Land Treatment of Sewage. 



takes about one and a half hours to reach the tanks 

 from the town, the Distance being about 1 mile. 

 Sewer Capacity. — A portion of the sewage is brought 

 to one set of settling tanks by a 36-in. circular brick 

 culvert, with a gradient of 1 in 718, and the re- 

 mainder by a 12-in. syphon, 1,000 yds. long, to the 

 settling tanks on the farm. Whatever sewage the 

 12-in. syphon will not take passes by an 18-in. pipe 

 to the low-level tanks, and thence all goes on to the 

 farm. There is one Storm Overflow, but it is not 

 recorded that it has come into use within recent 

 years. Ohemical Treatment. — The sewage is treated 

 before entering the tanks with alumino-ferric, lime 

 and sulphate of iron ; alumino-ferric alone being 

 used at night. At the low-level tanks about 

 144 gallons each of lime and sulphate of iron 

 solutions are used during the twelve hours and two 

 blocks of alumino-ferric, or about 1 cwt. per twenty- 

 four hours. The lime and copperas were run into 

 the sewage from tubs, and the amount.'! varied 

 considerably. The alumino-ferric was suspended in 

 an iron cage in the sewage channel, above the 

 junction of that channel with the tanks. A large 

 quantity of oil occasionally goes into these tanks 

 and was found very injurious to the rye grass on 

 the farm. It is now skimmed off twice a day from 

 the surface of the tanks, but is not utilised in any 

 way. The same chemicals are used at the high- 

 level tanks. The Screens at the low-level tanks are 



Soil 

 and Subsoil. 



the continuous system, one at a time for a normal 

 flow but both for a storm, and are cleaned out once 

 a week. The discharge from the Rugby School 

 baths causes a large rush of water through the high- 

 level tanks and disturbs the sludge. The Sludge 

 (about 12 tons, wet, per week) is used by the tenant 

 of the farm as a top dressing for grass land else- 

 where. The Analyses, both chemical and bacterio- 

 logical, of the sewage will be found at the end of 

 this section compared with those of the effluent and 

 of the stream. 



The Soil has a depth of about 

 10 in. of clay. The Snhsoil is 

 yellow clay, which forms a belt 

 about 5 ft. to 6 ft. deep above the lias. Some of the 

 land cracks beneath the surface in hot weather. 

 Pot-holes of gravel occur in places. Under- drainage. 

 — The farm is under-drained with 2-in. socketted 

 pipes, laid herring-bone fashion, G& ft. apart at a 

 depth of 3 ft. 9 in., and connected to 4-in. and 6-in. 

 butt main drains. Subsoil Water and Floors. — There 

 is not much subsoil water on the farm now. 

 Formerly there was a large quantity in the pot- 

 holes of gravel, but drains have now been laid to 

 these and the water has a free outflow. The 

 irrigable land is not liable to floods. 



The Mechanical Analysis shows the following per- 

 centage composition of the ignited soil. The subsoil 

 was not analysed. 



MECHANICAL ANALYSIS. 



Fine gravel (above 2 mm.) — medium sand (above 0"25 mm.) 



Sand(0-25-0-05mm.)-silt(0-05-0-01 mm.) 



Dust (O'Olmm. — settling from water within twenty-four hours) 



tated by dilute nitric acid) 



Loss on ignition (separate determination) 



clay (still finer precipi- 



99-08 



of wood with 1^ in. holes, 3 in. apart each way. The 

 high-level screens are made of iron bars with f-in. 

 spaces. Settling Tanks. — The low-level tanks are in 

 duplicate, 87 ft. 6 in. by 25 ft. by 3 ft. 6 in. average 

 depth, with a combined capacity of about 95,000 

 gallons, and they are usually worked together on 

 the continuous system and are cleaned out about 

 once a fortnight, the sludge being drawn off by 

 chain pumps into sludge bays adjoining the tanks. 

 The high-level tanks are also in duplicate, 65 ft. by 

 15 ft. by 2 ft. average depth, having a capacity of 

 about 12,000 gallons each. These tanks are used on 



The approximate number of particles in 1 gramme 

 was 3,207,341,170, and in 1 c.c. 5,384,971,060. 



The Lime (parts per 100,000) dissolved by water 

 in twenty-four hours is for soil 0051, subsoil 071 ; 

 and dissolved by water saturated with carbonic acid 

 in forty-eight hours, for soil 0'482, subsoil 0-969. 



Acreage, 

 Population, &o. 



The total area of the farm is 

 40 acres, and of this 35 acres are 

 available for sewage treatment. 

 The average area under irrigation at one time is 

 7 acres ; the population served is 6,000, which works 



50 



