The good news is no new groundwater contamination sites were
discovered in San Benito County last year. The bad news is it takes
years of cleanup to remove toxins from a site, which are often
discovered after the damage is done.
The good news is no new groundwater contamination sites were discovered in San Benito County last year. The bad news is it takes years of cleanup to remove toxins from a site, which are often discovered after the damage is done.That was the assessment from the recently released annual report by the county’s water district on area groundwater contamination.
However, two known sites of contamination, the John Smith Landfill and the former Whittaker Ordnance Facility – now Quantic Industries – have been undergoing years of remediation. Both facilities have been under close supervision of the state’s Regional Water Quality Control Board with proven results.
Jointly owned by the City of Hollister and San Benito County, the John Smith Landfill has been operating since 1968. At that time, waste was not classified or segregated and no precautions were taken to protect the soil or groundwater supply. Because of this, the landfill was used as a dumping ground for hazardous material.
From 1974-77 hazardous waste was confined to the northern portion of the landfill until the 8.3-acre Class I facility was constructed.The landfill consists of 65.3 acres with 29 acres designated as a Class III Landfill. The county is the lead agency for the Class III section while the city is the responsible party for the Class I site. The city operated the Class I site from 1977-83, accepting liquid hazardous waste such as motor oil and pesticides.
“Back then they didn’t use any liners,” said David Athey, water resource control engineer for the Regional Water Quality Control Board. “Government regulations now mandate the use of liners.”
The RWQCB’s latest effort is to target gasoline and other man-made compounds. MTBE is just one contaminant affecting groundwater supplies and there are several toxins being dumped at landfills every day in the form of household products.
In 1989, a plume of volatile organic compounds was found beneath the landfill. Corrective measures were taken to capture the plume and to remediate the groundwater. Two gas extraction pumping wells were constructed on-site and two wells off-site to capture the plume, which is now deemed stationary.
“There is a significant decline in volatile organic compounds at the site,” Athey said. “They continue to pump the groundwater and treat it.”
The treated water is discharged into Hollister’s municipal sewer system by a three-mile pipeline from the landfill to the city’s wastewater treatment plant.
“There is no (wastewater) discharge coming out of the landfill,” Athey said.
Old carpeting, empty food containers and household cleaning containers all contain harmful toxins and gases, with one of the most commonly known being methane gas. Gas probes are used to calculate the effectiveness of the gas extraction system and to track migrating methane gas.
