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6
this most complete and up-to-date installation have fulfilled every
expectation, and as a useful means of auxiliary treatment the Council
still retain a large area of under-drained land for irrigation, and twelve
old contact-beds (each 60 ft. by 44 ft.)
"The process now followed may be roughly summarised as
follows :—
"The crude sewage from the whole of Wanstead flows to
the Works through the old main outfall sewer (2 ft. 4 in. by 3 ft. 6 in.)
traversing Wanstead Park, and the smaller main sewer of 18 in. which
collects the sewage of the Aldersbrook and Lake House Estates.
Passing through the detritus-tanks and their screens the sewage is
relieved of all the coarse heavier solids, and then flows on to the
settling-tanks where a further proportion of suspended matter is
deposited. From here the liquid passes to the humus-tank where a
final deposition of suspended matter occurs, and the effluent is now
fit for treatment on the great percolating filters over which the liquid
is sprayed in a thin film by the electrically-driven distributors which
form perhaps the most interesting feature of the scheme. By this
process of filtration, a clear, bright effluent is yielded which is suitable
for discharge into the most jealously guarded water-course.
"In times of heavy sewage-flow or when it is desired to 'rest'
the distributors, use can be made of the old contact-beds or the underdrained
grass-lands.
"Storm water is treated in a long scries of open tanks divided by
weirs.
"To remove the sludge and other deposits from the settlingtanks,
humus-tank, etc., recourse is had to electrically-driven
"Stereophagus" pumps which raise the thick and heterogeneous
mixture with the most unfailing and surprising readiness on to the
sludge lagoons where a natural drying process takes place. When
the varied components and stiff consistency of the sludge are considered,
it seems almost incredible that a pump of so small a bore should be
capable of lifting and discharging the dense fibrous gritty paste without
clogging or jamming.
"The wide interest caused by the unusual features of the
Council's Works is proved by the visit recently paid by the Chief
Engineer of the London County Council and his predecessor, Sir M.
Fitzmaurice."
All the work on the farm is carried on practically without noise,
and as the Council have thoughtfully forbidden the use of guns the
place has become a bird sanctuary. I have seen on the farm in my
time the following less common birds : the Kingfisher, the teal and
mallard ducks, the snipe, the heron, many varieties of finches, sandmartins
pied and yellow wagtails, and partridges. One of the older
men on the farm has told me that the former farm manager captured
a " golden heron." This may have been a specimen of the bittern.