Figure 12.—Disposal of drainage from kitchen fixtures, using a line of terra cotta or fiber drain tile surrounded with gravel. One or two rock-filled pits at the end of the line increase the absorption area and are desirable where there are several fixtures or the soil is nonporous. The pits may be lined with boards or masonry laid without mortar and provided with a tight cover.
These wastes are not likely to create serious health hazards, but they become nuisances if discharged promiscuously on the ground surface. Such drainage should never be permitted on the watershed of a spring.
Coarse sand and gravel, 12 to 18 inches deep, may be placed on the bottom of the pit, to strain out small particles of solids, which might clog the pores of the soil. If, after a few years, the sand or gravel becomes clogged with solids, it should be replaced with clean materials.
If excessive quantities of grease are permitted to enter the sink drain, a grease trap may be advisable.
[CESSPOOLS]
Cesspools are cheap in first cost but high in maintenance costs and often become nuisances. They should be located at least 150 feet from wells, 15 feet from seepage pits and property lines, and 20 feet from dwelling foundations. They should never be used in the vicinity of shallow wells and, in any case, only where permitted by State regulations.
The cesspool depends for its action upon seepage into the surrounding soil and consequently is particularly unsatisfactory in tight clay soils. In more open sand and gravel soils the seepage is reduced as the pores of the soil become clogged with particles of solids, until it stops entirely, and overflowing occurs. Emptying and then cleaning the walls and floor of a cesspool do not fully open up the clogged soil pores, and overflowing can be expected to occur soon again.
Solids in cesspools must be removed from time to time by bailing or pumping and should then be buried 18 to 24 inches deep in a trench where the water supply will not be endangered. Caustic potash (lye) will to some extent liquefy solids in a cesspool. This treatment does not eliminate the necessity of removing the contents when periodic inspection shows that the cesspool is nearly full. Caustic potash converts the greases into soft soap, whereas caustic soda forms a hard soap that does not readily dissolve. The chemical treatment is not effective in liquefying solids in the pores of the soil surrounding the cesspool.