Residents Ask For Wells Water Tests
Perchlorate Contamination SuspectedJan 20, 2003 | Knight Ridder Newspapers
More than 1,200 South County residents, worried that a chemical used in rocket fuel and highway flares has contaminated their drinking water, have contacted the Santa Clara Valley Water District to arrange for free tests of their wells.
By Monday evening, four days after officials disclosed that the chemical perchlorate has spread in an underground plume four miles south from Morgan Hill through San Martin, appointments had been made to test more than 450 private wells beginning Wednesday, water district officials said. Most of the wells serve more than one house.
The district also has launched a program to provide everyone potentially affected by the contamination with free bottled water for drinking and cooking.
District officials have gotten initial requests for more than 4,000 bottles of water. About 200 homes were getting the free water from Crystal Springs on Monday, with an additional 200 scheduled to receive bottled water Wednesday. The sudden demand resulted in the water company temporarily running out of bottles, said water district spokesman Mike Di Marco.
Meanwhile, officials continued to investigate how far the perchlorate has spread into the underground water aquifers. If past groundwater pollution incidents are any guide, the cleanup will take years and could cost millions of dollars.
Perchlorate is a salt that disrupts iodine intake in the thyroid gland, which regulates hormone functions. It is especially harmful to pregnant women and infants and can interfere with neurological development in fetuses. Some studies suggest it can cause thyroid cancer.
Water district officials estimate as many as 450 wells could be contaminated by perchlorate that has leached from a 13-acre site at Tennant and Railroad avenues in Morgan Hill where the Olin Corp. manufactured highway safety flares from 1955 to 1996.
Last March, perchlorate was detected at a Morgan Hill municipal well 250 feet from the Olin site. City officials shut down the well immediately. That event caused the water district and the Central Coast Regional Water Quality Control Board, a state agency, to test water in some wells off the Olin site.
"When the contamination hit the city well, there was no indication that the plume extended beyond there,' Di Marco said. "It was reasonable to think that the concentrations were accumulating at the site because of the power of the well to move water toward it.'
Further well tests in concentric circles around the site indicated the plume moved south. Perchlorate has turned up four miles away in a well near Masten Avenue in Gilroy.
"When the test results came in last week, they indicated a larger problem than we anticipated,' Di Marco said.
The highest concentrations were found in a well at the U- Save Rockery near the Olin site. Lesser amounts were found farther away.
Once the extent of the contamination has been determined, the cleanup will be a long, difficult process, officials said.
Olin has been ordered by the Regional Water Quality Control Board to clean up the contamination and pay all costs. Olin first will clean up the soil at the Morgan Hill site to prevent more perchlorate from moving into the underground aquifers, said Jim Crowley, who heads the district's underground cleanup programs.
The next step would be to clean the groundwater in the immediate area. The water would be pumped out, treated with ultraviolet light and peroxide, or ozone, or with biological systems to remove the chemical.
However, these treatments are expensive and not available to individual well owners.
Treated water could be used for agricultural irrigation or, if it meets higher standards, could be recharged back into the ground, Crowley explained.