Eshoo made the inquiry after a report by the nonprofit Center for Investigative Reporting and The Guardian exposed details of associated pollution that is created by treatment and transportation of toxic pollutants from Superfund sites. The report followed a toxic trail from a site in Mountain View across the country and back to Silicon Valley.
The Voice also published a series of stories on the issue in 2003, when community members first began to discuss the environmental consequences for an Indian reservation in Arizona. That was where carbon filters used to clean contaminated groundwater at Mountain View Superfund sites were being burned, emitting dioxin into the air, affecting Native American residents there.
According to the Environmental Protection Agency (EPA), there are 21 Superfund sites located in Silicon Valley, with 11 in Eshoo's 18th Congressional District, including eight in Mountain View and one at the former Hewlett-Packard site at 620-640 Page Mill Road in Palo Alto.
In a March 28 letter to EPA Administrator Gina McCarthy, Eshoo asked for more information regarding the extent to which the agency monitors the interstate transport and treatment of the hazardous waste, alternative cleanup methods and if the agency has adequate regulatory authority to monitor and control toxic materials after removal from Superfund sites.
"What I'm concerned about is that the Environmental Protection Agency is failing to properly monitor and regulate the emissions associated with remediating the toxic pollutants recovered from Superfund sites," Eshoo wrote.
"Of particular concern are the emissions of dioxin, which is on the EPA's 'Dirty Dozen' list of dangerous chemicals and is a known carcinogen. The carbon emissions associated with collecting, transporting and treating hazardous waste from Superfund sites are deeply troubling. I also understand that in some cases the traditional 'pump and treat' method for decontaminating groundwater may not be as effective as alternative treatment methods," she wrote. The Hewlett-Packard site uses pump-and-treat methods.
When residents of Mountain View first discussed the issue 11 years ago they worked with the EPA to fix the problem.
"Though I was among the community members who raised the issue of carbon 'regeneration' a decade ago, I believe it's important to put it into perspective," said Lenny Siegel, director of Mountain View's Center for Public Environmental Oversight, in an email. "I believe that Superfund cleanups represent a small portion of the carbon filters thermally treated in the U.S., and carbon filter disposal represents a small portion of the waste shipped from Superfund sites."
"The transfer of waste from one medium to another is one of the reasons we have been promoting in-situ treatment at MEW and Moffett Field (Mountain View's major Superfund sites), and we believe the adoption of new remedies here may serve as a national model," Siegel said.
Alternatives to carbon filtering of contaminated groundwater include the injection of special bacteria into the water table to break down toxics.
"But it's an area where we all need to tread carefully," he said. "Federal and private responsible parties are looking for excuses to reduce cleanup activity, and no active cleanup (monitored natural attenuation) generates less waste and costs less than both conventional remedies (pump and treat) and in-situ treatment."
A map of all Silicon Valley Superfund sites can be found at epa.gov/superfund/sites.
The sites in Palo Alto and Mountain View include:
• Hewlett-Packard, Palo Alto
• Spectra-Physics, Inc., Mountain View
• Teledyne Semiconductor, Mountain View
• CTS Printex, Inc., Mountain View
• Jasco Chemical Corp., Mountain View
• Moffett Naval Air Station, Mountain View
• Fairchild Semiconductor, Mountain View
• Raytheon Corp., Mountain View
• Intel Corp., Mountain View
Voice reporter Daniel DeBolt contributed to this story.