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supply of filtered water from the Shek Lai Pui Rapid Gravity Filters to be delivered into the already completed Pipers Hill Service Reservoir, whence it was discharged into the Kowloon distribution system by a 12′′ C.I. connecting main. The lower section of the work from Wong Uk to the Railway Point follows the line of Castle Peak and Nathan Roads.
Some delays occurred in the laying of this main, due to the realignment of the Castle Peak Road. Difficulties were encontered in the crossings of nullahs and in the avoidance of other services.
Connections from this main to the Kowloon distribution system have been made at Pipers Hill Service Reservoir, Prince Edward Road, Waterloo Road (for Yau- mati Hill Service Reservoir) and at Salisbury Road.
Two automatic recorders and self closing valves have been installed on the pipe line, one 560 feet distant from Shek Lai Pui Service Reservoir and the other at the Railway at Kowloon Point.
The pipes used for this main are of mild steel 1/4′′ and 5/16" thick, for the upper and lower sections respectively, having a bitumen or concrete lining and an outside wrapping of hessian cloth and bitumen. The joints are of yarn with lead rings caulked in cold.
The section under the Railway, about 300 feet long, is of heavier metal, 3/8′′ thick, the joints being welded and the whole pipe line encased in concrete.
The length of the pipe line from Shek Lai Pui Reservoir to its junction with the Cross Harbour Pipe at the Railway is 24,034 feet.
Pipers Hill Service Reservoir.
This Reservoir, whilst giving additional storage of filtered water for the Kow- loon and Lai Chi Kok Water Boat supplies, is so situated as to be capable of receiving filtered water from either the Shek Lai Pui Rapid Gravity or Kowloon Slow Sand filters.
The contract for construction was let in September, 1924, and the Reservoir was completed, satisfactorily tested and brought into use by the end of 1925.
The Reservoir has a capacity of 1-547 million gallons, a T.W.L. of 275.00 A.O.D. and a depth, when full, of 18' 3". It is trapezoidal in shape, being 152′ 0′′ long with an average width of 91′ 0′′. A division wall 13′ 6′′ high divides it into two compartments, from either of which water may be drawn off independently by means of 18" connections controlled by 12′′ Sluice Valves.
By means of 15" connections from the 24" trunk main from Shek Lai Pui Service Reservoir and from the supply main from Kowloon Filters, water is discharg- ed into a double compartment gauge basin whence it can be passed into either half of the Reservoir.
An overflow and means for washing out the Reservoir have been provided.
The Reservoir was constructed throughout of cement concrete, the main and division walls, which have bitumen expansion joints, being of gravity section but reduced in thickness where the nature of the ground permitted.
The invert is of concrete 12′′ thick and also has bitumen expansion joints.
The roof, which is of jack arching carried on reinforced concrete beams and supported on reinforced concrete piers, is of concrete and is covered with turfed earth filling 12′′ thick.
The total amount of concrete in this work is 3,614 cubic yards.