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with iron pipes from special designs, which permit the smallest
area of sewage being exposed in the manholes, and have
worked satisfactorily. The sewers are also carried at several
points under the New River, and recently the late New River
Company insisted upon a special system being 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 be
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 shafts erected at points of vantage in their place.
During the past sixteen 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 Districts there are now 41½ miles of foul sewers,
and 37 miles of surface-water sewers, and no less than 34¾
miles of these have been constructed during the past 7 years.
Sewers.—During the past year a total of 5,520 yards of
sewers were laid as follows:—