XN000022-1979-01-07 — Page 5

SUNDAY, JANUARY 7, 1979

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PREVENTING WASTAGE OF WATER THROUGH LEAKING MAINS ******

THE PUBLIC WORKS DEPARTMENT IS DOING EVERYTHING POSSIBLE TO PREVENT WASTAGE OF WATER THROUGH LEAKING MAINS.

THE WATER SUPPLIES DEPARTMENT OF PWD IS DETERMINED TO DETECT FAULTY AND LEAKING UNDERGROUND DISTRIBUTION MAINS AND TO FULLY MAINTAIN THE SYSTEM, ENSURING NORMAL SUPPLY TO RESIDENTS.

THIS TASK IS PERFORMED BY A SPECIAL UNIT WHICH HAS BEEN OPERATING FOR A NUMBER OF YEARS.

KNOWN AS THE WASTE DETECTION UNIT, THIS GROUP OF EXPERIENCED WATERWORKS STAFF ARE BEHIND THE SCENES WORKERS - USUALLY WORK ING FROM MIDNIGHT TO EARLY MORNING WHEN THE MAJORITY OF THE POPULATION ARE IN BED AND VERY FEW TAPS ARE IN USE.

MR. YEUNG ON-CHING, A SENIOR ENGINEER OF THE DEPARTMENT, EXPLAINED THAT ALL MAINS WERE THOROUGHLY TESTED BEFORE BEING LAID, BUT ADDED SOME COULD DETERIORATE AND BE DAMAGED OVER A PERIOD OF TIME FOR A VARIETY OF REASONS.

+THERE IS, OF COURSE, THE OCCASIONAL BURST MAIN, EASILY SPOTTED, HE SAID. BUT IF A LEAK IS SLIGHT, IT FREQUENTLY CANNOT BE OBSERVED AND WATER IN CONSIDERABLE QUANTITY CAN DISSIPATE IN THE SUB-SOIL. THE BEST WAY OF PREVENTING THIS IS BY MAKING THOROUGH CHECKS REGULARLY.+

TO FACILITATE DETECTION WORK, SOME 360 FRESH WATER AND 40 SALT WATER (FOR FLUSHING) WASTE DETECTION AREAS THROUGHOUT HONG KONG HAVE BEEN ESTABLISHED.

TESTS ARE CARRIED OUT BY ALLOWING WATER TO ENTER THROUGH THE INLET MAIN IN WHICH A WASTE DETECTION METER, TOGETHER WITH A PRESSURE RECORDER, ARE INSTALLED.

IF THE FLOW IS OF AN UNREASONABLY HIGH QUANTITY, A LEAKAGE TEST OF THE SYSTEM INVOLVED IS THEN REQUIRED.

THIS MAY INVOLVE THE SHUTTING OFF OF SUPPLY TO CONSUMERS AND CLOSING SOME BRANCH VALVES WITHIN THE AREA.

SIMULTANEOUSLY, VISUAL AND SOUND ING INSPECTION, INCLUDING THE USE OF SOME ELECTRONIC EQUIPMENT TO DETECT AND LOCATE LEAKS WILL ALSO BE MADE.

+WE ARE, AT PRESENT, DOING ABOUT EIGHT OR NINE TESTS A NIGHT ON A ROTATION BAS IS, SAID MR. YEUNG.

ALL DETECTION AREAS ARE TESTED REGULARLY AT QUARTERLY INTERVALS. ON THE AVERAGE, ABOUT 200 LEAKS ARE DETECTED EACH MONTH.