Sessional_Paper_1927 — Page 190

Annexe B.

186

I would propose that for the high level water the Station be equipped with three pump units each capable of delivering one million gallons per day, driven by variable speed electric motors. One unit would normally be a standby in case of break-downs, but during certain rainy periods of the year all three units would be in operation.

As high level water and low level water cannot be pumped simul- taneously, I would propose for the low level water two half-million gallons pumping units driven by two of the previously mentioned electric motors.

The pumps would be either single and double stage centrifugals or duplex or triplex plunger pumps, whichever are considered most suitable on further investigation.

Electricity would be obtained from the Hong Kong Electric Co.'s cables in Mt. Davis Road and I have informally approached the Co., regarding terms and Annexe B shows the calculations regarding cost of power and pumping.

The cost of pumping (power, stores and running expenses) works out at approximately 11 cents per 1,000 gallons for the high level water and 3 cents per 1,000 gallons for the low level water.

Rising and Delivery Mains.

Delivery Mains and Break

The Rising or Pumping Main 18" diameter and 1,500 ft. in length which Rising and would be of Cast Iron or Steel would follow the Sandy Bay Stream Course to Sandy Bay Gap and discharge into a cement concrete break pressure tank situated on the hill side above the Chinese Cemetery.

Pressure

Tank,

From the break pressure tank the delivery main 18" in diameter and 2,700 feet long would run along the Pokfulam Road and finally discharge in to the existing Elliott Filter Beds.

Filter Beds.

Pokfulam Reservoir

Connection.

Filter Beds.

The Elliott Filter Beds have a total area of approximately 4,400 square yards capable of efficiently filtering 14 million gallons per day while in full operation.

At certain periods of the year it will be necessary to deal with about 21 million gallons per day and I would propose to construct additional beds up to an area of about 2,000 square yards.

The beds would be practically similar to the existing Elliott Beds.

Pokfulam Reservoir.

I would propose some small alterations at Pokfulam Reservoir, so that the head of the Reservoir might be utilized. I would also propose to lay a 10" cast iron or Steel main from the Reservoir to join the new 18" main in Victoria Road.

This connection with a byepass round the Pumping Station would enal e water to be gravitated from the Reservoir to Elliott Filter Beds without pumping and thus enable the existing maximum draw-off of 2 million gallons per day to be more than doubled on occasions when conditions are favour- able.