f
July 16, 1896.]
water flowing from the catchment ared during such extraordinary rainfalls as the one occur- ring in 1889.
The overflow weir and bye-wash channel to be constructed of masonry and cement concrete throughout.
The construction of this reservoir will neces gitate the raising of the Aberdeen Road skirt ing its western bank and the diversion of the southern portion. The material for raising the road and portions of Farm Lots 18 and 19 to be obtained from the area of the reservoir, the banks of which are to be formed as shown on Drawing No. 4, the western bank being com- pos.d of filled in material it is proposed to pitch with stone.
The construction of this reservoir will further to some extent encroach on Rural Building Lot No. 51 and Farm Lois Nos. 18 and 19 and involve the destruction of the small village of Pokfoolum.
Proposed Main.--The elevation of the site does not admit of the discharge of the water from the proposed reservoir into the existing Pokfoolum conduit. It is therefore proposed to provide for the water being conveyed in a cast iron main 12 inches in diameter contouring the hillside on the west of the Pokfoolum Road till it reaches the northern boundary of the Chinese Christian Cemetery. From this point the main to be reduced to 19 inches in
diameter and follow the line of the Pokfoolum Road as far as Shektongtsui Nullah, where it enters Crown land and terminates in the pro- posed filter beds situated near the Bouliam Road pumping station.
This main will be capable of discharging 14 million gallons per 24 hours.
CHINA OVERLAND TRADE RËPORT.
in the valve tower being of insufficient strength to bear the increased, pressure of water safely, the carrying out of this work will necessitate emptying the reservoir, which cannot be done without seriously interfering with the water supply to the City of Victoria and Hill Dis- tricts until after the lower reservoir and the project previously described has been completed. The estimated cost of this work is $35,000.
.The completion of the two foregoing projects providing for the storage of 169 million gallons in two reservoirs having a combined catchment area of 500 acres, will practically exhaust the means available within the Pokfolum Valley for increasing the water supply.
Supply to be derived from Works in Pok foolum Valley. These works will secure a daily supply of 880,000 gallons, as compared with a daily supply of 540,000 gallons from the exist. ing works, throughout the year.
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cipal dam, which has a length of 150 feet. It is anticipated that the depth of water over the weir will not exceed 4 feet. The outlet com- mencing in a suitable valve well will be carried through the easterly dam and discharge into the existing gauge basin at the entrance to the Taitam Tunnel. The construction of this reservoir will involve a diversion of the road to -- Taitam Tuk, the building of a new residence for the caretaker, and a new Police Station. Estimated cost 860,000.
The completion of these works will practically exhaust the means available within the Tuitam Valley for increasing the water spply unless recourse is had to pumping water from the lower levels.
TOTAL SUPPLY OBTAINABLE BY GRAVITATION
FROM POKFOOLUM AND TAITAM.
the
The present storage capacity in Pokfoolum Valley is 68 million gallons, and on the completion of the proposed reservoirs în the Taitam Valley the storage capacity in that valley will be 520 million gallons, making a total of 588 million gallous.
The construction of a catchwater 6,000 feet in length contouring the bill on the westeru side of the Pokfoolum Valley at a level of 550 feet would intercept au additional catelnment area of some 170 acres and would ado.it of a ! The storage capacity required to secure daily supply of 1 million gallous being obtained i 3,200,000 gallons per diem is 432 million gallons; throughout the year. The estimated cost of į there would therefore be a surplus of 156 million this catchwater is $15,000,
gallons which would be available for storing water in wet years for use during dry years.
TAITAM VALLÈY.
Proposed Reservoirs.—In the Taitam Valley detail surveys have been made of fițe sites, all of which are more or less suitable for the con- struction of reservoirs.
Two of these sites, Nos. 1 and 2, aro situsted above the existing reservoir and within its dutchment area, the other three are situated lower dewu the valley, one of which, No. 3, is it a sufficient elevation to admit of water col- fected in a geservoir on it being discharged into the existing Taitam Tunnel.
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It is also proposed to connect the existing outlet pipe from the Pokfoolum reservar to this main and extend the latter to join the con- Proposed Reservoir Site No. 1. The pro- dait near the present filter Leds, In case of posed reservoir on site No. 1 would be forïded necessity this inaiu will be available for the : by the construction of a masonry and cotrrete purpose of conveying water from the existing i dan. This reservoir would have a capacity of reservoir to the present filter beds at the rate : 40 million gallous with a top level of 780 791 | of from 600,000-to 1 million gallous per twenty- ; above Ordnance Datum, a catchment area of four hours, according to the level of the water 1220 acres and a maximum depth of 50 feet. in the reservoir.
The waste weir is situated at the trötth end of the dam and has kngth of 80 feet. It is an ticipated that the depthì of water over this weir will not exreed 3 feet. The hyo-wash channel will be constructed '
on solid ground and discharge into the valley below the damn. The outlet commencing in a suitable valve well will be carried through the main dam and dis. charge into the stream below it. Estimated cost $140,000,
Proposed Filler Beds -The proposed filter beds in connection with this project are shown on Drawing No. 2; they are three in-uunher. I having a compined area of 1,566 »quare yards and are arranged to discharge into a sinall, service reservoir of a capacity of 250,0:80) gallons, which with the one now being constructed at Kennedytown will prevent the irregular action that would result from the variation in draw-off from the mains without such provision. The top water level of the service reservoir is 251.5 feet above Ordnance Datum admitting of a direct communication being made with the distribution mains below the exhaust from the hydraulic motors withont interfering with their
action.
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After considering the rainfall tables con- tained in the appendices, I am of opinion that this additional storage may be relied upon to increase the daily supply available by at least 300,000 gallons, bringing the total supply up to 3,500,000 gallons per diem, or equal to a supply of 15 gallons per head per diem to a population of 233,000 persoas, or the estimated population
in 1903.
Supplementing these works by the additions proposed in the Pokfoolum Valley, the supply from the several sources' would be as follows :-
Catch- Yield," Valley, ment May to August. acres, gallons, Pokfoólum.. 300 219,600,000 Poklonium
ACOL
Yield. September
to April. gallons,
Total
gallons.
74,000,000 223,000,000
Catchwater 170 56,000,000 Laat Taitum Catch-
water Fast 220
23.000,000 79,000,000
684 339,000,000 102,000,000 441,000,000-
Taitan Catch-
water West 186 Streans in-
tercepted by
conduit Wangneichong
72,000,000 20,000,000 102,000,000
G1,000,000 25,000,000 86,000,000-
71,000,000 96,000,000 170,000,000
365
Gap 100 50,000,000 15,000,000 615,000,000 Catchwater.. 90 30,000,000 12,000,000 42,000,000 | Proposed Reservair Sile No. 2-–-–The proposed
931,000,000377,000,000 1,308,000,000 reservoir on site No. 2 would be formed by the construction of a masonry and concrete dam. Average supply per diem=1308000000— This reservoir would have a capacity of 40|3,583,000 gallons storage” required—3,583,000 million gallons with a top water level of 830 | by 242 less the yield of the catchment areas feet above Ordnance Datum, a catchment area during the months of September to April of 60 acres which forms a portion of that of inclusive (S67,086,000 minus 377 millions), reservoir No. 1, and a maximum depth of 50 viz., 490,086,000 gallons. The storage capacity feet. The waste weir is situated in the centre of the reservoirs will amount to 689 million Construction of reservoir, including
of the dam, that portion being constructed of gallous, leaving a balance of 199 million gal-,, compensation and purchase of land $160,000 masonry and cement concrete throughout, and fons, say, which may be relied upon to increase Cast iron main.
55,000 Has a length of 20 feet. It is anticipated that the daily supply to 4 million gallons. Filter beds and reservoir
35,000 the depth of water over this weir will not exceed 3 feet. The outlet arrangements will $250,000 | be similar to those described for reservoir on site No. 1. Estimated cost $56,000.
Estimate.—The estimated cost of this project is as follows :
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Total...
The cost of the erection of pumping machinery 1 with the necessary buildings for pumping the water from the reservoir,into the existing con- duit has, fogether with the aunnal charges con- nected with such a project, been considered, and I am of opinion that the laying of the cast iron main is preferable.
Increasing the Capacity of the Existing Re- servoir. The practicability of increasing the capacity of the present reservoir has also been considered, and I am of opinion that after the construction of the reservoir on the lower site this work might be undertaken by raising and strengthening the embankment
The present outlet arrangements are unsatis factory, the whole of the water being drawn off from near the bottom of the reservoir.
The project includes raising the embankment 11 feet and the overflow weir 10 feet, thus in- creasing the storage capacity from 68 million gallons to 91 million gallons and the improve- ment of the outlet works, so as to admit of the water being drawn off at different levels. As this involves the fixing of a stopping plate in The existing culvert, the present plate situated
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The run-off from the catchment area of this reservoir during the months of May to Angust inclusive will not exceed 30 million gallous, but the total run-off from the catchment area of the reservoir on site No. 1 will be 109,800,000 gallons. qud the 39 millions over and above that required to fill the reservoir on site No. 1 can be diverted by a short length of catchwater constructed along the eastern slope of its catchment area. No difficulty is therefore anticipated in practi- cally filling these two reservoirs during the months of May to August inclusive from the catchment area available.
Proposed Reservoir on Site No. 3.-The pro- posed reservoir on site No. 3 situated immedi. ately below the present waste weir of the Tai- tam reservoir would be formed by the construc- tion of two masonry and concrete dams. This reservoir, which would practically form an ex- tension of the existing Taitam reservoir, would have a capacity of 20 million gallons with a top water level of 498 feet above Ördnance Datum, and a maximum depth of 27 feet. The waste water would discharge over the top of the prin
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This would be sufficient for a population of 266,000 persons, or the estimated population in 1910.
Though I have assumed that the rate of in- crease in the population of the City will be maintained for the next 10 years at the rate of 5,000 persons per annum. I am of opinion that,... considering the limited area of the City and its present overcrowded condition, such a rate of increase should not be permitted and is not. likely to occur.
In view of the recent improvements in Kow--- loon, it appears probable that the increase in the population of the colony will to a large extent be confined to that district, the water- supply of which is entirely separate from that of the City of Victoria.
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Should such, however, not be the case, material increase in the water supply derived from the Taitam Valley may be obtained by the construction.cf the reservoirs on sites Nos. 4 and 5 and the water pumped up to the existing - - reservoir. The catchment areas of these reservoirs, exclusive of the portions intercepted. by the existing and proposed catchwaters and present reservoir, are 260 acres and 250 respectively. As this project involv iug, the material for forming