Polyethylene pipe is not the cause of contaminated drinking water that communities are experiencing after wildfires, according to a new report from the Plastics Pipe Institute Inc.
"There is no evidence that the heating or burning of [high density] PE or [crosslinked] PEX plastic pipe is responsible for the contamination of the water system within Paradise, Calif.," according to the report.
The Irving, Texas-based trade group investigated reports of benzene, a known carcinogen, getting into Paradise's drinking water system following the deadly Camp Fire in November 2018.
A faulty electrical transmission line sparked the blaze that burned 153,336 acres, destroyed 19,000 structures and caused at least 85 deaths.
The fire swept through the mountain town of Paradise, home to some 27,00 residents, in about an hour, reducing 18,000 of the 20,000 structures to ashes and charred rubble while somehow leaving benzene in the water distribution system.
Benzene is formed by both natural processes and human activities, such as volcanoes, forest fires and the production of plastic, synthetic fibers, rubbers, lubricants, detergents and pesticides. Levels of the chemical in the drinking water exceeded allowable state and federal levels in various locations, posing risks for anemia and leukemia.
The uncontrolled fire caused damage throughout the region. PPI points to efforts to coordinate the removal of nearly 3.7 million tons of ash, metal, concrete and contaminated soil from Butte County.
"It's a sobering number," PPI President and Executive Director David Fink said in a phone interview. "That's twice the material removed from the World Trade Center after 9/11. That puts it in perspective as to how horrific the site was following the devastation from the fire."
There were allegations that heat from the fire created a chemical reaction in the buried plastic water pipes, which generated benzene from within the pipes themselves. PPI says there's no evidence "this theoretical reaction" actually occurred and no one has identified exactly which pipe material is involved with this reaction.
"For folks to point to burning plastics as the main contributor to benzene is absolutely false, and it's irresponsible to make such claims," Fink said.
The two main sources of benzene would be trees and the combustion of wood, followed by the burning of homes, cars and other structures, Fink said.
So, how did the contaminant get into the drinking water system?
PPI says it's likely that a negative-pressure event caused by the intense use of water by firefighters occurred in the municipal water system. This resulted in empty pipes into which toxic smoke and debris was siphoned.
"As water is used for firefighting or it runs out, it creates a negative pressure that allows contaminants to be drawn back in. Backflow is the technical term, and it can occur regardless of the piping material," Fink said.
In these cases, PPI recommends the water mains be flushed until water tests confirm that contaminant levels are in conformance with all federal and state drinking water requirements.
PPI also acknowledges it is possible that some service lines adsorbed contaminants during the fire and then released them back into the water. Unlike absorption, when materials chemically combine, in adsorption one material coats the surface of another. While PVC pipe doesn't adsorb, polyethylene pipe "has slight potential to adsorb," Fink said.
PPI also says the contamination of Paradise mains and water service lines appears random with neighboring houses showing different results. The group noted the contamination did not follow any pattern of materials or type of installation. PPI's probe found:
• Benzene contamination of water mains was not material-specific, and was found in segments buried deep in the ground and not subjected to the heat of the fire.
• Benzene contamination of service water was found in both plastic and metal service laterals, such as steel and copper.
• There has been no clear correlation of cause-effect with regards to the presence of benzene contamination and the location of pipelines or the pipeline material.