Altrinchanrii 



water gaining access to the sewers. Further, the 

 fact that the main storm overflow acted, when the 

 sewage was increased to less than twice the dry- 

 weather flow, placed during wet weather less burden 

 on the land than is perhaps usually the case in 

 most sewage farms. In this connection the ex- 

 tremely foul character of samples 67 and 68 (storm- 

 water overflow) may well be borne in mind. None 

 of the effluents were in a fit state to be turned into 

 a drinking-water stream." (Part III., page 47.) 



Effluent and 

 Stream Compared. 



The ratio of effluent to brook 

 water, normally, is approxi- 

 mately 1 to 3. The stream does 

 not appear to be in a very satisfactory state, and 

 contained (at the time of the visits to the farm) 

 sewage weed for about 500 yds. below the lowest 

 effluent outfall. The Sinderland Brook was pol- 

 luted before it reached the farm — speaking gener- 

 ally the effluent must have had an oxidising effect 

 upon it. This brook is frequently polluted by tan 

 refuse. A leirge storm overflow culvert from another 

 district also discharges into the stream, a little 

 distance below the farm. 



The amount of dissolved oxygen present when 

 the samples were analysed (maximum = 1 '3 c.c.) 

 was small. It is difficult to estimate the oxygen 

 in brown-coloured samples by the copper chloride 

 method, but this does not apply to the earlier 

 samples which were boiled out. In only one 

 sample of water from the stream was the amount 

 of dissolved oxygen at all great when the analysis 

 was made. The iron in the effluent, &c., would 

 also affect the figures adversely. 



chief difficulty in working the farm is the want of 

 sufficient land, and it is proposed to purchase 

 76'5 acres of the adjoining land, to construct new 

 settling tanks and to enlarge the present outfall 

 sewer. 



" The sewage (domestic) is 

 Conclusions, weak. Even for a filtration farm 

 Altrincham was treating a large 

 volume of sewage, both per acre of the ' working ' 

 daily irrigable area and per acre of the total irri- 

 gable area, and although the sewage was weak, the 

 farm was treating in the aggregate, so far as our 

 data suffice for a comparison, a large quantity of 

 organic matter. The soil and subsoil (porous peaty 

 soil lying upon sand admixed with a little gravel) 

 are not apparently of the best kind for purifying a 

 large volume of sewage, especially when the aver- 

 age filtration depth downwards to the drains (only 

 about 3 ft. 9 in.) is taken into consideration. At 

 the same time the results which we have obtained 

 from Altrincham lead us to consider, so far as 

 our data go, that the aeration through the soil and 

 subsoil must be better than would at first sight 

 appear. The combined sewerage system is in opera- 

 tion, but the farm does not treat much storm water. 

 The bacteriological results, apart from the total 

 number of bacteria (gelatine at 20 deg. C), do 

 not admit of the conclusion that 46,000 gallons per 

 acre (23,000 gallons per acre of the total irrigable 

 area) is too large a volume of a weak sewage to 

 be treated by settling and filtration through a peaty 

 soil lying upon sand and gravel (that is, where the 

 effluent is discharged into a non-drinking-water 



The only objectionable smell stream). The chemical results indicate that the 



. _._. ... on the farm was that caused by land at present is somewhat overtaxed, and that 



the floating masses of scum on with a smaller dose of sewage the results would 



the lagoon surface previously alluded to. The be distinctly good." (Part I., page 83.) 



31 



