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April 20, 1907.]
KQWLOON HONGKONG "!
WORKS SYSTEM.
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RAVK:--
CHINA OVERLAND TRADE REPORT.
that the WATER. ! probabla
original scheme, if carried ont. would
very soon hi ont of date At the same time it was found that a more
has an
suitable site for a masonry dam than the site subject at
originally selected for the earthen damexisted a point lower down the stream, and that at this site a dam could be constructed giving whilst still giving ample head abore the dis. reservoir of 350,000,000 galls, capacity,
triet to be supplied; and this project was operation. The writer in the meantime haring eventually selected as the one to be put into left the public service and joined the firm of Messrs. Denison, Ram and Gibly, his cong 'rn was entrusted with the carring out of the work
as the
Mr. L. Gibbs, A.M., lust. C. E., excellently illustrated paper on this in the Fur Eastern Review. Prior to the year 1898 the waicland portion of the Colony of Hongkong comprised an ares of about four square miles only. In 1981 the population of this area, known Kowloon Peninsula, including those living in boats near the shore, amounted to 26,500. It was about this date that the necessity for the public supply of water first forced itself the attention of the Government of проп the Colony. It being undesirable to obtain water from what
Chinese ter
WBS the
!
ritory the Rources of supply
Were con. sequently somewhat limited.
A scheme was proposed by Mr. Osbert Chadwick, Consulting Engineer to the Colonies, for obtaining water from the flat sandy valleys in the northern part of the peninsula. This scheme was carried out · under the direction of är. F. A. Cooper, Director of Public Works for the Colony of Hongkong. ¦ The works were completed in 1895 at a cost of $116,000 (Mexican currency). Three valeys, having a joint area of 220 acres, were reserv· di as a collecting area, the water in the flat candy bottoms of these valleys being intercepted by collecting pipes and led to shallow wells, below which dams were built across the valleys 10 prevent the escape of water underground. The wells were counseled by iron pipes to a fank having a capacity of 150, to galle, at Yaumati, and from this tank the water was pumped into: the distributing mains, the supply bing e- gulated by two small service reservoirs, one near Yaumati 215 inches above sea level and of 160,000 galls. capac ty, and the other at Hung- Hom 160 inches above scn-level and of 90 galls, capacity. The minimum supply chaiu- able was estimated to b 232,01 €
per day.
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DETAILS OF THE CONSTRUCTION l'hie final scheme, which is now fast approaching completion, comprises a storage reservær t hold 37 y un no0 galls, of water; two miles of cnfchwater channel: threa filt rheds. capable of filtering 59000) galls, per day; & each
servic· reservoir holding 2,00 400 galle; the Storare reservoir, filt-rbeds and service reservoir, necessary connecting pipes of exstiron betreut.
and about seven miles of additional mains to extend the present distributing system
and concrete dam which, when finished, will be The storage reservoir is formed by a masonry
high from the lowest part of the foundition. about 600 inches long on top and 112 iuries
The mass of the dam is of cement ceret. varying in proportion from 1 cement 2 sand 4 broken stone to I celent 24 sand d broken ali ne.
The cement nged is a sly the Hongs kong "tiren Island " brand. At the cam ~ 22 -
Messrs. Knight. cement of the work English.cement supplied by
eran & Sturge was used, au At одн time а consignment of German atively low test was demanded and all these Hermoor" cement was precared A compar.
sand obtained from beaches on the neighbouring cements have giren satisfaction. The sand is sen
costs, and the stone is hard igneous rock found in the neighbourhood and hand brokea, ORIGINAL AND REVISED NEW SCHEME.-
In the mass of concrete stones are bolded aver. In 1898 the consumption was found to be capidly faging about three culje fut each, no overtaking the available resources of supply, and ' l-ing nearer together than ti inches, at the ame time the acquisition of what is known at the new Territory, an area of shoot 35) squate mil-s-the mainland porti n of which lies to the north of Kowloon Peniusula-vare! promise of increased facilities for obtaining ! reduced to 2 feet thick at the top. The outer water. Under these circumstances, the writer ! face is of rubble masonry set in cement mortar. then an engineer in the Public Works the dam is of a gravity section and curved on Department was instruc ́ed to report on the plan, the curvature being introduced to avoid a question.
deep drop in the stream bed and at the same time in tal advantage of projecting spurs in the sides of the valley to reduce the length of top-water level.
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The physical conditions of the country and the incidence of the rainfall made a storige scheme the only practicable one. There are no 1 large watersheds, the country being a jumble of grass-covered hills rising from a few hundred to 3,000 divided by boulder-filled watercours- 8, carrying torrents, ring the summer rains, and almost dry during the no theast monsoon. Here,
and there these watercourses broaden out into comparatively flat valleys and make possible re- 89rvoir sites. The average yearly rainfall is 84' of this, 58" fall during the four months of M»y to August.
The scheme originally proposed comprised a storage reservoir of 120,00056 0 galls, capaci'ș, formed by an arthen dam 65 feet high, and commanding a drain»ge area of 330 acres. The lowest draw off was to have been at 390 feet she re all the inhabited parts of the peuiusula; filter. beds, a new service Leservoir of 2,490,00 + galle, capacity, and extensions of existing mains werk provided for. The works were estimated to cost $380,000 (Mexican currency) and to pro. vide a supply of 5940dd galin a
day. This scheme was approved by the les authorities, and submitted to Loudou for the Colonial Office, The Consulting Engineer, Mr. Chadwick, while generally approving the scheme, advised that a masonry daш be substituted for the proposed eartheu dam.
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The water fare of the dam is of granite masonry dressed on beds and set in cement, mortar, and behind this is a backing of rich
feel thick concrete,
al the bitter and
The foundation for a length of 400 fest, aud to a level of about 40 feet below overflow level is on hard rock, and shove this the ends are The ontlet
keyed into decomposed granite appliances are conced in a valte tower D
the inner fase of the da o, and consist of 1. inchos catiron eta idpipes with four inlet pipes different leve's so that the water will alway、 commanded by ti inches, valves and fixed
a'
be drawn from nea · the surfa » of the reservar
A subsidiary cam ab no 20 inches hign, built in a coprentent depression, forms the ov, riow Thi« i« 190 feet wide in «p hvanh d
ten İt feat openings and is designed to pack stormwater at the rate of 4 inches per h ar from the na'ma' dra tuge area with 1 inches per hour from cateḥwater area with a head of frat. The recorded heaviest rainfall in Hongkong occurred in Cay, 1889, when 11.9 inches fell in four hours.
to be let
Movable iron s'u cex are prov, led on the top of the hyewash down, These ara down when the heavy rains hire cussed at the end of the summer, and wil thus in or. 2 feet of ditary season impound extra
without using the water-level to greater height than it would reach during a heavy rainstorm.
water
About the time that this scheme was under discussion thereoccurred an unprecedented expan sion iu the population of this part of the colony. The land population of the península, which in 1891 stood at 20,000, was returned by the ce sax ot 1901 as £1,000, an 1 to this ha i tɗb`ailded-for purposes of water supply-the floating poput tion and two small towus known as Kowloou City and Sham Shui Poin the New Turritory : so that the population than requiring water smounted to 56,000 as against 14,000 when the scheme chancel
drawn in 1899. It therefore appeared
was
M
201
no
catchwater is AD open
channel out the hillsides at a gradient of 1 ia 2,400 and lined with concrete. Io the bottom of the catchwater a small. V-shaped channel is con- structel to carry the dry weather flow and pre- its loss by evaporation if spread over a board surface. It is estimate that the catch. water will carry from fet to 1 feet of rain par hour from the drainage area of 1,000 acres,
I
rent
Overflowers are provided in suitable places, exceeds this quantity. At the lower end of the which will come into action when the rainfall
estelwater, the dry-weather flow channel is on- pected to a small channal, passing round the kida of the reservoir, and connec1ing by means of an “inches castiron pips to the gauga bidin on the main supply pips from the reservoir This is edled the clearici e channel, its function bing to intercept the water from the straims and carry it direct to the filterbads, as after bourg rains the water in the res›rvɔir will remain for some days stirb d as to be practi- cally unfilterable.
Filtration.-Feor the storage reservoir a Minelas e istiron nip 3, on a «t a ly gradient, leade to the ganga basin already mentioned. From this gangs hwin an 18 inches cas'iron pip vata uniform gradiant of 1 in 1,4 0 conv-ystia water to the filterlida These arthrex in number, each of ~00 equira yarde ffres, the filtering material e insisting of 3 feet ti inch s of sand on (173 fot of
broken stone, arcangel for dawnward filtration, Adjustable oufl-ta will ba provided ta maintain A con tint height of water in th bl« mod Venturi meters tree and both the rate of filtration and the total How After leaving the filterbads the water will pass through a short tunnel in castiron pipes which are continued for about three unles to connee' with the old distributing which will measure the total supply. system, passing on the way & Venturi meter
Service Reservoir.—The service
resert ir
is situatel on a hill of decomposed granita just beyond the old boundary-lins of the British terri ore, no site at a suitable height being available near the center of the supply district It is built entirely in cutting, with for and kilowalls of coment cauerat nud vaulting of the same sterial carried ng brik arches and stous pillars. The rrvoir is 150 fast in diameter and 20 feet deep, and has a capacity of 100 yudu gall, the in and outlet pipe being arraugel so that the water flows in at the top and out from the bottom of the reservoir, thos insuring seration and circulation
Water Supply The water is supplied in the Chinesa quarter by means of self-closing taps, fred about in yards apart at the siles of the streets, all water laid into privata premises being charged for by meter. Bill fire hydrants will be fixed about 10 › yarde apert oa mil tosios
in the built area.
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Supplementary The construction is being done by China a esatenetore from the desigus and under th• sup›rvision of Misses. Denison, Ram & Gilha Concreting was commenced on the storage reservoir main dam in January 1904, and the masonry is now within 30′ Est of overflow level and impodading shoạt 19 400 1,000 galis of water. The exchwater is usarly mompleta, the filterbads and service reservoir in use, and the extension of the distributing system well in hand. The to'al 04 of the improv~~ ment is estimated to amount to $1,20 1000 (Mexican carr nay, and the supply in the driest year to 1,5mpon gills per day.
DAW
*****• 15.
W. Lara from the Athi that the Fako ka Camphor Offe› has sucosed«l in constructing and saccessfully op ating a new machina for the manufacture of camphor, which 14 said to be « valuable invention. The first adrantig · of the machine is that it on by employed in fie'oris on a 'arge or small, soale with equal The secont is that a oɔn linking apparatus is used, which promote say Éves ga sabetkurs from eutering the capsor oil in the course of in in«facture, at la's › prùvents oil lank- ing in the form of vapou“. Another advantage ic hat the new machine shorten< thi period required for distillation, said also marem fuel It is stated that the existing camphor minafastar - mwhinery is in a very primitive state, raudaring it impossible to carry on the industry on a large and profitable scale.
Drainage and Overdow The antural draig. age ares of the reservoir is only köri serus Experieuce gained with storag · reservairs on Hougsong Island ha 1-4 to the eigelus og
meat and storage of about 20ml weekly galle that it requires about ous square mile of catch.
to provide 100000 galls a day therefore evident that t orniaag- aeres mast í be increased.
tra For this purpose & citchwater construc"mi, intercepting the flow from ад Угра uf 400
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