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adopted, by which large cast-iron shield pipes are forced by
means of powerful hydraulic jacks through the clay under the
river, thus forming tunnels in which the sewer pipes are laid.
In the case of new streets, not a pipe is permitted to he
covered up until the work has been thoroughly inspected and
the foul sewers tested with water. The pipes used have
special joints, are made of the strongest stoneware clays, and
laid upon a thick bed of cement concrete. In addition, they
are laid to absolutely straight lines from point to point, and
by means of manholes can be examined and seen through
from end to end. At the head of every branch sewer means
are provided by vertical shafts—lampholes and flushing
chambers—through which thousands of gallons of clean water
are systematically delivered in order to prevent any deposit
within the sewers. There are upwards of 100 of these
flushing chambers in the district. Fortunately, all the sewers
in this district may be said to be self-cleansing, and within an
hour or two of any foul matter being discharged into a drain
or sewer it is delivered to the Edmonton Sewage Works.
The sewers are ventilated by means of gratings over the
manholes and by upcast shafts ; but the gratings intended to
be inlets for fresh air sometimes also discharge foul air, in
consequence of which many of them have been closed in, and
extra upcast chafts erected at points of vantage in their place.
During the past 15 years no drains of any house have
been permitted to be connected to the sewers unless they have
been provided with a chamber just within the boundary
adjoining the street or road containing a trapped interceptor.
Although the District is scattered over so large an area
there are very few houses which are not near a sewer, so that
fortunately very few cesspools now exist, and they are
becoming less every year.
In the District there are now 38¼ miles of foul sewers
and 30½ miles of surface-water sewers, and no less than 25
miles of these have been constructed during the past 5 years.
Sewers -During the past year a total of 10,942 yards
of sewers were laid as follows:—
New foul sewers ... ... 110 yards.
New surface-water sewers ... 2,591 ,,
New Estate Sewers.
Foul sewers ... ... 3,748 ,,
Surface-water sewers... ... 4,493 ,,