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37
disposal at sea. It is estimated that 1¼ million cubic feet of
gas per day will be produced by the digestion process and
utilized for production of power for use at the works.
In addition there will be a reclamation scheme for the
improvement of the river front, and new offices, scientific
laboratories and other buildings, the estimated cost of the
whole scheme being £9,750,000. Work is expected to be completed
in seven years' time.
In November, at the Public Works and Municipal Services
Congress, it was estimated that of 22 sewage works,
effluents from which discharge direct into the Thames
Estuary, the major source of pollution was attributed to the
effluent from the Northern Outfall of the L.C.C. at Barking,
Essex. Until 1955 (when the first part of a very large scheme
of extensions was put into operation), for many years, the
daily discharge from these works was 1,50 million gallons
of settled sewage, as well as 40 million gallons of effluent
from an activated sludge plant. In the Erith area two miles
to the east and downstream, a further 100 million gallons of
settled sludge enters daily from the L.C.C. Southern Outfall.
From 1949 to 1954. the average B.O.D. of the final mixed
effluent from the Northern Outfall has been calculated to be
240 parts per million, and the effluent from Southern Outfall
184 p.p.m. During the same period the estimated B.O.D.
load from these two sources was 290 tons per day of which
three quarters came from the Northern Outfall.
The calculations presented above, demonstrate to the
full, the magnitude of the problem relative to the cleansing
of the River Thames in the Erith area.
D (10) Factories