View report page

25
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
water 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 extia
upcast shafts erected at points of vantage in their place.
During the past 13 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.