When this happens, simply close the pit and dig a new one. Soakage Pit b. Soakage trenches are used when the groundwater level or a rock formation prevents the use of a soakage pit. A soakage trench consists of a central pit which is 2 feet square and 1 foot deep. A trench is dug outward from each side of the pit. The bottom of the structure is filled with a suitable contact medium such as small rocks.
Trenches are closed in the same manner as soakage pits.
Figure 9-17 shows a soakage trench with a pail type grease trap. Trap c. Evaporation beds are constructed to allow 3 square feet of evaporation area per person, per day, for field mess wastes and 2 square feet per person, per day, for bathing wastes. Each bed is constructed in the same manner and spaced so that wastes can be easily distributed to any one of them. An 8 foot by 10 foot rectangle is marked off. The top soil is scraped and used to form a dike around the perimeter of the bed.