DAIRY AND FARM SEWAGE 



135 



directly into a stream, the sewage may be taken from the top of 

 the tank, as shown by the connection marked X, in Pig. 5, and H, 

 in Pig. 6. In case the tank is to be cleaned, the plugs of the same 

 systems may be removed and thoroughly drained. Por irrigating 

 purposes it is advisable to use a siphon. This siphon removes the 

 water from the last compartment of the septic tank automatically 



-D LTA I i_ OT v> L. WA <^I_- 



-TAI? 

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-.Dr. 5 1 G; /-IT. T>- J5~r- PJ?OT.- O -I. T{ r- 



FIG. 8. Showing a simple square septic tank, used in places where there is mostly liquid 

 sewage to be disposed of. 



at intermittent discharges. The discharge at one time of a 

 quantity of sewage large enough to fill the irrigating system will 

 scour the system of pipe; besides it more uniformly distributes 

 the sewage throughout the whole irrigating system. Without a 

 siphon, on pulling the plug occasionally the same effect can be se- 

 cured, but if the sewage is allowed to overflow into the tile it will 

 run out into the soil nearest to the septic tank. In the latter case 

 the soil will become over-saturated with the liquid, and the purifi- 

 cation of the sewage in the soil is thereby rendered imperfect. 



