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105
Series of Bye-Laws re Drainage.
The Borough Engineer and the Medical Officer of Health, at the
request of the Public Health Committee, made the following report in
reply to a letter received from the London County Council in regard to
our practice and opinion in requiring manholes and interceptors to new
and reconstructed drains:—
With reference to the construction of Bye-law 5, the question of
the advisability of amending this Bye-law so as to do away with the
intercepting trap is one which must be approached with great care,
although there are a great many points in favour of abolishing the
intercepter. One of the most important of these is that freer ventilation
would be possible, and secondly, the question of the intercepter
acting as a retainer of sewage and allowing decomposition to take
place. Both these are important factors, and there is no doubt that
under perfect conditions of drains and sewers, with perfectly sound
drains and sewers and guaranteed construction, theoretically it would
be an advantage to have a free flow of air from the sewer passing out
through the outlets provided for the ventilation of the drains. If
these conditions are not possible, it would be in our opinion a great
risk to do away altogether with the intercepter. It is impossible
that all sewers and drains shall be absolutely perfect, for however
well constructed in the first place the work is bound to deteriorate
a.nd defects will arise, whereby the sewage is held and allowed to
decompose and to give off dangerous gases which would find their way
into private premises. Again, the time for sewage to pass from
some distant parts of London to the outfall is such that the sewage
must have decomposed when passing through the sewers of other
districts.
With regard to the access to the trap, this is one of those unfortunate
double arrangements which so often occur in the L.C.C.
Bye-laws, and which have tended in the past to so many failures in
litigation and so much expense to the local authorities. The latter
part of the section does not explicitly say what is required. In
section 4 of the L.C.C. Bye-laws, in the last paragraph under the
head of "drains under Buildings" it is stated, "means of access
must be provided at each end of the drain beneath a Building."
When this access does not provide adequate means of access to the
trap it is stated in section 5, "a separate manhole or other separate
means of access to such trap for the purpose of cleansing it shall be
provided." As the Bye-law stands it is not compulsory to provide a