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UCLA to Seek Ways to Purify Water in Tainted DWP Wells

November 21, 1986|MYRON LEVIN | Times Staff Writer

The Los Angeles Board of Water and Power Commissioners Thursday approved a $263,350 contract with UCLA to investigate alternative methods for cleaning up chemically tainted city water wells in the San Fernando Valley.

The two-year study--to be financed mainly with a grant from the federal Environmental Protection Agency--will test four experimental processes that are designed to break down chemical solvents into innocuous by-products. Methods currently in use for treating solvent-tainted water either put the chemicals into the air in vapor form, or trap them in filters that must be treated or disposed of as hazardous waste.

Dr. William H. Glaze, a professor at the UCLA school of public health who will supervise the research, said it will investigate processes that "in principle, at least, will destroy organic contaminants in water rather than just transfer them to another phase."

As part of the study, Glaze said, batches of tainted water will be treated with ozone; with a combination of ozone and ultraviolet light; with ozone and hydrogen peroxide, and with hydrogen peroxide and ultraviolet light. The ozone, which Glaze said will be confined, is a concentrated form of the gas that is the key component of Los Angeles' smog.

Glaze said all four treatment methods will be studied initially and the most promising one may then be incorporated into a pilot treatment plant to be built in the San Fernando Valley.

In a prepared statement, Rick J. Caruso, president of the water and power board, said that if the study verifies "the feasibility of these processes . . . it would be very beneficial to the DWP and many other communities throughout the country having contaminated ground water supplies."

The city draws about 15% of its water supply from Valley wells that have been contaminated by trace amounts of industrial solvents--mainly trichloroethylene (TCE) and perchloroethylene (PCE), both suspected cancer-causing chemicals. Water from the Valley wells--mainly in North Hollywood and near Griffith Park--goes to city residents on the southern side of the Santa Monica Mountains.

Wells operated by the cities of Burbank and Glendale and the Crescenta Valley County Water District have also been affected, prompting federal officials to add the entire ground water basin to the Superfund list of priority toxic sites.

Water officials have shut down the most polluted wells and have blended water from others with clean supplies to keep contamination within health guidelines.

However, the pollution is spreading to more wells. In 1981, for example, water from 24 of 110 wells in the area contained TCE levels above the health guideline of 5 parts per billion. Recent testing has shown that 48 of the 110 wells exceed this level, according to DWP statistics.

The DWP is preparing to build a $2.8-million aeration, or air stripping, tower in North Hollywood next year in a pilot program to treat ground water by causing solvents to evaporate. Bowing to public concerns, the utility agreed to install filters on the tower to keep solvent vapors from getting into the air.

Aeration and direct carbon filtering of water are the proven techniques for removing solvents from water. But the filters must be treated or disposed of as hazardous waste, making these methods less than ideal.

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