. Principles and practice of milk hygiene. Milk; Milk supply. 194 PRINCIPLES AND PRACTICE OF MILK HYGIENE pens, or other structures above springs is objectionable. Water from springs exposed to surface drainage should not be used for washing dairy utensils and vessels, but if no other source is available the spring should be pro- tected by impervious walls. Open springs are sometimes polluted by live stock or contaminated by dust, leaves, and other refuse blowing into them. Pollution of springs by subsurface drainage is not very common on farms, but may occur where the layer of earth above the
. Principles and practice of milk hygiene. Milk; Milk supply. 194 PRINCIPLES AND PRACTICE OF MILK HYGIENE pens, or other structures above springs is objectionable. Water from springs exposed to surface drainage should not be used for washing dairy utensils and vessels, but if no other source is available the spring should be pro- tected by impervious walls. Open springs are sometimes polluted by live stock or contaminated by dust, leaves, and other refuse blowing into them. Pollution of springs by subsurface drainage is not very common on farms, but may occur where the layer of earth above the water table is thin or readily permeable. The permeability will depend upon the material present. Fine sand is a good Aivef FTood pla'irt'. Fig. 22.—Section showing relation of water table to surface irregularities. (From Water Supply Paper 255, U. S. Geological Survey.) filter, but coarse sand and gravel permit the water to pass through rapidly, carrying some of the contaminat- ing material through with it. Clay and till (largely clay and sand) are good filters. When the layer of earth above the water table is thin or permeable, the water in the spring is likely to be warm. Cesspools, buildings, or anything else which may be a source of pollution should not be placed at a higher level than a spring be- cause of the danger of contamination by subsurface drainage (Fig. 23). When cracks or fissm-es extend from the surface into the water-bearing strata, as occiu-s in rock formation, or where tubular channels have been formed, the spring may be contaminated. This may. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Klein, Louis Amos, 1871-. Philadelphia and London, J. B. Lippincott Company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmilksupply, bookyear1
