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26
SEWAGE WORKS.—TREATMENT AND DRAINAGE.
The Local Government Memorandum for the year especially
asks for information as to:—
Sewerage and Drainage.
Method or Methods of Disposal.
Localities where improvements are needed.
In the report of 1908, I went exhaustively into the treatment
of sewage, most suitable to the position and locality of our sewage
works, taking into consideration the increase of our population,
explaining the Dibden system of Slate Beds, its economy combined
with efficiency, and producing an effluent satisfying all the conditions
of the Local Government Board. During the year, the Sewerage
and Public Health Committee had many meetings on this subject,
and in March last asked Mr. Dibden to inspect the works and to
advise them as to their future working. Mr. Dibden made the
following immediate recommendation, viz., the lowering of the
sump at the bottom of the pump well, and additional pump force
to regulate the flow of sewage into the tanks, to cleanse the
surfaces of the No. 5 and 6 contact beds and render them capable
of doing useful work instead of standing idle. To construct inlets
three feet wide to each of the six contact beds, thus enabling the
beds to be worked in rotation ; with the effect that the maximum
degree of drainage and aeration can be obtained from each bed,
instead of the bottom layers being always practically under water.
The irrigation plots to be cleaned and levelled, which will make
them in fair working order. The two plots on the island which
were covered with fungas to be drained and allowed to dry, and to
be thoroughly cleansed by the removal of years' of accumulation of
debris and foul growth. The storm water plot to be levelled and
one half covered with hard core, thus forming a horizontal filter.
A temporary connection to be made to the two tanks used as slate
beds to prevent the discharge from the slate beds being sent to the
pump well to be re-pumped as hitherto, to enable the slate beds to
be properly worked, the bottom layers of which have been under
water for prolonged periods, thus converting them into septic
tanks. The area of the present site of the works is ample for the
extension of such additional works as may be required for years to
come.