Cleaning Up : Tower Begins Purging Water of Pollutants

After speaking Thursday at the dedication of a new ground-water treatment plant in North Hollywood, Mayor Tom Bradley was told to play guinea pig. As a city water official jokingly told the mayor: “You get to drink the first glass of water . . . out of there, just to make sure it’s working right.�

There was no glass of water. But good humor and praise were in ample supply as the federal Superfund cleanup of Los Angeles city drinking water supplies finally got under way. With the push of a few buttons, 2,000 gallons a minute of chemically tainted ground water began coursing to the top of a steel aeration tower to be purged of traces of suspected cancer-causing solvents.

About 100 city, state and federal officials turned out for speeches and refreshments under a tent erected at the Department of Water and Power storage yard at 11845 Vose St. But the star of the show was the 45-foot tower, freshly painted blue-green and hailed by DWP officials as “a major step forward in the cleanup and future protection of Los Angeles ground-water supplies.�

After removal of chemical solvents, mainly trichloroethylene (TCE) and perchloroethylene (PCE), the water will be pumped from the tower to a small reservoir about half a mile south. Like all the ground water drawn by DWP from San Fernando Valley wells, it will actually be served to customers in East and West Los Angeles and central city areas after blending with aqueduct water from Owens Valley.

A broad area of the Valley and Verdugo Mountains has been designated for cleanup under the Superfund program due to contamination of ground-water supplies tapped by the cities of Los Angeles, Burbank and Glendale, and the Crescenta Valley County Water District.

First Measure

But after several years of studies, the aeration tower, to be operated by DWP, represents the first actual cleanup measure.

Wells in North Hollywood and near Griffith Park supply about 15% of Los Angeles’ water and even more in times of drought. But water from more than half of the 90 city wells exceeds health standards for TCE or PCE or both. The contamination exists in low concentrations of parts per billion, but experts think that there is a small added risk of cancer for those drinking such water over many years. Thirty-one of the 90 DWP wells are not in use because contamination is too high to meet health standards by blending with aqueduct water.

Although the aeration tower will treat only about 3% of the ground water that the city pumps each year, it will clean up some of the most contaminated wells and slow the spread of contaminants through the ground.

TCE and PCE--once widely used for dry cleaning and metal degreasing--were discovered in wells of DWP and neighboring utilities in about 1980. No one knows for certain what levels of the chemicals were present in the water being served before then.

Wells Shut Down

Utilities have controlled the problem since by blending to achieve health standards or shutting down wells. Apart from health concerns, however, the situation threatens to diminish water supplies in an arid and booming region.

Calling ground water “a resource of extraordinary value� in Southern California, John Wise, deputy regional administrator of the U.S. Environmental Protection Agency, said the North Hollywood project is part of a wider effort to “restore the integrity of our precious underground drinking water supplies.�

The EPA and state Department of Health Services are picking up the full $2-million construction cost under the Superfund toxic waste cleanup program. The EPA will also pay for 90% of the estimated $300,000 in yearly operation costs, with DWP paying the remaining costs of running the project for the next 20 years.

This is inexpensive compared to the much larger aeration system to be built in Burbank under the Superfund program. Burbank’s ground water contains higher TCE and PCE levels, and a series of aeration towers is likely to be built there at a cost of about $70 million.

Scheduled for start-up a year ago, the North Hollywood project was delayed by design changes and welding problems, but this did not increase the cost, DWP officials said.

Vanowen Street Site

In 1985, when the project was first proposed, officials sought to build on DWP property on Vanowen Street, a site ringed by homes and apartments. Residents were angered by DWP’s failure to propose air filters to catch the solvent vapors removed from the water.

Although DWP agreed to install filters, neighborhood opposition still rousted the project, which was shifted to the Vose Street site in an industrial neighborhood.

Several officials joked Thursday that the colorful aeration tower, fairly attractive for a pile of steel, had improved a neighborhood that contains rusting factory buildings. Duane Georgeson, chief of the water system for DWP, recalled his desire to find a place for the tower that no one would mind. Said Georgeson: “When the staff told me this was our new site, I thought, ‘Our prayers are answered.’ �

TCE and PCE readily evaporate, and an aeration tower takes advantage of that. Water is pumped to the top and cascades downward, while powerful blowers hit the water with a stream of air. The chemicals are driven out of the water as vapors that are captured in charcoal filters.

In recent trial runs, the tower successfully treated water containing 100-400 p.p.b. of TCE, according to Walter Hoye, DWP engineer of design. He said TCE levels were cut by 98% to 99% to well below the health standard of 5 p.p.b. PCE concentrations, which are at lower levels in the North Hollywood ground water, were reduced to non-detectable amounts, Hoye said.