PARADISE — Water experts are still finding traces of harmful chemicals in parts of the water systems burned by the Camp Fire and in interior plumbing more than a year after the disaster, but the cases are rare.
Fears about the contamination have been a hurdle for recovery. The water utilities say they are addressing the problem through tens of thousands of tests and hundreds of repairs.
One big question remained on the minds of residents: What about their own taps? Home plumbing is not the responsibility of the utility. Many residents paid for tests out of pocket. Now, an outside team of researchers is studying the issue with a grant.
So far, the team has found only a few cases where volatile organic compounds that are harmful to human health seened into home plumbing from the water system. Most of those cases tested largely below unsafe levels.
“We were kind of looking for those worst-case scenarios,” said Gina Solomon, the researcher leading the project. “What we found was actually really encouraging.”
Solomon presented the findings to the community at a meeting at the Paradise Alliance Church on Monday evening. Her study team includes experts from the Public Health Institute, UC San Francisco, and UC Davis. They sampled 125 structures in Paradise and Magalia in October and will continue sampling later this month.
Benzene, which has been linked to cancer, was detected in only two samples: one came from an outdoor hose bib that was unused since the fire, and the other came from inside an uninhabited home. Both were below the California regulatory limit.
Scientists are not exactly sure where benzene — which was first detected in water systems after an urban wildfire in Santa Rosa — comes from and how it spreads in a water system. One prevailing theory is that the contaminant comes from burnt plastic.
The team tested for over 100 volatile organic compounds.
Methylene chloride, a known carcinogen used in some solvents like paint and varnish removers, was also detected. It showed up at a quarter of the homes tested in Paradise. A handful of homes’ plumbing showed unsafe levels of the chemical. Paradise Irrigation District has also detected the chemical in some service laterals.
It might be formed from the burning of PVC pipes, according to some research recently unearthed by PID’s engineers. It might come from a reaction with galvanized pipes, which are more common in Paradise. It might also be a laboratory contaminant, said Solomon. So the team is re-sampling those homes to learn more.
Most commonly, they found disinfection byproducts linked to chlorine in most of the homes. The chemicals — trihalomethanes — are linked to cancer but did not surpass the regulatory limit in any of the samples and are not thought to be linked to the fire. Exposure can be limited with a water filter and with precautions like avoiding long hot showers, said Solomon.
Meanwhile, Paradise Irrigation District continues to test each service lateral to standing homes and lots that want to rebuild.
“We’re still finding the 5 percent, 2 percent that do have contamination, and it’s all over town and there’s no pattern, so it’s important that we still test,” said Sami Kader with Water Works Engineers.
A water quality committee looks over each test. More than 150 miles of main lines and 735 locations have been cleared so far. The utility is replacing service laterals to burned lots and service laterals with contamination. So far it has replaced 111.
Two weeks ago, PID approved a contract with a construction company to accelerate the repairs. The utility expects 650 laterals to be replaced by spring 2020.