Village Improvements and Farm Villages

by George E. Waring

Important as it is to secure the proper arrangement and construction of sewers and house-drains, it is still more important to provide for the safe disposition of the sewage.

We must begin at the outset with the understanding that all sewage matters not only are of no value to the community, but that it will cost money to get rid of them.

There is hardly an instance, after all the efforts that have been made, of the profitable disposal of the outflow of public sewers. The theoretical value of the wastes of human life is very great, but the cost of any method for utilizing them seems at least equally great. The question of cost is so much more important (to the community) than the question of agricultural value, that the practical thing to do is to make such disposition as will cost the least, while fully meeting the best sanitary requirements.

So far as village sewage is concerned, there are three means open for its disposal: to discharge it into running water or into deep tide-water, to use it for the surface irrigation of land, or to distribute it through sub-irrigation pipes placed at little distance below the surface of the soil. Experiments are being made with more or less promise of success in the direction of the chemical treatment of this liquid so as to purify its effluent water, and retain in a solid form, and in combination with certain valuable added ingredients, all of its undissolved impurities. None of these processes can as yet claim consideration in regulating public works.

The cheapest way to get rid of sewage is to discharge it into a running stream or into tide-water. So far as the community itself is concerned, this is often the best way; but there will very often arise the objection that the community has no moral or legal right to foul a stream of which others make use in its further course. Where the amount of water constantly flowing is very large, and where the discharge is rapid,—any given part of the sewage reaching the open air within a few hours from the time of its entering the pipes,—and where it flows in moving water for a considerable distance before reaching others who may have occasion to use the stream, no practical danger is to be apprehended. But where the sewage is more foul, more sluggish, or exposed in the open current for a shorter time, the danger may be serious. The pouring of sewage into tide-water is always admissible where floats show that there is no danger of a return and deposit of solid filth; but the delivery at all stages of the tide, in the immediate neighborhood of salt marshes and mud flats, and in land-locked harbors, is to be avoided.

Where an unobjectionable natural outflow cannot be provided, the irrigation of agricultural lands affords the best relief. The action of vegetation, the oxidation which takes in the upper and well-aërated layers of soil, and the well-known but not yet fully explained disinfecting qualities of common earth, are effective in removing the dangerous and offensive impurities, and in converting them into a more or less important source of fertility. Precisely how far this system may be available during winter, it is not easy to say. While the earth is locked with frost, there must be very little, if any, infiltration; but, as an offset, the action of a low temperature upon the sewage matters will clearly be antiseptic; and it is only necessary to provide against an undue washing away of the surface of the ground during thaws, and against the flowing of the sewage beyond the proper limits.

Generally in the neighborhood of villages it will be easy to find lands over which the delivery may be carried on throughout the year without objection. The sewer, or some form of covered channel, should lead far enough from any public road to avoid offence. From this point it may be led by open gutters to the land over which it is to be spread,—or rather through such a system of surface gutters as will enable us to deliver it at different parts of the field, according to the requirements of the crops, and so as to use fresh land at frequent intervals, leaving that which has been saturated to the purifying processes of vegetation and atmospheric action.

The gutters having been made, it is easy, by the use of portable dams,—of thin boiler-iron, like broad shovels,—which may be set in the course of the flow, to divert the current into any branch channel, or to stop it at any desired part of this channel. All the gutters having sufficient descent to lead the sewage rapidly forward, it is usual to set a dam near the far end of the gutter, and allow the sewage to overflow and run down over the surface until it has reached as far as the formation of the ground and the quantity of the liquid will allow it to spread. This portion having received its due amount of the liquid, the dam is moved to a higher point, and the overflow is allowed to spread over a second area. In this way, step by step, we irrigate all that may be reached by a single gutter. Then the moving of the dam in the main line turns the water into another gutter, and this is proceeded with in like manner. In practice it is found best to begin the overflow at the farthest end of the lowest-lying gutter, working back step by step until the higher parts of the field are reached. It would be better that there should be land enough to require the irrigation of any given area not oftener than once in one or two weeks. The amount required for a given population cannot be determined by any fixed rule,—so much depending on the amount of water used per capita, and on the absorptive character of the irrigated soil. In the case of villages, one acre to each five hundred of the population would generally be found ample.

There are several instances of the successful use of a much smaller area than is here indicated, by the use of intermittent downward filtration. The most noted success in this direction is that at Merthyr-Tydvil in Wales, a large mining town, where the allowance is only one acre to each two thousand of the population. There are two filter-beds of light loam over a gravelly subsoil thoroughly underdrained with tiles at a depth of six feet. One of these beds is cultivated with some crop like Italian rye-grass, which bears copious irrigation; and the other by some crop like wheat, which, in the absence of irrigation, will thrive on the fertility left over from the previous season. The volume of sewage is very great, but the action of the six feet of earth in removing its impurities seems to be complete; the water flowing out from the drains having been proved by analysis to be really far purer than the standard fixed by the Rivers Pollution Commission.

It is an important condition of this system that the sewage, where its quantity is small, shall be stored in tanks until a large volume has accumulated, and that it then be rapidly discharged over the soil. There is no objection to an actual saturation of the ground, provided the soil is not of such a retentive character as to be liable to become puddled, and so made impervious. The tanks being emptied, the flow ceases until they are again filled. During the interval, the liquid settles away in the soil, by which its impurities are removed. Its descent is followed by the entrance of fresh air, and the oxidizing action of this, accompanied during the growing season by the purifying effect of the growing crop, leads to an entire decomposition or destruction of all organic matters.