View report page

38
The Council accepted the suggestions made, and an examination
of the intercepting traps was carried out, but a few remarks may be
necessary in order to explain the conditions under which it was
deemed advisable that the house drains should be intercepted from
the sewer.
In No. 65 of the bye-laws made by the Council with respect to new
streets and buildings provides that every person who shall erect a
new building shall provide, within the curtilage thereof, in every
main drain or other drain of such building which may directly communicate
with any sewer or other means of drainage into which such
drain may lawfully empty, a suitable trap at a point as distant
as may be practicable from such building and as near as may
be practicable to the point at which such drain may be connected
with such sewer, and with convenient means of access from
the surface of the ground or paving under which it is placed.
The primary object of the bye-law is the prevention of the escape
of gas in the sewer into the house drains, but there is reason to
believe that in the absence of an intercepting trap, specific bacteria
can pass from the sewer into the air in the house drains. Major
Horrocks carried out a series of experiments for the purpose of
determining the conditions under which specific bacteria derived
from Sewage may be present in the air of ventilation pipes, drains,
inspection chambers and sewers, and his experiments showed that :
(1) Specific bacteria present in sewage may be ejected into the
air of ventilation pipes, inspection chambers, drains and sewers by
(a) the bursting of bubbles at the surface of the sewage, (b) the
separation of dried particles from the walls of pipes, chambers,
and sewers, and probably by (c) the ejection of minute droplets
from flowing sewage.
(2) A disconnecting trap undoubtedly prevents the passage of
bacteria, present in the air of a sewer, into the house drainage
system.
(3) An air inlet, even when provided with a mica valve may be
a source of danger when it is placed at or about the ground level.