating supplies. Sizes and dimensions of basic components can be expected to differ from those in the US and even require the use of metric tools. Also, certain nations may use different disinfecting methods than chlorine. Under these circumstances, the Army should consider hiring former local employees who are familiar with the equipment to operate and maintain the system.
1-55. After water is purified, it is released into the distribution system. The distribution of large quantities of water under tactical conditions will be by pipelines, trucks carrying bladders, and 5,000-gallon tanker trucks. Small quantities can be picked up from tank farms or storage and distribution points in 400-gallon water trailers or in refillable drums, 5-gallon cans, and individual containers.
1-56. Appendix B, Figure B-1, shows a water distribution system plan for a hospital area. The general location and size of the pipes are shown, together with the valves, sumps, water tank, and other fixtures. Generally, the symbols used on distribution-system plans are the same as those for water plumbing. (See Appendix B, Section II, for standard plumbing symbols.) The plumber who installs the system determines the location of the pipes and other equipment to suit the climate and terrain, and according to the National Plumbing Codes.
1-57. See Appendix E for water distribution system design procedures used in the TO.
1-58. A sewerage system consists of the pipes and apparatus that carry sewage from buildings to the point of discharge or disposal. The system includes sewer pipe and conduits, manholes, flush tanks, and sometimes storm-drain inlets. If it is not served by a processing plant, the system may include facilities for pumping, treating, and disposing of sewage. Roofs, inner courts, vents, shafts, light wells, or similar areas having rainwater drains should discharge to the outside of the building or to the gutter. Get administrative approval before connecting to the drainage system.
1-59. Figure 1-5 shows a typical sewerage system and a drain system.
Figure 1-5. Sewerage and Drain Systems
1-60. The building drain receives the discharge of sanitary and domestic wastes (or soil and waste) from within the building.
1-61. The house drain is located between and is connected to the building drain and the house sewer. The house drain, also called the collection line, receives the discharge of sanitary and domestic wastes from the building drain and carries it to the house sewer line or pipe, as shown in Figure 1-5. The house drain may be underground or suspended from the basement ceiling.
1-62. The house sewer line or pipe begins just outside the building foundation wall and ends at the main sewer line or pipe in the street or at a septic tank (Figure 1-5). A house sewer line or pipe carries liquid or waterborne wastes from the house drain to the main sewer lines. Sanitary sewers are not connected to the storm sewers, because the sanitary discharge must be treated before it is dumped into a stream or lake.
1-63. A storm sewer line or pipe carries rain water and subsurface water. Since the discharge sewer is runoff water, treatment is not needed. The storm drain receives storm water, clear rain, or surface-water waste only (Figure 1-5).
1-64. The industrial drain receives liquid waste from industrial operations. However, this type of drain is of little importance in TO construction.
1-65. The pipes and fittings for sewer systems are standard to the National Plumbing Codes and general usage.
1-66. Cast-iron soil pipe or plastic pipe is usually used for house sewers and drains. Bituminous-fiber pipe, when not prohibited, may be substituted for cast-iron pipe for the house sewer. Concrete or vitrified-clay pipe is found in older installations.
Vitrified-Clay or Concrete Sewer Pipe
1-67. These pipes are connected with resilient joints, using a rubber sleeve and/or rigid joints by compressing rubber or neoprene rings. Vitrified-clay tile is highly resistant to all sewerage and industrial wastes. Concrete pipe may be manufactured with steel reinforcement; it comes in diameters of 12 to 108 inches.
Cast-Iron Soil Pipe
1-68. Cast-iron soil pipe is classified as follows:
1-69. Acrylonitrile butadiene-styrene (ABS) is gray or black plastic pipe used for storm or sanitary drainage, above and below ground. It is connected with solvent-cement joints. This pipe comes in 10- and 20-foot lengths in various diameters.
Cast-in-Place Concrete Conduit (Tube or Pipe)
1-70. This conduit is used when a pipe larger than 60 inches is needed to increase the capacity in a main, a trunk, or an outfall sewer. The drains are arches or culverts reinforced with concrete.
1-71. Sewerage systems are usually constructed of pipe ranging in diameter from 2 to 36 inches. Both the house sewer and the house drain must be leakproof and large enough to carry off the discharge of all plumbing fixtures. If either the sewer or the drain is too small, fixtures may overflow. The house sewer and house drain are usually the same size. Waste matter is forced through the house drainpipe by water. Therefore, the pipe must be large enough to carry out all the water and waste discharged through it; but it must be small enough for the water to move rapidly, forcing the waste through to the sewer. A pipe sized to flow half full under normal use will have good scouring action and can carry peak loads when required.
Drainage Fixture Units (DFUs)
1-72. The discharge of a plumbing fixture is figured in DFUs. One DFU represents approximately 7.5 gallons of water being discharged per minute. The DFUs for standard fixtures are shown in Table 1-5.
Table 1-5. DFU Values
1-73. For example, assume that a plumbing installation consists of 2 water closets, 4 lavatories, 2 shower heads, 3 urinals, 1 slop sink, 1 laundry tub, and 1 floor drain. Determine the discharge in DFUs from Table 1-5. Assume that the cast-iron house drain will have a slope of 1/4 inch per foot.
Step 1. Multiply the number of each fixture by its DFU value from Table 1-5, for a total of 45 DFUs.
Step 2. Read down the 1/4 inch column in Table 1-6. The fixture unit capacity next higher than 41 is 96.
Step 3. Read horizontally across to the left to 4 inches.
1-74. As a result, the minimum pipe size required is 4 inches.
1-75. Table 1-6 lists the capacity (in DFUs) of various pipe sizes for horizontal drains. This table is for cast-iron soil pipe, galvanized-steel/iron pipe, or plastic house drains, house sewers, and soil and waste branches. When using copper tubing (drain, waste, and vent (DWV) type) for above ground only, it may be one size smaller than shown on the table.
Table 1-6. Horizontal Sanitary Drain Capacity (in DFUs)
1-76. To find the correct size of the pipe, plan the slope of the pipeline by counting the total number of DFUs emptying into a horizontal drain line.
1-77. A base of solid, undisturbed earth provides enough support for house sewer and drain piping. This prevents future settling, which might cause the weight of the pipe sections to press too heavily on the joints. If the soil is loose, each joint should be supported on concrete, cinder block, or brick.
1-78. Usually the first step in installing the house sewer is to connect the sewer thimble and then work back, grading up to the house drain. The hole cut in the sewer must be no larger than necessary to fit the sewer thimble. All joints must be supported. The thimble should be tapped in above the normal flow level. For example, if the street sewer is 24 inches in diameter and the normal flow is 50 percent, the tap should be at least 12 inches above the bottom of the pipe. Install the thimble with its discharge parallel to the direction of sewer flow. This prevents backflow during periods of high flow. Use the following installation steps:
Step 1. Tap gently around the circumference of the main sewer to find the depth of flow for placing the thimble. A dull sound results from tapping below the sewer level, and a ringing sound results from tapping above the sewer level.
Step 2. Use the thimble as a pattern for marking the size of the hole with chalk.
Step 3. Make the cut on this line with a small, cold chisel and an 8-ounce ball peen hammer, as shown in Figure 1-6. Use light blows to prevent damage to the main sewer.
Figure 1-6. Cutting a Hole in the Main Sewer
Step 4. Work around the cut until a depth of 1/8 to 3/16 inch is reached.
Step 5. Make a small hole in the center of the area to be removed. Always use light blows.
Step 6. Enlarge the hole into an oval shape as near the size of the sewer thimble as possible. Try the thimble in the opening often to see if it will fit without enlarging the hole.
Step 7. Place the thimble in the proper position and pack oakum around the edges of the flange.
Step 8. Complete the installation by packing a rich portland cement mortar (one part sand to one part cement) around the thimble. Use enough mortar under the thimble, on the bottom of the tap, and on the top and sides. Support the joint until the mortar sets.
NOTE: The system must be tested after it is completed.
1-79. When possible, house sewers should be graded to a slope of 1/4 inch per foot. Greater or lesser slope is permitted when necessary. Trenches for house sewers may be graded with surveying instruments or with a carpenter's level having a rising leg or a board under one end. For example, a 1/4-inch-per-foot slope would be 1/2 inch for 2 feet using a 2-foot carpenter's level with a 1/2-inch thick board under one end. If the pipe is sloped correctly, the level will read level anywhere on the pipe except the hub. The drain is graded toward the main sewer with the hub end of the pipe lying upgrade. A similar procedure uses an 8-foot board and a 4-foot level.
1-80. Manholes are entranceways to the sewer system (for cleaning, inspection, and repair). They are round and are constructed of cement with brick-and-mortar walls on a concrete slab. A removable heavy lid in a cast-iron ring closes the top. Figure 1-7, is a section drawing of a round manhole. The base slab slopes from 10 to 9 inches. The lid is 2 1/3 feet in diameter by 3 1/4 inches thick. There are three shelves around the pipes in an opening measuring 3 feet 6 inches in diameter. (Precast concrete manholes are available, but the military plumber rarely installs this type.)
Figure 1-7. Round Manhole Construction
1-81. Grease traps are placed in the flow line of the building's sewer system to catch grease and fats from kitchen and scullery sinks. (Solid grease usually clogs the waste pipes.) The box-type traps are made of brick, concrete, or metal, in various shapes and sizes. The grease trap should be set in the waste line as close as possible to the fixture. Figure 1-8, shows baffle walls, which control the flow. Baffle walls are placed in boxes to separate floating grease particles.
Figure 1-8. Grease Trap
1-82. A septic tank speeds up the decay of raw sewage (Figure 1-9). It may be concrete, stone, or brick, in box-section form. (Lumber is used when other materials are not available.) It should be watertight. The siphon chamber makes certain that liquid will flow from the chamber; however, the siphon chamber is not absolutely necessary. The baffle boards are usually 2-inch oak planks, which run entirely across the tank. The boards are suspended from hangers and extend several inches below the surface of the sewage. One board should be located 10 inches from the inlet pipe and the other about 4 inches from the outlet partition. The septic tank should have a manhole and cover to give access for cleaning and repair. Septic tanks must be designed to hold for 24 hours and not less than 16 hours, 70 percent of the peak water demand of that facility.
Figure 1-9. Septic Tank
1-83. Figure 1-10, shows a small sewerage system, which includes the septic tank. The distribution box, which permits equal flow to all the lines of the disposal field, can be either wood, concrete, or brick. The diversion gate is usually wood with a handle slot, so it can be moved to change the sewage flow.
1-84. The system shown in Figure 1-10 uses both a septic tank and a subsurface sand filter to dispose of sewage. A plumber needs both a plan and a profile (elevation) view of the system.
Figure 1-10. Small Sewerage System Plan
1-85. If a septic tank cannot handle the load, an Imhoff tank may be used. Figure 1-11 shows typical construction details. When a treatment plant is required, plans for a specific site should be prepared, taking into account soil conditions and features of the land's surface.
Figure 1-11. Cross Sections of an Imhoff Tank
1-86. The subsurface system is the most common type of drainage bed. A subsurface system is used where space and soil permit or where there is no stream or pond nearby. When laying the piping for a drainage bed consider the—
1-87. For example, a subsurface irrigation system must handle 2,000 gallons per day (GPD), and the average time noted in the soil absorption test is 10 minutes. From Table 1-7, this corresponds to 1.7 GPD per square foot.
1-88. The length of piping in a subsurface drainage bed depends on the type of soil and the volume of liquid to be treated. This is determined by a soil percolation test (paragraph 1-91). To compute the length of the drainage lines, an average percolation rate is used. Table 1-7, gives soil absorption rates of the drainage lines.
Table 1-7. Soil Absorption Rates of Drainage Lines
1-89. The solution would be (round up to the nearest 10 feet)—
1-90. If trenches are 18 inches wide (1.5 feet) (round up to the nearest 10 feet)—
1-91. Another factor of laying piping for a drainage bed includes performing a soil percolation test. Use the following steps to perform this test (Figure 1-12):
Step 1. Dig at least six test holes, 1 foot square, to a depth equal of that of the planned drainage bed.
Step 2. Place a 2-inch layer of gravel in the bottom of the holes and fill the holes with water.
Step 3. Let the test holes stand overnight if the soil is tight or has a heavy clay content. If the soil is sandy and the water disappears rapidly, no soaking period is needed. Pour water into the holes to a depth of 6 inches above the gravel. The batter board acts as a reference line, and a ruler should be used to record the level of water in the hole below the batter board.
Step 4. Measure the water every 10 minutes over a 30-minute period. The drop in water level during the final 10 minutes is used to find the percolation rate of the soil.
Figure 1-12. Soil Percolation Test
1-92. Leaching tanks and cesspools receive raw sewage or septic tank overflow. They can be made of 4- by 4-inch lumber or 5-inch round timber. Dry masonry may be used for wall construction when time and materials permit. Figure 1-13 shows the design for a small leaching tank.
Figure 1-13. Design for a Leaching Tank
1-93. Piping of surface irrigation and subsurface sand filter disposal systems is installed using plans and profiles. The plans and profiles are based on the area topography and a soil percolation test. The small sewerage system shown in Figure 1-10 shows a sand filter field.
1-94. Water usage generally results in wastewater that requires disposal. Depending on the source, wastewater may contain suspended solids and particulate matter, organic material, dissolved salts, biological and pathogenic organisms, and toxic chemicals. The volume of wastewater alone can cause significant problems in the field.
1-95. Army policy directs that wastewater and waterborne wastes be collected and disposed of in a manner that protects water resources and preserves public health. These procedures must have a minimal impact on unit readiness. The Army is required to comply with federal, state, and local environmental pollution and wastewater laws on US territory. (For more information about US laws and regulations, refer to Training Circular (TC) 5-400.) While in other countries, units may have to comply with the host nation's laws and procedures as determined by the theater commander. In a true contingency operation, the theater commander determines if local environmental laws apply in the area of operation. Regardless of laws and regulations, proper wastewater disposal is essential to protect the health of the force. Proper disposal prevents the contamination of water supplies and development of rodent and insect breeding sites. Large volumes of wastewater may impact on unit operations and help the enemy locate and identify the unit.
1-96. Units in the field are responsible for collecting and disposing of the wastewater they generate. Large-volume wastewater producers, such as hospitals, normally require engineer support. In the continental US (CONUS), this support usually comes from installation facility engineers. The preferred method for wastes disposal is through contractors when they are available. Theater combat engineers provide this support during deployments and contingency operations outside the continental US (OCONUS) when contractors are unavailable or when the mission dictates. In any event, the commander is responsible for coordinating proper wastewater disposal.
1-98. Base camps produce significant volumes of wastewater in relation to the volume of water consumed. No definitive studies have been done to quantify the volume of wastewater generated by the various base camps. A conservative estimate for planning purposes is that about 80 percent of all water used for purposes other than human consumption ends up as wastewater. The largest volume of field wastewater is generated by laundries, showers, and kitchens. While this wastewater is not unique to base camps, it contributes to the total volume requiring collection and disposal.
1-99. Field showers are generally collocated with a base camp to support both residents and transients. Quartermaster personnel operating the showers are responsible for collecting and disposing of shower wastewater. In some cases, this disposal may be in conjunction with that of the base camp. When possible, units should consider recycling shower and laundry water to reduce the volume requiring disposal.
1-100. Field laundries may also be collocated within the base camp. They are the largest source of wastewater. As with showers, quartermaster personnel operating the laundries are responsible for wastewater collection and disposal. When possible, units should recycle laundry water to reduce the volume requiring disposal.
1-101. The base camp's dining and food sanitation centers are a significant source of wastewater. In addition to volume, grease and particulate matter present a complicating factor. As such, grease traps must be constructed to remove food particles and grease before collecting and disposing of the wastewater. Design criteria for grease traps are outlined in Section VIII of this chapter.
1-102. The wastewater disposal method depends on the factors listed in paragraph 1-97. The following options should be considered in each case:
1-103. Existing installation disposal facilities should be used in most training scenarios in the CONUS. This also holds true for many noncombat operations outside the OCONUS, especially in developed countries. A point of contact (POC) should be established with the host nation, via joint task forces (JTF) or civil affairs. In some operations, preplanned base camp sites can take advantage of local sewer systems. Facility engineer assistance is needed to make the required connections and access the system. Pretreatment will not be required since the composition of wastewater is roughly equivalent to that of a fixed installation. Grease traps or filters may be required in areas, such as the dining-facility stream, to remove grease and particulate matter because they could affect the operation of the wastewater pumps.
1-104. If the installation sewer system is unavailable, collect the wastewater in containers, such as expandable pillow tanks or drums. The containers can be moved to a sewage-treatment plant or a sanitary sewer access by engineers or contractors. Storage containers, wastewater tank trucks, and pumps are not standard equipment so this option requires extensive prior planning and coordination.
1-105. Semipermanent collection, treatment, and disposal facilities may be possible in permanent training sites and preplanned deployment sites. Small package plants are also available as listed in the Army Facilities Components System (AFCS). Extensive construction engineer support is required to build and maintain such systems.
1-106. Actual field expedient disposal methods may not be permitted in training areas in the CONUS or most developed countries. However, personnel must know how to construct and operate these field expedient methods with limited or nonexistent engineer support. Obviously, some engineer support is almost always needed. Earthmoving equipment may be necessary due to the volume of wastewater generated. This support must be included in site- preparation planning.
1-107. Traditional field expedient disposal methods consist of soakage pits, soakage trenches, and/or evaporation beds. The effectiveness of these methods depends on geological conditions, soil composition, and the climate. These devices, especially soakage pits, are generally constructed for small volumes of wastewater. With proper design and operation, they can be effective for larger volumes of watewater. Since these methods result in final disposal, some wastewater pretreatment may be necessary to remove grease, particulate matter, and organic material. Design and construction critera for these devices are outlined in Section VIII. Guidance is also available from supporting engineers and preventive-medicine personnel. These methods are generally appropriate for short periods only, so consider the alternatives in paragraph 1-103 when occupying the same site for more than two weeks.
1-108. Soakage or evaporation may be impossible in arctic environments, or under certain geological or climatic conditions. The only alternative may be to collect wastewater in tanks or drums for removal by engineers or contractors. As in paragraph 1-103, this option requires extensive prior planning and coordination.
1-109. Proper human waste disposal (feces and urine) is essential to prevent the spread of diseases caused by direct contact, water contamination, or dissemination by rodents and insects. Proper disposal is critical because many disease organisms are transmitted through feces.
1-110. Army policy directs that human waste be disposed of with good sanitary practices; and the Army must comply with federal, state, and local environmental laws for human waste. (For more information on US laws and regulations, see TC 3-34.489 and FM 3-100.4.) Few laws specifically address human waste disposal in the field; nevertheless, proper human waste disposal is essential and requires command emphasis at all levels.
1-111. At installation level, facility engineers are responsible for constructing, maintaining, and operating fixed sewage systems. Commanders are responsible for providing human waste disposal facilities in the field. Engineer support may be required to construct some types of field disposal devices.
1-112. The type of field latrine selected for a given situation depends on a number of factors-the number of personnel, the duration of the stay at the site, and geological and climatic conditions. Preventive-medicine personnel and the unit's field sanitation team can help determine the right type, location, number, and size of latrines. Specific guidance on selecting and constructing field expedient facilities is discussed in Section VII.
1-113. The locations of base camp latrines are a compromise between the requirement for separation from dining facilities and water sources and convenience for personnel. Multiple latrine sites are clearly necessary for larger base camps. Sanitation and maintenance are critical to prevent disease transmission to and from personnel. An important factor is the requirement for hand-washing facilities adjacent to each latrine. Close and mark latrines according to the local policy and good field sanitation practices (paragraph 1-132).
1-114. As discussed in paragraph 1-102, the construction and use of field expedient facilities may be prohibited. In such cases, the only option is to get support from the installation facility engineer and/or contractor.
1-115. The preferred option is to establish the base camp in an area with latrine facilities already in place and connected to a installation sewage system. This may be possible in permanent training areas or predesignated deployment sites. An alternate option is the engineer construction of a stand-alone sewage system and fixed latrines. Again, this may be possible in predesignated training areas or deployment sites.
1-116. An option commonly used is contract-supported latrine facilities. These include chemical toilets or self-contained vault toilets. The contractor is responsible for emptying the contents on a scheduled basis. Contractors may be the only option available due to local regulations and policies.
1-117. The accumulation and disposal of solid waste is a major problem on the modern battlefield. Not only does the solid waste impact on military operations, it may also contribute to environmental contamination and it may serve as breeding sites for rodents and insects.
1-118. Army policy directs that all solid and hazardous waste be disposed of in an environmentally acceptable manner. Disposal must be consistent with good sanitary engineering principles and mission accomplishment. The Army is required to comply with federal, state, and local requirements for the collection and disposal of solid waste. Most legislation is not specifically oriented toward a field environment. The Army adopts federal laws that deal with solid and hazardous wastes as explained in TC 3-34.489 and FM 3-100.4. The theater commander determines the applicability of both US and host-nation regulations and policies. Proper waste disposal is required to protect the health of the force.
1-119. Depending on the nature and volume of waste, generating units are generally responsible for its collection and disposal. Certain types of waste require special handling that may be beyond the unit's capability. Large waste generators, such as hospitals, may not have the resources or equipment to properly dispose of all the solid waste. In these cases, installation facility engineers or theater engineers are responsible for solid-waste disposal support.
1-120. Solid waste is not unique to the base camp. The primary sources of solid waste are routine troop-support, maintenance, and motor pool operations; administrative functions; and medical and dining facilities. A major effort must be made to reduce the amount of waste generated. This in turn will reduce the burden on disposal systems. Disposal methods depend on installation or host nation requirements. Most solid wastes can be transported to a disposal point in unit or contract vehicles. In most cases, the volume of waste alone is an operational concern. With prior approval, small amounts of some solid wastes may be burned using field expedient incinerators.
1-121. Wastes that are not specifically classified as petroleum,oils, lubricants (POL), hazardous, or medical waste are considered general waste. General wastes include—
1-122. Special consideration must be given to rotting waste from dining facilities. It may not be hazardous or infectious, but it may present a serious aesthetic problem and become a breeding site for disease-carrying rodents and insects. Rotting waste must be removed and disposed of as soon as possible, especially in warmer weather. Burial, if permitted, must not be in the vicinity of the immediate base camp. General waste is normally disposed of through landfill operations. Installation facility engineers or theater engineers are responsible for constructing and operating these landfills.
1-123. This waste consists of all used oil and POL products (including fuel and petroleum derivatives and asphalt products). The products may be classified as hazardous waste if they become mixed with water or soil. Products are separated and stored in appropriate containers and the containers are disposed of through contractors or retrograde operations.
1-124. Certain types of solid waste (especially chemicals) are classified as hazardous waste. Examples include solvents, paints, and cleaners. These products require special handling, transportation, disposal, and documentation. Hazardous wastes are stored in appropriate containers, and the containers are disposed of through contractors or retrograde operations. Engineers and preventive-medicine personnel can provide guidance and assistance on hazardous-waste disposal. (See TC 3-34.489 and FM 3-100.4 for more information on hazardous waste.)
1-125. Medical waste is any waste that is generated by a health-care facility and that is capable of producing infectious diseases. For waste to be infectious, it must contain or potentially contain pathogens of sufficient quantity/virulence to result in an infectious disease in a ssqle host. Medical wastes should be disposed of through contractors, but they can be incinerated in certain cases. (See TC 3-34.489 and FM 3-100.4 for more information on medical waste.)
1-126. During wartime, commanders must exercise a high degree of resourcefulness. When adequate buildings and facilities are available, commanders must determine whether the added health benefits of using such facilities offsets tactical considerations. When adequate facilities are unavailable or the commanders choose not to use them, improvised facilities must be constructed to ensure the maintenance of proper sanitary standards. The devices discussed in this section can be simply constructed and they provide adequate sanitation.
1-127. The following general rules apply to constructing all types of latrines, except catholes (paragraph 1-133).
1-128. To ensure that food and water are protected from contamination, latrines should be at least 100 yards from the dining facility and 100 feet from the nearest water source. Latrines should not be dug below the groundwater table or where they may drain into a water source. (The groundwater table can be determined from information given by local inhabitants or excavating to the groundwater table.) Latrines are usually built at least 30 yards from the end of the unit area but within a reasonable distance for easy access. They should be lighted at night if the military situation permits. If lights cannot be used, tie pieces of cord or tape to trees or stakes as guides to the latrines.
1-129. Place a canvas or brush screen around each latrine or enclose it in a tent. If possible, heat the shelter in cold climates. Dig a drainage ditch around the screen or tent to prevent water from flowing over the ground into the latrine. For fly control, spray the shelter with an insecticide twice a week. If fly problems persists, spray the pit contents and box interior twice a week with a residual insecticide.
1-130. Install a simple hand-washing device outside each latrine. The device should be easy to operate and have a constant supply of water. The importance of hand-washing devices must be given aggressive emphasis. Hands contaminated with fecal material are a common means of disease transmission.
1-131. Police the latrines daily. Assign specific unit personnel the responsibility of ensuring that the latrines are properly maintained.
1-133. The simplest of all field human waste disposal devices is the cathole latrine (Figure 1-14). This latrine is used by individuals on the march and patrol. It is also used in similar situations where latrine facilities are not available. A cathole latrine should be dug at least 1 foot wide and 1 foot deep. After use, replace and repack the soil.
Figure 1-14. Cathole Latrine
1-134. The most common type of latrine for temporary (one to three days) bivouacs is the straddle-trench latrine (Figure 1-15). A straddle-trench latrine is dug 1 foot wide, 2 1/2 feet deep, and 4 feet long. It will accommodate two people at the same time. Provide straddle trenches to serve at least 4 percent of the unit's male strength and 6 percent of the female strength. Thus, for a unit of 100 men and 100 women, at least four latrines are needed for the men and six for the women. Place the trenches at least 2 feet apart. There are no seats with this type of latrine. Boards may be placed along both sides of the trench to provide better footing. Place toilet paper on a suitable holder. Protect it from bad weather by covering it with a tin can or other covering. Remove the earth and pile it at the end of the trench so that each individual can properly cover his excreta and toilet paper. Close the saddle-trench latrines as described in paragraph 1-132.
Figure 1-15. Saddle-Trench Latrine with a Hand-Washing Device
1-135. The deep-pit latrine is used with a latrine box (Figure 1-16). The standard latrine box has four seats, and is 8 feet long and 2 1/2 feet wide at the base. A unit of 100 men requires two four-seat latrine boxes. Cover the holes with flyproof, self-closing lids. Flyproof the cracks with strips of wood or tin. Place a metal deflector (can be made with a flattened can) inside the front of the box to prevent urine from soaking into the wood.
Figure 1-16. Deep-Pit Latrine
1-136. Dig the pit about 2 feet wide and 7 1/2 feet long. This will give the latrine box 3 inches of support on all sides. The depth of the pit depends on the estimated length of time the latrine is to be used. As a rough guide, allow a depth of 1 foot for each week of estimated use, plus 1 foot for the dirt cover when closed. Rock or high groundwater levels often limit the depth of the pit, but it should be no deeper than 6 feet. Support may be needed in some types of soil to prevent the sides from collapsing. If so, use planking or a similar material. Pack the earth tightly around the bottom edges of the box to seal any openings through which flies might enter.
1-137. To prevent flies from breeding and to reduce odors, keep the latrine box clean, the seat lids closed, and the cracks sealed. Maintain a good fly control program in the area. Applying lime to the pit contents or burning it does not effectively control flies or odor. Scrub the box and latrine seats with soap and water daily. Close deep-pit latrines as described in paragraph 1-132.
1-138. A bored-hole latrine consists of a hole that is about 18 inches in diameter and 15 to 20 feet deep. It is covered by a one-hole latrine box (Figure 1-17). The actual diameter is not critical, so make it as large as available augers permit. Sink a covered metal drum into the ground for use as a box. Remove both ends of the drum. Make a flyproof seat cover with a self-closing lid to fit the top of the drum. If a drum is not available, construct a flyproof, wooden box that is 18 inches high. A bored-hole latrine is satisfactory for small units.
Figure 1-17. Bored-Hole Latrine
1-139. The following latrines are limited to areas where the groundwater table is deep enough to prevent groundwater contamination or water standing in the latrine pit. They are also limited to areas that are free of impervious rock formations near the surface. Several alternatives are available for locations where a high groundwater table or a rock formation near the surface prevents digging a pit of adequate depth.
1-140. A dirt mound makes it possible to build a deep-pit latrine without the pit extending into water or rock (Figure 1-18). Construct a mound of earth that is at least 6 feet wide and 12 feet long. It must be able to support a four-hole latrine box. The mound should be high enough to meet the pit's depth requirement. Allow 1 foot from the base of the pit to the water or rock level. Break up or plow the area where it is to be placed to aid in seepage of liquids from the pit. If timber is available, build a crib of desired height to enclose the pit and support the latrine box. Build the mound and compact it in successive l-foot layers to the top of the crib as shown in Figure 1-18. Roughen the surface of each layer before adding the next. If timber for a crib is unavailable, construct the mound to the desired height in l-foot layers as described and dig the pit into the mound. It may be necessary to brace the walls with wood, sandbags, or other material to prevent them from collapsing. Flyproof and enclose a mound latrine the same as a deep-pit latrine (paragraphs 1-135, 1-136, and 1-137).
NOTE: The size of the mound base depends on the type of soil in the area. Make the mound larger if the slope is steep. Also, it may be necessary to build steps up a steep slope.
Figure 1-18. Mounded Latrine
1-141. A burn-out latrine is particularly suitable for jungle areas with high groundwater tables (Figure 1-19). It has been extremely useful in the past. Ensure that the burning location is downwind of the base camp. For a unit of 100 men and 100 women, at least eight men's latrines and eight women's latrines are needed.
Figure 1-19. Burn-Out Latrine
1-142. Place a 55-gallon drum in the ground. Leave enough of the drum above the ground for a comfortable sitting height. The drum may be cut in half, making two latrines of less capacity. Place a wooden seat with a flyproof, self-closing lid on top of the drum. Weld handles to the sides of the drum, allowing two men to carry the drum with ease, because it must be moved before the contents are burned out. Have two sets of drums, if possible, so one set can be used while the other set is being burned out. Encourage male personnel to urinate in a urine disposal facility (paragraph 1-145) rather than a burn-out latrine because more fuel is required to burn out a latrine with a liquid content.
1-143. Burn out the latrine daily by adding sufficient fuel to incinerate the fecal matter. Do not use highly volatile fuel because of its explosive nature. A mixture of 1 quart of gasoline to 5 quarts of diesel oil is effective; nevertheless, use it with caution. Burn the contents again if they are not rendered dry and odorless in one burning. Bury the residual ash.
1-144. Build a pail latrine when conditions (populated areas, rocky soil, marshes) are such that a latrine cannot be dug (Figure 1-20). Construct a standard latrine box according to paragraphs 1-135, 1-136, and 1-137. Place hinged doors on the rear of the box. Add a floor and place a pail under each seat. Position the box to form a part of the outer wall if the box is located in a building. Ensure that the rear of the box opens directly to the outside of the building. The box should be flyproof, and the seats and rear doors should be self-closing. Construct the floor of the box with an impervious material (concrete, if possible), and allow enough slope toward the rear to facilitate rapid drainage of washing water. Install a urinal in the male latrine with a drainpipe leading to a pail outside and enclose the pail in a flyproof box. Clean pails at least once daily. Bury or burn the contents or dispose of them by another sanitary method. Plastic liners for the pails reduce the risk of accidental spillage. Tie the filled bags at the top before disposal.
Figure 1-20. Pail Latrine
1-145. In permanent and semipermanent camps, urine disposal facilities are usually connected to the sewer system. In the field, separate devices for urine disposal may be necessary. Collocate such facilities in the male latrines to minimize fouling of seats. At least one urine disposal facility is required for each male latrine or per 100 personnel.
URINE SOAKAGE PIT
1-146. The best device for urine disposal in the field is a urine soakage pit (Figure 1-21). Dig the pit 4 feet square and 4 feet deep. Fill it with an aggregate material. Lay a border along each edge so that each side of the soakage pit's surface is 5 feet long. The border should be 6 inches wide, 4 inches deep, and composed of small stones. Depending on available materials, use either pipe urinals or trough urinals with this pit. An optional feature is the ventilating shafts with screened openings that extend from about 8 inches above the pit to within 6 inches of the bottom of the pit.
NOTE: A soakage trench (paragraph 1-156) may be used when the groundwater table or a rock formation precludes digging a standard urine soakage pit .
Figure 1-21. Urine Soakage Pit with Pipe Urinals
1-147. Pipe urinals should be at least 1 inch in diameter. Place them at an angle near each corner of the pit and, if needed, on the sides halfway between the corners (Figure 1-21). The pipes should extend at least 8 inches below the surface of the pit. Place a funnel made of tar paper, sheet metal, or similar material in the top of each pipe. The upper rim of the funnel should extend about 30 inches above the ground surface.
1-148. If materials are available and more permanent facilities are desired, build a trough urinal (Figure 1-22). The trough is U- or V-shaped and made of sheet metal or wood. If the trough is made of wood, line it with heavy tar paper. The four troughs forming the sides should be no more than 4 1/2 feet long when they are used with a soakage pit and an apron. Each trough should slope slightly toward one corner where a pipe carries the urine to the soakage pit.
Figure 1-22. Trough Urinal
1-149. The urinal represents a further modification for more permanent installation (Figure 1-23). Simply described, it is a 55-gallon drum containing oil that is placed over a recessed soakage pit, thus the name, urinoil. Waste POL can be used; but vegetable oil is preferred. Urine voided through the screen immediately sinks through the oil to the bottom of the drum. The action of the urinal is somewhat like that of a barometer. As more urine is added, the oil level rises in the 3-inch pipe. This continues until it reaches the 1 1/2-inch notch on the overflow pipe in the center of the drum. Atmospheric pressure and the weight of the oil causes the urine to overflow until equilibrium is reestablished in the drum. The oil acts as an effective seal against odors and flies. The screen is easily lifted with attached hooks for removal of debris. The urinal will operate in place as long as the soakage pit will accept the urine.
Figure 1-23. Urinal
1-150. To ensure proper operation of latrine facilities—
1-151. If the latrine is located some distance from sleeping areas, place a large can or pail at a convenient location for use as a urinal at night. Empty the can into the soakage pit every morning, and wash the pail with soap and water before reusing it.
1-152. When a urine soakage pit is abandoned or becomes clogged, spray it with insecticide. Mound it over with a l-foot covering of compacted earth. Place a rectangular sign on the mound indicating the type of pit and the date closed.
1-153. Wastewater from food service operations contains food particles, grease, and soap. Consequently, kitchen waste requires treatment before disposal.
1-154. In permanent or semipermanent camps, kitchen waste is passed through a grease trap. Afterwards, it is drained into a wastewater collection system. In temporary base camps, however, the soil absorbs kitchen waste. Install grease traps (paragraph 1-157) to remove the grease from the liquid to prevent clogging the soil and stopping absorption. Clean the grease traps frequently and, if permitted by federal and state regulations, burn or bury the removed grease. If not permitted, follow local procedures and unit standing operating procedures (SOPs) for proper disposal.
1-155. In temporary base camps, a kitchen soakage pit is constructed like a urine soakage pit (paragraph 1-146). It will normally dispose of liquid kitchen waste for a total of 200 persons. A grease trap is substituted in the kitchen waste soakage pit for the pipes or troughs in the urine soakage pit. If the camp is to last for several weeks, construct two kitchen waste soakage pits and alternate their usage on a daily basis. A rest period helps to prevent clogging. A clogged soakage pit will not accept liquid, and it must be properly closed. To close a kitchen pit, backfill and compact with soil 1 foot above the grade and mark the pit according to paragraph 1-132.
1-156. Use a soakage trench when the groundwater level or a rock formation precludes digging a pit. The trench consists of a pit, 2 feet square and l foot deep. The pit has a trench radiating outward from each side for a distance of 6 or more feet (Figure 1-24). Dig the trenches 1 foot wide, varying the depth from 1 foot at the center to 1 1/2 feet at the outer ends. Fill the pit and trenches with material similar to that used in the soakage pit. Build two units for every 200 persons fed and alternate their usage on a daily basis. Use a grease trap with the soakage trench, and close it according to paragraph 1-132.
Figure 1-24. Soakage Trench with Barrel-Filter Grease Trap
1-157. A grease trap should be large enough to prevent the addition of hot, greasy water from heating the cool water already in the trap. Otherwise, grease will pass through the trap instead of congealing and rising to the top of the water. A grease trap should be provided for each soakage pit except those under showers.
BAFFLE GREASE TRAP
1-158. A baffle grease trap is constructed from a 55-gallon drum or box (Figure 1-25). The box or drum is divided vertically into unequal chambers by a wooden baffle. This baffle should extend to within 1 inch of the bottom.
1-159. Waste is poured through a strainer into the large chamber. It then passes under the baffle and flows out into the small chamber. In the large chamber, the trap should have a removable lid and a strainer. The strainer may be a box with openings in the bottom. Fill the strainer with straw or burlap to remove coarser solids. Clean the strainer frequently by scrubbing it with soap and water to prevent clogging. Insert a 1-inch pipe, 3 to 6 inches below the top of the smaller chamber to carry liquid from the trap to the soakage pit. Clean the trap frequently to ensure proper operation. Remove the grease, drain the trap, and remove the sediment from the bottom. Burn or bury the grease, sediment, and strained material.
Figure 1-25. Baffle Grease Trap
BARREL-FILTER GREASE TRAP
1-160. The barrel-filter grease trap is constructed from a 30- to 50-gallon barrel or drum (Figure 1-26). Remove the barrel top and bore a number of large holes into the bottom. Place 8 inches of gravel or small stones in the bottom of the barrel and cover them with 12 to 18 inches of wood ashes or sand. Fasten a piece of burlap to the top of the barrel to serve as a coarse strainer. Place the trap directly over the soakage pit or on a platform with a trough leading to the pit. If the trap is placed over the pit, remove the bottom instead of boring holes into it. Empty the trap every two days. Wash the trap, remove and bury the ashes or sand, and refill the trap with fresh ashes or sand. Wash the burlap strainer every day or replace it.
Figure 1-26. Barrel-Filter Grease Trap
1-161. Evaporation beds may be used in hot, dry climates (Figure 1-27). They may also be used where clay soil prevents the use of standard soakage pits. Evaporation beds configured in three tiers, can be used when confined by available acreage (Figure 1-28).
Figure 1-27. Evaporation Bed
Figure 1-28. Three-Tier Evaporation Beds
1-162. Evaporation beds measure 8 by 10 feet. Construct sufficient beds to allow 3 square feet per person per day for kitchen waste and 2 square feet per person per day for wash and bath waste. Space the beds so that the waste can be distributed to any one of the beds. Scrape the top soil to the edges, forming a small dike around the bed. Spade the earth in the bed to a depth of 10 to 15 inches. Rake it into a series of rows with the ridges approximately 6 inches above the depression. Form the rows either lengthwise or crosswise, depending on which one allows for the best water distribution.
1-163. During the day, flood one bed with liquid waste to the top of the ridges. This is equivalent to an average depth of 3 inches over the bed. Allow the liquid waste to evaporate and percolate. After three or four days, the bed is usually sufficiently dry for respading and reforming. Flood the other beds on successive days and follow the same sequence of events.
1-164. Give careful attention to proper rotation, maintenance, and dosage. It is essential that kitchen waste be run through an efficient grease trap (paragraph 1-157) before putting it in an evaporation bed. If used properly, evaporation beds create no insect hazard and only a slight odor. Other waste disposal methods are possible if they are more adaptable to the particular situation.
1-165. Every device used for washing or drinking should have a soakage area. Soakage areas prevent pools and mud from forming. Excavate the area under and a few inches around hand-washing devices, wash racks, and lister bags. Fill the areas with small, smooth stones to form a soakage pit. Ensure that wastewater from wash racks is passed through a grease trap before it enters a soakage pit or trench. Each field shower only requires a soakage pit or trench.
1-166. The general considerations discussed in previous sections can be used for design purposes of company-sized or smaller elements. For larger base camps, the number of waste facilities would become excessive when using these general rules of thumb. Design waste facilities to suit the needs of the base camp to be established.
1-167. The amounts of wastewater generated by laundry, bath, and kitchen activities are directly related to the water-consumption planning factors for each facility. For bath and laundry facilities, waste disposal systems should be designed to handle 100 percent of the flow to that facility, since practically everything that flows into these facilities flows back out. Waste disposal systems for kitchen facilities should be sized to handle 70 percent of the design flow to these facilities, since part of the water is consumed within the facility.
1-168. Liquid waste from all these facilities should be discharged into a sewer pipe. For most theater facilities, a 6- to 12-inch plastic pipe placed at a 2 percent slope will suffice. The pipe should be buried, if possible, with minimum cover depending on the traffic in the area. The sewer pipe must empty its contents somewhere. In developed countries, a complete underground, waterborne sewerage system may be feasible and can possibly be connected to the host nation's main sewer system. However, several theater base camps are being constructed in undeveloped countries where no sewage system currently exists. In this case, base-camp design and construction must include waste treatment and disposal facilities. While an underground septic tank with a tile drain field is normally ideal, the amount of construction effort and materials required may make it unfeasible. If there are no waterborne toilets in the system, soakage pits or evaporation beds will usually be sufficient to handle the effluent from the laundry, bath, and kitchen facilities.
Step 1. Dig one or more holes 1 foot square by 1 foot deep.
Step 2. Fill the test hole(s) with water and allow it to seep into the surrounding soil.
Step 3. Refill the hole(s) to a depth of at least 6 inches while the bottom of the hole is still wet.
Step 4. Measure the depth of the water and record the time it takes for all of it to be absorbed into the soil.
Step 5. Calculate the time required for the water level to drop 1 inch.
NOTE: If the percolation rate exceeds 60 minutes, the soil is not suited for a seepage pit. A percolation rate over 30 minutes indicates borderline suitability for soil absorption, and other methods of wastewater disposal should be considered.
Table 1-8. Application Rate for Evaporation Beds
Table 1-9. Application Rate for Seepage Pits and Soakage Trenches
1-170. The required size of a seepage pit can be determined from a percolation test and the estimated amount of effluent from the facility. The pit should be 4 to 6 feet deep and dug in a square or rectangular fashion. The bottom of the pit should be at least 2 feet above the groundwater table and 5 feet above rock or other impermeable soil conditions. The effective absorption area is considered to be the total area of the walls in the pit; the bottom of the pit is not considered. Several smaller pits for a facility may be more feasible than one large pit. When more than one pit is used, ensure that there is equal distribution of the wastewater to all the pits. The distance between seepage pits should be at least twice the size of the pits. The pits should be located outside the base camp and at least 100 feet from the nearest water source.
1-171. Pits should be no deeper than 6 feet because deeper excavations might require wall shoring, which increases the construction effort. The design procedure is based on all absorption occurring in the walls only, and the required absorption area is obtained by increasing the length of the walls. Use the following steps to determine the required absorption area and pit size:
Step 1. Perform a percolation test (paragraph 1-169). The test should be performed twice-initially and again at the full estimated depth.
Step 2. Determine the application rate from Table 1-9.
Step 3. Find the required absorption area by dividing the total estimated effluent from the facility by the application rate.
Step 4. Divide the required absorption area (step 3) by 4 (the number of walls).
Step 5. Divide the required absorption area per wall (step 4) by the depth of the pit (normally 6 feet). This will be the length of each wall. Remember, the bottom of the pit must be 2 feet above the groundwater table and 5 feet above any type of impermeable soil conditions.
Step 6. Construct a pit by using walls of this length determined from Step 5.
NOTE: Using several small pits rather than one large pit reduces the excavation effort required.
Step 7. Fill the pit with large stones or rubble. Wastewater should be piped in near the center of the pit. Tar paper, plastic, or some other material can be used as a cover to prevent rainwater from filling the pit.
1-172. If a groundwater table or a rock stratum exists within 6 feet of the surface, a soakage trench may be substituted for a seepage pit. A soakage trench consists of a central pit that is 2 feet square and 1 foot deep. A trench radiates outward for 6 feet or more from each side of the pit. The trenches are 1 foot wide and increase in depth from 1 foot at the central pit to 1 1/2 feet at the outer end. The central pit and the radiating trenches are filled with gravel or broken rock. The length of the trench may vary as needed.
1-173. The design procedures for the soakage trench are similar to those for a seepage pit and are outlined below:
Step 1. Perform a percolation test (paragraph 1-169).
Step 2. Determine the application rate from Table 1-9.
Step 3. Determine the required absorption area by dividing the total estimated flow from the facility by the application rate.
Step 4. Divide the absorption area (step 3) by 8 (four radiating trenches; each trench has two walls). The absorption is considered to take place in the side walls of the trenches only, and this step yields the area of each wall.
Step 5. Divide the wall area from step 4 by the average depth of 1 1/4 feet, since each trench is 1 foot deep at one end and 1 1/2 foot deep at the other end. This step determines the length of each trench.
Step 6. Construct the soakage trench with four trenches of the determined length (step 5), each radiating from the central pit.
1-174. In places where a high groundwater table or clay soil prevents the use of standard seepage pits, evaporation beds may be used. Construct enough beds to handle the entire wastewater flow from the base camp laundry, kitchen, and bath facilities. Locate the beds outside the base camp and in an open, sunny area. Give careful attention to the proper rotation, maintenance, and dosage of the evaporation beds. If used properly, the beds create no insect problems and only a slight odor. An evaporation field is probably the simplest method of disposing of large amounts of wastewater from shower and laundry facilities. The design procedure is as follows:
Step 1. Perform a percolation test (paragraph 1-169). The test should be performed in at least 3 or 4 locations over the area of the proposed field.
Step 2. Determine the application rate from Table 1-8. The rates in the table include allowances for resting, recovery, maintenance, and rainfall.
Step 3. Divide the total daily effluent by the application rate to determine the required acreage.
Step 4. Construct enough beds to equal the acreage calculated in Step 3.
1-175. Although rare in theater construction, a waterborne sewage system for human waste may be desirable. If the sewer cannot be connected to an existing main sewer, a treatment facility must be constructed to support the base camp. The three types of treatment facilities that should be considered for theater base camps with waterborne human waste are-cesspools, sewage lagoons, and septic tanks with tile drain fields. While all three provide feasible solutions for the base camp, a septic tank with a tile drain field is preferred over the other two methods.
1-176. Cesspools are no longer used in developed countries because they may pollute the groundwater; however, they are common in undeveloped countries. If water sources are in the area where cesspools are used, the water must continually be checked to verify its purity. Cesspools are the least preferred method and should be used only as a last resort.
1-177. Sewage lagoons or oxidation ponds are common throughout the world. They can be used in all regions except arctic areas. Sewage lagoons are commonly used by small communities because they are less expensive to construct than sewage treatment plants. Although a sewage lagoon is easy to construct, it is not a recommended theater practice. Sewage lagoons must be located at least one-half mile from the population center because of the odors produced by anaerobic digestion. The increased length of the sewer collection system, compounded by the possible need for automatic lift stations, significantly increases the material cost and construction effort required for a complete system. Absorption from sewage lagoons into the surrounding soil is a problem and should be minimized. See Table 1-10 for relative absorption rates in sewage lagoons.
Table 1-10. Relative Absorption Rates in Sewage Lagoons
SEPTIC TANKS WITH TILE DRAIN FIELDS
1-178. Septic tanks are the preferred method of providing for primary and partial secondary treatment of sewerage containing human waste. Septic tanks are very common throughout the world. The preferred method of installation is to order a precast or fiberglass unit sized for the anticipated flow of wastewater; if available, septic tanks can be constructed in place. A septic tank separates and retains most of the solids in the sewage flow. The solids settle to the bottom of the tank and undergo anaerobic digestion. The effluent is dispersed into the surrounding soil by a tile drain field which is an underground system of porous pipes connected to the septic tank.
1-179. Subsurface irrigation is a method of sewage disposal commonly used in conjunction with septic tanks at small installations. This method allows sewage to seep directly into the soil or uses tile drain fields with application rates as shown in Table 1-11.
Table 1-11. Subsurface Application Rates of Sewage in Tile Drain Fields
Tile Drain Fields
1-180. A tile drain field consists of lines of concrete or clay drain tiles laid in the ground with open joints. Recently, manufacturers have begun to produce concrete pipe with 1/4- to 3/8-inch perforations in the bottom half. Also, a bituminized fiber pipe with holes bored in the lower portion of the pipe to allow drainage can be used for these drain lines. This pipe is light, can be easily laid in the trench, and is made in various sizes (2 to 8 inches in diameter and 5 to 8 feet in length). The long lengths of pipe are particularly valuable in soil where other types of drain fields may settle unevenly. Perforated plastic pipe offers the same advantages. Figure 1-29 and Figure 1-30 show typical field layouts. The following conditions are important for proper functioning of the tile fields:
Figure 1-29. Typical Layout of a Subsurface Tile System
Figure 1-30. Typical Layout of a Tile Field in Sloping Ground
1-181. The length of the tile and the details of the filter trench generally depend on the soil characteristics. The minimum width of trenches on the basis of soil are as follows:
1-182. Placing tile below the frost line to prevent freezing is not necessary. Tile placed 18 inches below the ground surface operated successfully in New England for many years. Subsurface tile should never be laid below groundwater level.
1-183. Design and construction should provide for handling and storing of some solid material to eliminate clogging of pipe joints. Pipe that is 3 to 6 inches in diameter is recommended. Larger pipe gives greater storage capacity for solids and a larger area at the joint for solids to escape into the surrounding gravel.
1-184. Lay pipe with 3/8-inch clear openings to provide for free discharge of solids from the line to the filter trench. Cover the top of the space with tar paper or similar material to prevent the entry of gravel. Bell and spigot pipe is easily laid to true line and grade. Good practice calls for breaking away two-thirds of the pipe along the bottom of the bells at the joint and using small wood-block spacers. The pipe is commonly laid at a slope of about 0.5 feet per 100 feet when taking the discharge directly from the septic tank, and 0.3 feet per 100 feet when a dosing tank is used ahead of the field.
1-185. Lay tile on a 6-inch bed of screened coarse gravel, with 3 inches of coarse gravel around and over the pipe. Gravel passing a 2 1/2-inch mesh and retained on a 3/4-inch mesh is recommended. This gravel bed gives a relatively large percentage of voids into which the solids may pass and collect before the effective leaching area becomes seriously clogged. Ensure that the soil which fills the trench does not fill the voids in the gravel around the pipe. A 3-inch layer of medium screened gravel over the coarse gravel and 3 inches of fine screened gravel over the medium stone is recommended.
1-186. Carefully design the tile layout. Generally, the length of the laterals should not exceed 75 feet. When tile is laid in sloping ground, distribute the flow so that each lateral gets a fair portion, and prevent the flow from discharging down the slope to the lowest point. Lay individual lines parallel to the land contours (Figure 1-30). Tile fields are commonly laid out in a herringbone pattern or with the laterals at right angles to the main distributor. Ensure that the distance between laterals is triple the width of the trench. You may want to connect the laterals to distribution boxes. Trenches 24 inches wide or more are the most economical. If a trenching machine is available, base the design on the width of the trench excavated by the machine.
1-187. Fence or post the tile field after it is constructed to prevent vehicle traffic from crushing the tile. Planting shrubs or trees over the field is not a good idea since the roots tend to clog the tile lines, but grass over the lines helps remove the moisture and keep the soil open. A typical section of a tile filter trench is shown in Figure 1-29.
Subsurface Drain Fields
1-188. Subsurface filter trenches or beds may be required where the soil is so dense and impervious that a tile drain field is impractical, and where lack of an isolated area prevents the use of an open filter. Drains that are under the subsurface filter trenches or beds may be discharged freely to the nearest satisfactory point of disposal, such as a small stream or a dry streambed.
1-189. Design filter trenches or beds for a rate of filtration not greater than 1 gallon per square foot per day. For filtering material use clean, coarse sand that passes a 1/4-inch mesh with an uniformity coefficent not greater than 4.0. Ensure that the filtering sand is at least 30 inches deep and coarse, screened gravel passes a 3 1/2-inch mesh and be retained on a 1/4-inch mesh. A typical section of an under-drained filter trench is shown in Figure 1-31. Governing conditions for field layout are similar to those for tile fields described above.
Figure 1-31. Typical Section of an Under-Drained Filter Trench
1-190. A typical plan and section for a subsurface filter bed are shown in Figure 1-32. Ensure that the slope of the distributors is about 0.3 feet per 100 feet when a dosing tank is used, and 0.5 feet per 100 feet when no dosing tank is required. For installations having more than 800 feet of distributors, build the filter in two or more sections with siphons to alternate the flow between the sections. Lay distribution pipelines in beds on 6- to 10-foot centers; under-drainpipes on 5- to 10-foot centers.
Figure 1-32. Typical Plan and Section of a Subsurface Sand Filter
1-191. Provide dosing tanks with automatic sewage siphons for tile or subsurface fields when the length of distribution tile exceeds 300 feet. Design dosing tanks to discharge a volume equal to 70 to 80 percent of the volumetric capacity of the distribution piping in the tile field or filter. The dosing tank can usually be constructed as part of the septic tank and in the same width as the septic tank (Figure 1-33).
Figure 1-33. A Septic Tank With a Dozing Siphon
1-192. For most theater construction, a 6- to 12-inch plastic pipe is sufficient to transport wastewater from the facility to a disposal system. Place the pipe at about a 2 percent slope to facilitate gravity feed. Use Table 1-12 to determine the size of pipe needed.
Table 1-12. Pipe Sizes
1-193. The minimum cover for wastewater pipe is as follows. In areas where freezing temperatures occur, the pipes must be placed below the frost line (except for subsurface tile systems).
4-1. A plumbing fixture must be supplied with a water flow rate that will fill it in a reasonable time. The pipe size required to supply each fixture depends on the psi pressure on the water main, the length of piping in the building, the number of fixtures and, for water closets, the types of flushing devices. Table 4-1 shows the pipe diameter for various fixtures. (Refer Chapter 6 for pipes and fittings.)
4-2. A water closet is a fixture used to carry organic body wastes to the sewer system. Water closets are made of vitreous china. They can be installed on a floor or suspended from a wall. They are available with various types of flushing action: washdown bowl, washdown bowl with jet, reverse-trap bowl, and siphon-jet bowl (Figure 4-1).
Figure 4-1. Water Closets
4-3. Each type has a built-in trap containing a water seal, based on the same atmospheric pressure on both sides of the trap.
4-4. Common Washdown Bowl. This bowl is the least expensive and the simplest type of water closet. The trap is at the front of the bowl, and small streams of water running down from the rim flush the bowl.
4-5. Washdown Bowl With Jet. This bowl is similar to the washdown bowl but is flushed differently. The unit has a small hole in the bottom, which delivers a direct jet as the unit is flushed. The jet, directed into the upper arm of the trap, starts a siphoning action.
4-6. Reverse-Trap Bowl. This bowl is similar to the washdown bowl, except that the trap is at the rear of the bowl, making the bowl longer. This bowl holds more water than the washdown bowl and is quieter in operation.
4-7. Siphon-Jet Bowl. This bowl is the most efficient, the quietest, and the most expensive water closet. It looks like the reverse-trap bowl but holds more water. It is almost completely filled with water.
4-8. Water-closet bowls are either floor-mounted or wall hung.
NOTE: The method of installing water closet bowls is the same regardless of the flushing action.
4-9. Floor-Mounted. To install a floor-mounted water closet bowl, the following items and materials are needed: a floor flange, a water closet bowl, a level, a wrench, and a wax or rubber gasket. When installing a water closet, use the following steps and Figure 4-2.
Figure 4-2. Floor-Mounted Water Closet Bowl
Step 1. Place the floor flange over the closet bend until the flange rests on the finished floor and then make a joint for the type of piping being used.
Step 2. Put two bowl bolts with their threaded ends up into the flange slots. If the bowl needs four bolts, place the bowl properly on the flange and mark the spots for the two additional bolts. Set these bolts into the positions marked. For a wood floor, use bolts with wood threads at one end and machine threads at the other end. For tile or concrete floors, set the heads of the machined bolts in the holes and fill with cement to floor level.
Step 3. Turn the bowl upside down on protective waste newspaper or wooden strips to avoid scratching. Set a wax gasket over the horn.
Step 4. Turn the bowl right side up and set it on the flange with the bolts through the holes of the bowl.
Step 5. Place a washer and nut on each bolt, tightening each alternately until the bowl is set.
Step 6. Ensure that the bowl is in a level position. If it is not level, use thin metal shims to make it level.
Step 7. Place a nut cap on each nut and tighten down. Do not over tighten.
4-10. Wall Hung. Install the bowl after the finished wall is up. A wall-hung, water closet bowl is installed on a carrier mounted between the wall studs. This type of water closet is used mainly in commercial buildings, but may also be found in residential buildings. Use the following steps and Figure 4-3 to hang a water closet bowl:
Step 1. Install a carrier using the manufacturer's instructions.
Step 2. Connect the carrier's outlet to the rough-in waste pipe.
Step 3. Place a sealing gasket in the rear opening of the bowl.
Step 4. Place the bowl against the wall with the carrier's bolts passing through the bowl's holes.
Step 5. Place a washer and nut on each bolt.
Step 6. Keep the bowl level and tighten the nuts alternately.
Step 7. Place beauty caps over the bolts.
Figure 4-3. Wall-Hung Water Closet Bowl
4-11. Tanks are classified as close-coupled (floor-mounted) or wall hung. A close-coupled tank is attached to a floor-mounted bowl. A wall-hung tank is attached to the wall above the bowl, using fittings for the bowl connection. The flushing mechanism is the same for both types.
4-12. To mount a floor-mounted tank, use the following steps and Figure 4-4.
Figure 4-4. Floor-Mounted Tank
Step 1. Push the cone-shaped gasket over the tank's flush-valve outlet. Place the cushion gasket (if included) on the bowl and line up the holes.
Step 2. Place the tank on the bowl with the bolt holes lined up.
Step 3. Slide a rubber washer on each bolt and, from inside the tank, push the bolts through the holes.
Step 4. Slide a washer over each bolt under the back lip of the bowl and tighten the nuts hand tight.
Step 5. Tighten the nuts alternately to seat the cone gasket and tank on the bowl.
4-13. To mount a wall-hung tank, use the following steps and Figure 4-5.
Figure 4-5. Wall-Hung Tank
Step 1. Install a 2- by 4-inch mounting board by notching the wall studs at the height recommended by the manufacturer.
Step 2. Install the elbow and spud connection (flange) to the rear of the bowl.
Step 3. Slide the slip nut, ring, and washer (in that order) onto the other end of the elbow.
Step 4. Attach the tank to the wall's mounting board with screw bolts. Make sure the elbow is in the tank's outlet and the tank is level.
Step 5. Check the elbow alignment and tighten the slip-joint nuts.
4-14. Figure 4-6 shows tank mechanisms and flushometers.
Figure 4-6. Flushing Mechanisms
Tank Flushing Mechanisms
4-15. A tank's flushing mechanism is mechanically operated to flush the water closet. The two most common mechanisms are the ball cock and float cup (Figure 4-6). Follow manufacturer's instructions to install a flushing mechanism in a tank. After installation, connect the water supply service, check the flushing mechanism's operation, and adjust it to maintain the proper water level in the tank.
4-16. The flushometer valve delivers (under pressure) a preset amount of water directly into a water closet for flushing. The flushing action is quick and shuts off automatically. Always follow the manufacturer's instructions to install a flushometer. After installation, turn on the water supply and operate the flushometer several times, checking for leaks and proper operation. The most common type of flushometer valves are the diaphragm and the piston (Figure 4-6).
TANK WATER SUPPLY CONNECTION
4-17. The water supply is connected from the rough-in plumbing to a shutoff valve and from the valve to the inlet at the bottom of the tank. Use Figure 4-7 and the following steps to connect the water supply:
Step 1. Slide the chrome cover on the pipe projecting out from the wall and push it against the wall.
Step 2. Coat the threads with joint compound or TeflonŽ tape and screw the shutoff valve onto the pipe. Tighten the valve so that its other opening is straight.
Step 3. Bend the flexible tube with a spring bender to get a proper fit. (Steel-coated flexible supply lines are commonly used.)
Step 4. Slide the inlet-coupling nut on with the tubing threads up, and attach it to the tank's inlet and tighten hand tight.
Step 5. Slide the coupling nut threads and compression ring down onto the tubing. Screw the coupling nut onto the valve hand tight.
Step 6. Tighten the inlet-coupling nut and valve-coupling nut.
Step 7. Open the shutoff valve for the water supply and check for leaks.
Step 8. Adjust to get a proper water level of 1 inch below the top of the overflow tube. If an adjustment is made, check the operation.
Step 9. Place the tank cover on the tank and install the water closet seat.
Figure 4-7. Tank Water Supply Connection
REPAIRS AND MAINTENANCE
4-18. See Chapter 3 for water-closet stoppages.
4-19. When the valve is not flushing or will not stop flushing, repair the flushometer (Figure 4-8). If the flushometer is a—
Figure 4-8. Flushometer Repairs
4-20. Use the steps below to repair handles (Figure 4-9) when there is a—
Figure 4-9. Flushometer Handle Repair
Tank Flushing Mechanisms
4-21. Fixture control devices are used for flushing water closets, holding water in a lavatory bowl, and draining waste. These devices get much usage and wear (Figure 4-10). Use the procedures below for ball-cock and float-cup repairs.
Figure 4-10. Tank Mechanism Repairs
4-22. Ball-Cock Repairs. Use the following steps to make repairs to the ball cock when—
4-23. Float-Cup Repairs. Use the following steps to make repairs to the float cup when—
4-24. A lavatory is designed for washing one's hands and face. Lavatories come in a variety of shapes, sizes, and colors. They are made of vitreous china, enameled cast iron, stainless steel, and plastic. Hot and cold water is supplied through the supply system and the waste drains into the sanitary sewer.
4-25. Figure 4-11 shows examples of wall-hung, vanity, pedestal, and trough lavatories.
Figure 4-11. Lavatories
4-26. This lavatory hangs on a bracket attached to the wall. It may or may not have legs for added support.
4-27. Vanities are installed on a cabinet or counter.
4-28. This lavatory's weight rests on the floor and does not require support.
4-29. This lavatory is mostly used in commercial plants and certain military facilities.
4-30. Use the following steps, the manufacturer's instructions, and Figure 4-12 to install a wall-hung lavatory:
Step 1. Install the mounting board between the studs at the proper height, using the same method as for a wall-hung flush tank (paragraph 4-10).
NOTE: Refer to the manufacturer's specifications and plans for the required height and elevation.
Step 2. Attach a hanger bracket on the finished wall using the proper length of wood screws at the recommended height. The metal bracket must be level.
Step 3. Place the lavatory on the bracket and push down. Make sure the lavatory is level.
Figure 4-12. Wall-Hung Lavatory Installation
4-31. See Chapter 7 for faucet installation and repairs.
4-32. The waste from the lavatory may be released by either a chain-type plug or a pop-up plug (Figure 4-13). Installation of the flange is the same for both types. (Follow manufacturer's instructions to install the pop-up plug mechanism to attach the tailpiece.) To install a flange—
Step 1. Apply a ring of plumber's putty around the drain outlet and set the flange firmly into the outlet.
Step 2. Connect the flange to the bowl with a washer and locknut.
Step 3. Coat the flange threads with pipe-joint compound and screw on the tailpiece.
Step 4. Connect the P-trap between the rough-in waste outlet and the tailpiece (Figure 4-14). All connections should be made with washers and slip nuts to form leakproof joints.
Figure 4-13. Drain-Plug Assembly
Figure 4-14. P-Trap Connection
Water Supply Connection
4-33. Figure 4-15 shows how to connect water services (hot and cold) for a lavatory. After installation, turn the water supply on and check for leaks.
Figure 4-15. Water Supply Connection
POP-UP PLUG REPAIRS
4-34. Use the repair steps below when the pop-up plug (stopper) fails to keep water in the bowl (Figure 4-16).
Step 1. Loosen the clevis screw with pliers.
Step 2. Push the pop-up plug (stopper) down so that it sits snugly on the flange.
Step 3. Tighten the clevis screw. Ensure that it fits snugly on the flange.
Step 4. Squeeze the spring clip and pull out the pivot rod from the clevis hole. The stopper then should operate easily. Place the pivot rod through the next higher or lower hole in the clevis.
Step 5. Close the stopper and fill the bowl with water.
Step 6. Check the water level to ensure that the stopper holds water in the bowl.
NOTE: If steps 1-6 do not fix the problem, continue by using the following steps:
Step 7. Tighten the pivot-ball retaining nut. If the leak continues, remove the nut with pliers.
Step 8. Squeeze the spring clip, sliding the pivot rod out of the clevis hole.
Step 9. Slide the pivot-ball retaining nut and worn washers off the pivot rod.
Step 10. Slide new washers (plastic or rubber) and the ball nut onto the pivot rod and tighten the pivot ball.
Step 11. Reassemble the pivot rod into the clevis hole.
Step 12. Run water into the lavatory and check the connection for leaks.
NOTE: Check the pop-up stopper's ability to hold water after repairing the pivot-ball connection.
Figure 4-16. Pop-Up Plug Repairs
4-35. Sinks are available for different uses and come in several sizes and shapes (Figure 4-17). They are made of enameled cast iron, enameled pressed-steel, galvanized steel, and stainless steel. (Refer to Chapter 7 for faucet installation.)
Figure 4-17. Sinks
4-36. Scullery sinks are large, deep sinks used in mess-hall-type facilities. Scullery sinks need only installation of faucets and connection to waste- and water supply lines.
4-37. Slop sinks are used for buckets and mops.
4-38. Kitchen sinks can be either single- or double-compartment and can be wall hung or set in a counter top. Kitchen sinks have a strainer to prevent food waste from entering the waste system (Figure 4-18). Connect the water service the same as for a lavatory (refer to Figure 4-15).
Figure 4-18. Kitchen Sink Drain Assembly
4-39. A urinal is a fixture that carries human liquid waste to the sewer. It is made of vitreous china or enameled cast-iron.
4-40. Urinal types are wall hung, stall, and trough (Figure 4-19).
Figure 4-19. Urinals
4-41. This urinal can have a built-in water-seal trap or a P-trap with a washdown or siphon-jet flushing action. The flushing device for a wall-hung urinal is a flushometer valve.
4-42. The stall urinal is set into the floor. A beehive strainer covers the waste outlet, which is caulked to a P-trap below floor level. The flushing action is the washdown-type produced by a flushometer valve.
4-43. A trough urinal is wall hung with a flush tank. The urinal has perforated pipe across the rear, which allows water to flow down the back of the trough when flushed.
4-44. Use the following steps and the manufacturer's instructions to hang a wall-hung urinal:
Step 1. Install the mounting board and bracket.
Step 2. Install the urinal on the bracket.
Step 3. Make the waste connection to the rough-in piping.
Step 4. Make the water connection to the rough-in piping to include the flushometer valve.
Step 5. Turn on the main water supply and flush the urinal several times to check for leaks.
4-45. Use the following steps and the manufacturer's instructions or military construction drawing to hang a trough urinal:
Step 1. Install the mounting board for the trough and tank.
Step 2. Attach the tank to the wall and install the flushing mechanism.
Step 3. Install the hanger for the trough bowl.
Step 4. Attach the bowl to the wall.
Step 5. Install the waste connection to the rough-in piping.
Step 6. Install the piping from the tank to the trough bowl.
Step 7. Install a water line between the tank and the rough-in piping.
Step 8. Turn on the main water supply and flush the urinal several times to check for leaks.
4-46. Refer to paragraph 4-16 for flushometers.
4-47. A shower has many advantages over a bathtub which include—the small amount of space required for installation, the small amount of water used compared with bathtub use, and sanitation. Figure 4-20 shows the types of showerheads. The two types of individual shower installations are: tiled and the steel-stall. (Group showers are usually tile or concrete.)
Figure 4-20. Showerheads
4-48. The tile shower has tile or marble walls on three sides with a waterproof shower curtain or door that can be closed while the shower is in use. The tiled floor slopes to the center (or rear) where a drain is placed. The wall should be waterproofed by setting the tile in waterproof cement. The floor is generally laid upon a lead shower pan, which forms a waterproof base on which to lay the tile, as shown in Figure 4-21.
Figure 4-21. Shower Pan Installation
4-49. The stall shower is a prefabricated unit with three sides and a base, fitted together. The sides are thin sheets of grooved steel, fitted together with a watertight joint. The base is usually precast concrete. Spray from the showerhead causes considerable noise as it hits the thin steel, and the metal sides tend to rust rapidly.
4-50. Complete waterproofing is the most important requirement of shower installation. Tile installed with good-quality waterproof cement provides a waterproofed wall. For the floor, a waterproof base (shower pan) under the shower is necessary, since water standing on the tile surface can seep through and cause leaks. (Refer to Chapter 7 for faucet assembly and installation.)
Lead Shower Pan
4-51. Before installing the lead shower pan, a carpenter must rough in the general outline of the stall and lay a solid base of subflooring or plywood. Without a solid base, the shower pan is soft and flexible. If not supported properly, the pan will sag and leak under the weight of the tile. Inspect the rough in of the trap underneath the flooring to ensure that the outlet is correctly placed.
4-52. Many types of shower drains are available. The one in Figure 4-21 has the proper-length nipple for placing the seepage flange at a level with the lead pan threaded into the nipple. The lead pan is made by using a solid sheet of lead 6 to 8 inches larger than the size of the shower floor and bending up the edges at right angles to the desired height. Use Figure 4-21 and the following procedure to install a lead shower pan:
Step 1. Cut a hole where the drain is located and lower the lead shower pan into place. The pan should rest firmly on the seepage flange of the shower drain.
Step 2. Coat the inside of the lead shower pan with asphalt.
Step 3. Place pipe-joint compound or putty under the top of the flange.
Step 4. Place the upper flange on top of the lower flange and attach them together to form a watertight joint between the shower waste and the shower pan.
Step 5. Thread the strainer down into the flanges to the desired level of the tile.
Step 6. Complete the installation by laying cement in the shower pan and tiling the floor.
Concrete Shower Pan
4-53. Concrete shower pans with prefabricated, steel shower stalls are easy to install. They are often set up after the original construction. In this case, the cement base is laid directly on top of the floor.
WATER SUPPLY CONNECTION
4-54. The water supply for a shower may be hidden in the wall or exposed. Figure 4-22 shows exposed hot- and cold-water lines tied into a single water line ending in a showerhead. The cold-water line is brought in on the right side while the hot-water line is brought in on the left. A variety of faucet and valve combinations is available on unexposed installations (Figure 4-23). The compression valve provides a tempered water line of chromium-plated tubing, ending in a gooseneck and showerhead. In the single-handle mixing valve, the hot and cold water are mixed in a cast-brass mixing chamber. The handle controls a piston-like valve. By turning the valve handle clockwise, warmer water is supplied to the showerhead. A greater variety of showerheads than valves is available (see Figure 4-20).
Figure 4-22. Shower With Exposed Piping
Figure 4-23. Showers With Unexposed Piping
4-55. A variety of built-in bathtubs is available. They are designed to be recessed for corner installation of square, rectangular, and angled tubs and tubs with one or more ledge seats. Tubs are made of enameled cast iron or steel and fiberglass.
4-56. Modern cast-iron tubs are designed to rest on the floor and fit against the wall framing (studs). They need no wall support, except that steel tubs have flanges supported by l- by 4-inch boards, nailed to the studs. Use a waterproofing cement to caulk the joint between the finished wall surface and the tub. Mount the over-rim tub filling, with or without a shower diverter, on the wall at one end of the tub. The drain may be the pull-out or pop-up type. Install removable service panel in the wall behind the tub to provide access to the trap and the water supply valve.
4-57. Laundry tubs are usually placed in the basement or utility room.
4-58. The most common type is concrete with a metal rim, although enameled cast-iron/steel and plastic units are also available. They come in single- and double-compartment styles (Figure 4-24).
Figure 4-24. Laundry Tubs
Step 1. Assemble the metal stand by bolting its sections together.
Step 2. Place the stand in a convenient place in front of the rough-in piping and carefully set the tub on the stand.
Step 3. Connect the P-trap to the tub as shown in Figure 4-25.
Step 4. Connect a swing-combination faucet to the hot- and cold-water supply lines. Usually, the faucet is furnished with a hose bib for attaching a hose.
Figure 4-25. Laundry Tub Installation
4-60. Drinking fountains (Figure 4-26) are made of porcelain enameled steel, cast iron, or stainless steel.
Figure 4-26. Water Fountains
4-61. The three types of drinking fountains are the pedestal, wall-hung, and electrically cooled. The pedestal fountain needs no wall support. The wall-hung fountain is bolted to a mounting board on the wall. The electrically cooled fountain has a refrigerating unit in which the water supply tubing passes over the refrigerating coils to be cooled before being supplied to the drinking outlet.
4-62. Sanitation is an extremely important consideration when installing drinking fountains. Water from the drinking outlet should not fall back on the bubbler head. The bubbler head should project at least 3/4 inch above the rim of the fountain and be located so that a person's mouth cannot touch it. The fountain drain should have a good strainer to keep chewing gum and other objects from entering the drain line.
4-63. Install fountains with the bubbler head at a height designed for the average user. Ensure that the mounting is sturdy to support considerable weight in addition to that of the fixture. Install a 1 1/4-inch P-trap below the waste pipe. The electrically cooled fountain requires a nearby electrical outlet. Follow the manufacturer's instructions when installing a water fountain.