Page 1737 - Week 06 - Thursday, 20 May 1993

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MINISTER FOR URBAN SERVICES

LEGISLATIVE ASSEMBLY QUESTION

QUESTION NO. 723

Water Supply - Chemical Additives

Mr Stevenson - asked the Minister for Urban Services:

Can the Minister for Urban Services list the names and total amounts of the different chemicals that were added to the ACT drinking water supplies during 1992 together with the reasons for the addition of each chemical.

Mr Connolly - the answer to the Members question is as follows:

During 1992, 50862 mega litres (Ml) of water was supplied to Canberra and Queanbeyan, 50664 Ml from Stromlo Water Treatment Plant and 198 Ml from Googong Water Treatment Plant.

There are five different chemicals added during the treatment processes of Canberras water supply. These chemicals are:

Chlorine (131 tonnes or 2.2 to 2.7 milligrams/litre (mg/l)) added for disinfection

Lime (235 tonnes) added for pH correction. This chemical is added in the form of Calcium Oxide (2 tonnes or 10 mg/1) at Googong and Calcium Hydroxide (233 tonnes or 4 to 5 mg/1 at Stromlo)

Fluoride (56 tonnes) added in the form of Sodium Silico Fluoride as a legislative requirement of 1 mg/1 of Fluoride ion

Aluminium Sulphate (15,910 litres or 44 mg/1) added as a coagulant in the Googong treatment process

Polymer (35 kilograms or 0.15 to 0.18 mg/1) added as an aid to coagulation during the treatment process

The Member should note that the derivatives of the chemicals Aluminium Sulphate and Polymer are removed from the drinking water as part of, and during, the treatment process.

All of the above chemicals are universally accepted by the industry for the effective and safe treatment of water within the quantities ACTEW use

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