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54
Frontage drains—that is, that portion of the house drain which is
under the Council's highway, and which, except in certain instances, is
the property of the owner—are, in 25 per cent. of the cases investigated,
the principal cause of rats escaping from the sewers and entering nearby
property. This is accounted for by two facts. Firstly, it has been the
practice in past years for owners to reconstruct the drain under the
building, and connect the new drain up to the old portion which is under
the roadway. Thus, while the drain of the building itself is in perfect
condition, the frontage drain is in such a bad state that it is an easy
matter for rats to escape therefrom and enter the buildings below the
foundation of the main front wall. Secondly, continual vibration by
heavy traffic on the road surface is very apt to cause settlement and
fracture of drainage pipes, especially if laid within a few feet of the road
level.
Considerable use has been made this year of the power provided in
section 40 of the Public Health (London) Act, 1936, which enables the
Council to enter premises after 24 hours' notice has been given to the
occupier, and open up the ground and expose the drains for examination
purposes. This method is exceptionally valuable where ordinary systems
of drain testing have failed, and yet there are reasonable grounds to
believe that the drains are at fault. It should be mentioned here that
the cost of carrying out this work is borne by the owner of the property,
if the examination reveals that the drain is defective.
The problem presented by the Black Rat is somewhat different. It
is principally warehouses, wharves and factories which are infested by
this species. Investigations in these cases prove that occupiers of such
buildings usually do everything that is possible to keep the rat population
at a minimum, otherwise considerable financial loss is incurred by the
destruction of valuable stocks. They are ever ready to accept and adopt
the advice which is given them concerning the best methods to prevent
harbouring and breeding of rats upon their premises.
By arrangement with the Borough Engineer and Surveyor, large
quantities of poisoned bait have been laid in the Council's sewers during
the first week of each alternate month. While the immediate effect of
this intensive poisoning cannot be calculated, it is undoubtedly a very
powerful means of reducing the rat population in the sewers.