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208
VENTILATION OF SEWERS.
In accordance with the instructions of the Council on 11th July
last, I submit the following report on the Ventilation of Sewers, with
special reference to the abatement of the foul smells lately complained of
arising from the open grids in the roadway at various situations in
the Borough.
The complaints are legitimate; the foul smells at times are
nauseating in the extreme, and cannot but be detrimental to the
public health.
Unfortunately, this nuisance is not confined to West Ham, but is
common to London and all towns in England which have adopted the
water carriage system together with open street ventilators, and I
think it will be admitted by the impartial traveller that, bad as the
street smells are in West Ham, they are not of equal volume and
potency with those which may be met with in many other districts.
Whether this be so or not does not affect the question of injury
to health from the inhalation of sewer air, as it is highly probable that
odourless air passing out of a sewer may cause damage as well as
noxious vapours.
It has hitherto been held necessary to provide means of ventilation
to sewers in order to avoid risk of pent-up gases, formed by decomposition
of sewage, especially where the gradient be insufficient, forcing
their way into houses through traps, the open grids fixed in the
roadway for this purpose being placed not more than 100 yards apart.
The conditions which determine the direction of air currents are
highly complex, including force and direction of the wind, variations
of temperature within and without the sewer, season of the year,
volume and velocity of sewage, etc. As a general rule, there is a
current of air in the reverse direction to the flow of sewage, and if