PARK SANITATION 



86 1 



tile line and the collecting drains. If a main drain is required this should 

 be a six or eight-inch water-tight sewer. 



Intermittent filtration. An intermittent filter consists of a bed of sand 

 from twenty-six to thirty-six inches in depth, resting upon a layer of graded 



VlTBinEDSEWfPPIPE- 



-LENGTH OF TILE FIELDS 

 rtOT TO BE GREATP THAft! 

 7O TILE -EACH l2"LO/1O i 



\\ 



J DIVFR5IOA CMAWBE& %^_ VITRIF.E_D 5EWEB_PlPE_^_^ -u 



DIVEP5IOAI 

 CMAMBEB 



3" OR 4" DEAIrt TILE - 12" LOAJG^* 

 LAID WITH 'A" OPErtJOl/NTS 



PLATE No. 337 

 TILE FIELDS FOR SUBSURFACE IRRIGATION 



(Pennsylvania Department of Health.) 



broken stone or gravel, in which are placed underdrains to carry away the 

 filtered sewage (Plate 341). About one acre of filter surface will be required 

 for seven hundred and fifty persons. 



The walls of the filter are usually made of earth, either as an embank- 

 ment or as the walls of a pit. The underdrains consist of four or six-inch 

 open joint tile placed from twenty to thirty feet apart on the floor of the 



-Cover 



"Vitrified Sewer 

 from 



PLATE No. 338 

 SECTIONAL VIEW OF A DIVERSION CHAMBER SHOWING GUIDES FOR STOP PLANKS 



(Commission of Immigration and Housing of California.) 



filter. The underdrains have a slight fall towards one end of the bed, and 

 lead into a main drain of tile or pipe, eight inches in diameter, through 

 which the effluent is carried away. On the floor of the filter is placed a six- 

 inch layer of broken rock or gravel, ranging from one to two inches in 



