Fig. 2. Raw sludge is mixed with wood 

 chips in the ratio of three 

 parts wood chips to one part 

 sludge. 



Fig. 3. A 20' X 60' bed of wood chips 

 is laid down for good dis- 

 tribution of air. 



Fig. 4. Four inch perforated pipe is 

 placed on the bed and covered 

 with four inches of wood 

 chips. 



Fig. 5. The chip/ sludge mixture is 

 piled on the bed and is 

 covered with approximately 

 one foot of composted mater- 

 ial for insulation. 



