PPI: Pipe not to blame for benzene contamination during wildfires

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.

As wildfires continue to ravage California and North America as a whole, PPI says accurate data is critical when working toward solutions and its members have been following the situation carefully and collecting evidence and data to share with interested parties.

PPI follows water quality investigations, monitors published reports and tracks media publications. Trade group staff members also have visited and been in direct contact with Paradise Irrigation District officials and researchers in California who are employed by PID or the state to help investigate the source of benzene and other chemicals persistent in the drinking water.

"It's a situation where unfortunately more fires will likely occur and competing interests seem to have an appetite to come after plastics when they do. They're spreading a lot of false information," Fink said.

Plastic pipe sales are outpacing metal pipes sales because they cost less, last longer, don't corrode and can withstand earthquakes.

"Competing materials are losing. Plastics are growing faster, and polyethylene is the fastest-growing material for piping," Fink said. "As you take [market] share away, things get interesting."

Plastic pipes will be part of Paradise's infrastructure solution going forward.

As the town rebuilds and residents return, PID is replacing all water service lines using high density polyethylene PE4710 water service pipe. The pipe meets industry standards, and the water utility has previous experience with HDPE pipe and a comfort level with installation practices.

From one of the lessons learned in 2018, the PID says residential connections are being installed with backflow prevention devices to protect service lines and water mains against contamination should a negative-pressure event occur in the future.

As a service to the industry, PPI said it prepared a technical report based on its investigation. The information in the report is offered in good faith and believed to be accurate at the time of its preparation, but is offered "as is," the group adds.

Fink said PPI intends to revise this technical report within five years, or sooner, in response to comments and suggestions from users of the document.

The tainted pipes in Paradise marked the second incident of what has been called wildfire-caused contamination of the drinking water system in the state. The other case happened 100 miles away in Santa Rosa, Calif., where the October 2017 Tubbs Fire burned 3,100 homes in a matter of hours.

Research published in July 2020 by the American Water Works Association following a study funded by PID and Purdue University says infrastructure may have become a secondary source of contamination.

Field data from Santa Rosa did not indicate a strong relationship between contamination and pipe material, AWWA research says. Samples from metal service lines, such as ductile iron, steel and copper, were somewhat less likely to demonstrate contamination than plastic pipes. However, the two locations with the highest measured benzene concentrations had copper service lines.

"It is also possible that destroyed structures are the primary source of contamination. Still, service lines for standing homes were contaminated, so damage alone does not account for contamination," AWWA research says.