Benzene contamination continues to haunt the city of Santa Rosa, California, months after deadly wildfires consumed parts of the city. And now new tests have indicated that benzene contamination may be affecting the water supply in a larger area than previously thought.
The Santa Rosa Press Democrat has been reporting on the city’s ongoing benzene problem in the Fountainhead neighborhood in the northern part of the city limits. Parts of the Fountainhead area were completely decimated by the October wildfires, especially a 184-acrea area encompassing Fountaingrove Parkway around Fir Ridge Drive. That part of the city used to be home to 350 families but now only 13 homes remain.
City officials formed an advisory zone around that area after the fires and issued a strict warning not to drink or boil the water due to benzene contamination. But a series of new tests found that seven additional locations outside the existing advisory area have benzene-contaminated water. Six of the locations had six parts per billion and one had 240 parts per billion. California’s maximum level for benzene, a human carcinogen, in drinking water is one part per billion.
The wildly varying results spread throughout the neighborhood in a patchwork fashion has made the common source of the benzene pollution difficult to find. However, researchers have found that none of the samples contain isooctane, which means that the benzene isn’t stemming from gasoline or other petroleum products, such as might be stored in a damaged underground storage tank.
Ruling out petroleum as a source has helped researchers to hone in on the plastic pipes and other infrastructure. Under high heat, pipes made from petroleum-based plastics such as polyethylene can release benzene.
City officials told the Press Democrat that the presence of vinyl chloride in some of the samples suggests that high-density polyethylene service lines or other plastic components in the water system are the likely culprit at this point, but the exact sources remain unclear.
The results, one city official told the Press Democrat, are “evidence of combustion or melting plastic of some sort.” Melted plastic components in the water delivery system, such as the laterals and other localized parts, could explain why benzene contamination varies drastically from one place to another within the same neighborhood.