Loan Works.
50
290. Item P, Byewash Reservoir.-This work was referred to in paragraph 248 (P) of last year's Report.
Fair progress was made with the works during the earlier part of the year, and by the end of May the dam was brought up to road level. Final cleaning down was completed early in August. Water was impounded from the beginning of the year and brought into supply on January 14th by connecting the 18" dia. draw-off to the existing supply main to the Kowloon Filter Beds. In June the Reservoir was emptied and the original 18" dia supply main from the Kowloon Reservoir, 2,100 feet long, was recovered from inside the Reservoir basin during which time the supply to Kowloon Filter Beds was maintained from the Reception Reservoir. The Byewash Reservoir was then allowed to fill and overflowed on 11th August. The existing overflow channel from the Reception Reservoir has been diverted so that it now discharges into the basin of the Byewash Reservoir.
The Access Road to the Shing Mun Filtration Plant which was continued beyond the dam as far as the Shing Mun Filters was completed in June. The dam is situated in the Lai Chi Kok Valley about 700 yards downstream of the existing Kowloon Dam and impounds the water which overflows from the latter as well as the overflow from the Reception Reservoir of the Shing Mun Valley Scheme. The Reservoir has a direct catchment area of ninety acres and a nett capacity of 185.5 million gallons. The top water level is 380.00 A.O.D. and at that level the area of the impounded water is approximately fifteen acres.
The dam is of gravity section constructed of mass concrete with pre-cast concrete block faces. The up-stream face is vertical except between the levels of 320.00 and 350.00 A.O.D. where it has a batter of one in sixteen while the down-stream face has a general slope of one in 1.492. The height of the roadway over the dam above the lowest foundation level is 143'-6" and 118 feet above the original stream bed.
The various mixes of concrete used in the construction of the dam are as follows:-
To seal and upstream face 1 cement, 2 sand, 3 broken stone.
To backing below 290.00 A.O.D. 1 cement 2 sand 4 broken stone with displacers.
To backing between 290.00 & 330.00 A.O.D. 1 cement 2¼ sand 4 broken stone with displacers.
To backing between 330.00 & 380.00 A.O.D. 1 cement 3 sand 5 broken stone with displacers.
To Reinforced Cement Concrete Arches. 1 cement 2 sand 4 broken stone.
To pre-cast Blocks. 1 cement 2 sand 4 broken stone.
To dam above 380.00 A.O.D. Lime and cement concrete, with displacers.
The pre-cast blocks forming the up-stream face of the dam are smooth faced with level joints while those on the down stream face have an imitation rock facing with margin drafts.
Loan Works.
50
290. Item P, Byewash Reservoir.-This work was referred to in paragraph 248 (P) of last year's Report.
Fair progress was made with the works during the earlier part of the year, and by the end of May the dam was brought up to road level. Final cleaning down was completed early in August. Water was im- pounded from the beginning of the year and brought into supply on January 14th by connecting the 18" dia. draw-off to the exist- ing supply main to the Kowloon Filter Beds. In June the Reservoir was emptied and the original 18" dia supply main from the Kowloon Reservoir 2,100 feet long, was recovered from inside the Reservoir basin during which time the supply to Kow- loon Filter Beds was maintained from the Reception Reservoir. The Byewash Reservoir was then allowed to fill and overflowed on 11th August. The existing overflow channel from the Recep- tion Reservoir has been diverted so that it now discharges into the basin of the Byewash Reservoir. The Access Road to the Shing Mun Filtration Plant which was continued beyond the dam as far as the Shing Mun Filters was completed in June. The dam is situated in the Lai Chi Kok Valley about 700 yards downstream of the existing Kowloon Dam and impounds the water which overflows from the latter as well as the overflow from the Reception Reservoir of the Shing Mun Valley Scheme. The Reservoir has a direct catchment area of ninety acres and a nett capacity of 185.5 million gallons. The top water level is 380.00 A.O.D. and at that level the area of the impounded water is approximately fifteen acres. The dam is of gravity section constructed of mass concrete with pre-cast concrete block faces. The up-stream face is vertical except between the levels of 320.00 and 350.00 A.O.D. where it has a batter of one in sixteen while the down-stream face has a general slope of one in 1.492. The height of the roadway over the dam above the lowest foundation level is 143'-6" and 118 feet above the original stream bed. The various mixes of concrete used in the construction of the dam are as follows:-
To seal and upstream face 1 cement, 2 sand, 3 broken
stone.
To backing below 290.00 A.O.D. 1 cement 2 sand 4
broken stone with displacers.
To backing between 290.00 & 330.00 A.0.D. 1 cement
21 sand 4 broken stonė with displacers.
To backing between 330.00 & 380.00 A.O.D. 1 cement
3 sand 5 broken stone with displacers.
To Reinforced Cement Concrete Arches. 1 cement 2 sand
4 broken stone.
To pre-cast Blocks. 1 cement 2 sand 4 broken stone.
To dam above 380.00 A.O.D. Lime and cement con-
crete, with displacers.
The pre-cast blocks forming the up-stream face of the dam are smooth faced with level joints while those on the down stream face have an imitation rock facing with margin drafts.
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