Sydney Pipes Sewage out to Sea
TOURISTS fresh off the plane from America are calling Joe Donnelly, the manager of Beachwatch, an organization that reports on the quality of Sydney's beaches.
"Are the beaches safe for swimming?" they want to know, because on the plane an Australian said Sydney's beaches are polluted with sewage.
Mr. Donnelly tells them that information was correct - two years ago. Today, he assures them, the beaches are clean.
The beaches are improved because the sewage now travels in three separate undersea tunnels three miles out to sea, where it is diffused with ocean water 200 feet under the surface. Strong currents act like a giant mixing bowl, and temperature differentials keep the sewage well below the surface. Twice a day, Beachwatch sends a helicopter offshore to look for any brown stain.
"You can't find it," says Donnelly, whose organization is independent but gets its funding from the Sydney Water Board, which runs the sewers.
This is a dramatic change from the way Sydney used to dispose of its effluent. Before, the city drained its system from cliff faces, with the sewage only 30 feet below the water surface. The plume stained the water brown, producing dramatic television footage. Beaches regularly showed high bacterial counts - indicating the presence of waste.
The Sydney solution of counting on deep-ocean currents to swallow its sewage is not unique. Melbourne pumps its sewage, after secondary treatment, into the Bass Strait - a turbulent body of water between Tasmania and mainland Australia. Hong Kong is now building an outfall pipe to handle its sewage as well as some effluent from the People's Republic of China.
And Boston is building a 9.5-mile pipe to dump up to 1.2 billion gallons of highly treated sewage water daily from 43 Boston-area communities into Massachusetts Bay. In fact, activists from Stop the Outfall Pipe in Boston are currently visiting Australia to communicate with environmentalists here.
What the Boston activists are likely to find is that their counterparts Down Under are unhappy about such outfall pipes.
"The extended outfall [pipes] were designed to hide the sewage from view," says Richard Gosden, a spokesman for Stop the Ocean Pollution, a Sydney group.
Sharon Beder, a sewage expert and professor at the University of Wollongong, says her main objection to the outfall pipes is that they spread toxic waste in a larger section of the ocean.
"I can see over time a building up of toxic contaminants over a very large area," says Dr. Beder.
But the Water Board believes the outfall pipes are a good solution. "Other cities have installed outfall [pipes] first and then upgraded with secondary treatment," says Judi Hansen, a senior scientist for the Water Board's Environmental Projects Group.
Dr. Hansen says the rationale behind the deep outfall pipe is to dilute the effluent away from the shoreline while upgrading the treatment plants. She says most of the effluent dumped in the ocean is organic.
"It is not like there are huge chunks of sewage coming out of the diffuser heads and being consumed by fish," Hansen says.
THERE are plenty of disagreements over the outfall pipes. For example, Donnelly no longer finds large fecal coliform bacterial counts on Sydney's beaches. According to the Water Board, 90 percent of the bacteria are killed within three hours of entering the ocean. Beder maintains, however, that other bacteria are now on the beaches as a result of the outfall pipe. Donnelly disagrees, claiming that these bacteria mainly come from animal feces washed into the sea from storm-water drains after a rain.
There are also disagreements over how far the sewage spreads in the ocean. Beder says it spreads over a large area. Oceanographers are still tracking the sewage to see how far the plume extends from the three outfall pipes. The New South Wales Fisheries Research Institute estimates that the sewage plume might have a maximum area of impact of 180 square kilometers (69 square miles). The Water Board figures the plume is about one kilometer wide and can be detected for no more than 10 kilometers before beco ming indistinguishable.
The outfall pipes are certainly not perfect. The Water Board admits grease balls are showing up on some beaches. "We have a major program to try to correct that," says Hansen.
The Board also acknowledges that sewage contains small quantities of toxic waste, pesticides, hydrocarbons, and heavy metals. On Jan. 7, the State Pollution Control Commission (SPCC), equal to the US Environmental Protection Agency, reported that fish caught near the old sewage tunnels contained heavy metals and organochlorine compounds above the maximum residue limit. The SPCC says the greater dispersion from the new outfall pipe, combined with tighter controls, will result in lower levels of these mate rials. But it will take two years to complete the tests to determine if that is happening.
Many of those compounds would be removed if the Water Board installed secondary treatment of its sewage. Although the Board has a stated policy of moving toward secondary treatment of sewage, it has set no date for meeting that goal. Instead, it hopes to have advanced primary treatment in place by 1998. This will remove 85 percent of suspended solids. It will continue to dump sludge - the material settled out in primary sedimentation tanks - from at least one of its ocean outfall pipes until 1993.