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The Wrong Way to Remove Toxics in Our Tap Water

April 06, 1986|MICHAEL S. BALTER | Michael Balter, a Los Angeles journalist and former science editor at UCLA's Center for the Health Sciences, writes on environmental issues.

The Los Angeles Board of Water and Power Commissioners, which oversees the Department of Water and Power, has given preliminary approval to a $2.5-million pilot project to begin cleaning up our city's contaminated underground water supplies.

Large amounts of this water--pumped from wells in the San Fernando Valley--are delivered to DWP customers in eastern, central and southern areas of Los Angeles during the hot summer months when supplies from Northern California dwindle.

For several years these wells have shown increasing levels of chemicals considered by the U.S. Environmental Protection Agency to be known or suspected human carcinogens. The predominant contaminants are trichloroethylene (TCE) and perchloroethylene (PCE), industrial solvents used extensively for decades by hundreds of industries located mainly in the North Hollywood area. Health officials believe that these chemicals seeped into groundwater from leaking underground storage tanks, landfills or the illegal dumping of toxic wastes.

While it is gratifying that the board has finally realized that something must be done about Los Angeles' deteriorating water quality, its current plans are shortsighted and wrongheaded. They will do little to protect public health, and may end up costing the city's taxpayers more money in the long run.

The proposal, developed by the DWP's staff, calls for the digging of eight shallow "collection wells" in an area of North Hollywood where the groundwater is highly contaminated. Water from these wells would then be pumped to the top of a 48-foot high "aeration tower," and TCE, PCE and other chemicals would be evaporated into the air. This technique, known as "air stripping," is a proven method of removing pollutants from water. However, there are at least two serious problems with the DWP's plans:

First, air stripping takes toxic chemicals out of the ground and puts them into the atmosphere. As might be imagined, several local environmental groups and numerous residents of the North Hollywood area have taken great exception to this idea. DWP officials have argued that the amounts released into the air would be negligible; nevertheless, the South Coast Air Quality Management District has agreed to hold hearings on the issue.

Second, even if the project is approved, the DWP currently plans to build only one aeration tower. According to Larry McReynolds, DWP assistant chief engineer, the department is hoping to "avoid putting treatment on all the production wells." Because there are about 75 wells in the valley, to treat them all would obviously be more costly. Yet DWP officials have admitted that they do not know how effective the pilot program will actually be in reducing the levels of toxic chemicals showing up in our drinking water. As things stand now, the levels of TCE often exceed the California advisory guideline of five parts per billion.

The EPA currently recognizes two water-treatment techniques as "best-available technologies," meaning that they are proven effective and feasible. Air stripping is one; the other is the use of granulated activated carbon filtration. The latter process is used by many bottled-water companies and a number of smaller utilities around the country.

So far, however, DWP officials have vehemently opposed the use of carbon filtration, basically on two grounds: that the health risks from the TCE and other chemicals in the water are too low to cause a "significant health risk," and that granulated activated carbon filtration is three times as expensive as air stripping.

The department has gone so far as to lobby in Washington to loosen water-quality standards, but its position on health risks is at odds with current thinking at the EPA. Last November the agency recommended that utilities strive to reach a zero level for TCE.

As far as cost goes, here the DWP has simply forgotten that it is a public agency, beholden to the citizens of Los Angeles, and not a private corporation. The department has allowed toxic levels to climb higher each year while maintaining a low-key approach to the entire problem for fear of a "panic." The DWP has estimated that putting granulated activated carbon treatment on all production wells would cost $7.5 million per year, or about $1 per month per customer. While some may balk at any increase in utility rates, the carbon technique is capable of removing up to 99% of the contaminants in the water. It may be that most Los Angeles residents--given the choice--would find this a bargain if they could get cleaner, safer water in their taps. The recent well-publicized explosion in bottled-water sales should give DWP officials a clue that this might be the case.

If the DWP goes ahead with its current pilot program, at best the agency will only be able to keep our water just this side of violating federal law. If the program fails, the DWP will then have to go ahead and spend the money for more effective treatment anyway. Common sense and good public policy dictate that our public officials, within the limits of existing technology, strive to deliver the purest water possible.

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