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overflows and also catchpits to arrest the progress of the deposits of sand liable to accumulate. The Syphon head or inlet of the main will be kept 33 feet above its outlet extremity which will be in one of the existing City Tanks situate at a height of about 300 feet above the level of the sea. The Main will be 18 inches
internal diameter, the pipes of ... feet long and
13
1/4 of an inch thick. They will be laid under
the Race Course and part of
the
City,
along
the Public Streets
and the top of the pipes will be
1.5" below the surface of the roads.
Air Valves will be fixed at
every
the summit of
hill and washout Valves at the bottom
of every depression
on
the line of Main.
The Conduit and Main will be so laid out
that if future demands exact a greater head of
pressure, that is to say water, this can be had at
small Cost,
by adding a few extra
lengths of pipe to
extend the Main higher up the hill on which
the Conduit is constructed.
The whole of the foregoing works were designed
as portions of the Low Level Project in its integrity and therefore when at a future day the Embankment
comes to be built and an impounding reservoir, at Tytam is made, they will be found fully adequate.
The delivery Capacities of both Conduit and main have been carefully calculated to accord with the largest storage supply obtainable.
The Constructional details of the tunnel,
the Conduit and their Minor
adjuncts have already been the subject of a correspondence between the Crown Agents and Mr. Rawlinson, and as upon all these professional points there is perfect accord, there will be no need for me in this Memorandum to go
over the same ground again.
The accompanying roll contains the plans
of both the High and Low Level Projects. It was perhaps not necessary to include the
former,
yet
the drawings of the Lower which refer to the Embankment and
Storage Reservoir since these works are not to be
carried out, they are therefore only forwarded home.