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142
Report of the Medical Officer of Health.
1st. As to the interceptor itself, it is the source of
much trouble, it retains a quantity of sewage near the house
until decomposition commences and so forms a sewer gas
producer and consequently the sewage when it reaches the
sewer, is much more foul than if discharged direct.
2nd. It is the cause of most of the stoppages in house
drains.
3rd. It prevents a through circulation of air in every
part of the sewer and house drain.
Assuming for the moment, which is not the case that the
sewers themselves are all perfectly ventilated, there remain several
branches between them and the interceptors which have no means
of ventilation whatever, these therefore form gas holders of considerable
magnitude.
What is required, is, a proper means of obtaining a circulation
of fresh air and consequently a dilution of the foul air in every
sewer, branch and house drain; this can be done by abolishing
the interceptor (except perhaps where drains pass under dwelling
houses) and carrying up all soil and ventilating pipes to a sufficient
height to be clear of windows, &c., and retaining the surface road
gratings in places, or erecting shafts or columns, of course discharging
all waste pipes, &c., over trapped gullies. With all
drains and ventilators gas and water-tight and the traps of the
water-closets so constructed as to prevent syphonage, no harm
could arise from this course especially when the drains are outside
the buildings and the evils above enumerated would be overcome.
As instances of this there are many systems of combined back
drainage in the Borough and on some estates interceptors have
been introduced on the main drains, as well as on the branches,
there have been many complaints, and not without cause, as to
smells from the surface gratings in the streets on such estates,
but by taking out the stoppers from the cleansing eye of these
interceptors and thus allowing the through current of air between
the sewer and the combined main drain, which latter is ventilated
at its highest point, the nuisance in nearly every case has been
removed.
The following resolutions were passed at a Conference of
engineers and surveyors to the Vestries and District Boards of the
Metropolis in 1898, which was convened by the late engineer to
the London County Council, Sir A. R. Binnie.