Unusual or excessive foulness should be investigated. No chemicals should
be used in a septic tank; garbage, rags, newspaper, and other solids
not readily soluble in water should be kept out of sewers and tanks.
The plant should be inspected often, noting particularly if the siphon
is operating satisfactorily. If scum forms in the settling chamber it
should be removed, and the sludge should be bailed or pumped out yearly.
Frequently tanks are not cleaned out for three or four years, resulting in
large quantities of solid matter going through to the distribution system
and clogging it. Clogging may occur in the tile or in the adjacent soil.
In either case the tile should be dug up, cleaned, and relaid. In some
cases it has been found advantageous to relay the tile between the former
lines. When sewage is applied to fairly porous land at the slow rate here
recommended and the plant is well handled the tile lines should operate
satisfactorily for many years. Liming heavy soils tends to loosen and keep
them sweet.
=Field data.=--As a basis for outlining or designing a suitable
installation the following data should be known:
1. State, town, and whether in or near an incorporated municipality.
2. Usual number of persons to be served.
3. Average daily consumption of water in gallons.
4. Kind and depth of well, depth to water surface.
5. Character of soil, whether sandy, gravelly, loamy, clay, or muck.
6. Condition of soil as to drainage.
7. Character of subsoil.
8. Character of underlying rock and, if known, its depth below the
surface.
9. Depth to ground water at both house and field where sewage is to be
distributed.
10. Minimum winter temperature and approximate depth to which frost goes.
11. Number and kind of buildings to be connected with the sewer.
12. Number and kind of plumbing fixtures in each building.
13. Whether plumbing fixtures are to be put in the basement.
14. Depth of basement floor below ground.
A plan to scale or a sketch with dimensions showing property lines,
buildings, wells, springs, and drainage outlets should be furnished. The
direction of surface drainage should be indicated by arrows. The slope of
the land (vertical fall in a stated horizontal distance) should be given
or if possible a contour plan (showing lines of constant elevation) should
be furnished.
GREASE TRAPS
Farm sewage may contain from 10 to 30 pounds of grease and fats per person
per year. This grease, originating mainly in the kitchen-sink, hinders
septic action and clogs pipes, filters, and soils. Half the grease may be
stopped by a septic tank, but the remainder goes into the distribution
system, interfering with its action. A grease trap is a device for
separating the grease from other wastes. The need for it may be lessened
by carefully depositing waste greases and fats with the garbage; but
one should always be installed if the kitchen is carelessly managed or
discharges quantities of greasy water as at institutions, hotels, boarding
houses, and bakeshops.
[Illustration: Fig. 33.--Three types of grease trap. _A_, Ready-made
grease trap; vitrified, salt-glazed earthenware; stock sizes: 10-inch
diameter by 24 inches, 12-inch diameter by 24 inches, 15-inch diameter
by 24 inches. _B_, Homemade grease trap; concrete or well-plastered
brickwork; elbow, cross, and increaser to be recessed drainage fittings.
_C_, Type of grease trap used at United States Army camps]
A grease trap should have several times the capacity of the greatest
quantity of greasy water discharged into it at one time, in order that
the entering water shall be well cooled and the grease congealed. The
solidified grease rises to the surface of the water in the trap and is
retained therein. A dishpan of greasy water (2½ to 3 gallons) is the
largest quantity likely to be discharged at one time from an ordinary
kitchen-sink, hence the grease trap should have not less capacity than 7
or 8 gallons. Figure 33 shows three types of grease traps suitable for
farm use. In each the outlet pipe has small clearance at the bottom. This
feature, together with the =V=-shaped hopper bottom, tends to create a
scouring velocity and thus prevent the accumulation of coffee grounds and
other solid wastes in the bottom of the trap. A grease trap should be
close to the sink it is intended to serve, but not within the kitchen, on
account of objectionable odors when the trap is opened to remove grease.
It is good practice to place the trap in the cellar or basement, where it
is safe from frost yet close to the source of grease.
GENERAL PROCEDURE
Do not waste money by digging and partly constructing, afterwards seeking
information. Prepare a plan and work from it. Get in touch with your
county agricultural and home demonstration agents. Advice may be obtained
also from extension workers, State agricultural colleges, State and local
boards of health, the United States Public Health Service, and the United
States Department of Agriculture. Do not guess distances and levels.
Use a measuring tape and some type of level--engineer's, architect's,
drainage, hand, or carpenter's. Study this bulletin, and design, lay
out, and construct in accordance therewith. Remember to: (1) Isolate the
septic tank--locate it 50 to 100 or more feet from any dwelling and, if
practicable, to the leeward of prevailing summer breezes; (2) locate the
cesspool or sewage-distribution field downhill from the well or spring,
and, if possible, 300 feet therefrom; (3) select dry, porous, deeply
drained ground for disposal of all sewage; (4) do not apply more sewage to
a given area of land than can be thoroughly absorbed and oxidized; (5) lay
sewers straight and below the reach of frost, ventilate them thoroughly,
and make the joints water-tight and root-proof.
Makeshift methods, materials, or devices should be avoided or used
sparingly. Do not place a vent pipe in the top of a cesspool or septic
tank if near a dwelling. Siphon chamber and siphon may be omitted in those
rare instances where it is feasible to discharge into salt water or into
a large stream already badly polluted. Disposal of sewage in a running
stream should be a last resort. Such practice endangers water supplies
downstream, and unless the volume and velocity of flow are good nuisance
may be created in the vicinity. Do not neglect inspection and operation.
Clean out settling tanks yearly or oftener. All pipe lines below ground
should be marked with iron or stone markers to facilitate examination,
repair, or extension of the system.
There is a general but erroneous belief that the cost of sewerage is
little in the city but almost prohibitive in the country. All personal and
Realty properties in one eastern city represent a valuation of $10,382
per home, which pays $355 for sewers outside the cellar wall. An average
farm in a Middle West State represents a valuation of $17,259. Is not
the farmer justified in the small outlay required to dispose of the farm
sewage? Because of the issuance of bonds and the apportionment of sewer
assessments for a series of years the city dweller may have his burden
distributed over a long period. The farmer does not pay interest on these
obligations, and sewer work can be done more cheaply in the country than
in the city.
Safe disposal of farm sewage is not a passing fad but a vital necessity.
Besides being an asset a good sewerage installation greatly promotes the
wholesomeness and healthfulness of the farm. Moreover the benefits are
far-reaching, because farm products go into every home, and farm and urban
populations mingle freely.
ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
January 6, 1930
_Secretary of Agriculture_ Arthur M. Hyde.
_Assistant Secretary_ R. W. Dunlap.
_Director of Scientific Work_ A. F. Woods.
_Director of Regulatory Work_ Walter G. Campbell.
_Director of Extension Work_ C. W. Warburton.
_Director of Personnel and Business W. W. Stockberger.
Administration._
_Director of Information_ M. S. Eisenhower.
_Solicitor_ E. L. Marshall.
_Weather Bureau_ Charles F. Marvin, _Chief_.
_Bureau of Animal Industry_ John R. Mohler, _Chief_.
_Bureau of Dairy Industry_ O. E. Reed, _Chief_.
_Bureau of Plant Industry_ William A. Taylor, _Chief_.
_Forest Service_ R. Y. Stuart, _Chief_.
_Bureau of Chemistry and Soils_ H. G. Knight, _Chief_.
_Bureau of Entomology_ C. L. Marlatt, _Chief_.
_Bureau of Biological Survey_ Paul G. Redington, _Chief_.
_Bureau of Public Roads_ Thomas H. MacDonald, _Chief_.
_Bureau of Agricultural Economics_ Nils A. Olsen, _Chief_.
_Bureau of Home Economics_ Louise Stanley, _Chief_.
_Plant Quarantine and Control Lee A. Strong, _Chief_.
Administration_
_Grain Futures Administration_ J. W. T. Duvel, _Chief_.
_Food, Drug, and Insecticide Walter G. Campbell, _Director of
Administration_ Regulatory Work, in Charge_.
_Office of Experiment Stations_ --------, _Chief_.
_Office of Cooperative Extension Work_ C. B. Smith, _Chief_.
_Library_ Claribel R. Barnett, _Librarian_.
U. S. GOVERNMENT PRINTING OFFICE: 1930
For sale by the Superintendent of Documents, ---- Price 10 cents
Washington, D. C.
* * * * *
Transcriber Note
Minor typos have been corrected. Illustrations were moved to prevent
splitting paragraphs. Figure 19 was moved adjacent to the directions and
specifications on Page 24. Due to space considerations in the text only
version, emphasis of column headers were sometimes eliminated and some of
the tables were rearranged. Produced from files generously made available
by USDA through The Internet Archive. All resultant materials are placed
in the Public Domain.