DWP Accepts Higher Goal for New Water Purifier Tower

The Department of Water and Power, in a concession aimed at securing more than $2 million in federal funds for the cleanup of San Fernando Valley water wells, has agreed to meet a higher water treatment standard than it previously had promised.

In a lengthy report to the U.S. Environmental Protection Agency, DWP pledged that a North Hollywood aeration tower for which it is seeking funds will be designed and run to treat water to meet health guidelines without blending the water with clean supplies. Department officials previously had planned to rely partly on blending of the treated water to bring chemical pollution to acceptable levels.

“We clearly have to sing a different tune when we’re asking for federal funds,” said Henry Venegas, manager of the aeration project for DWP.

The agreement, reached after months of discussions between the two agencies, removes a key obstacle to financing the project under the federal Superfund toxic cleanup program, officials with both agencies said last week. They said construction funds could be provided as early as March.

EPA and DWP officials will discuss the project and take public comments at a meeting at 7:30 p.m. Tuesday at Fair Avenue School, 6501 Fair Ave., North Hollywood.

DWP Could Receive 90% of Cost

Under the Superfund program, DWP could receive 90% of the estimated construction cost of $2.2 million--down from a previous cost estimate of $2.8 million for the tower, piping and pumps. DWP officials said they also will ask that the yearly operating costs of about $258,000 be paid by Superfund for 10 years.

With or without federal help, DWP officials said they hope to start building the aeration tower next year in an effort to slow the spread of polluted water through city well fields that stretch southeast from North Hollywood past Griffith Park.

The wells, which produce about 15% of the city’s water for customers south of the Santa Monica Mountains, are contaminated with traces of trichloroethylene, or TCE, and perchloroethylene, or PCE--dry-cleaning and metal-degreasing compounds that the EPA has classified as probable human carcinogens.

An aeration tower removes volatile chemicals from water by evaporation. Water pumped to the top of the tower is allowed to cascade downward, and is blasted by a stream of air from a blower at the base. The air drives the chemicals off in vapor form through the top of the tower.

The tower will treat about 2,000 gallons of water a minute from a series of shallow wells to be sunk along a power line near Vanowen Street and Lankershim Boulevard. That area of North Hollywood, which has some of the worst ground-water pollution, also has a cluster of wells that furnish one-tenth of the city’s water.

Since 1980, traces of solvent pollution have been found in a wide area of the San Fernando Valley Ground Water Basin--a huge natural underground storage reservoir from which several communities draw part of their water. Four separate clusters of wells--operated by the cities of Burbank and Glendale and the Crescenta Valley County Water District as well as by Los Angeles--have been named by the EPA to the Superfund list of priority toxic sites.

The most polluted wells have been shut down, and water from moderately tainted wells is being blended with clean supplies to meet health standards.

The aeration proposal is separate from an EPA-DWP agreement under which the utility will oversee a $4-million study of long-term cleanup options at all four Superfund sites.

The aeration project, instead, is aimed merely at keeping more wells from being knocked out of service in the city’s most productive cluster of wells.

According to DWP figures, in 1980 water from 11 of 37 North Hollywood wells showed TCE concentrations in excess of the health guideline of 5 parts per billion.

According to some risk estimates, a person drinking water over many years containing TCE concentrations of 5 ppb could raise his risk of getting cancer by one chance in 1 million. Said another way, for every 1 million people drinking this water over long periods, one extra case of cancer would occur.

By 1983, according to DWP, 22 of the 37 North Hollywood wells exceeded the TCE limit.

Measurements last year showed that unacceptable amounts of TCE had invaded five more wells, bringing the total to 27.

“At this rate of migration, contamination could potentially spread to another five to 10 wells within the next two years,” the DWP report warned.

By intercepting plumes of tainted ground water, the tower could help protect clean wells that are immediately downhill from the heavily contaminated wells.

By blending surface water from the Owens Valley with ground water from the Valley wells, DWP has managed to keep average solvent levels within the 5 ppb guideline, although this amount has been exceeded occasionally during dry weather or aqueduct repairs.

Use of Blending a Fallback Effort

The aeration project also was to use blending as a fallback to assure the 5 ppb guideline would be met.

But EPA officials and some environmentalists argued that the strategy was too limited.

Michael Kent, a research associate with Citizens for a Better Environment, which criticized the original plan, said the stricter treatment requirement will leave the water system better prepared for drought conditions, when there might not be enough surface water for blending to meet health standards.

Kent contended that it is also worthwhile to cut solvent concentrations to as near zero as possible, since “any . . . amount of that chemical has a . . . health risk.”

Venegas said DWP will use design and operating improvements to assure that the aerated water meets the 5 ppb goal. He said DWP had been conservative in estimating that solvent levels in water would be cut by 95%. According to Venegas, DWP’s consultants believe that a removal efficiency closer to 99% can be achieved.

If necessary, Venegas said, tower operations will be altered, such as by reducing the volume of water coming in and increasing the air stream driving off the pollutants.

In addition to the change in the treatment goal, the report reflects other changes from earlier drafts--such as attitudes about the risks of TCE and PCE that are closer to the views of EPA than to those previously expressed by DWP.

One Change Disavowed

DWP officials, however, disavowed one such change and said they were at a loss to explain how it got into the report.

This concerned DWP’s decision last spring to control solvent vapors by putting carbon filters on the tower. The utility originally resisted this idea on grounds that the vapor posed no significant health risk and the filters would be costly.

Even after bowing to public pressure, DWP officials said they would install filters to allay public concern and not because they believed the protection was needed.

The new report said, however, that vapors from an aeration tower could “pose serious problems with regard to community public health.”

Asked about this statement, DWP officials last week called it an “unfortunate choice of words” that does not reflect their view.

Marjorie Shovlin, a senior microbiologist with DWP, said the report should have said “there was a perception” that the vapors were a threat to public health.

She said utility officials “still strongly feel” the tower was safe without the filters.