138 DAIRY AND FARM .SEWAGE 



cleaned for two years, and there is at the present time not more 

 than a foot of sediment in the bottom of the first compartment. 

 For creameries and cheese factories these tanks need not be 

 cleaned of tener than once a year. 



SIPHON 



The siphon to be used in this tank for irrigating purposes 

 can be purchased from any plumbing concern. 



COT OF A SEPTIC TANK 



The cost of a tank depends somewhat upon the locality and the 

 price of material in that locality. The following estimate is based 

 on average prices: 



COST OF TANK, FIG. 5. 



Digging $ 4 00 



Concrete and labor 21 00 



Lumber, 200 feet of 2-inch plank, @ $30 per M 12 00 



Posts, 4x4 50 



Labor 2 00 



One 15-inch sewer pipe 75 



Two 4-inch sewer-pipe bends 1 50 



One 4- inch sewer pipe 50 



One length of sewer pipe 25 



Total $42 50 



COST OF TANK. FIG. 6. 



Concrete and labor $24 20 



Digging 4 00 



Lumber 900 



Labor 2 00 



Two sewer-pipe bends 1 00 



One 4-inch T 50 



Two 4-inch pipe 40 



Total $41 10 



WATER-SUPPLY. 



While this plan of sewage disposal will practically eliminate any 

 pollution of well water, there are, however, other conditions to 

 which due regard must be given to prevent any contamination of 

 the well. It must be borne in mind that the well cannot be given 

 too much care, for it supplies water to creameries, cheese facto- 

 ries, the dairy farm, and the household. Well water is usually con- 

 taminated in two ways : First, by surface water which runs di- 

 rectly into the well and, second, by barn-yard drainage, household 

 slops, and cesspools. 



Nearly all of the bacterial life exists in the upper strata of the 

 soil. Soil ten or twelve feet below the surface of the earth is per- 

 fectly sterile, unless it has within it a crevice or opening so that 

 surface sewage can run down. Therefore, due care should be 

 taken in digging and constructing a well so that direct contamina- 

 tion will be prevented. 



