Disposal by Sanitary Fill
This method is practised by some cities, among them Seattle, Davenport, and New Orleans, which report its success. It is given more serious consideration than heretofore by several large cities. The method is different than that of burial, in that it is carried on by filling excavations, vacant low lying ground and natural ravines.
The garbage, rubbish and ashes are dumped and then mixed with sufficient earth to insure oxidation and thorough digestion of the decomposable wastes. The activity of the bacteria of the soil breaks down and mineralizes the organic matter and when there is sufficient oxygen, i. e. air, no putrefaction or other odors result. Success depends upon the following treatment:
(1) The garbage must not be buried so deep that bacterial activity is reduced.
(2) The garbage must not be spread in a thick layer on the surface of the ground.
(3) The ground must be sufficiently open and drained so that air can penetrate to a sufficient depth.
(4) The garbage must not overload the soil, but must be sufficiently diluted with earth, ashes and rubbish, so that putrefaction may take place, due to the presence of an ample supply of air in the pores of the soil.
The Chicago Waste Commission believes that this method “has been demonstrated to be not only sanitary, free from nuisance when properly carried out, but economical as well.” Incidentally, adds the Worcester Commission, it adds valuable taxable property from which the city subsequently derives an income.
At Davenport, 1.3 cubic yards of materials are required per ton of garbage and the total cost of upkeep, including rent of land, labor, etc., was 50 cents per ton. The garbage is received and buried by one foreman and three men in summer and one foreman and one man in winter. The city by this method is creating a valuable river front.
New Orleans seeds its dumping grounds as soon as a sufficient filled area is available, and later trims and plants the land for use as small parks and play grounds.
The Health Commissioner of Seattle, in a letter to the Municipal Engineering Journal, describes the system and results as follows:
“This method of filling works very satisfactorily in this climate, but I believe it necessary to include all waste materials, as ashes, boxes, tin cans, etc. These all assist oxygenation and nitrification. I do not believe pure garbage can be handled in this way.
“We also find that it is best to keep as little of the face of the fill exposed as possible. It is always best to keep a man constantly on the job, whose duty it is to rake down to the bottom of the fill all boxes, rough materials, etc., thus leaving the ashes to form a covering on top. When this is not sufficient, we cover with a layer of earth about five inches thick.
“The success lies in the proper mixtures of waste materials, and next the fill must be properly covered to protect from flies. Chemicals can also be used to protect it. This covering also prevents the slight sour odor of fresh garbage and by keeping out the sunlight, at the same time encourages bacterial growth by increasing the warmth inside the fill. People residing within one hundred feet of these fills make no complaint, but the public has to be educated when you first adopt this method. We aim to fill city property, as ravines, swampy lands or docks on the lake or salt water front.
“Our laboratory findings show that the process is simply one of slow incineration by nature, instead of the expensive method of burning by incinerators, and at the same time help prove that there is nothing detrimental to public health in these fills.
“We have eleven fills distributed over our city, thus making short hauls, and these are taken care of by eleven laborers disposing of approximately three hundred and fifty tons per day by this method alone, while one incinerator with about an equal payroll will only dispose of sixty to seventy-five tons per day, running twenty-four hours. A fill increases the value of property, while the refuse from our incinerator has to be hauled away at an added cost.”
After spreading, there is applied to the garbage an antiseptic spray of crude carbolic acid, rosin and caustic soda to kill eggs and larvæ of flies, mosquitoes and other insects that might breed.