Land Treatment of Sewaire. 



Bnspended solids is removed from the tanks as 

 sludge and a ttick fibrous scum 3 in. to 15 in. deep 

 is formed, particularly in hot weather and in the 

 absence of wind. Stay in Tanks. — The total com- 

 bined capacity of the tanks is 600,000 gallons — i.e., 

 less than 10 per cent of the normal dry-weather 

 flow. The sewage remains, therefore, about two 

 hours in the tanks. The Screenings are carted away 

 and sold ; the Sludge is partly disposed of on the 

 farm and partly sold. The Analyses, both chemical 

 and bacteriological, of the sewage will be found at 

 the end of this section compared with those of the 

 effluent and of the stream. 



Soil 

 and Subsoil. 



The Soil is of a very clayey 

 nature, 6 in. to 12 in. deep over 

 the greater portion of the farm. 

 About 25 acres to 30 acres near the Anstey Brook 

 are rather better, having a certain depth of alluvial 

 soil ; further, part of the soil has been lightened by 

 ploughing in sludge. The soil cracks badly in hot 

 weather. The Subsoil is 2 ft. 6 in. to 3 ft. of yellow 

 clay overlying hard boulder clay and Keuper marl. 

 Under-drainage. — Agricultural drain pipes have been 

 laid at distances varying from 24 ft. to 99 ft. and at a 

 depth of 4 ft. (two fields, 8 ft. deep), and they are 

 now put in at a depth of 3 ft. They are connected 

 to 4-in. to 6-in. master-drains. Subsoil Water and 

 Floods. — There is practically no subsoil water ; the 

 one sample referred to in the chemical analysis 

 as regards chlorine was obtained with gfreat difficulty. 

 The farm is situate on the slopes of a hill and is not 

 subject to floods. 



The Mechanical Analysis shows the following per- 

 centage composition of the ignited soil (average of 

 boiled and not boiled samples). The subsoil was 

 not analysed. 



in twenty -four hours is for soil 0073, subsoil 0017 ; 

 and dissolved by water saturated with carbonic acid 

 in forty-eight hours, for soil 0554, subsoil 0467. 



Aoreage, 

 Population, &c. 



The total area of the farm is 

 1,699 acres, and of this 1,350 acres 

 are available for sewage treatment. 

 The average area under irrigation at one time is 

 337 acres ; the population served is 197,000, which 

 works out at 146 persons per irrigable acre, or 555 per- 

 sons per acre for the average area irrigated. Thenormal 

 dry-weather flow is 36'8 gallons per head per diem. 

 The amount treated per acre for twenty-four hours 

 at the normal rate of flow is 21,500 gallons on the 

 average area irrigated, equal to 5,370 gallons on the 

 whole irrigable area. 



Treatment 

 and Cropping. 



With regard to the Treatment 

 of the sewage, I cannot do better 

 than quote the evidence of the 

 borough engineer and surveyor, Mr. E. George 

 Mawbey, m.inst.c.e., given to the Royal Commission 

 on March 7, 1901 :— 



" The way we prepared it was this : First of all 

 the ordinary ditches were widened and deepened to 

 serve as the main effluent drains leading to the 

 natural watercourses, and the drain of each field has 

 its own separate outfall, which is brought out on to 

 the surface of the lower field, and arranged so that 

 the foul effluent that always reaches the drains of a 

 clay farm can be treated a second or a third time on 

 other land as may be found necessary to effect a 

 sufficient purification. A surface effluent can always 

 be treated on successive areas until fit to send into 

 the streams — in the old orthodox way of irrigation, 

 that is. The top land which adjoins the sewage 

 carriers is all arable. There are 453 acres of that, 



The approximate number of particles in 1 gramme 

 was 2,204,335,000, and in 1 c.c. 2,744,416,680. 

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



part of which has been broken up from old pasture. 

 The crude sewage is first discharged on to this 

 arable land and finished ofE on the old pasture or rye 



36 



