Water contamination clearing up in Santa Rosa’s Fountaingrove neighborhood
Santa Rosa officials are increasingly hopeful that the full replacement of a portion of the water system in Fountaingrove contaminated after October’s wildfires may not be necessary, citing steady improvement in the water quality in parts of the system.
Instead of barreling ahead with replacing the entire system at a cost of up to $43 million, the city now is opting to replace the most contaminated parts and see if that helps resolve the contamination problem.
“The data suggests it may be premature to rush into full replacement,” said Ben Horenstein, director of Santa Rosa Water.
Tests in various parts of the 184-acre area are showing dramatically different levels of contamination based on where the samples are taken, officials said.
Results from water service lines — which run from the water mains to the water meters at the curb and have been isolated — are showing the highest levels of contamination, in some cases hundreds of times the allowable levels.
Unlike the service lines, water in the mains have been regularly flushed over the past several months and are showing steady declines in the levels of benzene and other volatile hydrocarbons.
Officials believe plastic pipes and system components that melted during the wildfires released the chemicals. Because of low water pressure in the area during the fires, the chemicals were sucked back into the service lines and mains. There, they adhered to or were absorbed into the pipes and other system components, such as rubber gaskets. The contaminants were then leached back into the water, officials believe.
After an initial period of fluctuation, benzene levels have steadily been decreasing in water sampled from fire hydrants, which draw directly from the mains, said Jennifer Burke, the city’s deputy director of water and engineering resources.
Benzene levels in the advisory area — which once encompassed 350 homes, all but 13 of which burned in the Tubbs fire — have been falling since January, she said. Tests show they have dropped below levels that require the city to report data, and in many cases are no longer detectable.
The water in the mains is flushed regularly, in part to ensure it doesn’t sit too long in any one area of pipe. The practice also ensures that chlorine levels are maintained to keep the water clean and free of organic contaminants such as bacteria.
That strongly suggests that flushing action, despite early evidence to the contrary, is helping resolve the contamination problem, Burke said.
To date, the city has flushed 220,000 gallons of water through parts of the system in the area. Flushing initially reduced contamination levels but didn’t eliminate them. In fact, in some cases the presence of benzene stubbornly bounced back, confounding water officials.
But over time, contamination levels in the water mains have dropped as the city has isolated the mains from the contaminated service lines, replaced many service lines and continued the flushing efforts.
The trend has prompted the city to reconsider the need to replace the entire water system in the advisory area. Instead, it is offering to install water filters for anyone seeking to rebuild in the area while it determines whether the entire system needs to be replaced.