Rural Hygiene

by Henry N. Ogden

In a number of states, laws have been passed which expressly prohibit the discharge of sewage, even from a single house, into a stream of any sort, even though the stream is on the land of the man thus discharging sewage and where it would appear as if he alone might control the uses of that stream. Unfortunately, the machinery of the law does not always operate to detect and punish the breakers of the law, but any law which, as in this case, has so positive a reason for its existence, and violation of which is so certain to bring disaster on persons drinking the water of the stream below the point where the sewage is discharged, any law which appeals for its enforcement so directly to the common sense and right feeling of all intelligent people, seems hardly to need legal machinery for its enforcement. It must depend, as indeed all laws must depend, upon the intelligent support of the community, and surely no law would commend itself more urgently than this one forbidding the pollution of drinking water.

In spite of the fact that the lack of air in the water will prevent bacterial action, there are, nevertheless, many cases where the discharge of sewage into a stream may be permitted as being the best solution of the disposal problem, provided always that the stream is not used and is not likely to be used for drinking water. Such cases occur where the stream is relatively large and where the level of the stream is fairly regular, so that there is no likelihood of the deposit of organic matter on the banks during the falling of the stream level. Examples of this sort might be cited in the vicinity of the Mohawk or Hudson River, or in the vicinity of any of the larger rivers of any populous state, since although the water of the Mohawk is used by the city of Albany for drinking purposes, yet the amount of organic matter which inevitably finds its way into such rivers precludes its use for drinking without filtration. Into the Hudson below Albany there can hardly be any question of the propriety of discharging sewage from a single house.

Again, houses in the vicinity of large bodies of still water may without question be allowed to discharge into those lakes. For example, houses in the vicinity of Lake Ontario or Lake Michigan, or even of much smaller lakes, should not contribute any offensive pollution to the waters of the lake. In New York State, some of the smaller lakes are used as water-supplies for cities, as, for example, Owasco Lake for the city of Auburn and Skaneateles Lake for the city of Syracuse, and, acting under the statutes, special laws have been passed by the State Department of Health, forbidding any discharge of any kind of household wastes into these lakes. The same is done in other states. Here, again, it is a question of the drinking supply which is being considered, and not a question of the possibility of any nuisance being committed.

Treatment of sewage on land.

If no stream suitable for the reception of sewage is available, then the sewage must in some way be treated on land before it passes into the nearest watercourse. For the second fundamental principle about the treatment of sewage is that of all places the action of putrefactive bacteria is most energetic in the surface soil and that it is there that the organic matter of sewage can be most rapidly accomplished. Experiments already referred to have shown not only this, but also that their activity is most noticeable in the surface layers of the soil and that their action continues for scarcely two feet downward, and it is customary to assume that the largest amount of work done is accomplished in the top twelve inches. Further than this, it has been established that in order to persuade the bacteria involved to do their work as promptly as possible, the application of sewage to any particular locality should be made intermittent; that is, that a resting period should be given to the bacteria between successive applications of sewage.

For example, one can recall without difficulty the conditions on the ground at the back of the house where the kitchen sink-drain commonly discharges. At the beginning of summer perhaps a rank growth of grass starts up vigorously in the vicinity, and the path of the surface drain can be traced by the heavy vegetation along the line of the drain. If the slope of the surface away from the house is considerable, no other effect may be noticed through the season, since the surface slope carries away the sewage, spreading it out over the ground so that the soil really has a chance to breathe between successive doses. But if the ground is flat, it will be remembered that before many weeks the sewage ceases to sink into it; the ground becomes "sewage-sick," as they say in England, and a thick, dark-colored pool of sewage gradually forms, which smells abominably. If a piece of hose a dozen feet long had been attached to the end of the drain and each day shifted in position so that no particular spot received the infiltration two days in succession, it is probable that no such pondage of sewage would occur, but that the mere intermittency of the application thereby secured would permit the successful disposal of this sink waste throughout the season.

The same effect is to be noted in some cesspools where, because of the great depth to which they are dug and because no overflow into the surface layers of the soil is provided, the pores of the ground around the cesspool become clogged and choked, and the cesspool becomes filled with a thick, viscous, dark-colored, objectionable-looking, and evil-smelling liquid.

The three principles which will avoid these conditions are, as already stated, plenty of air, presence of bacteria normally found in the surface layers of the soil, and intermittency of application.

In order to secure the operation of these three principles in the application of sewage onto land, the sewage must be made to pass either over the surface of the land in its natural condition in such a way that the sewage may sink into the soil and be absorbed and at the same time give up its manurial elements to whatever vegetation the soil produces; or, as a modification of this principle, the sewage may be required to pass through an artificial bed of coarse material by which the rate of treatment may be considerably increased. In the latter case, although probably the greater part of the action of the bacteria takes place in the top twelve inches, it is customary to make the beds about three feet thick, chiefly in order to prevent uneven discharge of the sewage through the bed. Finally, wherever, for æsthetic reasons, it is desirable that the sewage should not be in evidence, either before passing through the natural soil or exposed in an artificial bed, the practice may be resorted to of distributing the sewage through agricultural tile drain laid about twelve inches below the surface. In this way, the sewage is scattered through the top soil, where bacteria are most active, without being apparent, and a front lawn thus treated would not give any indication of its use.

Taking up now in order these three methods of treatment, we may consider some of the details of construction. In spreading the sewage over the lawn or in distributing it on the surface, due regard must be paid to the kind of soil. Clay soils and peaty soils are useless for the purpose of sewage disposal unless as the result of continuous cultivation a few inches of top soil may have accumulated on the clay. This top soil is adapted to sewage purification, provided the quantity applied is not excessive.