44 
BULLETIN 57, U. S. DEPARTMENT OF AGRICULTURE. 
The disposal system should be divided into at least two divisions 
for intermittent application, and the capacity of the system should 
be 10 to 15 per cent larger than for a double-chamber tank system. 
The single-chamber septic tank system requires considerable at- 
tention, since there is no provision for automatic discharge. Fig- 
ures taken from the work of the Wisconsin Agricultural Experiment 
Station show that in the long run there is little difference in the 
cost of the single and double chamber tank system. 1 
C./. MANHOLE 
OV LEVEL GROUND 
USE TH/S OUTLET. 
SSCT/ONAL V/£W. 
\.6 m s 60" 
o 
=£=t=£=t=£3 
TOP VIEW. 
Fig. 38.— Single-chamber septic tank for six people. 
THE GREASE TRAP. 
The grease trap acts as a separator of the grease and sewage from 
the kitchen sink or dairy room. If grease is allowed to enter the 
sewer it accumulates and eventually clogs the system. 
Figure 38 shows a grease trap. 1 Two large, glazed sewer tiles are 
placed in the ground. The inlet is usually a 2-inch iron pipe. The 
outlet must be so arranged that the mouth of it is at all times below 
the surface of the sewage. The grease, being lighter, naturally 
floats upon the water, and is thus prevented from entering the out-, 
let. The outlet is made of 4-inch glazed sewer tile and is connected 
with the sewer inlet of the septic tank. A concrete cover is provided, 
and grease and dirt which may accumulate are removed when 
necessary. 
Wisconsin Sta. Circ. Inform. 
