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97
The Borough Surveyor presented the following
report to the Works Committee upon the above
subject:—
In accordance with your instructions, I beg to submit to
you the following report as to co-operating with the Borough
Council of Lewisham in approaching the London County
Council with the object of obtaining the repeal of the By-law
made on the 30th October, 1900, which requires the provision
of a suitable and efficient intercepting trap in every main or
other drain of a new building.
The suggestion made by the Borough Surveyor of
Lewisham as a partial mitigation of the nuisance is that the
sewer ventilators, which are flush with the surface of the
roadway, should be put much closer together; and also that
efforts should be made by combined action of the Borough
.Councils to obtain the repeal of the above By-law, and that
every house should have a ventilating pipe from the highest
point of the drain to act as a ventilator to the sewer.
As regards the recommendation that the sewer ventilators
should be placed much closer together with a view of providing
additional fresh air inlets to the sewers; this appears
to be desirable, and would considerably improve the air in
the sewers.
The suggestion to do away with the intercepting trap
and to make the ventilating shaft of the house drain an outlet
for sewer gas, I do not agree with, as the result would be
that the only protection against the entrance of sewer air into
the houses would be the trap of the water-closets, and if these
were to become unsealed, the public sewers would be ventilating
directly into the houses.
My experience has been that, when the manhole covers
are open to allow them to act as fresh air inlets, and an
efficient system of ventilating shafts fixed to the fronts of the
houses to act as outlets, the air in the sewers can be kept
comparatively pure. The efficiency of this natural ventilation
varies somewhat on account of the variation of the temperature
in the sewer and in the outer air.
I cannot see that the owners of property should be called
upon to run the risk of getting sewer gas into their premises
for the sake of ventilating the public sewer.
I think, undoubtedly, that the sewers should be Tentilated
at the expense of the Local Authority, and that the ventilation
for public sewers should be separate from private drains, but
the ventilators might be taken from the sewer side of the
intercepting trap on private drains.