Sessional_Paper_1929 — Page 51

Dam No. 5, T. W. L. 250 O. D., having a length of 502 L. Ft. and Dam No. 5 a depth to stream bed of 100 ft.. will impound 400 million gallons. With a catchment area of 502 acres it will take 35 inches of effective rainfall to fill it without overflow from the upper reservoirs, but, if thought necessary, this area can be nearly doubled by means of a small catchwater.

Dam No. 6 will be situated immediately on the up stream site of Dam No. 6 Tai Wai Village and will have a top water level of approx. 100 A. O. D. It will be 1,740 L. Ft. in length with a total depth to stream bed of 85 ft. and will impound approx. 1,700 million gallons. The direct catchment area available for this reservoir is 1,203 acres, but by means of catchwaters a further 816 acres is made available, making 2,019 acres in all. Approx. 37 effective inches of rainfall are necessary to fill this reservoir without any overflow from the upper reservoirs.

Station & Ris-

The Pumping Station will be situated below Dam No. 6 and the Pumping Rising or Pumping Mains will follow the Access Road along the South ing Mains side of the valley to the gauge basin at the tunnel mouth, a distance of approx. 23 miles.

Bay

In the Gin Drinkers' Bay Valley there are two possible sites for Gin Drinkers a very large reservoir, but surface indications do not promise well for Reservoir foundations at a reasonable depth. If however either site on investi- gation should prove feasible, storage of between two and three thou- sand million gallons could be obtained in a position easily accessible to the main scheme. The water from this reservoir would be pumped to the South Conduit between the tunnels.

An Access Road 16 ft. wide having a maximum gradient of 1 in Access Road 16 will run from the Castle Peak Road at Tsun Wan to Pineapple Pass then down the Shing Mun Valley to join the Taipo Road above Shatin with a branch running North from Pineapple Pass to Dam No. 1. The portion of the road from Dam No. 6 to Dam No. 2 will serve a double pur- pose, as the pumping mains will be laid along it. The total length of this road when completed will be 6 miles,

The foregoing gives the broad outlines of the Scheme with ap- proximate areas and storage capacities as far as they can be ascertained from the information now available. It is however certain that as the work proceeds and further information is obtained considerable modi- fication will require to be made,

The works will be constructed in the following order:

Order of Construction

1st. Section. Access Road to Pineapple Pass approx. two miles ist. Section in length, small intake dam on Shing Mun River with temporary pipe- line, North Conduit, Smugglers' Ridge or North Tunnel, South Con- duit between tunnels, Golden Hill or South Tunnel, Reception Reser- voir, 1st. section of filter beds, service reservoir, trunk main through, Kowloon Peninsula across harbour to Public Gardens, and Service Reservoirs in Public Gardens, Hong Kong, and Pipers' Hill, Kowloon.

2nd. Section. Continuation of Access Road to Dams 2nd Section. Nos. 1 and 2, construction of Dam Nos. 1, 2, and 2A, Catchwaters discharging through Lead Mine Pass, 2nd section of Filter Beds, and Second Trunk Main to Kowloon &c.

3rd. Section Catchwaters draining areas A, B, C, D, & E, on 3rd Section. the Southern Slopes of Taimoshan discharging through Pineapple Pass, Dams Nos. 3 & 4 & 3rd. Section of Filter Beds.