Sessional_Paper_1891 — Page 141

137

No.

91.

HONGKONG.

REPORT ON THE PROGRESS OF WORKS CONNECTED WITH WATER AND DRAINAGE DEPARTMENT,

SIR,

Presented to the Legislative Council, by Command of His Excellency the Governor, on the

19th March, 1891.

THE WATER AND DRAINAGE DEPARTMENT, RESIDENT ENGINEER'S OFFICE,

HONGKONG, 7th February, 1891.

I have the honour to forward you the following report on the condition of the works in charge of this Department, and the progress of the new works that have been in course of construction during the past year.

EXISTING WORKS.

Tytam and Pokfulam Reservoirs. —The Tytam and Pokfulam Reservoirs have been maintained in a satisfactory state of repair without any extraordinary expenditure..

The only work calling for special mention being the diversion of the stream at the north end of the Pokfulam Reservoir by means of a 12-inch pipe laid along the western side of the reservoir.

By means of this bye-pass water very much freer of deposit can be delivered to the City during the greater part of the summer than hitherto, the result being a better quality of water if supplied to the districts at present unsupplied with filtered water, and a greater economy is effected in the maintenance of the filter-beds con- nected with the Pokfulam Works, the cost of maintenance to a large extent depending on the quantity of matters held in suspension which have to be removed by the process of filtration.

Tytam Filter-Beds.-The Tytam Filter-Beds have been in constant use throughout the year. During the early part of the year a portion of the coarse sand forming the filtering material was removed to a depth of one foot six inches, and replaced by sand of much finer quality, and gauge wells constructed in each of the beds to admit of accurately determining the quantity of water filtered by each bed.

Since the first of November I have had a daily record kept of the quantity of water passing through the filters, and find that during the month of November the quantity filtered was 61,298,000 gallons, giving an average rate of filtration--allow- ing for one bed always being out of use-of 743 gallons per 24 hours per square yard of filter area. The filters required cleaning once in 16 days.

During the month of December the total quantity filtered was 64,284,000 gallons, giving an average rate of filtration of 754 gallons per 24 hours per square yard of filter area. The filters required cleaning once in 21 days.

The Honourable

THE COLONIAL SECRETARY.