February_1965 — Page 39

Fabridam Installed at Tai Po Tau

FIRST OF THREE

ON PLOVER

COVE PROJECT

N

A INFLATABLE rubberised

dam

was put into operation last month on a river at Tai Po Tau in the New Territories of Hong Kong.

The dam known as the Fabridam, is the first installation of its kind outside America.

Another two are being installed in the New Territories. All three form part of the Plover Cove water sup- ply scheme.

The purpose of the one just com- pleted is to impound water which will flow by gravity to Plover Cove through a tunnel expected to be ready in two years. It will also create a supply for pumping into service reservoirs near Shatin.

The second one, under construc- tion on the Indus River near Lowu, is for a similar purpose, while the third, at Tau Pass between Taipo and Fanling, will reverse the flow of a stream from north to south and into the Tai Po Tau Fabridam through another series of tunnels.

In the dry winter months it will be possible to pump water back from Plover Cove and into the two Fabridams, This will enable the service reservoirs north of Kow- loon to be kept filled.

Costing only a fraction of a con- ventional structure, the Fabridam is made from neoprene-coated nylon by the Firestone Tire and Rubber Co., USA.

Sealed Tube

The rubberised, fabric is shaped into a sealed tube that is capable of being pressurised with either water or air It is adaptable for installa-

IMPOUNDED WATER

RUBBERIZED FABRIC DAM INSTALLED? AND WATER INFLATED

Water for Plover Cove will flow through the grilled intake pipe on the right. On the left is a smaller intake pipe for the pumping station which is capable of pumping 80 million gallons a day to the supply basin for the filtration beds. When the level is low water will go to the pumping station only. level it will fow into both intakes and if the level should get too high the dam At a higher will deflate to prevent flooding upstream. The view below shows anchorage of the dam to a concrete abutment

tion on any stream, river or water- way for varied purposes such as flood control, water conservation, tidal control, lock systems or recrea- tional facilities.

When fully inflated to its design

WATERCOURSE OR SPILLWAY WALL.

DOWN STREAM

height it acts as a fixed dam compar- able to a concrete structure. How- ever, when completely deflated it offers a minimum flow resistance and allows a maximum run-off dur- ing storm periods. One of the main features of the dam is its ability to change from the inflated to the de- flated state in a matter of minutes.

One way this can be accomplish- ed is with an inverted "U" siphon tube installed in the drain system. When the siphon becomes charged with water through pressurisation of the dam caused by overflowing water, the deflation of the dam starts and continues until empty unless in- terrupted by breaking the siphoning action. The deflation can be pre-set to commence at any height of over- flow merely by adjusting the height of the siphon. Automatic controls and powered equipment can be de- signed into the system.

The Fabridam is similar in many respects to a rubber tyre. Its basic strength is achieved through lamina-

Far East Architect & Builder February, 1965

71