In the field, devices necessary for maintaining personal hygiene and field sanitation must be improvised. Some of the devices for field sanitation that have been tried and used in the field successfully are described next.

LATRINES

When you are on bivouac or at a new location, it is unlikely that you will find a waterborne sewage system available for your use. The usual alternative is digging a hole (cat hole) about 1 foot deep and covering the feces completely with dirt or using a latrine.

NOTE: Latrines must be 100 yards from water supplies and messing facilities.

Straddle trench latrines are commonly used. Dig straddle trenches as soon as you arrive at a position. Use the 1:2:3 ratio (trenches 1 foot wide, 2 feet deep, and 3 feet long). No seats are provided, and the men stand along the sides. Add another foot of depth for each day you anticipate using the trench. Keep a pile of dirt and a shovel adjacent to the trench so each man may use some of the dirt to cover his waste materials. Boards may be placed around the sides to help keep steady footing. When the latrine is filled to within 1 foot of the ground level or is to be abandoned, the following steps should be initiated:

1. Using an approved residual insecticide or diesel fuel, spray the pit contents, the sidewalls, and the ground surface extending 2 feet from the sidewalls.

2. Fill the pit to ground level with successive 3-inch layers of earth, packing each layer down before adding the next one; then mound the pit over with at least 1 foot of dirt and spray again with insecticide or diesel fuel. This prevents flies that hatch in the closed latrine from getting out.

When there is a possibility that others may come into the area, it is better to mark the closed latrine so the site will not be used again. A sign "closed latrine" with the date of closing should be placed firmly in the earth over the spot.

As soon as possible, regular pit latrines should be dug. These latrines may be 20 to 30 feet deep if the ground permits. The sides must be straight and have no ledges that could catch feces. Latrine boxes, usually of

Figure 10-56.-Urinal pipes and soakage pit.

four or eight holes, and accessories, such as tent, urinals, tar paper, and screen wire, are finished ready for installation.

When the box is installed, it is lined with tar paper from the top to the bottom. The boxes also need a metal or tar paper urine deflector. This deflector is converted into a trough under the front of the seat so it drains toward one end. From this end, a pipe carries the urine to an outside soakage pit. This helps prevent a disagreeable odor from the urine. In some cases where the soil is rather porous, the urine drains into the latrine pit itself.

It is necessary to cover all cracks in the box to help make it flyproof. You do this by nailing strips of wood or tin over them. When the box is placed over the pit, it must be done carefully. If any cracks are showing, seal them by packing some dirt tightly around the edges. A separate urine soakage pit is built when the latrine pit is in soil that absorbs liquids poorly (fig. 10-56). This pit is about 4 feet square and 4 feet deep. It is filled with pieces of broken rock brick large stone or lava rock to within 1 foot from the top. Then oiled burlap is placed over the rocks and covered with sand or earth. Vents, inserted to reduce odor, are covered at the top with fine mesh screen.

Urinals may be made of 1-inch or large-sized pipe and placed at each corner of the pit and along the sides. The pipes should reach at least 8 inches below the ground surface. In the upper end of each pipe, place a funnel of sheet metal, tar paper, or similar material. These funnels are covered at the opening with wire mesh. This is to keep out flies, cigarette butts, or other items that would clog up the pipes.

In other cases, pail latrines maybe used in buildings where no adequate plumbing facilities are available or where it is not practical to build deep pit latrines. Usually a standard latrine box is adapted for use as a pail latrine. The pails are removed at least once daily and replaced by clean pails. Each pail should have about 1 inch of a 2-percent cresol solution or some slaked lime in it. Pails of excreta are removed from the latines by hand, cart, wagon, or truck. The contents maybe burned, buried, or placed in flyproof concrete tanks where it decomposes.

A trough urinal is usually built as part of a latrine. The trough may be made of tin, galvanized iron, or wind. When it is made of wood, it should usually be lined with tar paper.

The trough slopes toward one end and empties into a drain pipe. The drain pipe, fitted with a fine mesh fly screen, extends into the latrine or urine soakage pit. Sometimes the pipe is omitted and the trough extends into the pit.