View report page

Treatment of Sewers
The 31st and 32nd maintenance treatments of sewers were carried out in May and
October respectively when baits of oiled warfarin incorporating a mould inhibitor were
used. Of 42 manholes in which there was evidence of rat infestation in May, all were
cleared of infestation when rechecked with test baits in October, having been baited
to extinction in the earlier treatment.
In order to undertake the treatment of sewers it is necessary to have the temporary
use of men and equipment from the Department of the Borough Engineer and Surveyor,
to whom I am grateful for co-operation.
The amount of work involved is shown below:—
May, 1962 October, 1962
Total number of manholes baited 742 646
Number of poison "takes" 42 13
It is important to keep the rat population in the sewers at as low a level as possible
so as to limit the possibility of surface infestation. When buildings are demolished
prior to new development, rats may escape from a sewer by way of severed drains, and
though every effort is made to have connections sealed off at the time of demolition,
works of excavation may subsequently open up the drain and leave a possible source
of future surface infestation.
42