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86
Drainage of Existing Buildings.
The existing drains of dwelling houses and other premises,
which for various reasons are believed to be in a defective
condition, are Subjected to either the smoke or air tests. In
all cases of necessity the smoke test is supplemented by, or
used in connection with, an examination of the drains, after
the ground has been opened up under Section 41 of the Public
Health Act, 1875, and the Acts amending the same, and a
number of pipes exposed in different positions. During the
year, the condition of a large number of house drains was the
subject of special investigation, and, as a result, 122 were
found to be more or less defective.
In all, the drains of 86 houses were entirely reconstructed
and the existing drains of 36 other premises were properly
repaired. No less than 47 of the premises re-drained were
provided for by means of 8 combined systems of drainage.
This work involved the laying of 1694 yards of Stoneware
and 335 yards of heavy cast-iron coated pipe drains, 427 gully
traps, a large number of which were of a self-cleansing type,
and 33 intercepting traps were fixed, 83 manholes were built,
and 11 existing manholes were altered or repaired. In connection
with this work 436 water tests, 76 smoke tests, and
74 air tests were aplied.
New drains are, in all cases, required to be constructed
with salt-glazed stoneware or heavy cast-iron coated pipes, laid
on a solid bed of Portland cement concrete. Heavy cast-iron
pipes are invariably used when the drain passes under a
building, and, in many instances, owners wisely select this
material for the whole drainage system, thereby securing
practically permanent watertight drains, a condition which
cannot be guaranteed when stoneware pipes are used.
Means of access for cleansing and inspecting purposes are
provided by inspection chambers built in suitable postions;
the drains are disconnected from the public sewer by means