264 SEWAGE AND ITS PURIFICATION 



Champaign, Illinois, is remarkable for the rate at which the 

 septic tank, started in 1898, has dealt with a weak sewage. A 

 flow of 300,000 gals, per day, from 3,500 persons, fills the tank 

 13 times in 24 hrs.^ 



A report by Winslow on sewage disposal plants in 1905 in 

 Ohio, Wisconsin and Illinois, gives working details and 

 analyses from a number of places.^ 



Downers Grove, 111. (pop. 3,000), works completed Sept., 

 1905. Grit chamber, tank 60 X 18 X 7 ft. deep at inlet and 9 ft. 

 at outlet, = 64,000 gals. Flat concrete cover on beams and 

 piers. Upward filter, then distribution by automatic valves and 

 wooden troughs over filters of gravel and sand. Gross cost, 

 ;f 10,800. 



Marion, Ohio (pop. 15,000), works opened end of 1905. Dry 

 weather flow 250,000 gals., but plant for 500,000 gals. Grit 

 chamber, 3 covered tanks with baffle boards, an aerating 

 chamber, and 6 contact beds, 5,000 sq. ft. area and 4 ft. deep, 

 filled with broken limestone : distribution by sluices and troughs. 

 Finally 6 intermittent filters, each 5,200 ft. area, with 2 ft. fine 

 gravel and 8 in. sand. Works combined with an incinerator, 

 which ventilates the tanks and filters. 



Centerville, Iowa (pop. 6,000). Double tank, 60,000 gals., 

 8 ft. deep, 8 hrs.' capacity, baffle boards at entrance and exit. 

 Tank effluent passes over measuring weirs into the creek. Cost 



£604.' 



Columbus, Ohio, Experiments. — In 1905 the effects of plain 

 sedimentation and septic action were compared by means of 

 5 tanks : three 40 x 8 x 8 ft., a fourth circular I2| x 5J ft. ; the 

 fifth, a boiler shell 15 x 6 ft. diam., depth of sewage 5 ft., had a 

 pipe leading to a meter for registering the evolved gas. The 

 sewage had been screened, and, except in the last case, had also 

 passed through a grit chamber. The conclusions only apply 

 strictly to Columbus conditions, but some of them are general. 

 From 8 to 17 days was necessary for septic action to become 

 established, less in summer than in winter. A well-defined scum 

 was not a regular accompaniment. When run at such a rate 

 that the volume was displaced every 8 hrs., the volume of gas 

 ranged from 1-5 to 7 per cent, of that of the sewage. The 

 amount of dissolved solids was almost unchanged, even with 



1 "Economical Disposal of Sewage," by Robert Fletcher, New Hampshire 

 Sanitary Bulletin, 1900. 



2 Journ. of Amer. Assoc, of Eng. Societies, vol. xxxiv., No. 6. 

 2 Eng, Record, N.Y., March, 1906. 



