CO129-452 - Others & Individuals - 1918 — Page 365

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Photograph III:

The new gate is con- structed entirety of re- inforced concrete."

The New Gate.

A

The new gate is constructed entirely of reinforced concrete. site in the outlet channel of the old gate, close to the river, was selected and the excavation for the foundation was carried down to dead low-water level. The entire foundation, which is of soft mud, was then enclosed by sheet-piles and consolidated by short bearing-piles, closely spaced, A concrete invert, strongly reinforced, was deposited over the foundation, and, on this, counterforted walls, to form an opening in the connecting embankments 20 feet in width at the centre, 50 feet at the inner and outer toes and 29 feet in height, were erected. This opening is spanned by a buttressed division wall which carries a set of three cast iron pen- stocks and supports a roadway over the opening at the level of the top of the embankments. The three penstocks for the escape or admission of water are all at a low level. The headstocks for manipulating the penstocks are operated from the roadway.

The objectionable feature of the old structure, namely, a rigid masonry culvert on a yielding foundation subjected to unequal loading from the weight of the superimposed bank is thus done away with, the embankment being now completely divided by the new structure which permits the free passage of water through the penstocks.

The new gate with its wide-spreading base carrying only light walls,— the whole structure thoroughly reinforced to withstand the stresses which it has to bear, should not be liable to damage.

The geared penstocks are of strong but simple design and as they permit of the proper regulation of the flow of water should prove much more efficient than the ill-fitting, uncontrollable wooden doors of the old gate.

l'hotograph IV: "The approach channel

A series of curves."

Photograph V:

The outlet channel a

Approach and Outlet Channels.

An approach channel from the site of the old gate to the new one and an outlet channel from the new gate to the West River have been con- structed.

The approach chaunel is of cement concrete on a lime concrete foundation. It has no fall but is laid out for its entire length in a series of curves of large radius, with the object of preventing the accumulation

of silt.

The outlet channel is of similar design, but paved with cement con- aweeping curve from crete blocks where the wear will be greatest. It has a moderate full and

is laid out in one sweeping curve from the gate to the West River.

gale to river."*

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