Remediation work set to begin on toxic plume in downtown Delano
Jun. 30—A $5 million soil cleanup effort about to start in Delano will vacuum toxic vapors from an underground plume of contamination left over from decades of improper disposal of a carcinogenic chemical that had been used in local dry-cleaning.
Officials with the state Department of Toxic Substances Control unveiled a system Wednesday in downtown Delano that, upon activation next week, will filter vapors brought up from variable depths using a well and a powerful blower functioning as a vacuum.
Local activists welcomed the end of construction on one of two vacuum sites expected to be operated for the next five to 10 years, until state monitoring indicates the vapors pose an acceptably low health risk.
"This is extremely exciting because we know that the contamination is pretty wide at this point," said Lupe Martinez, a member of the Delano Guardians and secretary of Residents for a Clean Delano. "It hasn't been an easy journey."
Coming after more than a decade of research and planning, the state-funded cleanup is the first phase of an effort that will eventually require removing the same carcinogenic chemical — tetrachloroethylene, or PCE — from local groundwater.
PCE has not "yet" reached Delano's municipal water supply, but it is expected to do so eventually unless something is done about it, said Ryan Mitchum, an engineering geologist in the DTSC's Clovis field office. He said groundwater monitoring continues as part of an investigation into where the plume is migrating, and "after that we'll move toward a remedy."
Long-term exposure to PCE interferes with brain and body functions. It is associated with bladder cancer, non-Hodgkin's Lymphoma and multiple myeloma.
The state allows a maximum PCE of 5 parts per billion. In Delano, it has been detected at 88 times that concentration.
A groundwater test in 2008 provided evidence of PCE in local soil. Local activists pushed for a government response and the use of taxpayer dollars to address the problem.
Local efforts were joined in 2015 by environmental justice workers at The Center on Race, Poverty & The Environment, which has worked with Delano Guardians and others to make sure the state was receiving community input.
CRPE Assistant Director Ingrid Brostrom said state efforts highlighted Wednesday are the work of years of local collaboration, and it's not close to being finished.
"We're still at the early stages of this remediation," Brostrom said, adding, "There's a lot of work" still to be done.
Mitchum at the DTSC showed reporters how the vapor remediation system works. A well capable of sucking vapors at specific depths between 10 and 90 feet is connected to a system of tubes leading to three filtration cylinders filled with charcoal.
Depending on readings from a system that reads PCE concentrations, the vacuum will pull out vapors from different depths. After the vapor flows through the three filtration cylinders, the treated air vents to the atmosphere as nitrogen and oxygen. Charcoal will be removed, properly disposed of and replaced as frequently as monitoring determines is necessary, Mitchum said.
Mitchum added that the toxin was probably released into the local sewer system by dry cleaners operating in the city between about 1940 and 1980. He noted that PCE is being phased out in California, where plumes of the chemical have been found across the Central Valley.
Local activists said they are anxious to see work done that will avoid PCE contamination of the municipal water supply, which Brostrom said would pose a disaster requiring a very expensive groundwater remediation effort.
"We do want to protect our water before it's contaminated," said Yolanda Chacon-Serna, chairwoman of Residents for a Clean Delano, and treasurer for the Delano Guardians.
Mayor Bryan Osorio was on hand Wednesday lending support to the effort, which he said he first engaged with years ago as a college student.
"Hopefully we can speed up (groundwater remediation) so we can protect our city's health," Osorio said.
