CO129-572-3 Jubilee Reservoir- Shing Mun- defect in Pineapple Pass Dam. For extracted photographs see CN 3-48.... 1-12-1937 - 15-6-1938 — Page 24

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perfectly clear from the outer pipe.

REMEDIAL MEASURES

It is not possible to state what remedial measures

should be undertaken, until an exploration of the sand wedge

has been carried out to ascertain whether a cavity has

formed or not.

(a) It is advised that a line of holes be sunk in the

sand wedge at intervals of about 14 ft. to ascertain whether

cavities are met with and that such cavities, if encountered,

be filled as far as possible with "pea" gravel passed down

the tube to afford temporary support. It is possible that

the sinking of the tubes may bring about the collapse of any

sand arch which may be formed. The level in which water

stands in the tubes should be ascertained. The water

issuing from the outlet pipe referred to under paragraph (8)

should be kept under careful observation, a glass vessel

being provided to ascertain whether any fine sand is escaping

with the water. Should this prove to be the case, the

pipe should be plugged.

ALTERNATIVE I

Should it be found that cavities exist in the sand

wedge, the sand should be removed in layers of about 4 ft. at

a time, struts etc. being provided to take the thrust of the

Banking material, and "pea" gravel and small broken stone not

more than 3/8" in size should be substituted for the sand.

LEAKAGE

The excavation of the sand wedge will reveal cracks

which may have occurred in the corewall and these should be

made good by caulking if possible, or, if they prove to be too

fine, by placing a pad on the cracks strutted from the

rockfill by means of concrete.

grouted.

ALTERNATIVE II

The corewall should then be

Should no cavities be found in the sand wedge,