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defects of sewers.
Change in opinion as to method of construction of Sewers.
The other drawbacks are of a less important character, and
many are within the control of the Vestry, they may be briefly
summed up as occasioned by insufficient ventilation of the sewers
belonging to the London County Council, defective construction,
damaged sewers, insufficient fall, dead ends, want of ventilation,
inadequate flushing, and in this district the use of peat moss litter.
As the plans and sections shewing the size, level, and fall of all
the sewers in the district have been submitted and approved by the
Metropolitan Board, the London County Council and Yestry, nearly
all these sewers have been constructed under proper supervision,
there are not, therefore, many that can be said to be defectively constructed
or to want proper fall, but in former days such things as
numerous ventilators, flushing chambers, &c., were not considered
necessary; and many of the oldest sewers, such as those belonging to
the London County Council, although most carefully constructed,
have the least ventilation.
As illustrating the change of opinion on these subjects, many
engineers, if constructing an entirely new system of sewers, would
now adopt the dual or separate system, keeping the rainfall distinct
from the sewage.
In 1886 I reported on these matters and made the following
recommendations:—
RECOMMENDATIONS IN 1886.
"Fall of Sewers.—That particular attention be paid to the
fall of sewers.
Manholes and Ventilation of Dead Ends.—That manholes
and ventilators be provided at all dead ends, and that they be
connected with the nearest adjoining sewer by a 9-in. pipe
Steam and Obnoxious Matters.—That steam should not be
allowed to be discharged into the sewers, or any obnoxious
matter from factories, unless it has been previously specially
treated and deodorised.
Manholes.—That a 2-ft square manhole cover with a
ventilating area of 62 square inches, be placed on all the manholes
which are now covered with an iron plate.
Surface Ventilators 60 y&rds apart.—That surface ventilators
be fixed to all old sewers not more than 60 yards apart.
Best Lamps as Ventilators.—That all rest lamps be used as
ventilating shafts.
Special Shafts.—That special ventilating pipes or shafts be
erected wherever practicable.
Flushing.—That the present system of flushing be continued;
that the owners of courts and other properties be encouraged to
have their private drains flushed, and that the Vestry undertake
to do the work on payment of a small fee.