Meeting the Needs Down Under
From the Summer 2002 Waterline, the quarterly newsletter of the Minnesota Department of Health Public Water Supply Unit, Waterline, Minnesota Department of Health
By Jeanette Boothe
Sydney, Australia, a city of about four million people, is best known for its Opera House and the Sydney Harbour Bridge. It is also known as a city of extremes with weather patterns ranging from heavy rains that bring on floods to droughts that result in out-of-control bush fires. Its uncertain climate, combined with the regions growing population, means that Sydney has to store more water on a per-capita basis than any other comparable part of the world.
To ensure an adequate supply of drinking water, a raw-water reservoir was built. Warragamba Dam, which stores approximately 80 percent of Sydneys available water, holds about 2,000,000 megalitres. (A megalitre is one million litresabout the size of an Olympic-sized swimming pool.) The raw water coming from the dam is of good quality. It has relatively low turbidity and is low in color.
In 1996, the Australian Drinking Water Guidelines were adopted. These Guidelines were prepared by a joint committee of the Agricultural and Resource Management Council of Australia and New Zealand and the National Health and Medical Research Council. Since that time, the drinking water for Sydney has been filtered. Prior to that, less than 10 percent of the water was filtered. There are now 10 filtration plants around the city. One of them is the Prospect Water Filtration Plant, located in the community of Prospect Park.
The Prospect Water Filtration Plant, which opened in 1996, is one of the largest direct filtration plants in the world.
An example of engineering innovation and community effort, Warragamba Dam is one of the largest metropolitan water supply dams in the world. It stores approximately 80 percent of the available water for Sydney, Australia, providing the city with one of the most reliable drinking water supplies on the planet.
According to plant manager Claude Lubrano, the Prospect plant opened in 1996. It is operated by the Australian Water Services. They are jointly owned by Lend Lease Corporation, a global real estate and financial services company, and Suez Lyonnaise des Eaux, an international environmental services provider and world leader in water treatment technology and water systems management. They have leased the plant for 25 years, after which time, it will revert back to the city of Sydney. The cost of building the plant was $250 million (in Australian dollars).
The plant is one of the largest direct filtration plants in the world. It has the capacity to process 3,000 megalitres per day, but it normally processes 1,500 megalitres a day. The 15 operators who work at the plant have been trained in all aspects of the plant and rotate duties. The operators are given classifications from one to five, five being the highest. Since the operators rotate duties, they are all a classification five.
Coagulants are added to the raw water before filtering. Single-media sand filtration is the only treatment approach in particle removal at this plant. Disinfection is performed with chlorine. The pH level is corrected, if necessary, by adding lime. Fluoride is added to meet New South Wales health requirements. The water is tested at several stages during the treatment process to ensure that it meets Australian drinking water guidelines. SCADA equipment is also used to keep a close eye on the operations.
By-products from this plant are not sent to waste. The sludge is removed from the filters by trucks, spread out to dry, and then sold to a company to be made into compost. The sludge contains about 40 percent iron. On January 11, 2002, a backwash filtration plant, which further concentrates the backwash waste, went on-line at the same location. This plant was built at a cost of $20 million.
The National Council of Australia awarded a 5-Star rating to the Prospect Water Filtration Plant for Health and Safety Management. This is the highest rating in Australia. This plant is one of the first operations in Australia that has been given this rating on its first audit, quite an honor to the Australian Water Services and its employees.
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