Calif. storm pipes melted by wildfires prompt sinkhole warnings

By Dianne de Guzman 
San Francisco Chronicle

SANTA ROSA, Calif. — Santa Rosa residents were warned of the potential for sinkholes Sunday, as officials said plastic storm drain pipes that melted in the North Bay fires resulted in cavities beneath roadways.

City staff identified eight sites where pipes are missing -- along with 20 other "suspect" areas -- that could become problematic with forecasts of rain in the upcoming week, they said in a press conference.

"We identified in some of the areas specifically where we have plastic pipes made of high-density polyethylene storm drain pipes, the pipes caught fire and in some cases were destroyed for significant lengths, up to a few hundred feet," said Ben Horenstein, director of Santa Rosa Water.

"This resulted in underground voids or cavities where the pipe had been and creates a potential for sinkholes and resultant landslides and flooding concerns."

One sinkhole, measuring four feet in diameter and about seven feet deep, was discovered in the Fountaingrove area and was in the process of being filled Sunday afternoon, according to officials. About 250-300 feet of pipe was destroyed in the area, resulting in the sinkhole.

The majority of the sinkhole sites identified were located in the Fountaingrove neighborhood, and residents were told to "be vigilant" and report any sinkholes and landslides.

"I went to emphasize this is a fluid situation, we know the rain is coming, we want residents to be prepared," said Santa Rosa Deputy Fire Chief Bill Shubin.

"We ask our residents to, especially in the Fountaingrove area, to be extra vigilant and to have a plan to leave in the event that it is necessary," Shubin continued. "If you see evidence of flooding, mud or debris flows, buckling roads and sinkholes in the area, call 911 and avoid that area."

Horenstein said crews will be out in the field monitoring the situation during this week's rain, and said they will continue to do so for all upcoming storms until the sinkhole situation is stabilized.

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