Public-health officials are meeting in Tucson today after traces of a common solvent were found in three local wells this week, setting off an environmental investigation into how the pollutant got into Santa Cruz River groundwater.
The city closed an operating city well south of the airport Tuesday and informed Hughes Aircraft Co. that two of its wells were also contaminated with the industrial chemical trichloroethylene.
Officials from the city and the Arizona Bureau of Water Quality Control will meet with Hughes Aircraft representatives to "set up a monitoring program and find the source and extent of it (the contamination)," Ronald Miller, director of the state Division of Environmental Health Services, said in Phoenix yesterday.
It was the first time trichloroethylene had been found in underground water in Arizona, although it has turned up increasingly in other parts of the country, Miller said.
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Even though the harmful solvent has been diluted in a main city reservoir, it worries state officials because the city depends solely on underground sources for its water.
"Anyone who has a sole-source aquifer and dumps anything on top of it is a fool. Personally, I wouldn't like to drink it," said a federal health official who did not wish to be identified.
The solvent — used as a "degreaser" to clean machinery parts — appears on the U.S. Environmental Protection Agency's list of 52 substances determined to be carcinogenic.
It is a chlorinated hydrocarbon, long-lived like the pesticides DDT and DBCP, with the ability to remain in the environment for hundreds of years.
Gene Cronk, city water director, said trichloroethylene was found at low levels in the well. "But not knowing what a safety level is, we shut the well off," he said.
The Environmental Protection Agency took only one sample, which revealed 0.077 parts per million, in the operating city well, Cronk said.
He emphasized that the 350 gallons of water a minute pumped from that well is further diluted in the reservoir where millions of gallons from the Santa Cruz and Avra Valley basins mingle before they are pumped into homes.
No regulatory standard exists for the solvent, but the National Research Council has set a level of 15 parts per million as a "suggested no-adverse-response level" for seven days of exposure.
The city well has been operating for 15 years, but Cronk does not know when it became contaminated.
City officials are not ready to place blame for the contaminated well, he said.
"It could come from any direction. It could come from any source," Cronk said. "It could have come from a tank car leaking on a railroad spur."
Hughes Aircraft officials did not return calls to answer questions about whether the company's two wells had been used for human consumption. A security guard did call last night to refer all inquiries to the company's public-relations officer in Los Angeles, who could not be reached before today.
The EPA discovered the trichloroethylene and notified city water officials Tuesday, after it sent experts from San Francisco to test several wells south of the airport.
A yearlong study by the Arizona Department of Health Services had revealed in December 1979 that the water south of the airport had a high potential for groundwater contamination from a waste pond used by Hughes Aircraft from 1956 to 1977.
Hughes Aircraft has manufactured missiles and other aeronautics components south of the airport since 1952.
Measured on a scale, with 29 points representing the highest possible hazard to groundwater, Hughes Aircraft scored 26, according to the report. Out of 83 ponds in Arizona, the Hughes pond rated 24th from the top as the most potentially hazardous.
Until Hughes Aircraft built sealed evaporation ponds in 1977, it had disposed of liquid wastes — including chromium, cadmium, silver, lead, copper and perhaps arsenic — on its property near a tributary of the Santa Cruz, according to the health department's survey.
Several months ago, Hughes Aircraft officials told The Arizona Daily Star that no hazardous materials had gone into the ponds.
Ed Spaulding, an official in the company's environmental department, stressed that the company had not been violating any laws by its disposal methods.
Since the early 1950s, "we have always been in touch with the state department of health. We've always been in compliance," he said.
Before recent hazardous-waste laws were passed, a company did not have to report liquid wastes as long as they were not discharged beyond property lines, a state official said.
According to the state report, three other aircraft manufacturing and retrofitting operations — Douglas Aircraft Co., Consolidated Aircraft Co. and Grand Central Aircraft Co. — operated north of Hughes from the late 1940s through the 1960s. The other aircraft companies did not use disposal ponds, the report said.
Blaming the contamination of several wells on past disposal activities of Hughes Aircraft, the report concluded that "the depth to the groundwater table during that time was 85 to 125 feet, with the . . . zone comprised of a material that would permit the percolation of liquid wastes."
It goes on to say that the use of disposal pond liners did not begin until 1976, "showing positive results in the reduced contaminates. . . ."
Since the report was published, no monitoring has been conducted at the vulnerable wells north and west of the ponds used by Hughes Aircraft for more than 20 years.
The state had warned, "The total dependency on groundwater in the Upper Santa Cruz Basin for domestic supplies makes even the smallest amount of contamination in that aquifer a matter of grave concern.
A recently released report by the Council on Environmental Quality warned that toxic chemicals, specifically the chemical trichloroethylene, can contaminate groundwater for "hundreds of years, if not longer, because dilution and natural cleansing are insufficient."
It says that many chemicals once thought safe can have serious and substantial health risks even at concentrations in the low parts per billion or parts per trillion.