NORWALK — Chemicals suspected of causing cancer may be making their way to the city's water supplies in large enough amounts to contaminate drinking water and require a cleanup of underground water supplies, a consultant has warned.
A report by Ott Engineering Inc. of Mission Viejo said polluted ground water from Santa Fe Springs and the Whittier Narrows may be spreading to Norwalk.
State and federal health officials are investigating four city sites as possible sources of contamination.
Since 1982, ground water contamination has forced the closing of three wells providing water to Norwalk. The water from two other wells is being blended with clean water to reduce contamination levels to meet state standards for drinking water, the report said.
The primary contaminants are tetrachloroethane and trichloroethane, two industrial solvents that are suspected of causing cancer.
"It appears that the city of Norwalk may expect to find increased concentrations of (the two solvents) in their well system in the future," the consultants said in the report, made public Tuesday night.
Commissioned by the city in May, the report is part of an overall study to determine whether the water system serving Norwalk is adequate. Water that meets state standards is regarded as suitable for drinking, consultants said. In addition to looking at water quality, Ott Engineering will determine whether the water system provides adequate flow for firefighting contingencies, among other things.
As a result of the report, the city has commissioned another study to determine more precisely the extent of contamination of the aquifers from which Norwalk draws ground water. That study is to be completed next month, said C. Stephen Bucknam of Ott Engineering. Norwalk contracts with Bucknam to be its city engineer.
It could cost the city up to $120,000 to study the entire water system. The study should be completed in mid-1990, Bucknam said.
Mayor Grace Napolitano said the findings of the report presented Tuesday night did not surprise city officials.
"It confirms what we were hoping wasn't true," Napolitano said. "We are very concerned. That's why we went ahead (with the study), so we know exactly where we're at."
Ott drew its conclusions from recent water sampling required by state law.
Norwalk residents and businesses receive tap water from five water companies. Some of it is pumped from the ground, and some is imported water, bought from the Metropolitan Water District.
Norwalk's municipal water system serves 3,500 customers in the northern, central and southeastern portions of the city. The Park Water Co. serves 11,900 customers in central and southern Norwalk, while the Southern California Water Co. provides water to about 9,000 customers in northern and central Norwalk.
The city's remaining 1,600 customers are served by the County Water Co. and the Santa Fe Springs municipal water system.
So far, the Southern California Water Co. has had to contend with the largest pollution problem. Two of its wells have been taken out of service recently because their water was contaminated with industrial solvents. Water from two of the company's other wells is being diluted with clean water to bring contamination levels to state standards, the report said.
One well in the Santa Fe Springs water system was taken out of service in 1982 because of contamination.
Contamination was found in water from virtually all the wells servicing Norwalk, but aside from the five wells mentioned, the levels were within state limits, the report said.
The five companies serving Norwalk draw water from depths of 236 to 1,250 feet, the report said.
The sources of contamination are not known, Bucknam said.
The state Department of Health Services and the Environmental Protection Agency are evaluating four sites in Norwalk for soil and possible water contamination, the report said. One of those sites is the Department of Defense's jet fuel tank farm on the southeast corner of Norwalk Boulevard and Excelsior Drive.
But perhaps what city officials fear most is migration of ground water contamination from the closed Neville Chemical Co. plant in Santa Fe Springs, just north of Norwalk.
Dichlorobenzene, a suspected cancer-causing agent, has been detected in the ground water beneath the plant at concentrations more than 10 times above the state limit, a state health official said. Excessive amounts of cancer-causing dioxins and furans have been found in soil but not in the ground water beneath the plant, said Richard Hume, who is overseeing a cleanup of the site for the state. The Neville Chemical Co., which closed the plant in 1987, is paying for the cleanup, Hume said.
Dichlorobenzene contamination has been detected in ground water 100 feet beneath the ground. More monitoring is taking place to find out how deep the pollution has penetrated.