A
‘plume’ of the chemical potassium perchlorate from a now closed
industrial site has traveled much farther through the underground
aquifer than originally thought and might cause heath problems for
residents who rely on some of the hundreds of private wells in its
path.
A ‘plume’ of the chemical potassium perchlorate from a now closed industrial site has traveled much farther through the underground aquifer than originally thought and might cause heath problems for residents who rely on some of the hundreds of private wells in its path.
Residents who get their water from the city are in no danger. Gilroy and San Martin wells are also uncontaminated. Potassium perchlorate is a by-product of fusee production and is used, not only in flares and matches, but in solid rocket propellants and fireworks. It is a naturally occurring salt.
The chemical is known to cause tumors and thyroid problems but, so far, the amounts found in local wells are far below the danger levels, according to Santa Clara Valley Water District spokesman Mike DiMarco.
“At this point it’s not a huge public health threat,” he said Thursday.
On Wednesday the SCCWD announced that a state investigation had found that hundreds of private wells southeast of the site from Monterey Road to Foothill Avenue were in danger of being contaminated and would be tested. According to DiMarco, up to 450 wells are under scrutiny.
“It’s hard to test 400 to 500 wells,” DiMarco said. “You can test a well one day and get one reading, and test it a week later and get a different reading.”
The area of possible contamination stretches from Tennant Avenue on the north, south to Masten Avenue in San Martin, on the east to Center Avenue and west to Monterey Road.
City Manager Ed Tewes, who spoke at a press conference at water district headquarters in San Jose on Thursday, stressed that there is no need to panic because, so far, all the tested wells are either negative or show very low levels of contamination.
The water district report states that adverse health effects are not anticipated from levels between 4 and 18 parts per billion (ppb).
Of the wells tested in the area, one showed a level of 98 ppb, two showed levels of 32 ppb and all others were at 4-10 ppb or lower.
Thyroid problems
Dr. Martin Fenstersheib, the county health officer, said exposure to perchlorate can cause thyroid problems and is especially risky to pregnant women and fetuses. The signs of a perchlorate effect, he said, can be hypo-thyroidism, an increased chance of tumors, low birthweight in infants and preclampsia in pregnant women. In older children it may show up as a change in behavior and developmental issues. Fenstersheib said these effects result from high levels of exposure.
Fenstersheib said the county has not seen a cluster of thyroid problems because they are not a reportable illness.
“We haven’t gone out to look for it – yet,” he said.
Fenstersheib encouraged families living in the affected area who get their water from private wells to find alternative sources of water – such as bottled water – and to contact the water district for a free well test.
Walt Wadlow, chief operating officer for the water district, said little was known how perchlorate contamination might affect plants or animals that were exposed to the water. Lettuce, he said, is thought to have some potential to absorb the chemical but he was reluctant to encourage people to avoid crops grown in the area because there is so little research.
As reported in The Times on May 24, 2002, the Olin Corp. owns the property on Tennant Avenue near Railroad Avenue. Fusees, or highway safety flares, were manufactured on the site from 1955-96, first by the Standard Fusee Co. and then by Olin.
Olin notified the state Office of Emergency Services and county Health Department on Aug. 29, 2000, after the perchlorate was detected.
Olin had been cleaning up the land – the buildings had been razed – when it found that the perchlorate had percolated down through the soil and into the underground water table. The contaminated plume was found to have traveled south, off the industrial site, and Olin notified the city on April 15, 2002.
No perchlorate was found in the city well in during regular testing in December 2001 but, in two tests in April 2002, levels of 7 ppb and 4 ppb were found. The city immediately shut down the wells. Subsequent tests showed no contamination at all, Tewes said.
The California Department of Health Services regards as unsafe any count above four parts per billion of perchlorate. The Tennant well later averaged during testing 15 ppb at depths of 190 – 412 feet. Levels has been as high as 18 ppb at a depth of 200 feet, DiMarco said in May.
A new well was drilled out of reach of the chemical plume on Condit Road and San Pedro Avenues and a bill for $750,000 sent to the Tennessee-based Olin. California state law says the responsibility of cleaning up contaminated property rests with the property owner, not the affected city.
In January 2002 the state agency reduced its action level from 18 ppb to 4 ppb to provide a wider protective buffer for the public. Ashcraft said the state only began to require statewide testing for the chemical last year.
The city told owners of nearby wells in April 2002 to have their wells tested if the water was used for drinking.
The options for treating water contaminated by perchlorate are limited. Home water treatment systems may not be effective, according to the Water District.
Boiling water will not remove perchlorate and, in fact, may concentrate it further. Research is under way to find practical and cost-effective methods of removing low levels of perchlorate from drinking water.
Standard Fusee and Olin Corp. also produced skeet and clay pigeons coated with lead chromate from 1965-81 at the Tennant Avenue facility. Olin had begun testing the property in 2000 to prepare for a possible sale. Three monitoring wells were installed on the property in August 2000 to do environmental sampling.
There were indications then, DiMarco said, of problems.
The Central Coast Regional Water Quality Control Board based in San Luis Obispo became involved when the plume was discovered last spring. The board investigated how large the plume was, in what direction it was moving and which public and private wells might be in danger.
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Residents who live in the affected area and get their water from private wells should call the water district’s perchlorate hotline at 265-2607, ext. 2649 to arrange for a free test of the well. More information can be found at www.valleywater.org
