The Hollister City Council unanimously approved a new contract April 6 with company profiling levels of chromium-6 in local groundwater in an effort to determine amounts of the heavy metal and ensure compliance with state law in effect since July 2014.
The agreement for the study secures a fee of about $24,000 with BESST Inc., of San Rafael, according to City Manager Bill Avera, a drop of $6,000 compared to a previous quote. Avera told council members that the city received a signed amendment Monday for a slight "change of scope" of the planned assessments of sections of well no. 4, a public source of water off South Street in Hollister.
"They immediately will begin doing work," Avera told the council.
The study, according to Avera, will log the level of chromium-6 in the groundwater well, one of several operated by the city, to see whether any of its sections has a higher level of the naturally-occuring metal than the other sectional amounts.
The California Department of Public Health proposed a standard for drinking water in 2013 that set a maximum level of Chromium-6 at 10 milligrams per liter (mg/L). That rule took effect July 1, 2014, when the California State Water Resources Control Board took over administration of such regulation.
Local water expert Harry Blohm previously told the council that Hollister wells typically have a range of 14-16 mg/l of Chromium-6. "We're hopeful we can find an alternative solution that doesn't involve well head treatment" of water, he said at the time, noting that wells must be tested four times per year and that if levels of Chromium-6 exceed the state limits, "you have to seek action."
Chromium-6, according to the state's water board, can cause cancer as a result of inhalation. Blohm said it is a naturally-occuring mineral in local wells and "common throughout the county. It's in the groundwater as a result of our geology."
"Much of the low-level hexavalent chromium found in drinking water is naturally occurring, reflecting its presence in geological formations throughout the state," says the water board in a recent brochure. "However, there are areas of contamination in California from historic industrial use such as the manufacturing of textile dyes, wood preservation, leather tanning, and anti-corrosion coatings, where hexavalent chromium contaminated waste has migrated into the underlying groundwater."
Hexavalent refers to a valence of six — components of the power of an element.
Blohm said San Benito County is "not the only county in the state to have a very similar problem."
The city's agreement with BESST Inc. specifies that "the constituent of concern for the well is hexavalent chromium, chloride; and the purpose and need for the study are to quantify the source on a zone by zone basis within the well."